HK40112902A - Laser-induced carbon nanostructures - Google Patents
Laser-induced carbon nanostructures Download PDFInfo
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- HK40112902A HK40112902A HK62024100853.6A HK62024100853A HK40112902A HK 40112902 A HK40112902 A HK 40112902A HK 62024100853 A HK62024100853 A HK 62024100853A HK 40112902 A HK40112902 A HK 40112902A
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Abstract
A method of manufacturing a carbon nanostructure, such as a carbon foam material, is disclosed. The method comprises the steps of: (a) using a first laser beam to irradiate an encapsulated or sub-surface region of a carbon pre-cursor material below a surface of the material, to create carbon foam in that sub-surface region, and a disorganised, amorphous non-graphene material above the carbon foam, and then (b) using a second laser beam to remove or ablate the disorganised, amorphous non-graphene material sitting above the carbon foam, to expose at least some of the carbon foam. The resultant carbon foam material shows a significant D peak; the 2D peak is significantly less than the G peak; and the peak D: peak G ratio is significantly above zero. In appearance and Raman signature, it appears similar to a carbon nano-onion material. It can be used in biosensors, supercapacitors and pseudo-capacitors.
Description
Technical Field
This invention relates to laser-induced production of carbon nanostructures, including multilayer carbon foams with disordered layer twisting.
Background Technology
Carbon nanostructures are both highly attractive and a hot research topic. Carbon nano-onions (also known as multilayer fullerenes) exemplify this. See “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9 and “Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications”, DOI:10.1016/j.ica.2017.07.021, the contents of which are incorporated herein by reference.
As another carbon nanostructure, graphene has attracted widespread attention for many years due to its applications in biosensors, electrochemical sensing systems, supercapacitors, electrodes, and fuel cells. Known methods for producing 3D graphene include laser-induced graphene production as described in WO2019/038558; 3D graphene is formed on the surface of the exposed polyimide film when a suitable carbon precursor material (such as a polyimide film) is positioned on a supporting substrate and irradiated with a CO2 laser. Experience has shown that the thickness of 3D graphene produced by this method is less than 50 μm; furthermore, 3D graphene itself can be brittle and has poor adhesion to the underlying substrate, thus potentially peeling off. Therefore, 3D graphene is not suitable for many applications.
A note on terminology used in the field of carbon nanostructures: If we use only the term "graphene," there are many different forms of "graphene"; for example, the literature describes monolayer graphene, bilayer graphene, disordered graphene, graphene superlattices, graphene fibers, 3D graphene, graphene aerogels, wrinkled graphene, and many other forms. This presents a defining challenge, as using a specific term (e.g., "3D graphene") may imply limitation to only that specific form of graphene. Furthermore, IUPAC (International Union for Pure and Applied Chemistry) recommends using the name "graphite" for three-dimensional materials, and "graphene" only when discussing the reactions, structural relationships, or other properties of individual layers.
Therefore, in this specification, we use the term "carbon foam" as a general term, and this term should be broadly interpreted to cover any carbon nanostructure, such as 3D carbon material foam, including multilayer 3D carbon material foam with disordered layer twisting.
An example of the term "carbon foam" refers to a material manufactured using the methods described in this specification; such a material has slightly different properties from conventional graphene or conventional graphene foam. For example, graphene foam has several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature: the absence of a D peak; a 2D peak higher than the G peak; and a D peak:G peak ratio close to zero. As we will describe in more detail below, the carbon foam produced in specific embodiments of the invention does not possess these characteristics; it is hydrophilic with a contact angle less than 20°; it lacks the Raman signature indicative of graphene: it exhibits a prominent D peak; a 2D peak significantly smaller than the G peak; and a D peak:G peak ratio significantly higher than zero. In terms of appearance and Raman signature, it appears to be closer to carbon nanotube onion materials. Therefore, the term "carbon foam" in its scope also includes materials that are carbon nanostructures, such as carbon nanotube onions, carbon nanohorns, carbon nanotubes, carbon nanodots, nanodiamonds, and fullerenes, or any combination thereof.
Summary of the Invention
In this specification, we describe a method in which the surface of a carbon precursor is not converted into graphene at all; instead, the region beneath the surface of the carbon precursor, or the encapsulated region, is converted into carbon foam by a focused laser beam.
We summarize the invention as described in claim 1, namely a method for manufacturing carbon foam material, which includes the following steps:
(a) Using a first laser beam, an encapsulated or sub-surface region of the carbon precursor material is irradiated below the surface of the material to generate carbon foam in the sub-surface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Using a second laser beam to remove or ablate the disordered amorphous non-graphene material located above the carbon foam to expose at least some of the carbon foam.
The amorphous non-graphene material is positioned "above" the carbon foam because it is closer to the laser beam that generates the laser. One embodiment of the invention is described as a "dual-laser" process because two separate lasers are used in the production of the carbon foam material. The carbon foam material exhibits a significant D peak; the 2D peak is significantly smaller than the G peak; and the D peak:G peak ratio is significantly higher than zero. In terms of appearance and Raman signature, it appears more similar to carbon nanotube onion material. It can be used in biosensors, supercapacitors, and pseudocapacitors. In one embodiment, the carbon foam is referred to as "Gii" carbon foam.
Attached Figure Description
The invention will be described with reference to specific embodiments shown in the following figures.
Figures 1-6 schematically illustrate a dual-laser process for generating carbon foam when a polyimide (PI) film (which acts as a carbon precursor) is positioned on a substrate.
Figure 7 is a scanning electron image showing the unique surface morphology (x250) of carbon foam achieved using a dual-laser method.
Figure 8 is a scanning electron image showing the surface of conventional laser-induced graphene.
Figures 9-14B schematically illustrate a dual-laser process for generating carbon foam when the PI film (which acts as a carbon precursor) is not positioned on the substrate.
Figure 15 shows the cyclic voltammetry (CV) diagram of a carbon foam electrode produced using a dual-laser method.
Figure 16A is a graph showing the peak separation ΔE<sub>p</sub> of a carbon foam electrode produced using a dual-laser method as a function of the scan rate.
Figure 16B is a graph showing the peak separation ΔE<sub>p</sub> of a conventionally manufactured graphene electrode as a function of the scan rate.
Figure 17 compares the electrochemical impedance spectroscopy results of carbon foam electrodes produced using the dual-laser method with those of conventionally manufactured graphene electrodes.
Figures 18A and 18B show Raman analysis of carbon foam samples prepared using a dual-laser process.
Figure 18C shows the Raman analysis of carbon nanotube onion material.
Figure 19 is a scanning electron image showing dual-laser carbon foam and conventional graphene.
Figure 20 is a schematic image of a biosensor that includes dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Sens).
Figures 21-23 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Sens, Gii-Sens+, and PPC Gii-Sens variants).
Figures 24-27 are schematic images of a supercapacitor including dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Cap).
Figures 28 and 29 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Cap and Gii-Cap+ variants).
Figure 30 is a schematic cross-section of an integrated lab-on-a-chip (LoC) device that includes a biosensor and a supercapacitor made using dual-laser carbon foam.
Figure 31 is an exploded view of a fully integrated LoC device.
Figure 32 shows the LoC device displaying quantitative results on its monitor.
Figure 33 is an exploded view of an environmental monitoring device including the Gii-Sens sensor.
Figure 34 is a view of the assembled environmental monitoring device.
Figure 35 is a schematic cross-section of a device having a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 36 is a schematic diagram of a smart tag; it has a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 37 is a schematic cross-section showing the basic layering of different materials in the Gii-Thru variant, which is a three-dimensional structure of carbon foam.
Figures 38-42 are schematic diagrams of various Gii-Thru Gii-Cap/Gii-Cap+ three-dimensional supercapacitor devices.
Figures 43A and 43B are detailed process flow diagrams of the dual-laser carbon foam Gii-Thru Cap three-dimensional supercapacitor device.
Figures 44A and 44B are schematic diagrams of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device.
Figures 45A and 45B are schematic diagrams of the Gii-Thru sensor used in an eight-sample array microfluidic diagnostic device.
Figure 46A shows a perspective view of a fully assembled multi-sample array microfluidic diagnostic device.
Figure 46B is a top view of a multi-sample array microfluidic diagnostic device.
Figures 47 and 48 are views of a microfluidic diagnostic device.
Figure 49 shows the detailed manufacturing process of the high-sensitivity, low-cost Gii-Thru variant.
Figure 50 is a schematic diagram of a high-speed roll-to-roll or roll-to-sheet manufacturing system for Gii carbon foam.
Figure 51 shows the detailed process flow of the system in Figure 50.
Figures 52-57A show scanning electron images of dual-laser carbon foam at different magnifications.
Figure 57B is a scanning electron image of carbon nanotube onion material produced using conventional processes.
Figure 58 shows the Raman displacements of eight carbon foam sheets fabricated using a dual-laser process.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Figure 59 shows the carbon foam cyclic voltammogram measured at 25 mV/s for the anode voltage.
Figure 60 shows the carbon foam cyclic voltammogram for cathode voltage measured at 25 mV/s.
Figure 61 shows the galvanostatic charge-discharge (GCD) curves of carbon foam measured at 0.5 mA/ cm² for the anode voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves for the cathode voltage window, measured at 0.5 mA/ cm² .
Figure 63 shows carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 shows carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 shows carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 2: Gii-Cap+ Hydrogel
Figure 66 shows a typical CV curve for the Gii-Cap+ hydrogel device.
Figure 67 shows a typical GCD curve of the adjusted Gii-Cap+ hydrogel device.
Figure 68 shows the post-adjustment Nyquist (left) and Bode (right) curves of the Gii-Cap+ device.
Appendix 3 GiiCap Ion Gel
Figures 69-74 show the results of the GiiCap ionogel apparatus.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Figures 75-78 are schematic diagrams of the measurement procedure of the Gii-Sens 3D carbon foam measurement system.
Figures 79-81 show the surface chemistry of Gii-Sens 3D carbon foam.
Figures 82-83 show the label-free assay of Gii-Sens 3D carbon foam.
Appendix 6 Baseline Experimental Conditions
Figures 84-86 are graphs comparing the performance of Gii-Sens carbon foam and graphene electrode materials.
Figures 87-89 are graphs comparing the performance of Gii-Sens carbon foam and carbon-based electrode materials.
Figures 90-92 are graphs comparing the performance of Gii-Sens carbon foam and screen-printed gold.
Appendix 7: Optimization of surface immobilization of anti-human calcitonin (cAb)
Figure 93 shows an optimized direct assay procedure for surface immobilization of anti-human calcitonin (cAb).
Figure 94 is a schematic diagram of the surface fixation reaction.
Figure 95 shows the Rct and ΔEp signal responses of the Gii-Sens electrode with NHS functionalization.
Figure 96 shows cAb fixation on the GiiSens electrode.
Figure 97 shows the signal response from 2000 pg/ml in the direct determination form using a 100 μg/ml cAb surface coating.
It should be noted that Gii, Gii-Sens, Gii-Sens+, Gii-Cap, Gii-Cap+, Gii-Thru, and PPC Gii are trademarks of their respective owners. "Gii" generally refers to carbon foam produced using a dual-laser process. "Gii-Sens" refers to Gii carbon foam used in sensors (such as biosensors). "Gii-Cap" refers to Gii carbon foam used in supercapacitors. The "+" suffix indicates Gii carbon foam modified with a metal oxide layer or film. "Gii-Thru" refers to Gii carbon foam arranged in a specific three-dimensional structure. "PPC" refers to a specific manufacturing process, namely "post-printing conversion," in which Gii carbon foam is produced after various screen printing steps have been completed.
Figure Labels
Dual laser process
11 IR laser
12 IR laser beams
13. The interior of the PI film
14 PI film
15 substrate
16 Subsurface carbon foam region
17. Disordered amorphous non-graphene materials beneath the surface carbon foam region
18. Extended regions of disordered, amorphous, non-graphene material above the subsurface carbon foam region.
20CO2 laser
21 Unique surface morphology of exposed carbon foam regions
Biosensors
201 Polyimide substrate
202 Carbon Foam Working Electrode
203 Carbon foam counter electrode
204 carbon foam reference electrode
205 Screen Printed Silver Connecting Track
206 Dielectric Layer
The area where the 207 silver connection trajectory overlaps with the electrode
Gii-Cap Supercapacitor
Array of 241 carbon foam electrodes
242 Silkscreen Printed Silver Connector
243 Dielectric layer
244 Polyimide base layer
245 copper connector
246 Electrolyte layer
247 Aluminum Laminated Heat-Sealing Bag
250 carbon foam digits with rounded edges
Combined sensors and supercapacitors
301 Upper polyimide layer
302 Gii-Sens Biosensor
303 Lower polyimide layer
304 Supercapacitor
305 plastic parts
306 Microchannel
307 Connector Track
308 Flexible Electronic Devices
310 Induction Power Circuit
312 Gii-Cap Supercapacitor
313 Gii-Sens Biosensor
314 Device layer with microelectronic devices
315 Top Panel
316 monitor
317 Circular Analyte Well
Environmental monitors
330 Gii-Sens Carbon Foam Sensor
331 Control Electronic Devices
332 PV solar cells
333 Gii-Cap carbon foam supercapacitor
334 Peelable back
Combined supercapacitor and battery
351 First polyimide layer
352 Supercapacitor
353 Second polyimide layer
354 battery
355BMS (Battery Management System)
356 Flexible electronic devices
357 Electrical connectors
Smart Tags
360 Flexible Battery
361 Supercapacitor
362 Electronic Components Module
363 Exposed label surface; 364 Adhesive release liner; 364 Gii-Thru Cap
371PI membrane
372 Screen printing conductive ink or paste layer
373 Screen-printed collector
374 Dielectric Isolator
375 Encapsulated carbon foam layer; 376 Disordered, amorphous, non-graphene layer beneath the carbon foam layer; 377 Unique surface morphology layer.
390 Hydrogel Electrolyte Layer
391 Carbon foam layer with unique surface morphology
392 PI film
393 Screen Printing Carbon Paste Layer
394 Screen-printed silver connector layer
395 silver connector layer ketone insert
396 Distributed dielectric isolation layer
397 Second carbon foam layer with unique surface morphology
398 PI film
399 Hydrogel Electrolyte Layer
400 dielectric isolation layer
401 screen-printed silver current collector layer
402 copper insert
403 Screen Printing Carbon Paste Layer
404 carbon foam layer
405 PI film
Gii-Thru Sens
Three-point array microfluidic diagnostic device
440 Analyte Sample Wells
441 Laminated Hole Spacer Layer
442 Polyimide film
443 Screen-printed conductive carbon layer
444A Reference Electrode Connector
444B Working Electrode Connector
444C Counter electrode connector
447 Screen-printed dielectric layer
448A Reference Electrode
448B Working Electrode
448C counter electrode
449 Reference electrode screen-printed carbon layer
Eight-point array microfluidic diagnostic device
451 Laminated Hole Spacer
452 Array of eight analyte wells
453 Holes for the electrodes
454 Hole of the reference electrode
455 Polyimide layer
456 Polyimide layer
457 Eight working electrodes
458 pairs of electrodes
459 Reference Electrode
460 Screen-printed carbon bonding interface layer
461 Screen Printed Silver Connecting Track
462 Screen-printed dielectric layer
470 Top-layer microfluidic foil
471 Intermediate Layer Microfluidic Foil
472 Printed or molded microfluidic channels
473 Microfluidic foil with binder as the underlying layer
474Gii-Thru sensor
475 connector
481 Transparent Resin Barb Connector
482 Top Foil
483 Transparent Resin Molded Microfluidic Card
484 Microfluidic Channels
485-hole unit
486Gii-Thru sensor
Detailed Implementation
We will begin with a simplified, illustrative walkthrough of specific embodiments of the invention. We present two demonstrations; the first (Figures 1-6) will describe at a high level the carbon foam production process with a carbon precursor (e.g., a polyimide (PI) film, in this case, such as a membrane) mounted on a substrate; the second (Figures 9-14) covers the carbon foam production process without the polyimide film mounted on the substrate. In each case, we use a dual-laser process; the meaning of the terminology will be explained below.
In the first stage (see Figure 1), a laser 11 with wavelength λ uses a laser beam 12 to irradiate the interior 13 of a polyimide film 14, which is positioned on a substrate 15 suitable for end applications. This laser may be a pulsed IR laser that delivers IR radiation with a wavelength of 1064 nm.
As shown in Figure 2, a laser 11 with wavelength A is tuned so that the subsurface region 16 is transformed into carbon foam. The focus of laser A is gradually moved through the interior 13 of the polyimide film 14 to generate the entire carbon foam region 16. The depth or height of the carbon foam region 16 can be approximately 50 μm or greater, much higher than that achievable by other methods. Note that no carbon foam is generated at any time on the exposed surface of the polyimide film 14 (i.e., the surface on which the laser beam is incident). The region above the carbon foam 16 (i.e., closer to the laser than the carbon foam region 16) is not transformed into carbon foam. The region 17 below the carbon foam region 16 (i.e., the lower surface of the PI film) is also not transformed into carbon foam, but rather into disordered, amorphous, non-graphene material adhered to the underlying substrate 15.
Figure 3 shows that due to gas trapping, the laser 11 with wavelength λ causes physical expansion in region 18 above the internal carbon foam region 16 (i.e., closer to the laser than the carbon foam region 16). This region 18 is neither 3D graphene nor a polymer; it is a disordered amorphous material.
In the second stage, a laser 20 with wavelength B is now tuned to the disordered amorphous material region 18 above the carbon foam region 16, as shown in Figure 4. This can be a CO2 laser with a wavelength of 10.6 μm.
As shown in Figure 5, a laser 20 with wavelength B ablates some or all of the region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam region 16.
The laser 20 with wavelength B also reveals a lower carbon foam region with a unique surface morphology 21, as shown in Figure 6.
We refer to the process described in Figure 1-6 as the "dual-laser process".
Figure 7 is a scanning electron image showing the unique surface morphology (x250) achieved using a dual-laser method. In this case, the carbon source was first irradiated with IR radiation at a wavelength of 1064 nm from a pulsed IR laser, the radiation being focused into and gradually penetrating the carbon source. Then, the carbon source was irradiated with a laser beam at a wavelength of 10.6 μm from a CO2 laser. The thickness of the carbon foam layer in this image is approximately 220 μm.
As shown in Figure 8, the contrast with the surface morphology (x250) achieved using the conventional LIG method is striking: it features clear grating lines and less spiraling folds. The thickness of this carbon foam layer is less than 50 μm.
Based on the image in Figure 7, we can infer that the material produced using the dual-laser process does not have a surface morphology similar to conventional graphene foam; although it appears to be a multilayered, 3D carbon-based material with a chaotic, tortuous, foam-like structure, it is not necessarily a material commonly described as "graphene" in the conventional sense. More details are provided in Feature R below.
In the aforementioned demonstration (Figures 1-6), we investigated a dual-laser process for mounting a carbon precursor material (polyimide film) onto a substrate. In Figures 9-14 below, we will investigate a dual-laser process without mounting the polyimide film onto the substrate. We will later describe in detail the manufacturing processes for two specific implementations, referred to as Gii-Cap (supercapacitor) and Gii-Sens (sensor), which use a standard 220mm × 180mm sheet of polyimide film, which is not mounted onto the substrate; this size can be considered in standard laser scanning equipment, typically used for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). The manufacturing process also utilizes a standard flatbed screen printing apparatus and a standard conveyor belt dryer to easily accommodate thin PI films of different sizes. Other sizes of polyimide sheets can be considered.
As previously described, a laser 11 of wavelength Å (e.g., an IR laser) irradiates the interior 13 of the PI film 14; the film 14 is not currently mounted on the substrate, as shown in FIG9. It may be a sheet whose edges are supported or temporarily rested on a surface, or a sheet that forms part of a PI film roll when using a continuous manufacturing (e.g., roll-to-roll or roll-to-sheet) system (see Feature P below).
A laser 11 with wavelength λ is tuned to transform the subsurface region 16 into carbon foam, as shown in Figure 10. The focal point is gradually moved through the membrane 14 to create the entire carbon foam region 16. The height of the carbon foam region 16 can be approximately 50 μm or greater, much deeper or higher than could be achieved by other methods.
At no time does 3D graphene form on the exposed surface of the polymer film. The region above the carbon foam does not transform into 3D graphene.
As shown in Figure 11, due to gas retention, region 18 above the internal carbon foam region 16 undergoes physical expansion. This region is neither 3D graphene nor a polymer; it is a disordered amorphous material.
A laser 20 with wavelength B (e.g., CO2 ) is now tuned to region 18 above the carbon foam, as shown in Figure 12. The laser 20 with wavelength B ablates region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam 16, as shown in Figure 13.
Just as with the case where the polyimide film 14 is mounted on the substrate, the laser 20 with wavelength B also imparts a unique surface morphology 21 to the underlying carbon foam 16, as shown in Figure 14.
Some specific implementation details of this dual-laser method for producing carbon foam are as follows: In one example, the Nd:YAG solid-state laser is a wavelength A-wave laser, and it is positioned such that the IR laser radiation beam (wavelength 1064 nm) generated by the solid-state laser perpendicularly impacts the polyimide layer. Optics focus the IR laser radiation beam to a minimum beam convergence within a certain volume of the polyimide layer.
In the encapsulation region or subsurface region or location around the minimum beam convergence, the interaction between the laser and the polyimide leads to the carbonization of the carbon source. This carbonization results in the generation of carbon foams, such as twisted or disordered multilayer carbon foams, in the encapsulation region or subsurface region, and causes the formation of a disordered, amorphous, non-graphene material layer on the surface of the polyimide film.
While maintaining the laser beam focused at a specific depth within the polyimide layer, the laser scans laterally above the polyimide layer. In this way, the path entirely within the polyimide carbon source is traced and transformed into carbon foam. Thus, the polyimide is carbonized into carbon foam with a pattern corresponding to the path traced by the scanning, focused IR laser beam.
In one setup, the Nd:YAG IR laser pulsed at 80 kHz, and the laser beam scanned the surface at a speed of 9.4 cm/s. Other implementations utilized different parameters. For example, a pulse frequency of 50 kHz and a scanning speed of 35.5 cm/s were also successfully used to generate carbon foam. The laser power typically operated in the range of 8–20 watts, with an optimal value of 12 W; the laser focal length typically operated in the range of 50 mm–400 mm.
Once a predetermined area within the polyimide layer is irradiated by a focused IR laser beam in the manner described above, the depth of the encapsulated area or subsurface region or location within the polyimide is altered, and the IR laser beam scans the same predetermined area again. A standard computer-controlled laser scanning system can be used, which controls the X-Y position of the laser on the polyimide film. It may be necessary to pass the focused IR laser radiation through the same area more than once to generate carbon foam. In this specific implementation, the focused IR laser also irradiates adjacent but not substantially overlapping areas. This process of irradiating the carbon source with focused IR laser radiation at different focal depths is repeated until the desired depth of the polyimide layer is exposed to IR laser radiation and carbon foam is formed in the encapsulated area or subsurface region. However, the surface layer is a disordered, amorphous, non-graphene material.
In the second step, the polyimide layer is exposed to radiation from a CO2 laser for an ablation process, exposing at least some of the underlying carbon foam and obtaining exposed carbon foam with a specific surface morphology. The radiation from the CO2 laser scans the surface of the treated carbon source at a speed of 19 cm/s to match patterns or areas irradiated using an IR laser. Other embodiments utilize different parameters. For example, a pulse frequency of 50 kHz and a scan speed of 35.5 cm/s have also been used to successfully expose the underlying carbon foam. The laser power is typically in the range of 8–20 watts, with 12 W being optimal; the laser focal length is typically in the range of 50 mm–400 mm.
As described above, CO2 lasers ablate the disordered, amorphous, non-graphene material on the surface layer, thereby exposing the underlying carbon foam and altering the surface morphology of the carbon foam to produce exposed carbon foam with a greater number of defects compared to standard laser-induced graphene; as previously stated, this endows the carbon foam with extremely useful properties superior to standard laser-induced graphene.
Changing the laser parameters of one or two lasers (e.g., IR laser and CO2 laser), such as power, focus, wavelength, and scanning speed, alters the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
One useful property of exposed carbon foam fabricated using a dual-laser process is its high wettability: the contact angle can be less than 20°, making this carbon foam hydrophilic, compared to conventional graphene foams with contact angles between 70° and 150°, making them hydrophobic. This hydrophilicity of the carbon foam produced via the dual-laser process is highly relevant for two key applications: biosensors (a specific implementation called Gii-Sens) and supercapacitors (a specific implementation called Gii-Cap). For biosensors, high wettability allows the tested liquid (e.g., a liquid analyte) to spread rapidly and uniformly across the entire working electrode, resulting in higher sensitivity, consistency, and speed. For supercapacitors, high wettability means the electrolyte wets the supercapacitor electrodes better, leading to higher performance. While conventional graphene foams can be processed to make them more wettable, this carbon foam implementation does not require such an additional processing step.
Another useful property of exposed carbon foam produced by the dual-laser process is its high resistance to fouling: this can lead to enhanced sensitivity and extended lifespan of biosensors. Carbon foam can be used in applications where the accumulation of contaminants or residues may impair the performance or lifespan of components (e.g., filters, heating elements in e-cigarettes; electrodes); exposed carbon foam produced by the dual-laser process can be used in said components, resulting in enhanced performance or lifespan.
The performance of the carbon foam electrode produced using this dual-laser method has been explored by cyclic voltammetry (CV), as shown in Figure 15. Cyclic voltammetry plots of the well-characterized ferricyanide/ferrocyanide redox reaction were performed using electrodes prepared using the method described above and electrodes prepared using known conventional CO2 laser irradiation methods. Figure 15 shows CV curves obtained at scan rates of 10 mV/s, 25 mV/s, 50 mV/s, 75 mV/s, 100 mV/s, and 150 mV/s. Each curve shows data recorded using the carbon foam electrode produced using the dual-laser method of the present invention (light line) and the 3D graphene electrode produced using the known CO2 laser irradiation method (dark line). The peak at approximately 0.22 V in the cathode current direction corresponds to the reduction of ferricyanide to ferrocyanide; and the peak at approximately 0.28 V in the anodic current direction corresponds to the oxidation of ferrocyanide to ferricyanide.
Far from the prominent redox peaks, these graphs qualitatively show that the CV curves recorded using carbon foam electrodes produced using the dual-laser method disclosed in this specification are more rectangular than those recorded using 3D graphene electrodes produced by known methods. This is most evident at the high points of the voltage range (approximately 0.6 V) and at higher scan rates (see, for example, 100 mV/s). This increased rectangular appearance indicates increased capacitive behavior of the electrodes prepared using the dual-laser method of this invention, thus reflecting the very high surface area of the torsion or disordered multilayer carbon foam produced by this method.
The CV curves also clearly show that the voltage for separating the oxidation and reduction peaks is consistently lower for measurements using carbon foam electrodes produced by a dual-laser method compared to those using 3D graphene electrodes produced by conventional known methods. The peak separation ΔEp as a function of scan rate for CV measurements obtained using carbon foam electrodes produced by the method disclosed in this invention is plotted in Figure 16(a), and the peak separation ΔEp as a function of scan rate for CV measurements obtained using 3D graphene electrodes produced by known methods is plotted in Figure 16(b).
This data shows that ΔE<sub> p </sub> narrows when the electrode is prepared according to the dual-laser method. The theoretical peak separation parameter for reversible systems (such as ferricyanide/ferrocyanide reversible redox reactions) is 57 mV, but in practice this is sensitive to the influence of electrode structure on electrochemistry. Clearly, the voltage separation of the oxidation and reduction peaks in the cyclic voltammetry plots is close to the theoretical value. This demonstrates the quality of the electrodes produced by both known methods and the dual-laser method. Furthermore, results recorded using a carbon foam electrode produced by the dual-laser method show reduced separation, indicating improved porosity of the electrode produced in this manner compared to electrodes produced by conventional methods.
Figure 17 shows a comparison of electrochemical impedance spectroscopy results for a system comprising a carbon foam electrode produced using a dual-laser method (square) and a system comprising a 3D graphene electrode produced using a known method (circle). Bode plots show the change in phase angle as a function of frequency. The frequency responses of the two systems are significantly different. Specifically, measurements recorded using the carbon foam electrode produced using the dual-laser method lack the phase angle signal peak observed at approximately 1 kHz in measurements recorded using the 3D graphene electrode produced using a conventional method. The response from the electrode prepared using the dual-laser method indicates a rapid electron transfer response. These differences further clearly demonstrate that the carbon foam produced by the dual-laser method is distinct from and can be differentiated from 3D graphene produced by conventional methods.
Further details are clearly visible in Figure 18A. The Raman spectrum of the carbon foam fabricated using a dual-laser process is shown in Figure 18A, exhibiting three main peaks. Specifically, the D peak at approximately 1344 cm⁻¹ is characteristic of lattice defects, and the G peak at approximately 1577 cm⁻¹ is characteristic of sp² carbon hybridization, featuring distorted six-fold carbon rings. The 2D peak at approximately 2685 cm⁻¹ is characteristic of secondary transitions in 3D graphene, and the absence of a bimodal structure here indicates a lack of planar AB stacking found in multilayer 2D graphene or graphite. Fitting the 2D peak to a single Lorentzian peak centered at 2685 cm⁻¹ (with a full width at half maximum of 67 cm⁻¹ ) indicates the presence of only one or a few carbon foam sample layers in the 3D carbon formed using these two methods. Analysis of the D/G peak ratio (0.85) of the dual-laser process indicates a higher defect density compared to the conventional laser-induced graphene process using a single-laser step (0.67), as shown in Table 1 below.
| process | D/G | 2D/G | D/D’ |
| Dual laser | 0.85±0.1 | 0.95±0.12 | 3.7±1.3 |
| Conventional single laser | 0.67±0.13 | 0.75±0.05 | 2.6±0.22 |
Table 1
As we previously explained, Raman analysis of typical graphene foam revealed the following signature characteristics: absence of a D peak; a 2D peak higher than the G peak; and a D:G ratio close to zero. The carbon foam produced in this specific embodiment of the invention does not possess these characteristics; it is highly hydrophilic with a contact angle below 20°; it lacks the Raman signature characteristic indicative of graphene: Figure 18A shows the material produced via a dual-laser process: presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18B is another Raman analysis of carbon foam produced via a dual-laser process, again showing the presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18C is the Raman analysis of the carbon nano-onion material, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI: 10.1007/s00339-015-9315-9, and its similarity to the Raman analysis of carbon foam produced via a dual-laser process is evident. A plausible explanation is that the carbon foam produced by the dual-laser process is or contains carbon nanotube onion material. See also Figures 57A and 57B below.
Both dual-laser carbon foam and conventional graphene fabricated using a single-laser process exhibit microporous structures, as shown in the SEM images in Figure 19. Low-magnification images reveal significant differences in surface morphology. The single-laser surface shows a smoother, more textured surface with rougher edges, while the carbon foam fabricated using a dual-laser process displays a rougher surface. This region will be further described in the following section on characteristic R.
Key features
In this section, we outline the key features of specific embodiments of the invention. These features define the production of carbon fiber foam in the previously described dual-laser manufacturing process; this process offers numerous advantages over conventional CVD: we can compare the production of approximately 50 μm thick carbon foam at 1 cm² on plastic substrates (or virtually many other types of substrates) as shown in Table 2.
| process | Number of steps | time | temperature | pressure | cost |
| CVD | 6 | 300min | 800C | vacuum | $50 |
| Dual laser process | 1 | 2min | 20C | environment | Less than $1 |
Table 2
Features A-R define various aspects of the carbon foam manufacturing process, which is highly scalable, high-yield, highly reproducible, and easily adaptable to many different applications, all using the same process. For example, dual-laser carbon foam is particularly suitable for biosensors and electrochemical capacitors (e.g., supercapacitor and pseudocapacitor applications).
For biosensor applications, dual-laser carbon foam offers the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; higher wettability; and higher antifouling properties. One specific implementation of this biosensor is called Gii-Cap, which we will describe in more detail below.
For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; higher wettability; and better anti-fouling properties. One specific implementation of a supercapacitor is called Gii-Cap, which we will describe in more detail below.
Features A-R are organized into the following four groups:
Group 1: Subsurface carbon foam
Group 2: Dual Laser Processing
Group 3: Products
Group 4: Other aspects.
We can extend this organization as follows:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene material adhered to a substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual lasers operating in different frequency bands
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors in different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device
Feature M2: Screen-printed carbon foam supercapacitor layer
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Now let's look at Group 1:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
In the prior art section, we have described how earlier laser-induced graphene methods transformed the surface layer of a carbon precursor into 3D graphene. However, the resulting 3D graphene can be somewhat brittle, potentially peeling off from the underlying substrate, and is generally unsuitable for many real-world applications; furthermore, 3D graphene is typically relatively thin, with a depth of less than 50 μm.
In this specification, we describe an alternative method in which the surface of the carbon precursor is not converted into graphene at all; instead, only the subsurface region 14 of the carbon precursor is converted into carbon foam 16 by a focused laser beam 12; in one embodiment, the focused IR beam 12 generates a temperature above 500°C in the subsurface region or encapsulation region inside the polyimide film 14 for a very short time, between 1 ns and 10 μs (i.e., at a rate between approximately 5 × 10⁷ °C/s and 2 × 10¹² °C/s); this brief but intense heating is sufficient to form carbon foam 16 in this subsurface region or encapsulation region. This subsurface region or encapsulation region 16 has no substantial gas escape pathway; confining the gaseous products within the subsurface region or encapsulation region advantageously affects the structure of the carbon foam 16 formed in the subsurface region. The formation of carbon foam 16 only in the subsurface region was an unexpected discovery; the reasons for this unexpectedness include the extremely low absorptivity of the polyimide carbon precursor material to 1064 nm IR radiation, with a radiation absorptivity per centimeter (decimal) of less than 50 or as low as less than 10.
Under laser irradiation, the surface (e.g., the interface between the carbon precursor material perpendicular to and facing the laser and the gaseous environment surrounding the carbon precursor material) expands and transforms from the carbon precursor material into disordered amorphous non-graphene material 18. This disordered amorphous non-graphene material 18 forms a layer, which is typically at least 1% of the total thickness of the carbon precursor material; for a 500 μm thick polyimide film, the top 1 μm–10 μm is typically transformed into disordered amorphous non-graphene material 18; below this upper surface layer, within the bulk of the carbon precursor material, we obtain a region transformed into carbon foam 16.
The thickness of this carbon foam 16 is controlled by gradually moving the focus of the laser beam through the carbon precursor material; exceptionally thick carbon foam structures can be made using this process: carbon foam tracks with thicknesses of 50μm-200μm (approximately) have been achieved.
If a laser irradiates a carbon film precursor material, such as a polyimide film suspended in space (i.e., not mounted on a substrate) as shown in Figure 9-14B, after irradiation, as we gradually move through the material, we obtain disordered amorphous non-graphene material 18 on the upper surface (i.e., the surface facing the laser); then we obtain carbon foam regions 16. The laser beam 12 typically does not approach the lower surface of the carbon precursor material, such that the carbon foam regions 16 are located above the carbon precursor material that has not yet been converted into carbon foam. If the laser approaches the lower surface of the carbon precursor material, the carbon precursor near and located on the lower surface is converted into disordered amorphous non-graphene material.
Similarly, if a carbon precursor film, such as a polyimide (PI) film mounted on a substrate, is irradiated with a laser, as shown in Figures 1-6, we obtain the same material order; furthermore, the laser typically approaches the lower surface of the carbon precursor material resting on the substrate: the carbon precursor near and located on the lower surface is then transformed into a disordered amorphous non-graphene material 17. This disordered amorphous non-graphene material 17 adheres to the substrate 15; since the carbon foam region 16 is bonded to this disordered amorphous non-graphene material 17, the carbon foam region 16 itself is not directly bonded to the substrate 15, but is firmly attached to the substrate 15 via the intermediate disordered amorphous non-graphene material 17.
This method achieves carbon foam structures with significantly greater thickness than those achievable using previous methods that confine graphene foam formation to surface regions. Furthermore, this method enables carbon foam structures to adhere more robustly (but not directly) to the underlying substrate. It is important to note that with this method, carbon foam is not generated on any surface of the carbon precursor material; rather, it is generated only in the subsurface region within the carbon precursor material.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
In Feature A above, we define the region where carbon foam is generated by laser irradiation as the “under-surface” region. Another way to describe this region is to characterize it as “encapsulation”; this reflects the three-dimensional relationship between the carbon foam and its surrounding environment; the carbon foam 16 is “encapsulated” by the original carbon precursor material and by the disordered, amorphous, non-graphene material 18 generated by laser irradiation of the upper surface of the carbon precursor material 14.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of carbon precursor material, wherein said regions do not have substantial gas escape channels.
As we have seen above, the subsurface region or encapsulation region of the carbon precursor is transformed into carbon foam, and this subsurface region or encapsulation region has no substantial gas escape channel; confining the gaseous products within the subsurface region or encapsulation region affects the structure of the carbon foam 16 formed in the region.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to the substrate
As we have previously observed, when laser 11 irradiates the carbon film 14 mounted on substrate 15, the laser carbonizes the surface of the carbon film adjacent to substrate 15, forming a disordered amorphous non-graphene material 17 adjacent to substrate 15. This disordered amorphous non-graphene material 17 adheres to substrate 15. Because the internal, subsurface, or encapsulated carbon foam regions 16 are themselves bonded to this disordered amorphous non-graphene material 17, the carbon foam regions 16 themselves are not directly attached to substrate 15, but are firmly positioned on substrate 15 via the intermediate disordered amorphous non-graphene material 17. Compared to conventional laser-induced graphene, the carbon foam regions 16 adhere more firmly and are less likely to peel off even if the substrate is flexible, thus enabling applications such as biosensor applications where the substrate is typically a thin and flexible structure.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Previous features A-D covered the generation of carbon foam in the subsurface region or encapsulation region of the carbon precursor material. Because carbon foam does not form on exposed surfaces, and many applications require exposed carbon foam (e.g., for functionalization in biomedical sensing applications or supercapacitors), we can take additional steps to expose at least some of the carbon foam subsurface or encapsulate it.
We have previously seen the formation of disordered, amorphous, non-graphene material 18 beneath the surface or above the encapsulated carbon foam 16 by laser irradiation using an IR laser 11. We now use a laser (typically a long IR CO2 laser 20) to ablate or otherwise process this disordered, amorphous, non-graphene material 18, thus exposing the underlying carbon foam 16. Unlike the initial laser, this second laser 20 is typically defocused.
As mentioned earlier, we use standard 220mm × 180mm polyimide sheets (but other sizes of polyimide sheets can also be considered); this size is commonly used in standard laser scanning equipment, standard flatbed screen printing equipment, and standard conveyor belt dryers for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). Other sizes of polyimide sheets can be considered.
We have discovered that this secondary laser irradiation step alters the morphology and other characteristics of the underlying carbon foam in a surprising and advantageous manner, resulting in previously unobserved twisted or disordered multilayer carbon foams. Changing the parameters of the CO2 laser 20 can alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
This new exposed carbon foam possesses one or more of the following properties:
• Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
• Strong adhesion to any underlying flexible substrate
High porosity
High electrical conductivity
• Increase in capacitance or charge storage
• Rapid absorption of organic solvents and water-based solutions
• Higher hydrophilicity
High EMI shielding
• Electrode quality enhancement
High wettability
• Anti-fouling.
It should be noted that by changing the laser parameters of any one or both lasers used in the dual-laser process, one or more of these properties, as well as the size and extent of defects and the size (including relative size) of the Raman D and 2D peaks, can be altered. In this way, carbon foams tuned for or particularly suited to different applications can be produced. Surprisingly, the operation of the second ablation laser enables the production of usable exposed carbon foam regions, especially those with properties that can be adjusted by changing the parameters of the first and/or second lasers.
We can summarize it as follows:
A method for manufacturing a carbon foam material includes the following steps: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulated region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of it in the carbon foam.
Feature F: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
In the aforementioned feature E, we describe the formation of carbon foam 16 in the region by irradiating the encapsulated region or subsurface region of the carbon precursor with a laser 11 (e.g., an IR laser); the irradiation causes the upper (in the laser direction) carbon precursor material 14 to expand into a disordered, amorphous, non-graphene material 18; then, we expose or reveal the carbon foam 16 by ablating the upper disordered, amorphous, non-graphene material 18 with a second laser 20 (e.g., a CO2 laser). This second irradiation step not only ablates the upper disordered, amorphous, non-graphene material 18 and thus exposes the lower carbon foam 16, but also gives this lower carbon foam an unexpected and unusual surface morphology 21 with very desirable characteristics; such a carbon foam may be a torsion or disordered multilayer carbon foam.
However, because such foams may possess characteristics unrelated to graphene foams (such as a wide range of defects, appearance, wettability, and Raman spectra (see Feature R below), we explicitly describe such foams as “non-graphene carbon foams” in Feature F. Therefore, the term “non-graphene carbon foam” (as opposed to the term “carbon foam”) explicitly excludes graphene foams, including twisted or disordered multilayer graphene foams, but extends to foams covering any other 3D carbon material.
We can summarize it as follows:
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers in different wavelength bands
As we saw in features E and F above, we can use two separate laser irradiation steps. These steps are typically performed using two separate lasers: the first step, to generate subsurface or encapsulated carbon foam, is typically accomplished using a focused IR laser 11; and the second step involves irradiation using a defocused CO2 laser 20 at a longer wavelength, but other wavelengths (e.g., UV and visible light) can also be used.
The second laser 20 ablates the material 18 (e.g., disordered, amorphous, non-graphene material) located between the carbon foam 16 and the surface, exposing the underlying carbon foam 16. The exposure of the carbon foam 16 can also be altered by the second laser (e.g., in terms of its surface morphology 21); that is, the term 'exposure' should be broadly interpreted to include not only revealing at least some of the pre-existing carbon foam, but also transforming or altering at least some of the pre-existing carbon foam into a 3D carbon material foam with characteristics different from those of the pre-existing graphene foam.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
We have previously seen how we generate carbon foams, which can be twisted or multilayered: because of the special electrical properties of this material (e.g., conductivity, capacitance), we can attach or position one or more electrical contacts (including electrical objects such as flexible electronics, microprocessors, antennas, IoT devices, electrical interfaces, etc.) into the carbon foam. For printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate) and onto and inside a pre-existing 3D carbon material foam, such that the tracks form good electrical contacts with the foam and any structures formed on the foam, such as functionalized layers (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
In Feature H, we see that once the dual-laser process is complete, electrical contacts or circuitry are added to contact a pre-existing carbon foam; for example, simple silver electrical contacts can be screen-printed onto the carbon foam. In Feature I, we describe a process that begins by first screen-printing electrical contacts onto a polyimide film, and then completes the process by creating an exposed carbon foam through a second laser ablation step in the dual-laser process. This has several advantages because the screen-printing process can interfere with or destroy the carbon foam. We refer to this process as “PPC” (short for “post-printing conversion”), where the screen-printing step is performed prior to the dual-laser process to create the carbon foam. In Feature L5, we describe a biosensor fabricated using the PPC process.
Therefore, for screen-printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate), allowing carbon foam to subsequently form around one end of the printed tracks, thus providing a contact area with a large surface area and therefore very good electrical connectivity. Similar to the alternative processes described in Feature H above, the printed tracks also form good electrical contacts with any structures formed on the foam (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
An alternative sequence involves using a first laser beam to generate subsurface carbon foam, then screen printing electrical contacts, and then using a second laser beam to generate carbon foam to create good electrical contact with the electrical contacts.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed in the order of (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
We have previously observed that the thickness of the subsurface or encapsulated carbon foam region can far exceed that of conventional graphene foams confined to the surface layer: the laser focus of the first laser beam can be progressively moved downwards through the carbon precursor material to create a deep or thick subsurface or encapsulated carbon foam layer. Then, a second laser irradiation step is employed to ablate the material between the carbon foam and the surface of the carbon precursor material, resulting in an exposed region of the carbon foam. This now exposed carbon foam region has a thickness or depth of at least 50 μm; carbon foams with a thickness of 300 μm have been produced. The increased thickness is beneficial because it leads to better electrical conductivity, greater capacitance, and higher mechanical integrity.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
The specific properties or structure of the carbon foam produced by the second laser beam can be considered sensitive information because they define the characteristics of the final product. For the first laser beam process, it is desirable for the carbon foam supplier to perform the process at their manufacturing facility, then supply the carbon foam to the customer, who then uses the second laser beam for the final stage at their own manufacturing facility. As we explained earlier, by changing the parameters of the first and second lasers, it is possible to alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications. Typical parameters that can be changed or tuned in this way include: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface or encapsulation region.
By segmenting the manufacturing process in this way, suppliers do not need to know the specific manufacturing processes that customers use as part of the second laser ablation process (e.g., how they change the parameters of the second laser beam to give the exposed carbon foam the properties they need); customers can keep the details of how they produce the finished product confidential.
Therefore, the manufacturing process is a three-stage process involving the following steps: (a) irradiating the area below the surface of the carbon precursor material with the first laser beam at the manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Furthermore, this method enables the large-scale production (see feature P, for example) of carbon foam using only the first laser process, thereby reducing the cost of this material, which can be used in many different applications and for many different customers. The production volume of more specialized products using a second laser beam may be much lower than that of carbon foam produced using only the first laser process. Therefore, this method achieves more efficient and lower-cost manufacturing of the base material, namely carbon foam produced solely through the first laser process.
We can summarize it as follows:
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
For features A-K, the following optional features are particularly relevant. It should be noted that any one or more of the following optional features can each be combined with one or more other compatible optional features, as well as with one or more of features A-K:
We will cover the following areas:
Manufacturing process
First laser beam parameters and control scheme
Properties of the subsurface region or packaged region
carbon precursor materials
Substrate supporting carbon precursor materials
Carbonization at the surface where the laser beam is incident
ablation laser beam or second laser beam
Carbon foam.
It should be noted that any one or more of the following optional features may be combined with one or more other compatible optional features and with any one or more of the other “features” listed in this specification (e.g., features A-R):
The laser-based manufacturing process described above has many advantages over conventional CVD processes; these can be listed as the following optional features:
It is a room temperature process.
It is an environmental pressure process.
It can be done on plastic substrates (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
It takes about 2 minutes or less to create a 1 cm² carbon foam that is approximately 50 μm thick on a plastic substrate.
The formation of 3D carbon foam on a flexible substrate was achieved.
No graphene or graphene oxide precursors are required.
Carbon foam material is generated only in the encapsulation area or subsurface area of the carbon precursor material, and not on any surface of the carbon precursor material.
It uses a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
It is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
The parameters and control scheme of the first laser beam are crucial for the production of carbon foam; we define the relevant optional characteristics here:
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following:
Intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface or encapsulated region to form carbon foam.
• The laser beam generates temperatures exceeding approximately 500°C in the subsurface or encapsulated region to form carbon foam.
The pulse duration of the laser beam is between approximately 1 ns and 10 μs, resulting in a pulse speed of approximately 5 × 10⁷ °C/s.
Heating rate between 2 × 10¹² °C/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between approximately 50 kHz and 500 kHz.
• The laser pulse frequency is between approximately 1 kHz and 2 MHz.
• The laser wavelength is between approximately 0.7μm and 2.5μm.
The laser scans at speeds between approximately 9 cm/s and 40 cm/s.
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region through which the focal point passes.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region with a thickness of at least 50 μm.
• The focal point of the laser beam is moved through a depth of at least about 100 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region where the thickness of the carbon precursor is at least 100 μm.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scanning can result in a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm).
• The wavelength of the laser beam is not absorbed by the carbon precursor material.
• The carbon precursor material has extremely low absorption of the wavelength of the laser beam, with a radiation absorptivity per centimeter (decimal) of less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between approximately 0.7 μm and 2.5 μm.
The laser beam is an IR laser with a wavelength between approximately 0.75 μm and 1.40 μm.
The properties of the subsurface region or encapsulation region where carbon foam is generated can be defined using the following optional features:
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity and the choice of carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or more below the surface of the carbon precursor material.
• The thickness of the subsurface region or encapsulation region can be between approximately 10 μm and 200 μm.
• The subsurface region or encapsulation region is located at a certain distance below the surface of the carbon precursor material. This distance is a function of various factors, such as laser intensity, other laser parameters, and the selection of the carbon precursor material used. For example, the top of the subsurface region or encapsulation region may be at least 1%, 10%, 20%, 30%, or 40% below the total thickness of the surface carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the midpoint of the minimum cross-section of the first laser beam, and the volume is within 500 or 100 micrometers or 1 micrometer of this midpoint.
Carbon precursor materials can be defined by the following optional characteristics:
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam (see Group 3 below) is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300±50 cm⁻¹ .
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of a first and/or second laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
A substrate can be considered as a material having a surface on which carbon precursors are positioned; the specific material, thickness, and properties of the substrate are determined by the application: for example, for some sensors, the substrate may be a thin, flexible plastic film; for other applications, the substrate may be a rigid polyimide plate on which electronic circuitry can be mounted. An IR laser can directly irradiate the carbon source; alternatively, radiation from the IR laser can first pass through the substrate and then reach the carbon source, in which case there are two alternative scenarios: first, the substrate is substantially transparent to IR radiation, and the mechanism of carbon foam formation is as described above. In the second scenario, the substrate is substantially opaque to IR radiation: then, rapid heat transfer from the substrate to the carbon precursor material first generates a disordered, amorphous, non-graphene layer at the interface with the substrate, and then carbon foam forms in the subsurface region or encapsulation region within the carbon precursor material.
The carbon precursor material can be positioned and supported on a substrate, which can be defined by the following optional characteristics:
The substrate is a plastic body, film, or foil.
The substrate is flexible.
The substrate is a polyimide circuit board.
The substrate has an extremely low absorption rate of the first laser beam.
The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
The substrate has a high absorption rate for the first laser beam, absorbing more than 60% of the first laser beam.
The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
The substrate is formed from one or more of the following: silicon (Si), silicon dioxide (SiO2), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing silicon and silicon dioxide.
The substrate is a carbon source.
The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident can be defined by the following optional characteristics:
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by the first laser beam.
The disordered, amorphous, non-graphene material occupies a thickness below the surface of the adjacent carbon precursor material, which is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
The disordered, amorphous, non-graphene material extends to a distance below the surface of the carbon precursor material, said distance being at least 10 μm.
The disordered, amorphous, non-graphene material extends from the outer surface of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
The ablation laser beam or the second laser beam can be defined by the following optional characteristics:
The parameters of a laser beam include one or more of the following: intensity, wavelength, pulse duration, pulse profile, scanning speed, and heat generated in the subsurface region or packaged region.
Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
Changing laser parameters alters one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
The second laser beam alters the carbon foam as part of the process that exposes it.
The second laser beam alters the shape of the carbon foam as part of the process that exposes it.
The second laser beam is automatically controlled to scan on the same, and/or overlapping, and/or non-overlapping areas (e.g., raster scanning).
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
The carbon precursor material has an absorption coefficient for the second laser beam that is greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam that is greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300±50 cm⁻¹ .
The laser power is typically in the range of 8-20 watts, with 12W being optimal.
The typical working range of laser focal length is 50mm-400mm.
The second laser beam scans in a pattern that includes non-overlapping areas or lines.
The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam can be defined by the following optional characteristics:
The carbon foam has a thickness of at least 50 μm.
The thickness of the carbon foam ranges from 50 μm to 300 μm.
Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
Carbon foam is or includes carbon foam with a defective spatial distribution, resulting in high electrochemical reactivity.
Carbon foam is or includes carbon foam with vacancy basal defects, resulting in high electrochemical reactivity.
The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Carbon foam has one or more of the following properties:
Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
It has strong adhesion to the underlying flexible substrate.
High porosity
High electrical conductivity
Increase in capacitance or charge storage
Rapid absorption of organic solvents and water-based solutions.
ο Higher hydrophilicity
οEMI shielding high
Electrode quality enhancement
The contact angle is approximately 20° or less.
The properties of carbon foam can be selected by choosing specific laser parameters to generate carbon foam materials with one or more of the following desired properties or parameters: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
Group 3: Products
Feature L1: Biosensor
Carbon foams fabricated using the dual-laser method described above have wide applications in many different types of sensors. For simplicity, we will use the phrase "carbon foam" in this feature to refer to any carbon foam or 3D carbon material foam fabricated by the methods described in this specification. Appendix 1 includes further details on this field, describing in more detail a biosensor comprising a carbon foam functionalized by adding receptors specific to a target or analyte, and a connector enabling the receptors to attach indirectly to the carbon foam; (some receptors cannot attach directly to the carbon foam because of their poor stability in contact with a surface; instead, a connector must be used as an intermediary between the carbon foam and the receptor. During fabrication, the connector is first added to the carbon foam, and then the receptor is added to the connector.)
For biosensor applications, functionalized carbon foam has the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; enhanced wettability; and a contact angle of approximately 20° or less.
At a higher level, functionalized carbon foam can be used in sensors because it can generate detectable changes in state; its high sensitivity is a function of its large surface area. It can be used to detect specific chemicals, specific gases, mechanical stress, and temperature, among other variables. We will briefly look at each category.
First, chemical sensors: Chemical detection systems rely on detecting the electrical response of carbon foam when a target chemical substance is present; many different detection principles can be used, such as changes in capacitance, resistance, voltammetry, redox potential, and charge transfer resistance.
For example, the binding can be detected when a specific analyte or target binds to a carbon foam because it alters the surface of the carbon foam. Biomolecules, such as specific antibodies or aptamers (aptamers are short, single-stranded DNA or RNA molecules that can selectively bind to specific targets, including proteins, peptides, carbohydrates, small molecules, toxins, and living cells), are added to the carbon foam. When the target is present and binds to the aptamer, the morphology of the aptamer changes (e.g., by reducing surface area), and the capacitance of the combined carbon foam and aptamer system decreases in a measurable manner.
Using this principle, highly sensitive and selective sensors can be built; due to the quantitative reduction of measurable variables (e.g., capacitance), a LOC (lab-on-a-chip) can be built, which includes not only carbon foam and aptamer biosensors, but also power sources on the LOC, such as supercapacitors or other energy storage devices using carbon foam as their electrodes, as well as circuitry for measuring variables, calculating biosensor outputs, and displaying said outputs (e.g., the presence or absence of a target; the concentration of a target) on the LOC screen; this is further described in the feature O3 (Gii-Thru: HISLOC for Gii-Sens).
Carbon foam sensors can also measure the redox potential of a target; for example, a current peak can be detected when the oxidation of a target chemical is catalyzed by a specific catalyst added to the carbon foam; since the current is usually a function of the concentration of the target chemical, it is possible to quantitatively measure the target concentration.
Other technologies already applied to conventional graphene sensors, such as thermal conductivity measurements for detecting specific chemicals, resistance measurements for inferring temperature, physical deformation, or transitions in the presence of specific chemicals, and piezoresistive deformation for detecting motion, can all be applied to carbon foam sensors fabricated using the dual-laser method described above.
An important application of the large electrochemically effective region and fast electron transport rate of carbon foam generated by a dual-laser method is the implementation of an electroanalytical sensing electrode optimized for biosensing (called "Gii-Sens").
For example, the electroanalytical sensing electrode can be used in point-of-care diagnostic devices; the sensing electrode has extremely high sensitivity, reliability, purity, wettability and conductivity.
Figure 20A is a perspective view of a biosensor called Gii-Sens. The assembly consists of: a polyimide substrate 201; a working electrode 202 made of Gii carbon foam; a counter electrode 203 made of Gii carbon foam; a reference electrode 204 made of screen-printed silver-silver chloride; three screen-printed silver connection traces 205; and a screen-printed dielectric layer 206.
Figures 20B-20D show the four main manufacturing stages. Figure 20B shows step 1, in which the dual-laser process uses a polyimide substrate 201 as a precursor to produce a Gii carbon foam working electrode 202 (area of 18.94 mm² ) and a counter electrode 203 (area of 20.84 mm² ).
Figure 20C shows step 2, in which a silver-silver chloride reference electrode 204 (with an area of 8.99 mm² ) is screen-printed onto a polyimide substrate 201.
Figure 20D shows step 3, in which silver connection traces 205 are screen-printed onto the polyimide substrate 201; these overlap with the carbon foam electrodes at the electrical contact regions 207. The area of the silver traces is 1 x 18.85 mm² , and the area of the three silver traces is 3 x 56.55 mm² . The area overlapping with the underlying carbon foam electrodes is 1 x 2.21 mm² , and the area overlapping with the three carbon foam electrodes is 3 x 6.63 mm² .
Figure 20E shows step 4, in which the dielectric layer 206 is screen-printed over carbon foam electrodes 202, 203, 204 and silver connection traces 205. The active regions of the electrodes are as follows: working electrode 202: 12.64 mm² ; counter electrode 203: 14.18 mm² ; reference electrode 204: 2.59 mm² . The exposed areas of the silver connection traces 205 are 1 x 7.15 mm² and 2 x 21.45 mm² .
Figure 20F shows a single polyimide sheet on which an array of 100 carbon foam working and counter electrodes has been produced using the dual-laser process described in step 1 above. The sheet is a standard type of polyimide sheet, 220 mm × 180 mm, allowing it to be processed using standard screen printing and laser scanning equipment; it can be A5 size or any other suitable size.
Figures 20G and 20H show the final form of the sheet after step 4. 100 individual units can be cut and assembled into 100 finished Gii-Sens biosensors.
One specific use case for the Gii-Sens sensing electrode is a reversible polymer displacement sensor mechanism for electrochemical glucose monitoring. A graphene sensor for this use case has been proposed: see "Polymer indicator displacement assay: electrochemical glucose monitoring based on boronic acid receptors and graphene foam competitively binding with poly-nordihydroguaiaretic acid", Wikeley et al., DOI:10.1039/d1an01991k. This paper describes glucose... A pyrene-derived boric acid chemical acceptor was adsorbed onto a graphene foam electrode. The spontaneous oxidative polymerization of nordihydroguaiacol (NHG) onto the graphene foam electrode yielded a redox-active membrane (poly-NHG) covalently attached to the boric acid acceptor. Oxidation of the poly-NHG released the boric acid acceptor to interact with glucose in the solution phase, which was detected due to competitive binding upon recombination of the reduced poly-NHG with the boric acid functional groups. The sensor exhibited the expected boric acid selectivity for fructose-glucose. Glucose sensing was performed using the charge ratio at the voltammetric peaks of unbound and bound poly-NHG, with a substantially linear analytical range from 1 to 50 mM glucose in a pH 7 aqueous buffer.
The implementation of Gii-Sens sensing electrodes offers several advantages over current sensing electrodes, such as those used in graphene sensors:
It uses amplification-free, enzyme-free, and label-free electrochemical biosensor with a low detection limit.
Enhanced reproducibility.
Optimize the available dynamic range.
Minimize background noise.
Reduce planning time and operations.
It is scalable for low-cost manufacturing.
High sensitivity and selectivity.
Provide quantitative numerical results.
It can be printed into specific patterns, such as interdigitated patterns, to achieve miniaturized integrated devices.
Existing biometric and testing formats (e.g., ELISA, PCR, RT-PCR) can be translated into electrochemical microfluidic POCs without affecting performance quality.
It can perform impedance-based measurements with extremely high sensitivity, reliability, and extremely low background signal interference.
It replaces expensive, large-scale laboratory testing and low-sensitivity lateral flow testing.
It can be implemented in microfluidic analysis (single-objective or multi-objective) and lab-on-a-chip (LOC) devices.
It can be used in any sensor application where the user aims to immobilize (biological) molecules of interest (e.g., the carboxyl/n-hydroxysuccinimide moiety can be added to the sensor surface to provide a platform for subsequent immobilization and conjugation chemistry reactions).
It can be used for a variety of diagnostics: point-of-care (POC) human and animal health, food safety, in-situ environmental health and safety, and agricultural health and safety, all of which have enhanced biosensing sensitivity, selectivity, and reproducibility due to its purity and high specific surface area.
Enhanced wettability (e.g., contact angle below about 20°).
Enhanced stain resistance.
We can summarize it as follows:
A method of manufacturing a biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
L2: Fabricating carbon foam biosensors in a scalable and low-cost manner using screen printing technology.
We have already seen above how screen printing is widely used in manufacturing processes: it is a well-known, scalable, predictable, and low-cost technology. The detailed manufacturing process of the Gii-Sens carbon foam biosensor is shown in Figure 21.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric to at least partially cover the electrodes and connection traces.
Optional features include the following:
In the method defined above, in step 1, the dual-laser process uses a PI substrate as a precursor to generate a carbon foam working electrode and a counter electrode.
In the method defined above, in step 2, a reference electrode, such as a silver-silver chloride electrode, is screen-printed onto a PI substrate.
The method defined above, in step 3, involves screen printing connection traces, such as silver traces, onto a PI substrate to overlap with the carbon foam electrode. Note: The order of steps 2 and 3 can be reversed.
The method defined above, wherein in step 4, a dielectric layer is screen-printed over at least some of the carbon foam electrodes and silver connection traces.
Other aspects include:
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each sensor electrode comprising at least partially a carbon foam made by a method defined as any one of features A-K above, and each sensor electrode being electrically connected to a screen-printed track and also at least partially covered by a screen-printed electrolyte.
A point-of-care diagnostic device comprising a biosensor as defined above.
L3: Adding functional groups to biosensors at different manufacturing facilities
For Gii-Sens biosensors, the biosensors are manufactured in one facility, but customers add functional groups that biomolecules can attach to in another facility (usually their own). This accelerates the development and testing of these functional groups and also protects their trade secrets and proprietary technology in the final design of these functional groups and the biosensors.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in a different manufacturing facility.
L4: Adding functional groups to biosensors is part of the biosensor manufacturing process.
For the Gii-Sens+ biosensor, the manufacturing process includes adding functional groups. Figure 22 shows the detailed manufacturing process of Gii-Sens+.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
L5: Using PPC to manufacture biosensors: Post-printing conversion
A PPC variant of the Gii-Sens manufacturing process is shown in Figure 23. PPC is an abbreviation for "Post-Print Conversion," in which the screen printing step is completed before the dual-laser process to create carbon foam. The specific steps are as follows:
1. Screen printing a carbon layer onto a substrate (e.g., polyimide).
2. Screen-printed Ag/AgCl reference electrode
3. Screen printing Ag electrical connection traces
4. Screen-printed dielectric
4. Use a dual-laser process to generate carbon foam in the substrate.
All screen printing steps (1-3) can be completed using roll-to-roll or roll-to-sheet processes, followed by the use of a dual-laser process to generate carbon foam, and then the materials are kept flat and stacked.
Alternatively, only the first laser process (subsurface foam generation) can be completed in the facility, after which the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation). The customer can add functionalizing groups in their own manufacturing facility, different from the facility performing the first laser process step (or both laser process steps) in the dual-laser process. Alternatively, functionalization can be performed in the facility performing the dual-laser process.
Screen printing before manufacturing the carbon foam has advantages: because we don't dry the carbon foam, it's less hydrophobic. The carbon layer acts as a bridge between the carbon foam formed in the polyimide (e.g., carbon foam and non-graphene disordered amorphous foam) and the silver connectors.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode including at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on the substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon and the electrical connection trace and the reference electrode; and then (d) producing the carbon foam sensor electrode using a method as defined in any one of features A-K above.
Feature M1: Energy storage device: supercapacitor
Because carbon foam manufactured using any one of the characteristics A-K has a very large electrochemical active region and a fast electron transport rate, it is an ideal material for electrodes of capacitors, supercapacitors, or pseudocapacitors.
One important application is in supercapacitors (specifically implemented as "Gii-Cap") or other energy storage devices (e.g., lithium-ion batteries). For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; and higher wettability.
Carbon foam can be processed with metal oxides or other pseudocapacitive materials (variants of which we call Gii-Cap+) (e.g., to produce metal oxide layers or films), and the metal oxide films have extremely large surface areas and fast surface Faraday mechanisms.
It should be noted that when we use the term Gii-Cap, we include the Gii-Cap+ variant unless the context explicitly indicates that we specifically exclude the Gii-Cap+ variant. It should also be noted that we use the term "supercapacitor" to include (i) electrically double-layer (EDLC) capacitors, where charge is stored electrostatically with no interaction between the electrode and electrolyte ions, and (ii) pseudocapacitors, where there is electron charge transfer between the electrode and electrolyte, and in any energy storage device using a combination of electrically double-layer capacitors and pseudocapacitors. Finally, it should be noted that the term "supercapacitor" should be broadly interpreted to cover any electrochemical capacitor, including EDLC supercapacitors, pseudocapacitors, and mixtures of these. The Gii-Cap+ variant is primarily a pseudocapacitor, but we still refer to it as a "supercapacitor."
Compared to conventional supercapacitors, the carbon foam electrodes in the Gii-Cap supercapacitor enhance both electrostatic double-layer capacitance and electrochemical pseudocapacitance. Appendix 2 provides further details about the supercapacitor and describes a specific implementation in which an interdigitated carbon foam electrode in the active region is encapsulated by a hydrogel electrolyte (e.g., a salt with a high molar concentration) to generate an enhanced operating voltage window.
The implementations of EDLC supercapacitors Gii-Cap and pseudocapacitors Gii-Cap+ offer numerous advantages over conventional rechargeable batteries:
Fast charging
High power
Recyclable
Not easy to explode
Flexible forms and shapes
Solid gel electrolytes or polymeric electrolytes (e.g., ionogels or hydrogels) can be used, which are solid at room temperature and have a high transition temperature far exceeding the normal operating temperature (e.g., 90°C); this greatly reduces the risk of electrolyte leakage.
It can be used in a very wide range of devices and power storage needs, such as lab-on-a-chip (LOC), IoT devices, electric vehicles, UAVs, and EV applications.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
Figure 24 is an exploded perspective view of the Gii-Cap supercapacitor. It consists of a series of carbon foam electrodes 241 connected to a pair of screen-printed silver connectors 242, fabricated using the dual-laser process described above. A dielectric layer 243 is screen-printed over the carbon foam electrodes 241 and the screen-printed silver connectors 242. The carbon foam electrodes 241 are formed on a polyimide substrate 244. A pair of copper connector tabs 245 are connected to the pair of screen-printed silver connectors 242. An electrolyte layer 246 covers the carbon foam electrodes 241 (e.g., an ionogel electrolyte, such as a polymer hydrogel electrolyte, which is a gel or semi-solid at room temperature to minimize the risk of leakage and reversibly liquefies above 90°C, thus allowing application in liquid form during manufacturing). The assembly is sealed within an aluminum laminate heat-sealed bag 247.
Figure 25 is an exploded perspective view of a supercapacitor assembly: it consists of an interdigitated array of carbon foam electrodes 241 forming the supercapacitor; a screen-printed silver connector track 242 provides current to the carbon foam electrodes 241 and is covered by an electrically insulating dielectric layer 243. A polyimide sheet 244 forms the base of the assembly.
Figures 26A-H illustrate the manufacturing sequence. Figure 26A shows step 1, where interdigitated carbon foam electrodes are produced using a dual-laser process. The magnified area in Figure 26B shows the interdigitated carbon foam electrodes in more detail; group A electrodes form an electrode assembly, and group B electrodes form another electrode assembly; capacitive coupling between the two groups of electrodes stores energy. The carbon foam electrodes have a thickness of approximately 20-30 μm.
Figure 26C shows step 2, screen printing the silver collector electrodes. A silver connector A' supplies current to the A group of electrodes, and a silver connector B' supplies current to the B group of electrodes. The thickness of the silver layer is approximately 20-40 μm, and several layers can be applied.
We use a "common collector" layout: a typical interdigitated supercapacitor has two long silver collectors with graphene fingers extending from one side of each long silver collector. The long silver collectors have high resistance due to their length and require a significant amount of silver. Furthermore, printing the curved portions of the collectors is difficult. In the "common collector" method shown in Figure 26D, we have carbon foam fingers C extending from both sides of the shared collector 242: this maximizes the space utilization of the fingers and therefore maximizes the capacitance, reduces the amount of collector material required, and eliminates the difficult curved collector portions.
The region 250 of the carbon foam finger connected to the common collector electrode has rounded edges; these rounded edges reduce the chance of stress fracture and increase the reliability of the electrical connection.
Figure 26F shows step 3, in which the dielectric layer 243 is screen-printed over the silver collectors to make them electrically insulated; the thickness is approximately 10-30 μm.
Figure 26G shows step 4, adding copper connector tab 245 (made of conductive metal strip) to connect to the silver current collector 242. Figure 26H shows step 5, depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions. The electrolyte can be a combination of hydrogel and salt (see Appendix 2). Figure 26I shows step 6, packaging the entire assembly into an aluminum laminate heat-sealed bag 247, leaving only the copper connector tab 245 exposed. It should also be noted that step 4, adding the copper connector tab 245, can be performed before step 2 (screen printing the silver current collector) and after step 5 (depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions).
Figure 27 shows how a single polyimide sheet will accommodate six 220mm × 180mm Gii-Cap components; other sizes (e.g., A4, A5, A6, or sizes other than the standard A-series sizes) are also possible.
The detailed manufacturing process of Gii-Cap is shown in Figure 28.
The specifications for producing and operating Gii-Cap supercapacitors using hydrogel electrolytes in a single production run are shown in Table 3 below.
Table 3
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, the screen-printed electrical connection traces are formed above at least a portion of each electrode, and the screen-printed dielectric layer at least partially covers the electrodes and connection traces.
Feature M3: Carbon foam supercapacitor: common collector electrode
We saw how to use a "common collector electrode" above.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrodes comprise at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
PPC (Post-Printing Conversion) is shown in Figure 29. The steps are as follows:
1. Screen print the silver current collector onto a substrate (e.g., polyimide).
2. Print carbon screen printing over the silver current collector and then dry it.
3. Screen print the dielectric over the carbon layer and then dry it.
4. Carbon foam is generated in the carbon layer using a dual-laser process; the carbon foam is attached to the underlying polyimide substrate via a non-graphene interlayer.
5. Distribute electrolytes.
6. Add copper/aluminum inserts to make contact with the silver collector (or step 1).
7. Add a cap/small bag.
All screen printing steps (1-3) can be completed using a roll-to-roll process, followed by the generation of carbon foam using a dual-laser process, and then the material is kept flat and stacked. Alternatively, only the first laser process (generating carbon material foam under the surface) can be completed in the facility, and then the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation) and steps 5-7.
Screen printing before fabricating carbon foam has advantages: if carbon foam is made first, it may have sharp edges; the silver screen printing layer applied over these sharp edges may crack at these edges. However, by screen printing before creating the carbon foam, we avoid this problem. Additionally, because we don't dry the carbon foam, it is not hydrophobic.
We can summarize it as follows:
A method for manufacturing energy storage devices such as supercapacitors or pseudocapacitors;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
The Gii-Cap+ variant is produced using a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x ); its capacitance is much higher than that of the standard Gii-Cap device (see Table 4).
Table 4
This metal oxide electrochemical deposition process can be applied to both the Gii-Cap Supercap manufacturing process and the PPC process, and therefore all Gii-Cap products can also be Gii-Cap+ products. A detailed process flow diagram is shown in Figure 29.
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying a pseudocapacitive material, such as a metal oxide, to the energy storage electrode via an electrochemical deposition process.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
We use an ionic gel (an ionic liquid with fumed silica SiO2 ) that provides a voltage of 3V-6V. It is solid below 90°C, so it does not leak during transport and normal use, and is therefore particularly suitable for smart tags and IoT devices; above 90°C, it liquefies, and is therefore printable, with electrochemical printing occurring at temperatures above 90°C. Ionic gels are typically made from an ionic liquid (e.g., 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4)) plus a gel-forming agent (e.g., fumed silica SiO2 )).
Typically, manufacturing is carried out in an inert atmosphere (e.g., argon) because the presence of O2 and H2O can lead to a decrease in voltage and stability.
The optimal sites for achieving the best balance between increased capacitance and decreased voltage for O2 and H2O levels are described in more detail in Appendix 3 (GiiCap Iongel).
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
In the preceding sections covering features M1-M6, we focused on some general characteristics of Gii-Cap carbon foam supercapacitors. In the following sections covering features N-S, we focus on some more specific products that realize Gii-Cap.
Feature N1: Electrical conductor
For the biosensor devices described above, it is possible and desirable to fabricate electrical conductors providing measurement signal connections from carbon foam materials produced by a dual-laser method: because these conductors have extremely low resistance, sensitivity is maximized. Electrodes (e.g., functionalized biosensor working electrodes, and reference electrodes described above as being screen-printed; capacitor plate electrodes) are examples of electrical conductors covered by this feature N1. Additionally, this feature N1 also covers electrodes whose primary function is solely to carry signals and current, for example, to replace conventional silver connection traces, such as the screen-printed Ag electrical connection traces we described in the biosensors above.
We can summarize it as follows:
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
Features L1-L4 above describe biosensors using carbon foam fabricated by a dual-laser method in their sensor electrodes; features M1-M6 describe supercapacitors and pseudocapacitors using carbon foam fabricated by a dual-laser method in their electrodes.
A highly sensitive and selective biosensor can be established, and this biosensor and this supercapacitor can be combined into a single integrated device. The device also includes electronic circuitry for measuring the detected or measured variable, calculating the biosensor output and sending the output to a POC diagnostic device or displaying the output on the device's display screen (e.g., the presence or absence of the target; the concentration of the target).
Figure 30 is a schematic cross-section of this integrated LOC device: there are two separate polyimide membrane layers, the upper layer 301 comprising a functionalized carbon foam biosensor (Giii-Sens) 302, as described in feature L; and the lower layer 303 comprising a supercapacitor 304 (Giii-Cap), as described in feature M. Although the polyimide layers are shown back-to-back, they can also be arranged side-by-side; additionally, a single polyimide membrane can be used to integrate the biosensor 302 and the supercapacitor 304 together onto a single object.
A plastic component 305 with microchannels 306 provides a microfluidic system for dispensing test fluid over the biosensor 302; a subsurface carbon foam electrode or conventional connector track 307, as described in Feature O, guides the biosensor to a flexible electronics 308 (e.g., a microcontroller for measuring changes in the electrochemical properties of the biosensor in the presence of a target analyte; a display panel for displaying diagnostic results; a power management system for controlling power from the supercapacitor 304 to the electronics 308). The supercapacitor 304 (Gii-Cap) is charged (e.g., via a wireless sensing process (not shown) controlled by the microcontroller) and provides power for the biosensor measurement process and an integrated display showing the quantitative measurement results. Alternatively, a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) can charge the supercapacitor 304, which then provides power for the biosensor measurement process. Another variation uses a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) that charges the supercapacitor 304 and also provides power for the biosensor measurement process. The supercapacitor 304 is then reserved for powering high-power processes, such as wireless data transmission, enabling the LOC to function as a standalone LOC device capable of diagnostic processes and wirelessly transmitting result data without requiring the user to be near the LOC, which would be necessary if the LOC used conventional NFC (Near Field Communication). The electrical connector trace from the supercapacitor 304 to the flexible electronics 308 is not shown.
An exploded view of the fully integrated LoC device is shown in Figure 31. From the bottom up, we have (i) an induction power circuit 310; (ii) a Gii-Cap supercapacitor 312, which is wirelessly powered by the induction circuit 310; (iii) a Gii-Sens biosensor 313; (iv) a layer 314, which has electronics for the biosensor powered by the supercapacitor 312 and microfluidic channels; and (v) a top panel 315, which includes a display 316, also powered by the supercapacitor, and an annular aperture 317 into which samples are delivered.
Figure 32 shows the LOC (Local Occurrence) of the quantitative results displayed on its monitor.
Figure 33 shows an exploded view of an environmental monitoring device including a Gii-Sens sensor 330 configured to detect environmental parameters such as CO2 levels, volatile organic compounds, and other atmospheric pollutants. The Gii-Sens is not limited to being a biosensor and can also detect any molecule that can be functionalized to detect using a carbon foam sensor electrode. The environmental monitoring device includes the Gii-Sens sensor 330 and associated control and wireless transmission (e.g., LoRaWAN) electronics 331, as well as a PV solar cell 332 and a Gii-Cap supercapacitor 333. The electronics 331 include a secondary or primary battery (which may be a printed battery) and work in conjunction with the PV solar cell 332 to power those electronics and charge the Gii-Cap supercapacitor 333. The Gii-Sens sensor can also be configured to measure temperature, humidity, and pressure. The device has a back 334 that can be peeled off to expose an adhesive surface, allowing the device to be attached to a wall, etc. The PV solar cell, combined with a secondary or primary battery on electronic device 331, provides power to charge the Gii-Cap supercapacitor 333, which in turn provides the peak burst power required for data transmission. Unlike current environmental monitoring devices, this device can be permanently installed and maintained in place for many years without requiring battery replacement. It can detect atmospheric pollutants with a signal-to-noise ratio superior to conventional devices. The assembled device is shown in Figure 34.
Many other types of devices can be realized using a combination of carbon foam sensors and carbon foam supercapacitors; for example:
Any biosensor capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor, can benefit from wearable health monitoring devices such as continuous glucose monitors and other wearable monitors that sense electrolyte, potassium, sodium, and lactose levels.
This benefits from any sensor device capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor.
This benefits from any IoT device capable of transmitting data (e.g., wirelessly), where the data transmission is powered by a supercapacitor.
The device may include electronic components powered by a supercapacitor.
The device may include a battery to charge energy storage devices and/or power device electronics.
The device may include a PV battery to charge a secondary battery in an energy storage device and/or in a device and/or power device electronics.
We can summarize it as follows:
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
In this example, we combine two distinct power sources into a single device to form a combined or hybrid power source: the device has a battery (e.g., a printed battery or a conventional battery) and a supercapacitor, the supercapacitor using carbon foam made by a dual-laser method in its electrodes; they work together in a complementary manner. The battery can be a disposable, non-rechargeable battery (“primary” battery), or it can be a rechargeable battery (“secondary” battery).
The power sources serve complementary purposes: batteries can provide slow, long-term charging for supercapacitors or power relatively low-power-consuming electronic devices; supercapacitors can provide rapid, high-power discharging and power functions requiring higher power levels, such as wireless data connectivity and data payload transmission. It should be noted that the supercapacitor can be an EDL supercapacitor or a pseudocapacitor, or any other form of energy storage device. The device can be used in situations where high power is occasionally required (e.g., powering a transmitter to connect to a data network and send data payloads), but the device needs to be standalone and continuously used in the field for months or years: the device could be a high-value asset tracking tag that only occasionally needs to broadcast its information, but requires broadcasting at a higher power than conventional printed batteries can provide.
A schematic diagram is shown in Figure 35. There are two separate polyimide film layers: one layer 351 includes a supercapacitor (Gii-Cap) 352 as described in feature M, and the other layer 353 includes a cell 354, such as a printed cell; this can include electrodes made using carbon foam manufactured using a dual-laser process or conventional processes. It is also possible to fabricate the printed cell 354 and the supercapacitor 352 on the same sheet of polyimide, but yield may be affected because any defects in the printed flexible cell or supercapacitor will render the equipment unusable.
As described above, the subsurface carbon foam electrode (or conventional printed electrode) leads from the supercapacitor (Gii-Cap) 352 and the printed battery 354 to the BMS (Battery Management System) 355; the BMS 355 provides power to the flexible electronics 356; the subsurface carbon foam electrode or conventional connector track 357 connects different parts of the flexible electronics 356. The BMS 355 controls the flow of power from the battery 354 to the electronics 356; the battery 354 can trickle charge the supercapacitor 352. (The supercapacitor can also be the primary power source, designed to be charged once in the facility and then not need to be recharged.)
Battery 354 can be a printed battery, and can be a rechargeable secondary printed battery or a primary, non-rechargeable primary battery; battery 354 can trickle charge supercapacitor 352 and provide power to sensor or other device electronics 356; then, supercapacitor 352 provides power (e.g., instantaneous peak power) to circuits (such as data transmitters) that have short-term demands for relatively high burst power. As described above, the printed battery, supercapacitor, and electronics can all be part of a single integrated device, for example, all on a single substrate, or on a separate but attached substrate.
Although back-to-back polyimide layers are shown, they can also be side-by-side; in addition, there can be a single polyimide film that integrates the battery 354 and the supercapacitor 352 into a single object.
The battery 354, supercapacitor 352, and electronic device 356 can all be formed on one or more substrates as part of a continuous or batch manufacturing process (e.g., you don't use a previously manufactured battery and combine it with a supercapacitor). This allows the interconnects to be constructed as an integral part of the manufacturing process, resulting in lower costs, faster manufacturing, and higher performance (e.g., shorter interconnects).
The device can be used in smart tags (see below), or IoT environmental monitoring devices (e.g., temperature or humidity sensors), train seat occupancy sensors, or medical monitoring devices (e.g., continuous glucose monitors). More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
We can summarize it as follows:
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
One important application is the smart label, shown in Figure 36, with the bottom surface shown on the left and an exposed label surface 363 with human-readable text shown on the right. The label includes an adhesive release liner 364 to allow the bottom surface to be attached to packaging, components, etc. The label includes a thin, flexible battery 360 printed onto a polyimide film, and then a Gii-cap supercapacitor 361 formed on the same polyimide layer (or a different polyimide layer bonded to the printed battery polyimide film). The thin, flexible battery can be a non-rechargeable primary battery or a rechargeable secondary battery. The supercapacitor provides power to the data transmitter; the printed battery provides power to the smart label's electronics (including sensors) and power management electronics. Human-readable printed information 363 is included on one surface of the smart label; the back side...
The smart tag includes an electronics module 362 with power management, sensors (e.g., solid-state vibration, temperature, pressure, GPS, etc.) and data transmission electronics (e.g., an LTE transmitter or an ultra-low-cost LoRaWan transmitter). Once a data connection is established, the supercapacitor 361 provides sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in an "advertising" signal; instead, the smart tag can establish a data connection with a data receiver and then transmit the data payload once the connection is established; thus, it can be reasonably ensured that its data has been received. More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
For scalable manufacturing (e.g., producing millions of smart tags at low cost), roll-to-sheet manufacturing of smart tags is ideal (see Feature P: Gii 3 below).
We can summarize it as follows:
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics such as sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
The supercapacitor in the aforementioned example of feature M can provide power to the antenna but is not integrated with the battery: for example, it can provide power from a solar cell or draw power from local WiFi or a wireless charger (e.g., the Qi standard).
We can summarize it as follows:
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor
A useful feature is the combination of an energy harvester with a carbon foam supercapacitor. The energy harvester can be a solid-state energy harvester such as a solar cell, or a vibratory energy harvester (e.g., based on piezoelectric fibers), or a thermoelectric generator (e.g., a Seebeck generator). The supercapacitor can provide power (e.g., instantaneous power) to circuits with short-term demands for relatively high burst power (e.g., data transmitters and antennas). The device may also include a primary battery (e.g., a non-rechargeable printed battery) or a secondary rechargeable battery.
The energy harvester can be on the same substrate as the supercapacitor, or on a separate but connected substrate; the supercapacitor can be on the same side of the substrate as the energy harvester, or on opposite sides.
When the device includes a battery (e.g., a printed rechargeable secondary battery), the energy harvester charges the battery, and the battery provides power to low-power subsystems (e.g., sensors) and also charges the supercapacitor; the supercapacitor provides instantaneous high power for data transmission. Alternatively, the energy harvester can charge the supercapacitor directly.
This approach can be used in smart tags, or IoT environmental monitoring devices (such as temperature or humidity sensors), train seat occupancy sensors, wearable devices, and medical monitoring devices (such as continuous blood glucose monitors). This method is particularly useful in situations requiring continuous (or highly regular) power to the device, such as when continuous monitoring of the environment or an individual's health is necessary.
The device may include LoRaWan or other ultra-low power transmitters. Once a data connection is established, the supercapacitor can provide sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in the announcement signal; instead, the smart tag can establish a data connection with the data receiver and thus ensure that its data has been received.
More generally, the energy harvester can be a solid-state energy harvester, such as a solar cell, or a vibration energy harvester (e.g., based on piezoelectric fibers) or a thermoelectric generator (e.g., a Seebeck generator); the device can include one or more sensors powered by the energy harvester; the energy harvester can charge a supercapacitor; the device can include a primary or secondary battery; the device can be a smart tag, or an IoT environmental monitoring device (e.g., a temperature or humidity sensor), a train seat occupancy sensor, a wearable device, or a medical monitoring device.
We can summarize it as follows:
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
In an earlier chapter, we described the carbon foam in the Gii-Cap supercapacitor as a single planar interdigitated finger layer. In this section, we describe a three-dimensional structure of carbon foam that enables the carbon foam supercapacitor electrodes to be formed as a parallel-plate 3D structure with a greater energy storage potential than a single layer of interdigitated graphene foam fingers.
Figure 37 shows the basic layering of different materials in the core structure. Multiple screen printing steps are performed on the PI polyimide film 371 sheet. First, a conductor (such as a carbon ink or carbon paste layer 372) is screen-printed onto the lower surface of the polyimide film 371. Then, a current collector 373 (e.g., a screen-printed silver current collector) is screen-printed over the carbon layer 372. Finally, a dielectric layer 374 is screen-printed over the current collector.
Figure 38 shows the carbon foam layer formed in the polyimide film 371 using the dual-laser process described above: more specifically, an IR laser forms an encapsulated carbon foam layer 375 in the PI film 371; beneath this carbon foam layer is a disordered, amorphous, non-graphene layer 376 formed on the lower surface of the PI film 371. A CO2 ablation laser exposes the previously encapsulated carbon foam layer 370, thereby giving the exposed surface layer 377 a unique morphology.
This structure provides a conductive path from the current collector layer 373, through the conductive ink or paste layer 372, through the disordered amorphous non-graphene layer 376, and then to the carbon foam layer 375. In this way, the potential of the large-area carbon foam 375 can be increased, enabling it to act as a capacitor plate; the structure forms part of a half-cell.
Typical thicknesses are as follows: polyimide film 371: 127 μm; carbon ink layer: 20 μm; silver current collector layer 373: 30 μm; dielectric layer: 40 μm; carbon foam layer 375 and disordered amorphous non-graphene layer 376: 127 μm; unique surface morphology layer 377: 25 μm.
It should be noted that Gii-Cap+ (a variant that uses a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x , see Feature M2 above) and delivers significantly higher capacitance than the standard Gii-Cap device) can be used in Gii-Thru.
We can summarize it as
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising a carbon foam material made at least partially by a carbon precursor film as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Multiple structures as described in Figure 38 can be stacked together; since the surface area of the carbon foam layer can be very large (significantly larger than the surface area of the finger sites in the previously described planar interdigitated supercapacitor), this enables the production of high-performance supercapacitors.
The half-cell is illustrated in Figure 39. It comprises (gradually moving downwards through the structure): a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in a PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper tabs 395 for connection points; a screen-printed dielectric isolation layer 396; a second carbon foam layer 397 with a unique surface morphology in a PI film 398; and a hydrogel electrolyte layer 399 at the base of the stack. It may be helpful to associate this structure with the schematic diagram in Figure 38: in Figure 40A, we group the four main layers shown in Figure 38 at point A, i.e., moving downwards along the stack, the carbon foam layer, then the carbon ink layer, then the silver collector layer, and then the dielectric layer. Figure 40B is a cross-section of the structure of Figure 40A, showing the features of group A. Figure 40B is the same cross-section, but this time all the elements in Figure 39 are labeled.
The complete unit is shown in Figures 41A and 41B. In Figure 41A, we only label the features that are also present in Figure 39 (using the same numbering). So it includes: a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in the PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper inserts 395 for connection points; and a screen-printed dielectric isolation layer 396.
In Figure 41B, we now add an additional layer; moving down through the structure, we have a screen-printed dielectric insulating layer 400, followed by a screen-printed silver collector layer 401 with copper inserts 402, then a screen-printed carbon paste layer 403, and then a carbon foam layer 404 with a unique surface morphology in a PI film 405.
In Figure 41C, we group the four main layers shown in Figure 38 together at point A; the four top layers are grouped together at point B in the reverse order. Groups A and B are separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399, which is dispensed using a conventional electrolyte dispensing system.
Figure 41D is a cross-section of this structure, showing the A and B layers separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399. Figure 41E is the same cross-section, but this time the layers are numbered according to the schematic diagram in Figure 38.
Figure 41F is a perspective view of the assembled supercapacitor.
Figure 42 shows a stack of four full-cell supercapacitors; the carbon foam layer is shown in A, and the polymer hydrogel electrolyte is shown in B. Additional cells can be added to the stack to obtain the desired performance.
Figure 43A shows the detailed manufacturing process of the Gii-Thru supercapacitor, and Figure 43B shows the detailed manufacturing process of the Gii-Thru multi-stacked supercapacitor.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from the carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
The Gii-Thru structure described in Figure 38 can be used not only for supercapacitors but also for Gii-Sens sensors, such as biosensors.
For microfluidics, the Gii-Thru HISLOC (High Sensitivity, Low Cost) platform approach allows liquid and carbon foam sensors to be mounted on the upper surface of the biosensor device, with electrical connectors to the carbon foam sensor mounted on the lower surface. Microfluidics typically use functionalized gold electrodes, where all electrical connectors to these functionalized gold electrodes are coplanar; compared to these functionalized gold electrodes, Gii-Thru biosensors offer advantages in cost, yield, and performance. Furthermore, moving the electrical connectors to the bottom or base of the biosensor enables greater miniaturization and compatibility with point-of-care (POC) systems.
Figure 44A is a schematic cross-sectional view of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device. The top layer has three sample wells 440; the fluid to be analyzed flows into each of these samples 440. The wells 440 are formed as small pores in a laminated spacer layer 441 located above the polyimide film layer 442.
Three functionalized carbon foam regions are formed in the polyimide film layer 442, which form a reference electrode 448A, a working electrode 448B, and a counter electrode 448C; the upper surface of each electrode 448A-448C is exposed to the analytical flow present in the pore 440.
The base of the reference electrode 448A may include an Ag-AgCl layer (or a screen-printed carbon layer) 449; the base of the working electrode 448B is a screen-printed conductive carbon layer 443; and the base of the counter electrode 448C is another screen-printed conductive carbon layer 443. In this way, the reference electrode 448A is in electrical contact with the reference electrode connector 444A; the working electrode 448B is in electrical contact with the working electrode connector 444B; and the counter electrode 448C is in electrical contact with the counter electrode connector 444C.
The screen-printed dielectric layer 447 forms the base of the structure.
The interesting aspect of this structure is that the electrode connectors 444A-C are not coplanar with the functionalized carbon foam electrodes 448A-C, unlike conventional screen-printed sensors. Instead, they lie in the plane below the functionalized carbon foam electrodes 448A-C, on the opposite side of the aperture 440. This structure enables greater miniaturization and compatibility with POC (point-of-care) systems.
Figure 44B shows an isometric exploded view of the microfluidic diagnostic device of Figure 44A. Three sample wells 440 are located in a laminated spacer layer 441, which sits above a polyimide film layer 442. A reference electrode 448A, a working electrode 448B, and a counter electrode 448C are shown; the end of the reference electrode 448A is covered by an Ag-AgCl layer or a screen-printed carbon layer 449; the working electrode 448B and the counter electrode 448C are covered by a screen-printed conductive carbon layer 443. As noted above, the reference electrode 448A is in electrical contact with a reference electrode connector 444A; the working electrode 448B is in electrical contact with a working electrode connector 444B; and the counter electrode 448C is in electrical contact with a counter electrode connector 444C.
It should be noted that the three functionalized carbon foam regions 448A-C are shown as planar squares located on different planes; however, this is merely an artificial creation of the CAD drawing used to generate the figures, and the carbon foam regions 448A-C are better represented in Figure 44A. A screen-printed dielectric layer 447 forms the base of the structure.
Figures 44A and 44B above show a three-point array microfluidic diagnostic device. In Figures 45A and 45B, we present an eight-point array microfluidic diagnostic device. In isometric Figure 45A, the laminated pore spacer 451 includes an array of eight analyte holes 452 for the working electrode, plus holes 453 for the counter electrode and holes 454 for the reference electrode; the laminated pore spacer 451 is located above the polyimide layer 455. Gii carbon foam in the polyimide layer 456 forms eight working electrodes 457 and counter electrodes 458, and is fabricated using a dual-laser process. It should also be noted that the carbon foam electrodes 457, 458 are shown as planar squares located on three different planes; however, this is merely an artificial CAD design, and the carbon foam forms a continuous region within the polyimide layer 455.
The reference electrode 459 is covered with a thin screen-printed Ag-AgCl layer. A thin screen-printed carbon bonding interface layer 460 is located below the working electrode 457 and the counter electrode 458; screen-printed silver bonding traces 461 form electrical connections with all electrodes 457, 458, and 459. Then, a screen-printed dielectric layer 462 forms the housing of the device. Figure 45B is a pair of top views of the device of Figure 45A; the lower figure shows the path of the lower bonding traces.
Figure 46A shows a perspective view of the fully assembled multi-sample array microfluidic diagnostic device; Figure 46B is a top view.
We can summarize it as
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode, at least partially made of a carbon precursor film by means of any one of the features A-K above, in a layer below the sample orifice, and a reference electrode connector, a working electrode connector, and a counter electrode connector are also in the layer below the reference electrode, working electrode, and counter electrode.
Figure 47A shows an exploded view of a microfluidic diagnostic device comprising multiple laminated layers; it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. The top layer 470 of the device is a microfluidic foil; the middle layer 471 is a microfluidic foil with an adhesive and includes printed or molded microfluidic channels 472, and the bottom layer 473 is a microfluidic foil with an adhesive. The Gii-Thru sensor 474 is a three-point array (3SA) biosensor and includes a connector 475. Figure 47B is a top view showing the internal structure. The Gii-Thru sensor 473 can be replaced with different biosensors (e.g., 8SA) for greater flexibility.
Figure 48B shows an exploded view of a microfluidic diagnostic device comprising a printed or molded microfluidic card, and it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. This device includes a transparent resin barbed connector 481, a top foil 482, a transparent resin molded microfluidic card 483 with microfluidic channels 484, a perforated unit 485 made of microfluidic foil with an adhesive, and a Gii-Thru sensor 486. Similarly, the Gii-Thru sensor 486 can be replaced with different biosensors (e.g., 8SA) for greater flexibility, and the molded microfluidic card 483 can be replaced with designs featuring different microfluidic characteristics to allow for use on different assay platforms. Figure 45B is a top and side view.
Feature O4: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
The HISLOC manufacturing process can be summarized as follows:
1. Screen print the elastic layer onto the underside of the polyimide film.
2. Screen-printed silver connectors.
3. Screen printing silver/silver chloride reference electrode (steps 3 and 4 can be rearranged into 4 then 3).
4. Screen-printed dielectrics.
5. Gii carbon foam sensor electrodes are generated in a polyimide film using a dual-laser process.
The detailed manufacturing process is shown in Figure 49.
We can summarize it as follows:
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising a carbon foam material made at least partially from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Group 4
Feature P: Scalable manufacturing: G-ii 3
Gii-3 is a scalable manufacturing facility for roll-to-roll or roll-to-sheet production of all the Gii-based materials described above. A key commercial advantage is that Gii-3 manufacturing does not require custom equipment; it utilizes off-the-shelf computer-controlled lasers for dual-laser carbon foam manufacturing, along with conventional screen printing and drying techniques: these are well-known, easy-to-understand manufacturing processes and equipment that enable reproducibility and reliability.
Figure 50 is a schematic diagram of the overall manufacturing process, and Figure 51 shows the detailed process flow.
We can summarize it as follows:
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other Gii applications
The Gii carbon foam described in this specification can be used in a wide variety of applications, including many applications where conventional graphene foam is considered suitable.
We can summarize it as follows:
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, a tactile sensor for robots; a prototype sensor is shown that uses polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as the active layer in a piezoresistive pressure sensor for robotic touch sensing applications: several carbon foam layers are capable of exhibiting pressure sensitivity of 0.0418 mV/kPa in the range of 0 to >50 kPa. See DOI:10.4028/p-oy94hj. and DOI:1109/CDE52135.2021.9455738. These contents are incorporated herein by reference to the maximum extent permitted.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection. See DOI:10.1016/j.bios.2022.114954, the contents of which are incorporated herein by reference to the maximum extent permitted.
Continuous monitoring of chemical sensors.
Glucose Monitoring Sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring is shown; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competitively binding with polynordihydroguaiaric acid. See DOI:10.1039/D1AN01991K, the contents of which are incorporated herein by reference to the fullest extent permitted.
Lactic acid sensor: Employs a synthetic organic acceptor molecule based on attaching boric acid to a carbon foam to provide functionality and selectivity in competitive analyte binding, with surface redox polymer indicator substitution used. See DOI:10.1016/j.snb2022.133089, the contents of which are incorporated herein by reference to the maximum extent permitted.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1). See DOI:10.1016/j.elecom.2022.107394, the contents of which are incorporated herein by reference to the fullest extent permitted.
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
Under a scanning electron microscope, conventional graphene foam appears to have large open ring structures, typically 500 μm in size. Carbon foam generated using a dual-laser process looks very different; Figures 52–57A are SEM images of this Gii carbon foam.
Figure 57B is a SEM image of carbon nano-onions, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI:10.1007/s00339-015-9315-9 and "Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications", DOI:10.1016/j.ica.2017.07.021. Its similarity to Gii carbon foam is obvious.
As previously mentioned, graphene foam possesses several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature features: the absence of a D peak; a 2D peak higher than the G peak; and a D:G peak ratio close to zero. However, carbon foam produced using a dual-laser process does not exhibit these characteristics; it is hydrophilic with a contact angle below 20°; and it lacks the Raman spectral signature indicative of graphene: it displays a prominent D peak; a 2D peak significantly smaller than the G peak; and a D:G peak ratio significantly higher than zero. Figure 58 shows the Raman shifts of eight carbon foam sheets fabricated using a dual-laser process, demonstrating the consistency of the Raman signature. It also shows a prominent D peak; a 2D peak smaller than the G peak; and a D:G peak ratio significantly higher than zero. As we previously stated, this Raman spectrum shares many similarities with carbon nanotube onions. See also Figure 18C, also from “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9. The specific dual-laser parameters used to generate this low-resistivity carbon nano-onion variant of Gii carbon foam are shown in Table 5 below:
Table 5
We can summarize it as follows:
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
It should be noted that any of the devices described above, such as sensors, pressure sensors, biosensors, Hall effect sensors, supercapacitors, hydrogen fuel cells, and filters, can be characterized using these materials, and therefore we can summarize as follows:
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Appendix 2 Gii-Cap+ Hydrogel
Appendix 3 GiiCap Ion Gel
Appendix 4 Feasibility Study Recommendation (3 Months)
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Material via Connectors
Appendix 6 Baseline Experimental Conditions
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
It should be noted that Appendices 1-7 describe specific implementations of Gii carbon foam.
Appendix 8: Combined list of features and optional features
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
background
A supercapacitor is a device that stores electrical charge. Based on its structure and function, a supercapacitor falls between an electrolytic capacitor and a rechargeable battery.
The properties of supercapacitors make them superior to rechargeable batteries in applications requiring short charging times and those involving many charge/discharge cycles. However, compared to batteries, supercapacitors have disadvantages including a weaker ability to store energy over long periods.
The operational limitations of supercapacitors are determined by the material properties of their components. Specifically, the maximum voltage at which a supercapacitor can operate (i.e., can be charged) depends on the stability of the electrolyte and/or electrodes. The maximum voltage of a capacitor is an important parameter, especially since the energy stored in a capacitor is proportional to the square of the voltage. Supercapacitors with organic electrolytes typically support higher voltages than those with aqueous electrolytes. By utilizing organic electrolytes, supercapacitor designers can produce devices with an operating range of 2.5 to 2.7 V. In contrast, while aqueous electrolytes are often preferred due to their lower cost and lower toxicity, they typically result in devices with a lower operating voltage range. Known symmetrical aqueous supercapacitors generally cannot support voltages higher than 1.3–1.5 V. This voltage limitation can reach 1.8–2.0 V if electrodes made of different materials are used. The limitations of water-based supercapacitors are attributed to the electrolysis of water, which, in principle, occurs when water is exposed to a potential difference of 1.23 V. However, in practice, a larger potential difference is required before electrolysis occurs to overcome the effects of overpotential.
Carbon-based electrodes have been associated with supercapacitors since their early development. Initially, carbon attracted attention as an electrode material because it offered the possibility of fabricating electrodes with large surface areas. Later in the development of supercapacitor devices, the importance of the so-called double layer on the electrode surface was realized. This complex and often elusive phenomenon, related to the use of carbon as an electrode material, is central to the high capacitance values associated with supercapacitors. Supercapacitor devices incorporating carbon-based electrodes are thought to involve a double layer on the electrode surface, with energy stored electrostatically. Such supercapacitors are called electrostatic double-layer capacitors, or EDLCs.
Other types of supercapacitors also exist. Electrochemical pseudocapacitors utilize metal oxide electrodes or conductive polymer electrodes. Compared to the electrostatic charge storage mechanism of EDLCs, charge storage in pseudocapacitors is primarily electrochemical. A third type of supercapacitor is the hybrid capacitor. Hybrid capacitors have asymmetric electrodes. One electrode is typically made of carbon and exhibits electrostatic charge storage properties; the other electrode is typically a lithium-containing or lithium-doped material, which primarily exhibits electrochemical charge storage properties.
Conventionally, a supercapacitor can be considered and modeled as two capacitors connected in series, with each electrode associated with one capacitor. Each capacitor is located at the interface between the electrode and the electrolyte and is formed by the supercapacitor electrode, a dielectric layer (called the inner Helmholtz plane) formed by solvent molecules present in the electrolyte, and a charge carrier layer (called the outer Helmholtz plane) provided by the electrolyte as the opposite charge charging the electrode. This triple structure of the electrode, inner Helmholtz plane, and outer Helmholtz plane forming the capacitor system at each electrode is called a double layer or electrical double layer.
Summary of features in Appendix 1
A first aspect of the aforementioned features provides a symmetrical supercapacitor device comprising: two electrodes, each comprising a carbon foam as described in this specification (e.g., see features A-K in Appendix 8); and an ion gel or hydrogel electrolyte encapsulating the electrodes in active regions.
We have found that symmetrical supercapacitor devices, based on a combination of the characteristics described above, produce an enhanced operating voltage window. The term "symmetrical" refers to the fact that the electrodes comprise the same material and may be constructed from the same material.
The operating voltage window, or operating range, of a supercapacitor is a critical parameter of such a device and is determined by the breakdown voltage of the electrolyte. For supercapacitors based on aqueous electrolytes, water decomposition typically leads to limitations on the operating voltage window.
Although the reasons for the unexpectedly large operating window observed using the device disclosed in this invention are not yet fully understood, it is evident, without being bound by any theory, that the special property is a result of the combination of the carbon foam electrode and the electrolyte, and especially of the interface between these elements.
In electrochemistry, the large operating window of the device of this invention is equivalent to an unexpectedly large overpotential at the electrode. An overpotential is a potential difference exceeding the thermodynamic redox potential required for a specific reduction/oxidation reaction to occur. Overpotential is often a difficult phenomenon to understand, partly because many factors contribute to it. For example, overpotential depends on the electrode material, electrode morphology, and the properties of the electrolyte. In this invention, the large surface area provided to the electrolyte by the carbon foam electrode is considered likely to play a role in device performance. It is known that how ions diffuse from the electrolyte bulk to the electrode surface and the associated consumption of charge carriers on the electrode surface affect the overpotential. This may play a role in the device of this invention. The diffusion rate of charge carriers in the electrolyte may be affected by the presence of hydrated ions, which are larger than non-hydrated ions. The interaction between charge carriers and the morphology of the carbon foam electrode may also affect the overpotential. The presence of ion-gel or hydrogel polymers is also considered to influence the diffusion of charge carriers to the electrode surface, possibly due to spatial effects and related to the carbon foam morphology.
Hydrogels are gels whose liquid component is water and can be formed from a network of polymer chains. Supercapacitors with a hydrogel electrolyte forming the dielectric are expected to have performance characteristics associated with aqueous electrolyte-based supercapacitors. However, to this expectation, the inventors have found that the performance of a supercapacitor according to a first aspect (i.e., a symmetrical device in which the electrodes are made of the same material, including carbon foam and encapsulated in a hydrogel electrolyte) surpasses the expected performance of an aqueous device. The operating voltage window of the device is unexpectedly enhanced compared to aqueous electrolyte-based devices. The operating window is more similar to that of organic solvent-based supercapacitors.
Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), sodium polyacrylate, acrylate polymers, and copolymers, which have a large number of hydrophilic groups, are examples of polymers that can be utilized in hydrogels. Fluorinated hydrogels can also be used. The combination of hydrogels and ionic charge carriers helps to achieve a surprisingly large operating window through the system of the present invention.
The electrodes of the device disclosed in this invention are located on a substrate, and the electrolyte is present on top of the electrodes in a manner that seals at least a portion of the electrode structure, thus forming an active region. The active region of a supercapacitor is the region in a supercapacitor that stores charge, including the electrolyte and the electrodes.
The electrodes of the device can have an interdigitated geometry, meaning they can be interdigitated. This interdigitated electrode geometry helps maximize the capacitance of the supercapacitor. It also enables a device without a separator. Supercapacitors typically include separators between opposite electrodes to prevent short circuits. The absence of a separator facilitates the construction of supercapacitor devices. Separators can also negatively impact device performance, such as inhibiting charge flow and reducing charge/discharge rates. The absence of a separator avoids these negative performance effects.
Interdigitated electrode geometries are well-suited for symmetrical devices. Constructing an interdigitated electrode geometry with opposite electrodes made of different materials is significantly more complex than with electrodes made of the same material. If the electrodes are made of the same material, they can be fabricated in-situ in a single step. Using different electrode materials requires multiple fabrication steps, greatly increasing the complexity of the manufacturing process.
In addition, the absence of a separator eliminates any negative impact that a separator might have on device performance, such as inhibiting charge flow and causing a decrease in charge/discharge rate.
The hydrogel electrolyte can contain a sufficiently high charge carrier concentration to produce the enhanced operating voltage window.
An enhanced operating voltage window may depend on the concentration of charge carriers.
Charge carriers can have redox potentials that support an enhanced operating voltage window.
The charge carrier can be provided by aqueous solutions of acids, bases, or salts. Usable acids include sulfuric acid. Usable bases include potassium hydroxide.
Hydrogel electrolytes may comprise a mixture of hydrogel and salt. The electrolyte may be composed of a hydrogel polymer, such as PVA or PVP. The salt may be, for example, NaClO₄ , NaNO₃ , or Mg( ClO₄ ) ₂ . The molar concentration of the salt may be, for example, 0.5 M or greater, such as 1 M or greater, such as 2 M or greater, such as 2.5 M or greater, such as 3 M or greater, such as about 5 M. The molar concentration of the salt may be, for example, between 1 M and 10 M, or it may be, for example, between 2.5 M and 7.5 M.
Salts that can be used include phosphates, perchlorates, nitrates, and arsenates. Examples of salts include sodium sulfate, sodium bisulfate, sodium persulfate, sodium perchlorate, lithium perchlorate, magnesium perchlorate, sodium nitrate, and lithium hexafluoroarsenate. Aqueous solutions of these salts can be used in electrolytes to provide ion carriers.
Charge carriers can be ions. Charge carriers can be hydrated ions.
Hydrated ions are ions in an aqueous environment. Polar water molecules arrange themselves around the ions, forming hydrated spheres centered on the ions. The details of the mechanism behind the surprisingly wide enhanced operating voltage window observed with respect to the features of this invention are difficult to understand, and the inventors do not wish to be bound by theory. However, the surprisingly advantageous properties of the device of this invention are a result of the synergistic effect between the electrodes and the dielectric material. The enhanced performance is a lack of water splitting under voltage conditions under which electrolysis is expected to occur by those skilled in the art. The interface between the electrode and the electrolyte is expected to be the origin of its performance. There may be a synergistic interaction between the size of the charge carrier (possibly a hydrate) and the size of the pores present in the electrode. The hydrogel contains a network of polymer chains, and this chain network of the hydrogel may also have physical (spatial) effects that limit the exposure of water molecules to potential differences that could lead to their decomposition.
The increased size of hydrated ions is thought to combine with the porous structure of the carbon foam electrode to impede diffusion near the electrode surface, leading to an increase in overpotential.
The electrodes of a symmetrical supercapacitor device may include porous carbon foam. Optionally, the electrodes may not include additional adhesive material.
Porous carbon foam electrodes are thought to be combined with charge carriers in the electrolyte to increase overpotential, thereby enhancing the operating window of supercapacitors.
Carbon foam consists of one or more 2D carbon sheets (each sheet being a layer of sp2-bonded carbon) folded back-to-back to form a three-dimensional structure rather than planar sheets. Carbon foam lacks the regular AB stacking of planar carbon sheets found in graphite or multilayer 2D carbon. Carbon foam materials are typically porous. Carbon foam has a high surface area. By changing the parameters of the growth method, the porosity of the carbon foam can be controlled, and thus the surface area of the foam. This has the advantage of allowing control over the porosity of the device electrodes during the electrode fabrication process.
Carbon foam electrodes can be mounted on a substrate. Carbon foam electrodes can be mounted on a polyimide substrate. The polyimide substrate can be polyimide. The substrate can form the substrate of a supercapacitor device. The substrate can be thin enough to be flexible, thereby creating a flexible supercapacitor device. The substrate can contain one or more of the following materials (e.g., formed therefrom): polyimides (e.g., poly(4,4'-oxydiphenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde resins.
These substrate materials can be used as a carbon source and transformed into carbon foam using the dual-laser process described above. Carbon foam can be produced in this way by irradiating a polyimide substrate (e.g., with radiation, such as laser radiation). The resulting carbon foam is chemically and indirectly fixed to the substrate via an intermediate layer of amorphous, non-graphene material directly attached to the substrate (see earlier in this specification), resulting in a robust structure. Therefore, electrodes can be produced in situ by using a portion of the substrate as a carbon source, i.e., as a reagent for producing carbon foam. The structure is both robust and flexible. Flexible devices have advantages in many ways. Flexible devices can be conveniently packaged, for example, by rolling them up. For example, flexible devices can also be attached to the surface of curved structures.
The substrate can be substantially planar. The substrate can be a film, such as a thin film. The substrate thickness can be greater than 5 μm. The substrate thickness can be less than 120 μm. The substrate thickness can be between 5 μm and 120 μm. The substrate thickness can be substantially uniform across the substrate surface. The substrate can be flexible. The substrate can be tough.
The substrate may be a polyimide strip (e.g., a polyimide strip) having a first surface and a second surface.
Electrodes can be mass-balanced to optimize the operating voltage window.
A supercapacitor can be viewed as two capacitors connected in series. To maximize the capacitance of a supercapacitor, the capacitances of the two constituent capacitors should be equal. This can be engineered by adjusting the surface area of each electrode, thereby compensating for other factors affecting the capacitance, such as the properties of solvated ions. This process of adjusting the individual electrodes is called mass balancing. Electrode mass balancing has the advantages of maximizing the capacity of the superconducting device and extending the lifespan of the supercapacitor.
In a second aspect, there is a method for manufacturing a symmetrical supercapacitor device according to the first aspect, wherein:
Electrodes are formed on the substrate;
Electrolyte precursors containing charge carriers and hydrogels are applied to electrodes;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the active region.
Carbon foam electrodes can be fabricated by: converting a portion of a substrate (if the substrate is or includes a carbon source) into carbon foam; or by using chemical or physical deposition methods, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), sputtering, laser-induced growth, pulsed laser deposition, cathodic arc deposition, spin coating, dip coating, or sol-gel methods. In this way, electrodes are produced in situ on the substrate.
Electrolyte precursors can be prepared by preparing an aqueous solution of the charge carrier and then mixing this aqueous solution with a hydrogel. Electrodes can be formed using laser radiation.
When preparing the electrolyte precursor, it is important to remember that precipitation or crystallization of salts in the electrolyte is undesirable. Precipitation of salts or any solids in the electrolyte can lead to device breakage, or other defects in the device, or defects in its performance. This sets an upper limit on the concentration of the salt solution. Avoiding the use of supersaturated salt solutions may be advantageous. The precise upper limit of concentration may depend on the specific chemical composition present. For sodium perchlorate, the inventors have found that an electrolyte produced at a concentration of 5M avoids salt precipitation or crystallization, and, in combination with other features, allows the operating window of the supercapacitor device to extend beyond what would be expected based on considerations of the individual components. The electrolyte may include a salt solution with a concentration greater than 4M. The electrolyte may include a salt solution with a concentration greater than 3M, or greater than 2M, or greater than 1M, or greater than 0.5M.
At higher concentrations, salts were observed to precipitate readily from the electrolyte gel, and at such a rapid rate that the device became unusable. This precipitation may be caused by water evaporation. Hydrolysis and water loss could be another cause. In any case, the inventors found that although the electrolyte gel could be formed using sodium perchlorate at concentrations up to 16.5 M, precipitation problems were observed at all concentrations above 10 M.
High-molar salt solutions can be used when manufacturing hydrogel electrolytes.
For cost reasons, lower concentrations of salt solutions are generally advantageous.
The thickness of the carbon foam layer can be between 10 μm and 100 μm. This contributes to the flexibility of the device, allowing it to be rolled up for greater compactness.
A gap between 100 μm and 1000 μm can separate the electrodes from each other. The capacity of the device depends on the gap between the electrodes, and therefore adjusting this gap will affect the amount of charge that can be stored.
The operating window of the device of the present invention can be greater than 1.5V, or it can be greater than 2V, or it can be greater than 2.5V.
Any optional or preferred feature of any aspect of the system can be a feature of any other aspect of the system.
Appendix 1: Description of the Drawings
We have referenced the following attached figures, in which:
Figure 59 shows the carbon foam cyclic voltammetry measured at 25 mV/s for a positive voltage.
Figure 60 shows the carbon foam cyclic voltammetry measured at 25 mV/s for negative voltage.
Figure 61 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a positive voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a negative voltage window.
Figure 63 presents carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 presents carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 presents carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 1 Detailed Description
Dual-electrode supercapacitor
A typical carbon foam supercapacitor device based on this characteristic has interdigitated carbon foam electrodes, as shown in Figure 26. To summarize, a polyimide substrate supports the supercapacitor electrodes, which in this example are constructed of carbon foam and arranged in an interdigitated comb geometry, forming an interdigitated electrode structure. Silver current collectors extend along each side of the device, making each opposite electrode electrically integrated. The non-substrate side of the interdigitated electrode structure is encapsulated in a hydrogel. A polyimide cap can be added to contain the hydrogel, or the device can be packaged in other suitable ways.
As explained above, carbon foam electrodes can be formed on a polyimide substrate. Carbon foam is formed above a suitable substrate (i.e., a substrate providing the carbon source, in this example, a polyimide substrate) by exposing it to a laser beam. The carbon foam produced in this way grows from the substrate and indirectly adheres to it. The substrate and the carbon foam electrode formed in situ in this way form a single unit.
The carbon foam electrodes are manufactured using an infrared CO2 laser under ambient conditions. The substrate is a commercially available polyimide film with a nominal thickness of 127 micrometers. One example has eleven parallel carbon foam strips per electrode. This number can obviously vary. The carbon foam strips of the positive electrode are offset relative to the carbon foam strips of the second electrode, thus forming an interdigitated structure.
Electrode dimensions are shown in Table 6:
| <![CDATA[<u>mass balance ratio</u>]]> | 1.18 |
| <![CDATA[<u>Positive half-cell "electrode finger"</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.0472 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.20768 |
| <![CDATA[<u>Negative half-cell “electrode finger”</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.04 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.176 |
| Distance between fingers (cm) | 0.04 |
| <![CDATA[Total active electrode surface area (cm<sup>2</sup>)]]> | 0.38368 |
| <![CDATA[Total active electrode volume (cm<sup>3</sup>)]]> | 0.0019184 |
Table 6
Three-electrode device
In addition to the two-electrode supercapacitor device, a three-electrode testing device including a reference electrode was also fabricated. The three-electrode device comprises a working electrode, a counter electrode, and an Ag/AgCl reference electrode. Each of the working and counter electrodes is made of carbon foam, which in this specific embodiment is generated by dual-laser irradiation of a polyimide substrate, as previously described. This device is used to determine the stable voltage range of the NaClO4 hydrogel electrolyte. The three-electrode device is stabilized for at least one hour after fabrication before any measurements are performed.
Preparation of hydrogel electrolytes
Each of the disclosed two-electrode and three-electrode devices is based on a 5M sodium perchlorate solution, and the electrolyte is prepared as described herein. The 5M sodium perchlorate solution is prepared by dissolving sodium perchlorate (98% purity, from Sigma-Aldrich) in deionized water (dosage: 3.061 g NaClO₄ dissolved in 5 mL deionized H₂O ). The sodium perchlorate solution is then stirred with a magnetic stirrer on a hot plate at 120°C while polyvinyl alcohol (PVA, 99% hydrolyzed, Sigma-Aldrich) is added. 1.5 g of PVA is dissolved per 10 mL of solution. The mixture of sodium perchlorate solution and PVA is removed from the hot plate and allowed to cool, subsequently forming a white, opaque gel-like solution. The gel solution is then heated to 120°C until it liquefies and becomes transparent. It is then deposited onto a graphene electrode. After deposition onto the electrode surface, the liquefied hydrogel electrolyte material solidifies within approximately 5 minutes at room temperature. The amount of electrolyte deposited on the electrode depends on the surface area to be covered. For the test setup, deposit 150 μL of electrolyte.
Experimental results of the three-electrode device
The performance achievable from supercapacitors is ultimately limited by the stability of the electrolyte.
To test the electrolyte stability in the system of this invention, several experiments were performed using the three-electrode apparatus described herein. Differential pulse voltammetry (DPV) was initially used to select which voltage windows to investigate via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements.
i-Cyclic Voltmeter Method
Cyclic voltammetry measurements were performed to determine the stability of the electrolyte. In a standard three-electrode measurement, the potential between the working electrode and the reference electrode was scanned at a constant rate from the open-circuit potential (OCP; nominal 0V) to a predetermined upper limit, and then scanned downwards again. The current response of the working electrode was monitored during this period.
The results of these measurements are shown in Figures 59 and 60. Figure 59 shows the results of scanning the voltage from OCP in the positive direction.
The upper results set shows four voltammograms with maximum potentials of 1V, 1.2V, 1.3V, and 1.4V. The lower results set also includes a voltammogram with a maximum potential of 1.6V. As the upper voltage limit increases above 1.2V, the shape of the cyclic voltammograms becomes less "square." The tails become increasingly pronounced as the final scan voltage increases, indicating electrolyte degradation, which may be attributed to water electrolysis. These voltammograms indicate that the electrolyte is stable up to +1.2V.
Figure 60 shows a similar set of results, but for the negative electrode voltage. These data indicate that the electrolyte is stable up to -1.4V.
In summary, the data in Figures 59 and 60 provide an operating window of 2.6V for the device. This is significantly higher than expected when using an aqueous electrolyte.
ii. Constant Current Charge-Discharge (GCD) Data
Constant current charge-discharge (GCD) measurements were performed to determine coulombic efficiency based on charge and discharge times. In these measurements, a current was applied between the counter and the working electrode, and the voltage response of the working electrode (relative to the reference electrode) was measured. The GCD curves measured for the positive electrode voltage using a discharge current of 2 × 10⁻⁵ A (0.5 mA/ cm² ) for a selected voltage window are shown in Figure 61. The curves plateau above 1.2 V, indicating electrolyte degradation. The GCD curves for a selected negative electrode voltage window are shown in Figure 62.
A significant plateau was observed in the voltage windows up to -1.6V and -1.8V, indicating electrolyte degradation. The -1.4V voltage window exhibited a triangular GCD curve, indicating stability.
The results of cyclic voltammetry and constant current charge-discharge measurements of the three-electrode system are summarized in the table below.
The first table (Table 7) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the positive voltage window.
Table 7
The second table (Table 8) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the negative electrode voltage window.
Table 8
In these summary tables, coulombic efficiency is the ratio of stored energy to delivered energy measured in the second GCD cycle; areal capacitance in mF/ cm² is calculated using the following formula:
Area Capacitor
Furthermore, the discharge energy is the integral of the charging and discharging portions of the GCD curve over time.
The GCD curve indicates that +1.2V and -1.4V are the actual positive and negative voltage limits.
These voltage limits and areal capacitance values allow for the calculation of mass balance using the following formula:
Where, m + = mass of the positive electrode, m - = mass of the negative electrode, C + = capacitance of the positive electrode (F), C - = capacitance of the negative electrode (F), ΔE + = positive electrode voltage window limit, ΔE - = negative electrode voltage window limit.
Experimental Results of a Two-Electrode Device—Supercapacitor Performance
For the dual-electrode supercapacitor device, galvanostatic charge-discharge (GCD) data were collected within an applied current density range of 0.25 mA/ cm² to 30 mA/ cm² . Figure 63 plots the GCD results obtained from five different devices (CH1-CH5). These data were collected using a voltage window of 2.6 V, and greater electrolyte stability was observed at higher current densities. Further performance data for the dual-electrode supercapacitor are presented in Figure 64, showing cyclic voltammetry plots recorded from five different devices (devices #1 to #5) according to an embodiment of the invention at scan rates from 0.01 V/s to 5 V/s.
The cyclic voltammograms in the right column were recorded at low scan rates (0.01 V/s, 0.025 V/s, 0.05 V/s, 0.075 V/s, 0.1 V/s, 0.25 V/s, and 0.5 V/s), while the cyclic voltammograms in the left column were recorded at high scan rates (0.75 V/s, 1 V/s, 2 V/s, 3 V/s, 4 V/s, and 5 V/s). The trend shown in these data is that higher scan rates correlate with higher electrolyte stability. In each set of cyclic voltammograms shown in Figure 64, faster scan voltages resulted in larger differences in the current response between voltage rise and voltage fall.
In addition to the devices disclosed above, devices were also constructed in a similar manner but using hydrogel electrolytes comprising the following: (a) 3M NaClO 4 and PVA, (b) 1M NaClO 4 and PVA, (c) 2.5M NaNO 3 and PVA, (d) 3M Mg(ClO 4 ) 2 and PVA, and (e) 5M NaClO 4 and PVP.
The cyclic voltammetry results of these additional devices are shown in Figure [.]10. For each electrolyte, cyclic voltammetry was run between 0V and 0.7V, 0V and 0.8V, 0V and 0.9V, 0V and 1.0V, 0V and 1.2V, 0V and 1.3V, and 0V and 1.4V. Similarly, for each electrolyte, cyclic voltammetry was run between 0V and -0.7V, 0V and -0.8V, 0V and -0.9V, 0V and -1.0V, 0V and -1.2V, 0V and -1.3V, and 0V and -1.4V. These data are shown in Figure 65.
Data indicate that, in each device, for (d) 3M Mg(ClO 4 ) 2 and PVA and (e) 5M NaClO 4 and PVP, the electrolyte is stable up to the limits of -1.4V and +1.1V and up to +1.2V.
Further changes and modifications may be made within the scope of this disclosure.
Appendix 1 Concepts
1. A symmetrical supercapacitor device, comprising:
Two electrodes, each comprising a carbon foam material; and
Hydrogel electrolytes encapsulate electrodes in their active regions.
2. The symmetrical supercapacitor device according to Concept 1, wherein the hydrogel electrolyte comprises a mixture of hydrogel and salt.
3. A symmetrical supercapacitor device according to Concept 1 or Concept 2, comprising an ion charge carrier.
4. The symmetrical supercapacitor device according to Concept 3, wherein the ion charge carrier is hydrated.
5. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam.
6. The symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam material.
7. A symmetrical supercapacitor device according to any one of concepts 1, 5 and 6, wherein the carbon foam material is formed on a substrate.
8. The symmetrical supercapacitor device according to Concept 7, wherein the substrate is a polyimide substrate.
9. The symmetrical supercapacitor device according to Concept 7 or Concept 8, wherein the substrate forms the substrate of the device.
10. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the symmetrical supercapacitor device is flexible.
11. A method for manufacturing a symmetrical supercapacitor device according to any one of concepts 1 to 10, wherein:
Electrodes are formed on the substrate;
An electrolyte precursor containing charge carriers and hydrogels is applied to the electrode;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the effective region.
12. A method for manufacturing a symmetrical supercapacitor device according to Concept 11, wherein the electrolyte precursor is prepared by preparing an aqueous solution of a charge carrier and by mixing the aqueous solution with a hydrogel.
13. A method for manufacturing a symmetrical supercapacitor device according to Concept 11 or Concept 12, wherein the electrodes are formed in situ.
14. A method of manufacturing a symmetrical supercapacitor device according to any one of claims 11 to 13, wherein the electrodes are formed by irradiating the substrate with laser radiation.
Appendix 2: Gii-Cap+ Hydrogel
In this Appendix 2 section, we demonstrate the effectiveness of Gii carbon foam as an ideal substrate on which pseudocapacitive materials can be deposited, resulting in a significantly enhanced capacitance compared to using Gii carbon foam as the sole electrode material. For the context, these carbon foam-only devices exhibit full-cell specific capacitance in the 0.25–0.4 mF/ cm² region.
Sample preparation
Electrodeposition was performed on A7-sized Gii-Caps to cast a layer of pseudocapacitive material on them. Both v4 and v5 designs were suitable for electrodeposition, yielding similar performance. Results for the v4 sample will be detailed in this document.
First, the sheet containing six Gii-Cap devices (2 rows, 3 columns) was cut in half to obtain two 3-device half-sheets. The two half-sheets were then mounted on internally fabricated fixtures and placed inside the MiniPlant 3 electrodeposition tank. MnOx was deposited on the sample first, followed by rinsing with deionized water, and then FexOy was deposited. After FexOy deposition, the sample was rinsed again and dried in air at 40°C for at least 2 hours.
The deposition details are as follows. The manganese oxide precursor solution contained a mixture of manganese acetate tetrahydrate (40 mM) and surfactant (Tween 20, 0.1 wt%). Deposition was performed using constant current pulses. The on-time was 0.5 seconds, and the off-time was 2 seconds. The applied on-time current was 744 mA (19.14 mA/ cm² , based on the nominal geometry of the electrode). The off-time was 0 mA, i.e., the circuit was open. A total of 390 cycles of MnOx deposition were performed (3.7 C/ cm² per electrode). The FexOy precursor solution contained 40 mM MFe-TEA complex (TEA is triethanolamine). It contained FeCl₃ , TEA, and NaOH. Deposition was also performed using constant current pulses. The on-time was 1 s, and the off-time was 2 s. The applied on-time current was 233 mA (6 mA/ cm² ), and the off-time was set to 0 mA. The deposition process was repeated 1,000 times, yielding 6 C/ cm² for each electrode.
After deposition and sample drying, the samples are divided into individual devices. A quasi-reference electrode (RE) containing screen-printed Ag/AgCl ink is fixed along one edge of the device outside the working area (used to monitor the potential of each electrode during testing). The electrolyte is then applied to the working area of the device and extends onto the RE. The electrolyte used is an aqueous hydrogel containing NaClO₄ as the salt and PVA (polyvinyl alcohol) as the gelling agent. The hydrogel stock solution contains 199.5 g NaClO₄ monohydrate, 256.9 ml deionized water, and 42.4 g PVA. The mixture is solid at room temperature and becomes liquid at temperatures close to the boiling point of water. To dispense the hydrogel, it is heated to 94°C to liquefy it. Dispensing is performed by dropping the liquid electrolyte onto the working area and the RE, typically 3–4 ml per device. The hydrogel on the sample is then allowed to cool and re-solidify after approximately 10 minutes. After solidification, an imide film is applied to the device to prevent excessive electrolyte evaporation. Once capped, the device is ready for testing.
Electrochemical test parameters
Electrochemical tests were performed on the samples using a Biologic VMP-3 voltage/current regulator. Initial performance characterization was performed, followed by 500 charge-discharge cycles (conditioning protocol) for final characterization. The reported nominal values are those obtained in the second characterization step. The conditioning protocol was applied to further stabilize and consistent the sample performance.
During testing, the voltage was controlled at the battery level (the absolute difference between the positive and negative electrodes), with a minimum of 0V and a maximum of 2V. The potential difference between each electrode and the common RE was also measured, allowing for the calculation of individual electrode performance metrics.
These two characterization steps are called the Ragone test. They are identical and include the following:
a) Cyclic voltammetry (CV). Three scan rates were used: 50, 100, and 250 mV/s. Five cycles were performed at each scan rate.
b) Galvanic charge-discharge (GCD). Seven current densities were tested: 1, 2.5, 5, 7.5, 10, 20, and 30 mA/ cm² (based on a total device geometry of 12.96 cm² ). Five cycles were performed at each current density.
c) Electrochemical impedance spectroscopy (EIS). Voltage controlled, using a 1V DC applied voltage and a 10mV AC signal. Measurements were taken in the 1MHz–10mHz region.
The adjustment process was achieved by performing 500 GCDs at 10 mA/ cm² .
The nominal capacitance value is calculated based on the GCD after adjustment at 5 mA/ cm² . The ESR (Equivalent Series Resistance) is calculated based on the voltage drop at the start of the discharge half-cycle in the GCD. The reported ESR value is also derived from the final GCD at 5 mA/ cm² . The ESR can also be calculated from the Nyquist plot obtained from EIS. The results are almost identical.
Results and Conclusions
Average values were calculated for a total of 48 devices. Samples from batches 3258 and 3259 were used. Typical CV curves are shown in Figure 66. The full-cell response (left panel) shows a quasi-rectangular shape, indicating that the storage mechanism is not purely capacitive. This is expected, as both MnOx and FexOy are redox-active materials. Most of the capacitance of the device is concentrated above the cell voltage of 0.5V, as can be seen from the small envelope of the full-cell curve in the 0–0.5V region. The explanation for the smaller capacitance at lower cell voltages can be seen in the half-cell curve, shown in the right panel of Figure 66. This figure shows that MnOx is used as the positive electrode, while FexOy is the negative electrode. MnOx is a near-ideal pseudocapacitive material, as evidenced by its roughly rectangular CV (grey trajectory).
Meanwhile, the FexOy electrode exhibits a more asymmetric response to potential. Its capacitance is largely concentrated below 0V vs Ag/AgCl. When the potential is greater than 0V vs Ag/AgCl, FexOy displays a very small capacitance, as shown by the small envelope of the blue trace at these potentials. Therefore, this asymmetric FexOy response explains the smaller capacitance obtained at low voltages in a full cell.
Figure 66 shows the post-adjustment CV curves obtained at 100 mV/s from sample 3258-1#4. The left panel shows the full-cell CV, while the right panel shows the half-cell curves obtained during the full-cell measurement.
GCD curves were used for capacitance calculations because they provide more accurate values. Typical adjusted GCD curves are shown in Figure 67, displaying measurements for both full and half cells. The device exhibits a good capacitance response with quasi-triangular curves. The full cell exhibits linear discharge from maximum voltage down to approximately 0.5V, indicating that the pseudocapacitance of MnOx and FexOy achieves near-ideal capacitance behavior. As seen in the CV curves, FexOy exhibits an asymmetric capacitance-potential relationship, which explains the faster discharge below 0.5V of the battery voltage.
Figure 67 shows the post-adjustment GCD curves obtained at 5 mA/ cm² from sample 3258-1#4. The full-cell and corresponding half-cell responses are shown in the top, middle, and bottom lines, respectively.
In addition to different pseudocapacitive behaviors relative to potential, the MnOx and FexOy electrodes also exhibit different levels of capacitance. Both electrodes occupy the same geometric area in the device, but the MnOx electrode experiences a much smaller electrochemical window within the device (see the difference between the maximum and minimum electrode potentials in Figures 66 and 67). The smaller MnOx window (0.65 ± 0.06 V) is due to its larger specific capacitance compared to FexOy (1.35 ± 0.06 V window). For the device evaluated in this study, the regulated capacitance of the MnOx electrode reached 246.8 ± 36.0 mF/ cm² , while the regulated capacitance of the FexOy electrode was 171.4 ± 38.4 mF/ cm² . Therefore, these Gii-Cap+ devices are symmetrical in terms of electrode size but asymmetrical in terms of electrode composition and potential split.
Since a full cell is essentially two capacitors connected in series (formed by a double layer between the electrodes and the electrolyte counterions), the total cell capacitance will be lower than the capacitance of a single electrode. The adjusted average full cell capacitance is 52.5 ± 9.4 mF/ cm² . At the same current density (64.8 mA, 5 mA/ cm² , cell level) as the reported nominal capacitance, the ESR calculated based on the voltage drop at the start of discharge is 0.85 ± 0.12 Ω.
EIS measurements further confirmed the good capacitive response of these devices, as shown in Figure 68. The ESR can be estimated by locating the intersection of the Nyquist plot with the y-axis. For the sample shown in Figure 68, the ESR calculated by EIS is 0.78 Ω, which matches very well with the 0.73 Ω calculated by GCD for the same sample. The Bode plot provides information about the device's behavior at different frequencies. At high frequencies, such as 100–10000 Hz, the device functions essentially like a resistor with a phase angle of 0°. As the frequency decreases, the phase angle increases, indicating a greater contribution from capacitance (the phase angle of an ideal capacitor is -90°). When the phase angle exceeds the 45° mark, the device is considered to be essentially capacitive. Therefore, the time when the 45° phase shift occurs can be considered the characteristic time constant of the device. For the sample in this study, the average time constant is 4.48 ± 1.18 seconds. This time constant can be interpreted as the cycle time threshold for an effective capacitive response. When the cycle time is below the time constant, the device will not operate fully.
Figure 68 shows the regulated Nyquist (left) and Bode (right) curves obtained by electrostatic EIS at 1V DC (full cell) for sample 3258-1#4. The inset in the left figure shows a magnified view of the high-frequency response.
Considering that devices using Gii as the sole electrode material exhibit a specific capacitance of 0.25–0.4 mF/ cm² , adding pseudocapacitive materials enhances the energy storage capacity of these Gii-Caps by more than 100 times. Furthermore, adding these metal oxides does not significantly increase the ESR of these devices, thus maintaining their usefulness in high-power applications. The electrodeposition process is controllable, allowing for the fabrication of cells with less deposited material and consequently less total capacity, if desired. The resulting devices are inherently asymmetric, with MnOx as the dominant positive electrode and FexOy as the negative electrode.
Appendix 3 GiiCap Ion Gel
Objective: To demonstrate the specific capacitance and electrochemical stability window (ESW) of an electrolyte formulation comprising a room-temperature molten salt 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) and fumed silica, referred to as Iongel, in conjunction with an A7 apparatus, conducted in a “low” humidity and “airless” argon atmosphere.
Experimental conditions:
All electrochemical tests were performed in a “3-electrode” setup, in which regular interdigitated A7 devices were fabricated, the area ratio of the “working” electrode to the “counter” electrode was 1:2, and a third quasi-reference electrode comprised of screen-printed AgCl ink was used to monitor the potential of each electrode during the tests.
The electrolyte Iongel was prepared and stored in an airless environment.
Before applying the electrolyte to the A7 device for testing, heat Iongel to 90°C and then distribute a thin, uniform layer onto the A7 using a doctor blade. Allow the electrolyte to cool before preparing the device for testing and connection. For airless devices, testing is performed in the same airless environment where the electrolyte was stored and distributed, with the device connected to the electrochemical testing instrument: a Biologic VMP-3 regulator.
For low humidity environments, move the device to a humidity-controlled room with a relative humidity set to 20%, and seal and connect it to the instrument.
For each humidity level, a series of maximum electrode potentials (Emax) (in volts (V)) close to the nominal literature value 1 of the net electrolyte were tested. They are:
Positive electrode: 2.0, 1.9, 1.8, 1.7, 1.6, 1.5
Negative electrode: -2.0, -1.9, -1.8, -1.7, -1.6.
For each combination of humidity and electrode potential, N=8 samples are prepared from scratch.
Electrochemical test parameters:
A standard protocol was used, with a test window of 0.0-Emax V vs OCV. OCV quantification was 0.25 V vs AgClQref.
The electrochemical testing was divided into three stages: a) Ragone characterization; b) long-term (LT) cycling; c) Ragone characterization (post-).
Ragone characterization before and after LT cycling included: OCV, 1 hour; cyclic voltammetry (CV), 5 cycles each at 100 and 1000 mV/s; galvanostatic charge-discharge (GCD), 10 cycles each at 5 and 10 mA/cm²; and potentioelectric impedance spectroscopy (PEIS), between 10 MHz and 0.01 Hz.
The LT cycle includes: CV, 5000 cycles at 750mV/s.
Electrochemical stability was determined by post-hoc visual analysis of electrode damage and electrolyte discoloration, as well as by assessment of changes in coulombic efficiency across LT cycles. Device performance was determined based on the specific capacitance via GCD after 5000 LT cycles.
in conclusion:
ESW was determined by plotting the coulombic efficiency of the LT CV cycle against the number of cycles. When the coulombic efficiency remained consistent throughout the 5000 cycles, the cycle Emax was determined to be stable under given environmental conditions. Based on this analysis, the Iongel-A7 device was found to be stable in air with a relative humidity of 20% at negative and positive electrode potentials of -1.6 and +1.6 V, respectively. In the absence of air, the positive and negative ESWs were determined to be -1.8 and +1.7 V, respectively.
Regarding performance evaluation, the specific capacitance of the device at 20% relative humidity and in an airless environment was found to be 2.11 and 1.60 mF/ cm² , respectively, under the positive electrode window conditions. The specific capacitance of the negative electrode window was 1.55 and 2.11 mF/ cm² , respectively, under 20% relative humidity and in an airless environment.
Figures 69, 70, and 71 show the relevant results.
Figures 72, 73, and 74 show other relevant results.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Target:
The feasibility of the project was demonstrated using reagents that are critical to the Gii-Sens 3D carbon foam analysis system.
Phase 1: Surface Fixation
Objective: To maximize mAb(2) surface immobilization. To evaluate the most convenient surface chemistry for immobilizing mAb onto a surface.
Deliverables: Data supporting maximum surface coverage and the selected procedure.
Phase 3: Target Analyzer Sensing Range and LOD
Objective: To establish the electrochemical immunoassay procedure and results. To develop the electrochemical immunoassay procedure (incubation time, concentration, volume) and to establish parameters that produce the most sensitive analytical assay.
Deliverables: Data supporting the performance of electroanalytical immunoassays.
Experimental Section
Solution composition
Surface Chemistry
10 mM pyrene butyric acid in DMF
4mM EDC/10mM SulfoNHS
PBS 0.1M pH 7.2
Read aloud
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 0.02 M KCl.
0.02M PBS
Sensor modification program
10 μL of PyrBuOOH was applied to the sensor surface and incubated in a humid chamber for 2 hours, after which the solvent was allowed to evaporate spontaneously.
15 μL EDC/NHS, for 30 min
10 μL of A1 or C1 mAb in PBS for 1 hour
Electrochemical technology
Electrochemical impedance
Applied voltage = 0V
Amplitude = 0.01VRMS
Frequency range -5000 to 0.1Hz
Measurement Procedure
Direct determination: Unmarked: See Figures 75 and 76.
Direct determination: label-free and reagent-free: see Figures 77 and 78.
Calibration curve
Repeat at each point, n=5 (minimum) different disposable sensors (single readout, sensor disposed of).
Each calibration curve contains data (inter- and intra-assay variability) obtained by different operators over the following days.
Phase 1: Surface Chemistry
According to the scheme in Figure 79, the selected surface chemistry is Pyr-COOH modified graphene and EDC/NHS conjugates that capture mAb (A1 and C1), and the figure shows a schematic diagram of the surface immobilization reaction.
The concentrations of surface-fixed mAbs (A1 and C1) were screened using electrochemical impedance spectroscopy. (See Experimental Section). See Figure 80 (mAb A1 fixation on the surface. Inset normalized signal) and Figure 81 (mAb C1 fixation on the surface. Inset normalized signal).
Both A1 and C1 showed a logical trend in surface coverage. Based on the normalized curves, A1 showed a slightly larger surface coverage. The optimal coverage range selected was between 15 and 250 μg/mL. This concentration range was estimated to be sufficient to provide optimal sensor performance.
Phase 3: Determination and Target Analyte Investigation
Further evaluation of the potential and benefits of using it as a sensing electrochemical platform has been conducted in label-free assay formats.
Simultaneously, a reagent-free formulation was also explored, where the solution used for incubation and generating the readout signal was simply a buffer solution, as described in the experimental section. The dynamic range of the assay was also investigated at high concentrations, and the potential to extend this concentration range is expected to be identified.
Due to the interesting results obtained during the investigation described above and the general time constraints, the assay sensitivity was explored down to 10 pg/mL, and the aim was to explore the high concentration range up to 1000 ng/mL.
Label-free assay investigation
Label-free assays, as previously described, include assays that do not require secondary antibodies but use specific electrochemical readout solutions. In this study, the electrochemical solution was also used as the carrier solution, thus eliminating the need for a washing step or any other assay complications.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 82, which shows the label-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
To further investigate how to enhance measurement performance, the overall concentration range was divided, and the same data were used to explore different sensitivity ranges.
Label-free and reagent-free assay investigation
As mentioned earlier, label-free assays include assays that do not require secondary antibodies. In the absence of reagents, there is also no need for an electrochemical readout solution, as all incubation and measurement are performed solely in a buffer solution, which also acts as a carrier solution, further eliminating the need for additional washing steps.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 83, which shows the label-free and reagent-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Materials via Connectors
background
Sensors are analytical devices that detect changes or reactions and respond to some input from the environment. In recent years, their use has increased significantly due to their advantages such as high specificity and sensitivity, rapid and reliable results, ease of processing, and immediate diagnostics. Because of these advantages, sensors have entered various technological fields, such as chemical and medical diagnostics, environmental impact analysis, the food industry, and the marine sector.
Different forms of graphene and its derivatives have been used in the production and development of sensors, particularly biosensors. Graphene's electrochemical, physical, and chemical properties make it a material of interest for these applications. However, conventional graphene (e.g., 2D graphene) is difficult to handle in practical applications due to its ultrathin structure and flexibility, which makes it prone to curling, creases, and wrinkles. This significantly reduces the analytical performance of sensors, especially their sensitivity. To date, numerous strategies and techniques have been implemented to fabricate different types of graphene (e.g., different morphologies, different surface properties, and different functionalized derivatives, such as graphene quantum dots, graphene oxide, or reduced graphene oxide), and these have led to differences in sensing performance between sensors.
E.A.Obaje, G.Cummins, H.Schulze, S.Mahmood, M.P.Y.Desmulliez and T.T.Bachmann, Journal of Interdisciplinary Nanomedicine, 2016; 0(0), doi:10.1002/jin2.16 investigated the electrochemical properties of a newly fabricated sensor in relation to the function of its underlying composite material, and evaluated the selection of carbon and dielectric pastes by characterizing properties such as surface roughness, wettability, and susceptibility to nonspecific DNA binding.
L.H. Hess, A. Lyuleeva, B.M. Blaschke, M. Sachsenhauser, M. Seifert and J.A. Garrido, ACS Appl. Materials & Interfaces, 2014, 6, 9705-9710, describe a platform for biosensing applications based on polymer-modified CVD-grown graphene transistors.
C. Fenzl, P. Nayak, T. Hirsch, O.S. Wolfbeis, H.N. Alshareef and A.J. Baeumner, ACSSensors, 2017, 2, 616-620 describe laser-scribed graphene (LSG) electrodes as highly sensitive and reliable biosensor transducers in serum analysis.
S. Singal, A.K. Srivastava, S. Dhakate, A.M. Biradar and Rajesh, RSC Advances, 2015, 5, 74994-75003 describes an electroactive graphene-multi-walled carbon nanotube hybrid-loaded impedance immunosensor for the detection of human cardiac troponin-I.
Despite the existence of all existing technologies, there remains a need to improve the sensing activity of graphene-based sensors. Furthermore, it is still desirable to improve the sensitivity of these sensors without compromising at least one of their other aspects, such as their robustness, stability, durability, ease of functionalization, and/or ease of manufacture.
Summary of features in Appendix 5
In a first aspect, a sensor is provided comprising: (i) a carbon foam electrode, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam electrode via the connector. The carbon foam electrode is manufactured at least in part by a method defined by any one of the features A-K above.
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, comprising the following steps in sequence: (i) providing a carbon foam electrode as described in the first aspect; (ii) treating the carbon foam electrode with a connector; and (iii) treating the connector-modified carbon foam electrode obtained in step (ii) with a receptor.
In a third aspect, a method for sensing a target is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
Carbon foam materials typically possess a folded structure, which gives them a porous morphology and high specific surface area. Without being bound by any theoretical constraints, it is believed that the analytical performance of a sensor is influenced by the morphology of the carbon foam and its available surface area. The 3D structure leads to an increased usable surface area, allowing connectors and receptors (such as enzymes, proteins, nucleic acids, and antibodies) to bind efficiently to the carbon foam, thereby improving sensor performance and sensitivity.
Furthermore, it is desirable to construct the sensor using a very thick carbon foam layer. Preferably, the carbon foam layer thickness is greater than 50 μm. Since carbon foam can be porous, such a thick carbon foam layer is expected to provide a larger surface area, which is beneficial for enhancing analytical performance, especially sensing properties, compared to other conventional graphene-based sensors.
connector
In the context of the features of this invention, carbon foam is modified with a connector as part of the process for forming the desired sensor. The carbon foam described above (e.g., a thick porous carbon foam with a folded structure) provides an improved basis for modification because the increased surface area can be used for interaction with the connector, resulting in improved sensor sensitivity.
The modified carbon foam is then treated with an acceptor to obtain a sensor. Therefore, the adapter acts as an intermediate between the carbon foam and the acceptor. It is possible that at least a portion of the adapter is disposed (e.g., dispensed) within the carbon foam. It is also possible that the entire adapter is disposed (e.g., dispensed) within the carbon foam.
The connector can be selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof. Typically, the connector is selected from polymers (e.g., (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
Typically, the organic compounds described above comprise one or more functional groups independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymers, or mixtures thereof, optionally combined with linear, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. In the same embodiments, the optional structure may be a C1-C20 straight-chain, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residue, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. Still in the same embodiments, optionally, the organic compound having the functional groups described above may also comprise one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly linked to at least one of the functional groups, or the connector is a derivative of an ester or salt of such organic compound, or a compound that releases such organic compound in a reaction with the desired 3D carbon foam. Representatively, the connector is selected from the organic compounds described above in this paragraph.
Typically, the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
The joint can be covalently or non-covalently bonded to the carbon foam. For example, a diazo compound (e.g., a diazonium salt) can be covalently bonded to the carbon foam. For non-covalent bonding, the joint can be bonded to the carbon foam through at least one of the following: π-π interactions, ionic bonding, hydrogen bonding, hydrophobic or hydrophilic effects, electrostatic interactions, polymer encapsulation, adsorption, and grafting (e.g., photografting). For example, a joint containing one or more cyclic moieties as described above (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof) can be bonded to the carbon foam through π-π interactions.
In the context of this feature, the acceptor is bonded to the carbon foam via a linker. Therefore, the acceptor is indirectly bonded. When at least a portion or preferably the entire linker is disposed (e.g., dispersed) within the carbon foam, at least a portion or the entire acceptor may also be disposed (e.g., dispersed) within the carbon foam.
In this document, "receptor" refers to any molecule capable of responding to a target material (i.e., the target) present in the sample to be analyzed. The sample can be biological, chemical, optical, physical, or mechanical, but is typically biological. Therefore, "target" encompasses, but is not limited to, biological materials, chemical substances or mixtures, optical objects, physical or mechanical articles, etc., typically biological materials. The term "response" can include, but is not limited to, biological, and/or chemical, and/or optical, and/or physical, and/or mechanical interactions, typically biological and/or chemical interactions. These typical interactions can include, but are not limited to, binding or hybridization between the receptor and the target, or hydrophobic effects.
Therefore, receptors can include, but are not limited to, one of the following: electrochemical receptors, chemical receptors, biological receptors, optical receptors, physical or mechanical receptors. Receptors can be selected from, but are not limited to, crown ethers, ligands, catalysts, boric acids, carbohydrates, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof.
Typically, the receptor is a biological receptor (i.e., the sensor is a biosensor). Receptors are typically selected from aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles, or other cellular components, or mixtures thereof. More typically, receptors are selected from proteins (e.g., immunoproteins, non-immune proteins, immunoglobulin-binding proteins, glycoproteins), nucleic acids, antibodies, enzymes (e.g., oxidoreductases (preferably glucose oxidase, alcohol oxidase, or lactate oxidase), dehydrogenases) or mixtures thereof. Representatively, receptors are selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or mixtures thereof.
Typically, the target is biological material. Biological material can include, but is not limited to, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, protein complexes, nucleic acids, antibodies, antigens, lipids, fatty acids, fatty acid esters, vitamins, microorganisms, micelles, cells, organelles, or other cellular components, viruses, enzymes, or mixtures thereof. Typically, biological material is selected from deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, nucleic acids, antibodies, antigens, enzymes, or mixtures thereof. More typically, biological material is selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof. It should also be understood that, in the context of this feature, both biological receptors and biological materials can be naturally occurring or synthetically produced.
Receptors can attach to linkers. Receptors can be bonded to linkers by physical, biological, and/or chemical means. Typically, receptors are chemically bonded to linkers. Hereinafter, chemical bonds can include, but are not limited to, covalent bonds, non-covalent bonds (e.g., ionic bonds), metallic bonds, hydrogen bonds, chelate bonds, and non-covalent interactions such as van der Waals forces, π-π interactions, hydrophobic or hydrophilic effects, and electrostatic interactions. Typically, receptors (e.g., biological receptors) are covalently bonded to linkers. Typically, receptors (e.g., biological receptors) are bonded (e.g., covalently) to one or more functional groups contained in the linker (e.g., functional groups of organic compounds as previously described). For example, biological receptors can be covalently bonded to the carboxyl, amino, amine, or amide group of the linker (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide).
sensor
Sensors according to this feature typically comprise a carbon foam layer, which can be produced by a previously disclosed dual-laser processing method. Typically, the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm. Typically, at least a portion or all of the connector is disposed (e.g., dispersed) within the carbon foam. Optionally, at least a portion or all of the receptor is also disposed (e.g., dispersed) within the carbon foam (i.e., when at least a portion or preferably all of the connector is disposed (e.g., dispersed) within the carbon foam). Typically, at least a portion of the connector and optionally a portion of the receptor are disposed (e.g., dispersed) at a depth below the surface of the carbon foam (e.g., the carbon foam layer), said depth being greater than 1% of the total depth of said carbon foam, preferably greater than 5% of the total depth, more preferably greater than 10%, even more preferably greater than 15%, and even more preferably greater than 20%. Typically, at least a portion of the connector and optionally at least a portion of the acceptor are disposed (e.g., dispersed) at a depth greater than 1 μm below the surface of the carbon foam (e.g., a carbon foam layer), preferably greater than 5 μm, more preferably greater than 10 μm, even more preferably greater than 15 μm, and most preferably greater than 20 μm below the carbon foam surface. The entire connector and optionally the entire acceptor can be disposed (e.g., dispersed) at a depth greater than 1% of the total depth of the carbon foam. The thickness of the carbon foam layer can be any range described above (e.g., at least greater than 50 μm). "Dispersed" herein means that the connector (optionally, and acceptor) molecules, at least partially disposed within the carbon foam, are distributed therein to form multiple discrete domains other than a single cluster. These domains can be uniformly and/or continuously distributed (e.g., distributed as a uniform and/or continuous layer) within the carbon foam. Without being bound by any theory, it is believed that the replacement of the connector (optionally, and the acceptor) leads to the improved functionalization of the carbon foam, thereby enhancing the sensor's sensing activity (i.e., sensitivity).
Furthermore, and optionally, neither the connectors nor the acceptors are disposed (e.g., dispersed) throughout the entire depth of the carbon foam (e.g., carbon foam layers). In other words, the core of the carbon foam is not modified with connectors or acceptors.
The adapter may be selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof, and the receptor may be selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin or a mixture thereof.
The sensor may also include a substrate. In a first method of obtaining carbon foam, if a carbon source is provided on or adjacent to the substrate, the final sensor may include the substrate as a component. In a second method requiring the use of a substrate, the final sensor may also include the substrate as a component. Regardless of the method by which it is obtained, the carbon foam may optionally be adhered to the substrate within the sensor. Thus, the substrate included in the sensor may have one of the characteristics described previously for substrates used in the production of carbon foam and/or one possible combination of these characteristics. Alternatively, the sensor need not include a substrate. In other words, even if the carbon foam is produced to adhere to the substrate, it may be removed from the substrate as part of preparation for subsequent modifications.
Typically, the sensors characteristic of the present invention are chemical, physical or mechanical, biological or optical sensors, preferably biosensors (i.e., when the receptor is a biological receptor). Typically, the sensor (e.g., a biosensor) takes the form of an electrode or electrode device. The sensor (e.g., a biosensor) may include a multi-electrode platform, for example, a three-electrode platform including a counter electrode (CE), a working electrode (WE), and a reference electrode (E or RE). The electrode (e.g., WE) may be made of modified carbon foam (i.e., carbon foam modified with a receptor via a connector) characteristic of the present invention. Other electrodes (e.g., CE and/or RE) may also be carbon foam-based, preferably carbon foam-based, and more preferably based on the same carbon foam without any modification. All electrodes may have the same or different dimensions.
Sensors (e.g., biosensors) may be supplied as products, wherein the sensors are housed within packaging, and the products preferably include instructions for use. Typically, the packaging includes a primary package in which the sensor is housed. The sensor may be provided on an adapter housed within the primary package. Suitable examples of primary packaging are caps, pockets, folders, envelopes, boxes, containers, cartons, housings, etc. Optionally, the packaging may also include secondary packaging. Such secondary packaging is typically packaging that holds one or more sensors together. Suitable examples of secondary packaging are plastic cartons, cardboard boxes, blister packs, boxes (e.g., cardboard or plastic boxes), housings, containers, cardboard or plastic crates, pallets, bundles with or without one or more air bags, etc. Still optionally, the packaging may include tertiary packaging, which may be selected from boxes, housings, cartons, containers, etc. Suitably, at least one of the above-described packages may protect the sensor from light (e.g., direct sunlight), moisture, physical and/or chemical damage and contamination. The instructions may provide detailed steps for using the sensor according to its features. Instructions may be provided in printed form as labels, brochures, manuals, or leaflets. Instructions may also be printed on product packaging.
Sensor manufacturing
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, wherein the steps include: (i) providing carbon foam; (ii) treating the carbon foam with a connector; and (iii) treating the connector-modified carbon foam with a receptor.
The method may include the step of manufacturing the carbon foam before providing and processing it with a connector. Thus, the carbon foam is produced by one of the laser processing methods disclosed herein, typically the first or second method, but more typically the first method. The carbon foam thus produced may be adhered to, attached to, or provided on a substrate. Typically, the carbon foam can be removed from the substrate before processing the connector in step (ii). In other words, the carbon foam in step (i) is provided without a substrate. Alternatively, it is not necessary to remove the carbon foam (e.g., the carbon foam remains adhered to the substrate). In other words, the carbon foam in step (i) is provided with a substrate.
The carbon foam can be incubated together with the adapter. Incubation can occur in a buffer solution, preferably a buffer solution. Additionally or optionally, adapter modification may require at least one of the following conditions: light (ultraviolet, visible, or infrared radiation) or heat. After incubation, the adapter-modified carbon foam can be washed.
The adapter-modified carbon foam can be incubated with the receptor. After incubation, the sensor thus obtained can be cleaned before use. After cleaning, the sensor may be passivated. Passivation is understood as blocking any remaining activation sites that have not been functionalized by the receptor.
The receptor is used to process the connector-modified carbon foam in step (iii).
The sensor can be an electrode or an electrode device including a multi-electrode platform. Therefore, the manufacturing steps described above can be applied to the manufacture of electrodes. When the sensor is an electrode device including a multi-electrode platform, the manufacturing steps described above are applicable to the production of the working electrode (WE), and the method further includes the additional steps of producing a counter electrode (CE) and a reference electrode (E or RE).
Use of sensors
In a third aspect, a method of using a sensor is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing a target; (iii) measuring the response of the sensor; and (iv) optionally, correlating the response with the level of the target in the sample.
The target can be the target disclosed herein, and is usually the biological material disclosed herein. The sample can be the sample disclosed herein, and is usually the biological sample disclosed herein.
Before use, the sensor (e.g., a biosensor) can be appropriately stored under ambient conditions (e.g., room temperature of approximately 20°C and 1 atmosphere). Typically, the sensor is stored under dry conditions. After use, the sensor can be properly disposed of (i.e., the sensor is a disposable sensor).
The sensor can be immersed in a sample. The sample may contain phosphate-buffered saline (PBS). The concentration of the target in the sample may be at least 1 ppm. The equilibration time may be at least 0.5 minutes, or at least 1 minute, or at least 10 minutes, or at least 30 minutes, typically not exceeding 2 hours, or not exceeding 1 hour, or not exceeding 40 minutes. The sensor can be cleaned after contact with the sample, and then the response can be measured. The sensor can be cleaned by rinsing with PBS. The sensor can be dried after cleaning (e.g., by airflow, or by natural drying).
The response can be measured using differential pulse voltammetry and/or impedance spectroscopy. The measured response may be further correlated with the target level in the sample. The method may include steps (i), (ii), and (iii) as described above, and additionally includes the following steps in sequence: (iv) contacting the sensor with one or more samples (i.e., control samples) containing a known level of the target; (v) measuring the sensor's response to one or more control samples; (vi) comparing the response to a sample containing or suspected of containing the target with the response to one or more control samples; and (vii) correlating the response to a sample containing or suspected of containing the target with the level of the target in the sample.
Appendix 5 Concepts
1. A sensor comprising: (i) a carbon foam, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam via the connector.
2. The sensor according to Concept 1, wherein the carbon foam is obtained by a method of generating carbon foam at at least one location within a carbon source by concentrating infrared radiation at that location, and the infrared radiation is provided by a laser beam, wherein the laser beam is an infrared laser beam.
3. The sensor according to Concept 2, wherein the concentrated infrared radiation includes diffraction of the infrared radiation to form an interference pattern, each fringe of the interference pattern being located within the carbon source.
4. The sensor according to Concept 2 or Concept 3, wherein the at least one position is laterally moved inside the carbon source and/or the at least one position is moved within the depth of the carbon source.
5. The sensor according to any one of Concepts 2 to 4, wherein the infrared radiation directly irradiates the carbon source, or the infrared radiation passes through a substrate before irradiating the carbon source, wherein the carbon source is disposed on the surface of the substrate or adjacent to the surface of the substrate.
6. The sensor according to any one of Concepts 2 to 5, wherein the carbon source is additionally irradiated with additional radiation, and the additional radiation is performed before, simultaneously with or after the step of focusing infrared radiation at at least one location within the carbon source.
7. The sensor according to Concept 6, wherein the additional radiation is rasterized on the surface of the carbon source.
8. The sensor according to Concept 6 or Concept 7, wherein the additional radiation directly irradiates the carbon source or passes through a substrate as described in Concept 5 before irradiating the carbon source.
9. The sensor according to any one of the foregoing concepts, wherein at least a portion of the connector is disposed (preferably dispersed) within the carbon foam; and optionally, at least a portion of the receptor is disposed (preferably dispersed) within the carbon foam.
10. The sensor according to any one of Concepts 2 to 9, wherein the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm.
11. The sensor according to Concept 1, wherein the carbon foam is obtained by providing a carbon source on or adjacent to a substrate surface and exposing at least a portion of the carbon source, comprising a carbon-containing material, and/or at least a portion of the substrate to a laser beam, thereby converting at least a portion of the carbon source into the carbon foam.
12. The sensor according to Concepts 5, 8 or 11, wherein the substrate comprises one or more of the following: silicone, silicon dioxide, gallium nitride, gallium arsenide, zinc oxide; or alternatively, one or more polymers; or alternatively, one or more metals selected from aluminum, copper, gold or other metals, or oxides, nitrides or arsenides of said metals.
13. The sensor according to any one of the foregoing concepts, wherein the carbon foam contains less than 3% oxygen, preferably less than 1.5% atomic percentage, and/or less than 3% nitrogen atomic percentage.
14. The sensor according to any one of the foregoing concepts, wherein the connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
15. The sensor according to Concept 14, wherein the connector is selected from polymers (preferably (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
16. The sensor according to Concept 15, wherein the one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, optionally in combination with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
17. The sensor according to Concept 16, wherein the organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of an ester or salt of the organic compound, or a compound that releases the organic compound in a reaction with the carbon foam.
18. The sensor according to Concept 17, wherein the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
19. The sensor according to Concept 17 or Concept 18, wherein the connector is bonded to the carbon foam via π-π interactions.
20. The sensor according to any one of the foregoing concepts, wherein the receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
21. The sensor of claim 20, wherein the receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof.
22. The sensor according to Concept 21, wherein the receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
23. The sensor according to any one of the foregoing concepts, wherein the receptor is bonded to the connector in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
24. A method of manufacturing a sensor according to any one of the foregoing concepts, comprising the following steps in sequence: (i) providing a carbon foam as described in any one of concepts 1 to 13, 19; (ii) treating the carbon foam with a connector as described in any one of concepts 1, 14 to 19, 23; and (iii) treating the connector-modified carbon foam obtained in step (ii) with a receptor as described in any one of concepts 1, 20 to 23.
25. A method for sensing a target, comprising the following steps in sequence: (i) providing a sensor according to any one of Concepts 1 to 23; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
It should also be noted that the sensor described in Appendix 5 may be the Gii-Sens carbon foam sensor described earlier in this specification.
Appendix 6 Baseline Experimental Conditions
1 mM potassium ferrocyanide/potassium ferrocyanide was used in 0.1 M strontium nitrate, with at least five replicates randomly selected. Cyclic voltammetry was performed at scan rates of 25 and 200 mV/s as a comparative technique. Various characteristics were investigated and conclusions were drawn to evaluate the performance of the differential electrode materials.
Electrochemical impedance spectroscopy was performed at the equilibrium potential with an amplitude of 5 mV and a frequency range of 0.1 to 100 kHz.
Use a built-in or external silver/silver chloride reference electrode for the sensor.
Gii Sens carbon foam compared to conventional graphene electrode materials
The Gii Sens carbon foam sensor was evaluated and compared with other commercially available graphene-based sensors. See Figure 84.
The recorded reduction and oxidation peak currents show a 25% increase in efficiency per unit geometry in terms of current density. This clearly reflects the larger usable electrochemical area offered by the Gii Sens 3D carbon foam. See Figure 85.
According to cyclic voltammetry, the assessment of reduction-oxidation peak separation can be interpreted as a measure of the surface's electronic redox response to voltage scans and its ability to efficiently perform rapid redox reactions. The study showed that the reduction-oxidation peak separation remained below 70 mV, and no increase in separation was observed from 25 to 200 mV/s.
Other graphene electrode surfaces showed significant voltage separation from reduction to oxidation, indicating low efficiency of the redox Faraday reaction and pronounced detrimental effects associated with faster scan rates. See Figure 86.
The charge transfer resistance values for different surfaces show a significant improvement for the GiiSens sensor surface. This demonstrates the great potential of GiiSens for achieving reliable impedance-based measurements with minimal background signal interference.
Gii Sens compared to other carbon-based materials
Carbon-based electrode materials are very common in electroanalytical applications. Carbon paste electrodes are a common material for screen-printed sensors. They are the most widely used electrode surfaces in practical, immediate applications due to their fabrication flexibility and affordability. At the other end of the spectrum are glassy carbon surfaces, which are expected to offer better performance, but their availability is limited by fabrication flexibility and affordability. See Figure 87.
The Gii Sens carbon foam exhibits performance comparable to pure glassy carbon materials in terms of available electrochemically active area, while increasing the usable area by 50% for a carbon paste electrode of the same size. See Figure 88.
The separation of reduction-oxidation peaks obtained from cyclic voltammetry initially revealed the poor performance of the carbon paste material, which is highly dependent on slow scan rates to achieve a relatively acceptable redox reaction on its surface. The Gii Sens response outperformed pure glassy carbon even at any scan rate, demonstrating its significant potential for manufacturing flexibility and superior performance. See Figure 89.
The measurement of surface charge transfer resistance highlights the enormous potential of Gii Sens as an impedance-based sensing surface superior to glassy carbon, and opens up areas previously unreachable by carbon paste electrode materials.
Gii Sens compared to screen printing gold
Screen-printed gold sensors possess two crucial properties that enable the sensor material to be used in practical electrochemical sensing applications: flexible fabrication processes and excellent electrochemical reactivity. Two commercially available screen-printed gold samples were evaluated. See Figure 90. Gii Sens carbon foam was demonstrated to possess these properties as well, while also being affordable.
Recorded reduction and oxidation peak currents show that the available electrochemically effective region per geometric unit area has increased by at least 20%. See Figure 91.
As expected, screen-printed gold showed the most responsive electrode surface material in the evaluation batch; however, Gii-Sens matching further improved this performance, especially at fast scan rates. See Figure 92.
Comparing the charge transfer resistance of the electrode surfaces of screen-printed gold and Gii Sens also highlights the great potential of Gii carbon foam materials; in all cases, it exhibits low resistivity-related values.
The comparison between Gii Sens and screen-printed gold aims to demonstrate the superiority of Gii Sens in terms of ease of manufacture and superior performance, while affordability and scalability are undoubtedly beneficial inherent features of the Gii Sens sensor.
in conclusion
The Gii Sens sensor outperforms any other carbon-based or even graphene-based sensor on the market. It even surpasses screen-printed gold surfaces, eliminating any concerns about the overall convenience of using Gii Sens surfaces as the ultimate electrochemical sensing platform. Gii Sens demonstrates for the first time the perfect choice of fabrication and scalable materials for electroanalysis applications, while maintaining peak performance, ensuring maximum sensitivity and flexibility for high-throughput and point-of-care diagnostic applications.
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
Target:
Optimization of surface immobilization of anti-human calcitonin (cAb)
Summary of Results
Select a surface NHS production method. Match existing standard manufacturing processes.
Optimal cAb surface coverage was achieved using 100 μg/ml cAb.
For standard bare sensors, the typical %CV is 7%. For all sensors shown in the experiments presented in this report, the %CV for a 100 μg/ml cAb coating was 10%.
Using a 100 μg/ml cAb coating, 2000 pg/ml Ag was successfully detected by direct determination. The %CV of the signal output was 10%.
Experimental Section
Solution composition
Surface Chemistry
NHS modification
pyreneNHS
Capture antibody (cAb):
Product Name: Antih PCT 4004SPTN-5
Antigen (Ag):
Product Name: Recombinant PCT Antigen
Echem Readout Solution
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 20 mM KCl.
cAb fixation solution
Anti-hPCT in 1×PBS (pH 7.2)
Antigen (Ag) detection solution
In 20 mM KCl, 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ + Ag
Electrochemical technology
Electrochemical impedance
Applied voltage: OCP
Amplitude: 0.01V RMS
Frequency range: 100000-0.1Hz
Cyclic voltammetry
Scan rate: 25mV/s
Initial potential: -0.3V
High potential: 0.6V
Low potential: -0.3V
Measurement Procedure
NHS fixed
10 mM Pyr NHS prepared in DMF.
10 μL was drop-coated onto the working electrode of each sensor.
Place the sensor in an airtight box and incubate it for 12 to 18 hours.
It was confirmed that PyrNHS/DMF had been fully evaporated from the surface.
cAb fixation procedure
Place the NHS GiiSens+ sensor on a flat surface.
10 μL of cAb was drop-coated onto the working electrode of each sensor.
Place the sensor in a sealed container and bathe it in water for 2 hours.
Remove the sensor and gently rinse off the solution with DI water, then gently dry it with a stream of N2 gas.
Measurement procedure: Direct measurement 1 - see Figure 93
1) cAb readout: Apply the electrochemical readout solution to the sensor surface, and then perform EIS measurement.
2) Solution removal: Remove the electrochemical readout solution from the sensor surface.
3) t'1 readout: Apply the electrochemical readout solution containing the antigen to the sensor surface, followed by EIS measurement. There is approximately 1 minute between solution addition and measurement.
4) Read t'2 and perform EIS measurement. There is approximately 6 minutes between adding the solution and the measurement.
5) Read t'3 and perform EIS measurement. There is approximately 11 minutes between adding the solution and the measurement.
See the appendix for the electrochemical reading procedure.
1. Characterization curve graph
Each point is sampled repeatedly, with n = 5 (minimum) different disposable sensors (single readout, sensor is disposed of).
Phase 1: Surface Chemistry
The chosen surface chemistry is NHS-modified carbon foam, followed by conjugation of cAbs via amide bond formation. See Figure 94: Schematic diagram of the surface fixation reaction.
NHS generation on the carbon foam surface was monitored using electrochemical impedance spectroscopy and cyclic voltammetry. See Figure 95: Rct and ΔEp signal responses of the electrode for NHS functionalization.
The increases in Rct and ΔEp relative to the bare electrode confirm the NHS functionalization of the carbon foam electrode.
A range of cAb concentrations between 50 and 800 μg/ml were screened using electrochemical impedance spectroscopy. See Figure 96: cAb immobilization on the electrode.
For immobilization on the NHS-modified sensor, a logical increase in Rct was observed with increasing cAb concentration. The optimal coverage on the NHS electrode was estimated to be 100 μg/ml cAb, a concentration that provided the best sensor performance without wasting material for minimal gain. Excellent reproducibility (%CV 3%) was observed at this concentration.
Phase 2: Electrochemical Signals
The generated electrochemical signals were evaluated for direct assay, meaning that secondary antibodies are not required to assist antigen detection.
An antigen concentration of 2000 pg/ml was selected for the direct assay study. Based on the results of Phase 1 of this report, the surface antibody coating was fixed at 100 μg/ml. The Ag-Ab incubation time was selected as the initial assay parameter for the study. See Figure 97: Signal response from 2000 pg/ml in the direct assay using a 100 μg/ml cAb surface coating.
The 100 μg/ml cAb again showed a good level of reproducibility (%CV 8%). The difference in mean Rct between cAbs was significant, yielding different quantifiable signal outputs (ΔRct). The ΔRct signal output also showed an acceptable level of reproducibility, with %CV ≥ 10% at each readout time. The stability of the output signal between 1, 6, and 11 m indicated no additional Ab-Ag interactions after the first measurement. The 5-minute time interval between measurements is attributed to the time length required for EIS measurements. For 2000 pg/ml Ag samples, the optimal assay incubation time is as low as 1 minute.
Table 9: Key experimental and electrochemical parameters for cAb fixation
Table 10: Key experimental and electrochemical parameters for Ag detection
Appendix 8:
Combined list of features and optional features
Appendix 8 is a combined list of features and optional features. It should be noted that each of any one or more features A-R can be combined with one or more other compatible features A-R, as well as with any one or more optional features.
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene materials adhered to a substrate
Group 2: Dual-laser processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual Laser
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device: supercapacitor
Features M2: Details of Carbon Foam Supercapacitor
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate a subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the subsurface region.
An apparatus comprising a laser-induced carbon foam material produced by irradiating a subsurface region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an encapsulation region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the encapsulation region.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulation region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
A laser-induced carbon foam material is manufactured by means of a laser beam configured to irradiate an encapsulated, subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to a substrate
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between the graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between a graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing graphene material includes the following steps: (a) irradiating an encapsulation region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulation region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove at least some of the disordered amorphous non-graphene material and expose at least some of the carbon foam.
A laser-induced carbon foam is made by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
An apparatus comprising laser-induced carbon foam prepared by:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers operating in different frequency bands
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating a region of the carbon precursor material, below the surface of the material or a region below the surface of the material, with a laser beam operating in a first wavelength band to generate carbon foam in the region of encapsulation or the region below the surface, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
A laser-induced carbon foam material, which is made by the following:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of the carbon precursor material below the surface of the material using a laser beam operating in a first wavelength band, to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is carried out in one manufacturing facility, and step (b) is carried out in a different facility.
Feature L1: Biosensor
A method for manufacturing a biosensor, the biosensor comprising a sensing electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
A biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes a biosensor with sensing electrodes comprising carbon foam made at least in part by a method as defined in any one of features A-K above.
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric material to at least partially cover the electrodes and connection traces.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam made by a method defined as any one of features A-K above, and said biosensor includes (i) a screen-printed electrical connection trace over each electrode and (ii) a screen-printed dielectric that at least partially covers the electrodes and the connection trace.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and said method comprising an additional step of adding functionalized groups to at least the working electrode in a different manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam manufactured at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups added to at least the working electrode at different manufacturing facilities.
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least a portion of a carbon foam produced at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups that have been added to at least the working electrode at the same manufacturing facility.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon produced by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on a carbon precursor substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon layer, the electrical connection trace, and the reference electrode; and then (d) producing a carbon foam sensor electrode using a method as defined in any one of features A-K above.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, wherein the biosensor includes (a) a carbon layer screen-printed on a carbon precursor substrate; (b) screen-printed electrical connection traces and a screen-printed reference electrode; (c) a dielectric layer screen-printed over the carbon layer, the electrical connection traces, and the reference electrode; and (d) a carbon foam sensor electrode fabricated using a process as defined in any one of features A-K above.
Feature M1: Energy storage device
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
The method includes the steps of screen printing electrical connection traces over at least a portion of each electrode and screen printing a dielectric layer to at least partially cover the electrodes and connection traces.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Includes a screen-printed electrical connection trace formed above at least a portion of each electrode and a screen-printed dielectric layer that at least partially covers the electrode and the connection trace.
Feature M3: Carbon foam supercapacitor: common collector electrode
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
The method includes the step of screen printing electrical connection traces over at least a portion of each electrode, wherein a single electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrodes comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) a screen-printed electrical connector on a substrate; (b) a screen-printed carbon layer above the current collector; (c) a screen-printed dielectric over at least some of the carbon layer; and then (d) a carbon foam energy storage electrode produced at least in part by a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Supercapacitor: Metal Oxide Variant
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of electrochemically depositing a pseudocapacitive material, such as a metal oxide, onto the energy storage electrode.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) a pseudocapacitive material, such as a metal oxide, applied to said energy storage electrode.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel electrolyte in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) an ion-gel electrolyte having been applied in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in said environment are measured and controlled to optimize the capacitance of said energy storage device.
Feature N1: Electrical conductor
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
A method for manufacturing a smart tag includes the steps of combining or integrating a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as described in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor.
A method of manufacturing an integrated device includes the step of combining or integrating an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above.
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode formed at least partially in a layer below the sample orifice by means of a carbon precursor film formed by any one of the features A-K above, and a reference electrode connector, a working electrode connector, and a counter electrode connector in the layer below the reference electrode, the working electrode, and the counter electrode.
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
A method for manufacturing a lab-on-a-chip device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a conductive layer over the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) Screen printing a dielectric layer above the current collector layer;
(vi) The sensor electrode comprising carbon foam material is prepared from the carbon precursor film by at least part of the method defined in any one of features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Feature P: Scalable manufacturing of carbon foam: Gii 3
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other carbon foam applications
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, tactile sensors for robots; prototype sensors that use polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as an active layer in a piezoresistive pressure sensor for robotic touch sensing applications.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection.
Continuous monitoring of chemical sensors.
Glucose monitoring sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competing for binding with polynordihydroguaiaric acid.
Lactic acid sensor: Employs synthetic organic acceptor molecules based on attaching boric acid to carbon foam to provide functionality and selectivity in competitive analyte binding, using surface redox polymer indicator displacement.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1).
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material produced at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a prominent D peak; a 2D peak smaller than the G peak; and a D peak:G peak ratio greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Optional features
It should be noted that each of the following optional features can be combined with one or more other compatible optional features and with any one or more of the main features A-R.
Manufacturing process
The manufacturing process is a room temperature process.
The manufacturing process is an atmospheric pressure process.
It can be done on a plastic substrate (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
The manufacturing process requires approximately 2 minutes or less to create a 1 cm² carbon foam, which is about 50 μm thick, on a plastic substrate.
The manufacturing process enables the formation of 3D carbon foam on a flexible substrate.
The manufacturing process does not require graphene or graphene oxide precursors.
The manufacturing process generates carbon foam material only in the encapsulation and subsurface region of the carbon precursor material, and does not generate carbon foam material on any surface of the carbon precursor material.
The manufacturing process utilizes a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
The manufacturing process described herein is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
First laser beam parameters and control scheme
The first laser beam and the second laser beam are generated by different laser systems.
The first laser beam and the second laser beam are generated by the same laser system.
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface region or encapsulation region to form carbon foam.
• The laser beam generates temperatures exceeding 500°C in the subsurface region or encapsulated region to form carbon foam.
• The pulse duration of the laser beam is between 1 ns and 10 μs, resulting in a heating rate between approximately 5 × 10 7 ℃/s and 2 × 10 12 ℃/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between 50kHz and 500kHz.
• The laser pulse frequency is between 1 kHz and 2 MHz.
• The laser wavelength is between 0.7μm and 2.5μm.
• The laser is scanned at a speed between 9 cm/s and 40 cm/s (or ±50% of these ranges).
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The focal point of the laser beam is moved through a depth of at least 100 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scan can achieve a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm in size).
• The wavelength of the laser beam is not absorbed by the carbon precursor material, or the absorption rate is extremely low.
• Carbon precursor materials have extremely low absorption rates for the wavelengths of laser beams.
The radiation absorptivity per centimeter (decimal) is less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between 0.7μm and 2.5μm.
The laser beam is an IR laser with a wavelength between 0.75μm and 1.40μm.
Properties of the subsurface region or packaged region
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region is at least 10 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 20 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 30 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 40 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 50 μm below the surface of the carbon precursor material.
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
• The thickness of the subsurface region or encapsulation region is between 10 μm and 200 μm.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity or other laser parameters, and the selection of the carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, or more below the surface of the carbon precursor material.
• The distance between the subsurface region or encapsulation region and the surface of the carbon precursor material is at least 1% of the total thickness of the carbon precursor material, or at least 10% of the total thickness of the carbon precursor material, or at least 20% of the total thickness of the carbon precursor material, or at least 30% of the total thickness of the carbon precursor material, or at least 40% of the total thickness of the carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the center of the minimum cross-section of the first laser beam, and the volume is within 500 micrometers, 100 micrometers, or 1 micrometer of the center.
carbon precursor materials
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300 ± 50 cm⁻¹.
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of the laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
Substrate supporting carbon precursor materials
• The substrate is a plastic body, film, or foil.
• The substrate is flexible.
The substrate is a polyimide circuit board.
• The substrate has an extremely low absorption rate of the first laser beam.
• The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
• The substrate is formed of one or more of the following: silicon (Si), silicon dioxide (SiO 2 ), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing both silicon and silicon dioxide.
• The substrate is a carbon source.
• The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
• The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
• The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam.
• The thickness of the disordered, amorphous, non-graphene material occupying the surface of the adjacent carbon precursor material is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
• The disordered, amorphous, non-graphene material extends from its surface into the carbon precursor material matrix by at least 10 μm.
• The disordered, amorphous, non-graphene material extends from its outer surface into the body of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
Carbonization at the physical interface with the substrate supporting the carbon precursor material
• The carbon precursor material is transformed into a disordered, amorphous, non-graphene material at the physical interface with the substrate by the laser beam to a depth defined by the parameters of the laser beam.
The disordered, amorphous, non-graphene material adheres or otherwise attaches to one region of the carbon foam and to another region of the substrate, thus providing stability to the carbon foam.
• The thickness occupied by the disordered amorphous non-graphene material, as measured from the interface between the carbon precursor material and the substrate, is about 1%, less than about 1%, less than about 5%, or less than about 10% of the total thickness of the carbon precursor material.
• The thickness of the disordered, amorphous, non-graphene material occupying the interface between the carbon precursor material and the substrate is at least 10 μm.
• The disordered, amorphous, non-graphene material extends from the interface between the carbon precursor material and the substrate to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
ablation laser beam or second laser beam
The parameters of the laser beam include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the region below the surface or in the encapsulation region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
• A second laser beam alters the carbon foam as part of the process that exposes it.
• A second laser beam alters the shape of the carbon foam as part of the process that exposes it.
• The second laser beam is automatically controlled to scan in the same area, and/or overlapping area, and/or non-overlapping area.
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
• The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
• The carbon precursor material has an absorption coefficient for the second laser beam greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300± 50cm⁻¹ .
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The second laser beam scans in a pattern (e.g., a grating) that includes non-overlapping areas or lines.
• The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
• The second laser beam is the same as the laser beam that irradiates the encapsulation area or subsurface area of the carbon precursor material to generate carbon foam in the encapsulation area or subsurface area.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam
• The carbon foam is a multi-layered twisted or disordered carbon foam.
• The carbon foam is non-graphene carbon foam.
• Carbon foam includes carbon nanostructures such as carbon nano-onions, carbon nano-horns, carbon nanotubes, carbon nanodots, nanodiamonds and fullerenes, or any combination thereof.
• The thickness of the carbon foam is at least about 50 μm.
• The thickness of the carbon foam is between approximately 50 μm and 300 μm.
• Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
• Carbon foam is or includes carbon foam with a spatial distribution of defects that lead to high electrochemical reactivity.
• Carbon foam is or includes carbon foam with basal surface defects at vacant sites that lead to high electrochemical reactivity.
• The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Compared to conventional graphene foams produced using conventional laser processes, carbon foams possess one or more of the following properties: easier control over thickness or depth; greater flexibility compared to the highly brittle graphene produced using conventional laser processes; stronger adhesion to underlying flexible substrates; higher porosity; higher electrical conductivity; increased capacitance or charge storage; faster absorption of organic solvents and water-based solutions; higher hydrophilicity; contact angle less than approximately 20°; enhanced antifouling properties; higher EMI shielding; and improved electrode quality.
Biosensor Use Cases
• Carbon foam has been functionalized as a biosensor.
• Carbon foams are functionalized into biosensors by adding receptors that are specific to the target or analyte.
• Carbon foam has been functionalized into a biosensor with a reversible polymer displacement sensor mechanism for use in
Electrochemical glucose monitoring.
The reversible polymer displacement sensor includes a pyrene-derived boric acid chemical acceptor for glucose adsorbed onto an electrode comprising the carbon foam.
Carbon foams are functionalized as biosensors by adding receptors that are specific to a target or analyte and connectors that enable the receptors to attach to the carbon foam.
The connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
The connector is selected from polymers (preferably (meth)acrylate polymers), organic compounds containing one or more functional groups, carbodiimides, diazo compounds, or mixtures thereof.
• The one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, and optionally combined with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
The organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of the organic compound as an ester or salt, or a compound that releases the organic compound in a reaction with the carbon foam.
• The connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof.
The joint is bonded to the carbon foam via π-π interactions.
The receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
The receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes or mixtures thereof.
• The receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
The receptor is bonded to the adapter in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
Supercapacitor Use Cases
The carbon foam forms electrodes in an energy storage device, such as an electrochemical capacitor, supercapacitor, pseudocapacitor, or capacitor.
The carbon foam is treated with a metal oxide film to provide pseudocapacitance.
The carbon foam forms at least one electrode in the energy storage device, such as an electrochemical energy storage device.
A capacitor, supercapacitor, pseudocapacitor, or capacitor, and a hydrogel electrolyte encapsulates the electrode or each electrode in the active region to produce an enhanced operating voltage window.
The carbon foam forms the electrodes in the battery.
The carbon foam forms an electrical conductor.
Technical Field
This invention relates to laser-induced production of carbon nanostructures, including multilayer carbon foams with disordered layer twisting.
Background Technology
Carbon nanostructures are both highly attractive and a hot research topic. Carbon nano-onions (also known as multilayer fullerenes) exemplify this. See “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9 and “Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications”, DOI:10.1016/j.ica.2017.07.021, the contents of which are incorporated herein by reference.
As another carbon nanostructure, graphene has attracted widespread attention for many years due to its applications in biosensors, electrochemical sensing systems, supercapacitors, electrodes, and fuel cells. Known methods for producing 3D graphene include laser-induced graphene production as described in WO2019/038558; 3D graphene is formed on the surface of the exposed polyimide film when a suitable carbon precursor material (such as a polyimide film) is positioned on a supporting substrate and irradiated with a CO2 laser. Experience has shown that the thickness of 3D graphene produced by this method is less than 50 μm; furthermore, 3D graphene itself can be brittle and has poor adhesion to the underlying substrate, thus potentially peeling off. Therefore, 3D graphene is not suitable for many applications.
A note on terminology used in the field of carbon nanostructures: If we use only the term "graphene," there are many different forms of "graphene"; for example, the literature describes monolayer graphene, bilayer graphene, disordered graphene, graphene superlattices, graphene fibers, 3D graphene, graphene aerogels, wrinkled graphene, and many other forms. This presents a defining challenge, as using a specific term (e.g., "3D graphene") may imply limitation to only that specific form of graphene. Furthermore, IUPAC (International Union for Pure and Applied Chemistry) recommends using the name "graphite" for three-dimensional materials, and "graphene" only when discussing the reactions, structural relationships, or other properties of individual layers.
Therefore, in this specification, we use the term "carbon foam" as a general term, and this term should be broadly interpreted to cover any carbon nanostructure, such as 3D carbon material foam, including multilayer 3D carbon material foam with disordered layer twisting.
An example of the term "carbon foam" refers to a material manufactured using the methods described in this specification; such a material has slightly different properties from conventional graphene or conventional graphene foam. For example, graphene foam has several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature: the absence of a D peak; a 2D peak higher than the G peak; and a D peak:G peak ratio close to zero. As we will describe in more detail below, the carbon foam produced in specific embodiments of the invention does not possess these characteristics; it is hydrophilic with a contact angle less than 20°; it lacks the Raman signature indicative of graphene: it exhibits a prominent D peak; a 2D peak significantly smaller than the G peak; and a D peak:G peak ratio significantly higher than zero. In terms of appearance and Raman signature, it appears to be closer to carbon nanotube onion materials. Therefore, the term "carbon foam" in its scope also includes materials that are carbon nanostructures, such as carbon nanotube onions, carbon nanohorns, carbon nanotubes, carbon nanodots, nanodiamonds, and fullerenes, or any combination thereof.
Summary of the Invention
In this specification, we describe a method in which the surface of a carbon precursor is not converted into graphene at all; instead, the region beneath the surface of the carbon precursor, or the encapsulated region, is converted into carbon foam by a focused laser beam.
We summarize the invention as described in claim 1, namely a method for manufacturing carbon foam material, which includes the following steps:
(a) Using a first laser beam, an encapsulated or sub-surface region of the carbon precursor material is irradiated below the surface of the material to generate carbon foam in the sub-surface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Using a second laser beam to remove or ablate the disordered amorphous non-graphene material located above the carbon foam to expose at least some of the carbon foam.
The amorphous non-graphene material is positioned "above" the carbon foam because it is closer to the laser beam that generates the laser. One embodiment of the invention is described as a "dual-laser" process because two separate lasers are used in the production of the carbon foam material. The carbon foam material exhibits a significant D peak; the 2D peak is significantly smaller than the G peak; and the D peak:G peak ratio is significantly higher than zero. In terms of appearance and Raman signature, it appears more similar to carbon nanotube onion material. It can be used in biosensors, supercapacitors, and pseudocapacitors. In one embodiment, the carbon foam is referred to as "Gii" carbon foam.
Attached Figure Description
The invention will be described with reference to specific embodiments shown in the following figures.
Figures 1-6 schematically illustrate a dual-laser process for generating carbon foam when a polyimide (PI) film (which acts as a carbon precursor) is positioned on a substrate.
Figure 7 is a scanning electron image showing the unique surface morphology (x250) of carbon foam achieved using a dual-laser method.
Figure 8 is a scanning electron image showing the surface of conventional laser-induced graphene.
Figures 9-14B schematically illustrate a dual-laser process for generating carbon foam when the PI film (which acts as a carbon precursor) is not positioned on the substrate.
Figure 15 shows the cyclic voltammetry (CV) diagram of a carbon foam electrode produced using a dual-laser method.
Figure 16A is a graph showing the peak separation ΔE<sub>p</sub> of a carbon foam electrode produced using a dual-laser method as a function of the scan rate.
Figure 16B is a graph showing the peak separation ΔE<sub>p</sub> of a conventionally manufactured graphene electrode as a function of the scan rate.
Figure 17 compares the electrochemical impedance spectroscopy results of carbon foam electrodes produced using the dual-laser method with those of conventionally manufactured graphene electrodes.
Figures 18A and 18B show Raman analysis of carbon foam samples prepared using a dual-laser process.
Figure 18C shows the Raman analysis of carbon nanotube onion material.
Figure 19 is a scanning electron image showing dual-laser carbon foam and conventional graphene.
Figure 20 is a schematic image of a biosensor that includes dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Sens).
Figures 21-23 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Sens, Gii-Sens+, and PPC Gii-Sens variants).
Figures 24-27 are schematic images of a supercapacitor including dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Cap).
Figures 28 and 29 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Cap and Gii-Cap+ variants).
Figure 30 is a schematic cross-section of an integrated lab-on-a-chip (LoC) device that includes a biosensor and a supercapacitor made using dual-laser carbon foam.
Figure 31 is an exploded view of a fully integrated LoC device.
Figure 32 shows the LoC device displaying quantitative results on its monitor.
Figure 33 is an exploded view of an environmental monitoring device including the Gii-Sens sensor.
Figure 34 is a view of the assembled environmental monitoring device.
Figure 35 is a schematic cross-section of a device having a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 36 is a schematic diagram of a smart tag; it has a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 37 is a schematic cross-section showing the basic layering of different materials in the Gii-Thru variant, which is a three-dimensional structure of carbon foam.
Figures 38-42 are schematic diagrams of various Gii-Thru Gii-Cap/Gii-Cap+ three-dimensional supercapacitor devices.
Figures 43A and 43B are detailed process flow diagrams of the dual-laser carbon foam Gii-Thru Cap three-dimensional supercapacitor device.
Figures 44A and 44B are schematic diagrams of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device.
Figures 45A and 45B are schematic diagrams of the Gii-Thru sensor used in an eight-sample array microfluidic diagnostic device.
Figure 46A shows a perspective view of a fully assembled multi-sample array microfluidic diagnostic device.
Figure 46B is a top view of a multi-sample array microfluidic diagnostic device.
Figures 47 and 48 are views of a microfluidic diagnostic device.
Figure 49 shows the detailed manufacturing process of the high-sensitivity, low-cost Gii-Thru variant.
Figure 50 is a schematic diagram of a high-speed roll-to-roll or roll-to-sheet manufacturing system for Gii carbon foam.
Figure 51 shows the detailed process flow of the system in Figure 50.
Figures 52-57A show scanning electron images of dual-laser carbon foam at different magnifications.
Figure 57B is a scanning electron image of carbon nanotube onion material produced using conventional processes.
Figure 58 shows the Raman displacements of eight carbon foam sheets fabricated using a dual-laser process.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Figure 59 shows the carbon foam cyclic voltammogram measured at 25 mV/s for the anode voltage.
Figure 60 shows the carbon foam cyclic voltammogram for cathode voltage measured at 25 mV/s.
Figure 61 shows the galvanostatic charge-discharge (GCD) curves of carbon foam measured at 0.5 mA/ cm² for the anode voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves for the cathode voltage window, measured at 0.5 mA/ cm² .
Figure 63 shows carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 shows carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 shows carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 2: Gii-Cap+ Hydrogel
Figure 66 shows a typical CV curve for the Gii-Cap+ hydrogel device.
Figure 67 shows a typical GCD curve of the adjusted Gii-Cap+ hydrogel device.
Figure 68 shows the post-adjustment Nyquist (left) and Bode (right) curves of the Gii-Cap+ device.
Appendix 3 GiiCap Ion Gel
Figures 69-74 show the results of the GiiCap ionogel apparatus.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Figures 75-78 are schematic diagrams of the measurement procedure of the Gii-Sens 3D carbon foam measurement system.
Figures 79-81 show the surface chemistry of Gii-Sens 3D carbon foam.
Figures 82-83 show the label-free assay of Gii-Sens 3D carbon foam.
Appendix 6 Baseline Experimental Conditions
Figures 84-86 are graphs comparing the performance of Gii-Sens carbon foam and graphene electrode materials.
Figures 87-89 are graphs comparing the performance of Gii-Sens carbon foam and carbon-based electrode materials.
Figures 90-92 are graphs comparing the performance of Gii-Sens carbon foam and screen-printed gold.
Appendix 7: Optimization of surface immobilization of anti-human calcitonin (cAb)
Figure 93 shows an optimized direct assay procedure for surface immobilization of anti-human calcitonin (cAb).
Figure 94 is a schematic diagram of the surface fixation reaction.
Figure 95 shows the Rct and ΔEp signal responses of the Gii-Sens electrode with NHS functionalization.
Figure 96 shows cAb fixation on the GiiSens electrode.
Figure 97 shows the signal response from 2000 pg/ml in the direct determination form using a 100 μg/ml cAb surface coating.
It should be noted that Gii, Gii-Sens, Gii-Sens+, Gii-Cap, Gii-Cap+, Gii-Thru, and PPC Gii are trademarks of their respective owners. "Gii" generally refers to carbon foam produced using a dual-laser process. "Gii-Sens" refers to Gii carbon foam used in sensors (such as biosensors). "Gii-Cap" refers to Gii carbon foam used in supercapacitors. The "+" suffix indicates Gii carbon foam modified with a metal oxide layer or film. "Gii-Thru" refers to Gii carbon foam arranged in a specific three-dimensional structure. "PPC" refers to a specific manufacturing process, namely "post-printing conversion," in which Gii carbon foam is produced after various screen printing steps have been completed.
Figure Labels
Dual laser process
11 IR laser
12 IR laser beams
13. The interior of the PI film
14 PI film
15 substrate
16 Subsurface carbon foam region
17. Disordered amorphous non-graphene materials beneath the surface carbon foam region
18. Extended regions of disordered, amorphous, non-graphene material above the subsurface carbon foam region.
20CO2 laser
21 Unique surface morphology of exposed carbon foam regions
Biosensors
201 Polyimide substrate
202 Carbon Foam Working Electrode
203 Carbon foam counter electrode
204 carbon foam reference electrode
205 Screen Printed Silver Connecting Track
206 Dielectric Layer
The area where the 207 silver connection trajectory overlaps with the electrode
Gii-Cap Supercapacitor
Array of 241 carbon foam electrodes
242 Silkscreen Printed Silver Connector
243 Dielectric layer
244 Polyimide base layer
245 copper connector
246 Electrolyte layer
247 Aluminum Laminated Heat-Sealing Bag
250 carbon foam digits with rounded edges
Combined sensors and supercapacitors
301 Upper polyimide layer
302 Gii-Sens Biosensor
303 Lower polyimide layer
304 Supercapacitor
305 plastic parts
306 Microchannel
307 Connector Track
308 Flexible Electronic Devices
310 Induction Power Circuit
312 Gii-Cap Supercapacitor
313 Gii-Sens Biosensor
314 Device layer with microelectronic devices
315 Top Panel
316 monitor
317 Circular Analyte Well
Environmental monitors
330 Gii-Sens Carbon Foam Sensor
331 Control Electronic Devices
332 PV solar cells
333 Gii-Cap carbon foam supercapacitor
334 Peelable back
Combined supercapacitor and battery
351 First polyimide layer
352 Supercapacitor
353 Second polyimide layer
354 battery
355BMS (Battery Management System)
356 Flexible electronic devices
357 Electrical connectors
Smart Tags
360 Flexible Battery
361 Supercapacitor
362 Electronic Components Module
363 Exposed label surface; 364 Adhesive release liner; 364 Gii-Thru Cap
371PI membrane
372 Screen printing conductive ink or paste layer
373 Screen-printed collector
374 Dielectric Isolator
375 Encapsulated carbon foam layer; 376 Disordered, amorphous, non-graphene layer beneath the carbon foam layer; 377 Unique surface morphology layer.
390 Hydrogel Electrolyte Layer
391 Carbon foam layer with unique surface morphology
392 PI film
393 Screen Printing Carbon Paste Layer
394 Screen-printed silver connector layer
395 silver connector layer ketone insert
396 Distributed dielectric isolation layer
397 Second carbon foam layer with unique surface morphology
398 PI film
399 Hydrogel Electrolyte Layer
400 dielectric isolation layer
401 screen-printed silver current collector layer
402 copper insert
403 Screen Printing Carbon Paste Layer
404 carbon foam layer
405 PI film
Gii-Thru Sens
Three-point array microfluidic diagnostic device
440 Analyte Sample Wells
441 Laminated Hole Spacer Layer
442 Polyimide film
443 Screen-printed conductive carbon layer
444A Reference Electrode Connector
444B Working Electrode Connector
444C Counter electrode connector
447 Screen-printed dielectric layer
448A Reference Electrode
448B Working Electrode
448C counter electrode
449 Reference electrode screen-printed carbon layer
Eight-point array microfluidic diagnostic device
451 Laminated Hole Spacer
452 Array of eight analyte wells
453 Holes for the electrodes
454 Hole of the reference electrode
455 Polyimide layer
456 Polyimide layer
457 Eight working electrodes
458 pairs of electrodes
459 Reference Electrode
460 Screen-printed carbon bonding interface layer
461 Screen Printed Silver Connecting Track
462 Screen-printed dielectric layer
470 Top-layer microfluidic foil
471 Intermediate Layer Microfluidic Foil
472 Printed or molded microfluidic channels
473 Microfluidic foil with binder as the underlying layer
474Gii-Thru sensor
475 connector
481 Transparent Resin Barb Connector
482 Top Foil
483 Transparent Resin Molded Microfluidic Card
484 Microfluidic Channels
485-hole unit
486Gii-Thru sensor
Detailed Implementation
We will begin with a simplified, illustrative walkthrough of specific embodiments of the invention. We present two demonstrations; the first (Figures 1-6) will describe at a high level the carbon foam production process with a carbon precursor (e.g., a polyimide (PI) film, in this case, such as a membrane) mounted on a substrate; the second (Figures 9-14) covers the carbon foam production process without the polyimide film mounted on the substrate. In each case, we use a dual-laser process; the meaning of the terminology will be explained below.
In the first stage (see Figure 1), a laser 11 with wavelength λ uses a laser beam 12 to irradiate the interior 13 of a polyimide film 14, which is positioned on a substrate 15 suitable for end applications. This laser may be a pulsed IR laser that delivers IR radiation with a wavelength of 1064 nm.
As shown in Figure 2, a laser 11 with wavelength A is tuned so that the subsurface region 16 is transformed into carbon foam. The focus of laser A is gradually moved through the interior 13 of the polyimide film 14 to generate the entire carbon foam region 16. The depth or height of the carbon foam region 16 can be approximately 50 μm or greater, much higher than that achievable by other methods. Note that no carbon foam is generated at any time on the exposed surface of the polyimide film 14 (i.e., the surface on which the laser beam is incident). The region above the carbon foam 16 (i.e., closer to the laser than the carbon foam region 16) is not transformed into carbon foam. The region 17 below the carbon foam region 16 (i.e., the lower surface of the PI film) is also not transformed into carbon foam, but rather into disordered, amorphous, non-graphene material adhered to the underlying substrate 15.
Figure 3 shows that due to gas trapping, the laser 11 with wavelength λ causes physical expansion in region 18 above the internal carbon foam region 16 (i.e., closer to the laser than the carbon foam region 16). This region 18 is neither 3D graphene nor a polymer; it is a disordered amorphous material.
In the second stage, a laser 20 with wavelength B is now tuned to the disordered amorphous material region 18 above the carbon foam region 16, as shown in Figure 4. This can be a CO2 laser with a wavelength of 10.6 μm.
As shown in Figure 5, a laser 20 with wavelength B ablates some or all of the region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam region 16.
The laser 20 with wavelength B also reveals a lower carbon foam region with a unique surface morphology 21, as shown in Figure 6.
We refer to the process described in Figure 1-6 as the "dual-laser process".
Figure 7 is a scanning electron image showing the unique surface morphology (x250) achieved using a dual-laser method. In this case, the carbon source was first irradiated with IR radiation at a wavelength of 1064 nm from a pulsed IR laser, the radiation being focused into and gradually penetrating the carbon source. Then, the carbon source was irradiated with a laser beam at a wavelength of 10.6 μm from a CO2 laser. The thickness of the carbon foam layer in this image is approximately 220 μm.
As shown in Figure 8, the contrast with the surface morphology (x250) achieved using the conventional LIG method is striking: it features clear grating lines and less spiraling folds. The thickness of this carbon foam layer is less than 50 μm.
Based on the image in Figure 7, we can infer that the material produced using the dual-laser process does not have a surface morphology similar to conventional graphene foam; although it appears to be a multilayered, 3D carbon-based material with a chaotic, tortuous, foam-like structure, it is not necessarily a material commonly described as "graphene" in the conventional sense. More details are provided in Feature R below.
In the aforementioned demonstration (Figures 1-6), we investigated a dual-laser process for mounting a carbon precursor material (polyimide film) onto a substrate. In Figures 9-14 below, we will investigate a dual-laser process without mounting the polyimide film onto the substrate. We will later describe in detail the manufacturing processes for two specific implementations, referred to as Gii-Cap (supercapacitor) and Gii-Sens (sensor), which use a standard 220mm × 180mm sheet of polyimide film, which is not mounted onto the substrate; this size can be considered in standard laser scanning equipment, typically used for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). The manufacturing process also utilizes a standard flatbed screen printing apparatus and a standard conveyor belt dryer to easily accommodate thin PI films of different sizes. Other sizes of polyimide sheets can be considered.
As previously described, a laser 11 of wavelength Å (e.g., an IR laser) irradiates the interior 13 of the PI film 14; the film 14 is not currently mounted on the substrate, as shown in FIG9. It may be a sheet whose edges are supported or temporarily rested on a surface, or a sheet that forms part of a PI film roll when using a continuous manufacturing (e.g., roll-to-roll or roll-to-sheet) system (see Feature P below).
A laser 11 with wavelength λ is tuned to transform the subsurface region 16 into carbon foam, as shown in Figure 10. The focal point is gradually moved through the membrane 14 to create the entire carbon foam region 16. The height of the carbon foam region 16 can be approximately 50 μm or greater, much deeper or higher than could be achieved by other methods.
At no time does 3D graphene form on the exposed surface of the polymer film. The region above the carbon foam does not transform into 3D graphene.
As shown in Figure 11, due to gas retention, region 18 above the internal carbon foam region 16 undergoes physical expansion. This region is neither 3D graphene nor a polymer; it is a disordered amorphous material.
A laser 20 with wavelength B (e.g., CO2 ) is now tuned to region 18 above the carbon foam, as shown in Figure 12. The laser 20 with wavelength B ablates region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam 16, as shown in Figure 13.
Just as with the case where the polyimide film 14 is mounted on the substrate, the laser 20 with wavelength B also imparts a unique surface morphology 21 to the underlying carbon foam 16, as shown in Figure 14.
Some specific implementation details of this dual-laser method for producing carbon foam are as follows: In one example, the Nd:YAG solid-state laser is a wavelength A-wave laser, and it is positioned such that the IR laser radiation beam (wavelength 1064 nm) generated by the solid-state laser perpendicularly impacts the polyimide layer. Optics focus the IR laser radiation beam to a minimum beam convergence within a certain volume of the polyimide layer.
In the encapsulation region or subsurface region or location around the minimum beam convergence, the interaction between the laser and the polyimide leads to the carbonization of the carbon source. This carbonization results in the generation of carbon foams, such as twisted or disordered multilayer carbon foams, in the encapsulation region or subsurface region, and causes the formation of a disordered, amorphous, non-graphene material layer on the surface of the polyimide film.
While maintaining the laser beam focused at a specific depth within the polyimide layer, the laser scans laterally above the polyimide layer. In this way, the path entirely within the polyimide carbon source is traced and transformed into carbon foam. Thus, the polyimide is carbonized into carbon foam with a pattern corresponding to the path traced by the scanning, focused IR laser beam.
In one setup, the Nd:YAG IR laser pulsed at 80 kHz, and the laser beam scanned the surface at a speed of 9.4 cm/s. Other implementations utilized different parameters. For example, a pulse frequency of 50 kHz and a scanning speed of 35.5 cm/s were also successfully used to generate carbon foam. The laser power typically operated in the range of 8–20 watts, with an optimal value of 12 W; the laser focal length typically operated in the range of 50 mm–400 mm.
Once a predetermined area within the polyimide layer is irradiated by a focused IR laser beam in the manner described above, the depth of the encapsulated area or subsurface region or location within the polyimide is altered, and the IR laser beam scans the same predetermined area again. A standard computer-controlled laser scanning system can be used, which controls the X-Y position of the laser on the polyimide film. It may be necessary to pass the focused IR laser radiation through the same area more than once to generate carbon foam. In this specific implementation, the focused IR laser also irradiates adjacent but not substantially overlapping areas. This process of irradiating the carbon source with focused IR laser radiation at different focal depths is repeated until the desired depth of the polyimide layer is exposed to IR laser radiation and carbon foam is formed in the encapsulated area or subsurface region. However, the surface layer is a disordered, amorphous, non-graphene material.
In the second step, the polyimide layer is exposed to radiation from a CO2 laser for an ablation process, exposing at least some of the underlying carbon foam and obtaining exposed carbon foam with a specific surface morphology. The radiation from the CO2 laser scans the surface of the treated carbon source at a speed of 19 cm/s to match patterns or areas irradiated using an IR laser. Other embodiments utilize different parameters. For example, a pulse frequency of 50 kHz and a scan speed of 35.5 cm/s have also been used to successfully expose the underlying carbon foam. The laser power is typically in the range of 8–20 watts, with 12 W being optimal; the laser focal length is typically in the range of 50 mm–400 mm.
As described above, CO2 lasers ablate the disordered, amorphous, non-graphene material on the surface layer, thereby exposing the underlying carbon foam and altering the surface morphology of the carbon foam to produce exposed carbon foam with a greater number of defects compared to standard laser-induced graphene; as previously stated, this endows the carbon foam with extremely useful properties superior to standard laser-induced graphene.
Changing the laser parameters of one or two lasers (e.g., IR laser and CO2 laser), such as power, focus, wavelength, and scanning speed, alters the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
One useful property of exposed carbon foam fabricated using a dual-laser process is its high wettability: the contact angle can be less than 20°, making this carbon foam hydrophilic, compared to conventional graphene foams with contact angles between 70° and 150°, making them hydrophobic. This hydrophilicity of the carbon foam produced via the dual-laser process is highly relevant for two key applications: biosensors (a specific implementation called Gii-Sens) and supercapacitors (a specific implementation called Gii-Cap). For biosensors, high wettability allows the tested liquid (e.g., a liquid analyte) to spread rapidly and uniformly across the entire working electrode, resulting in higher sensitivity, consistency, and speed. For supercapacitors, high wettability means the electrolyte wets the supercapacitor electrodes better, leading to higher performance. While conventional graphene foams can be processed to make them more wettable, this carbon foam implementation does not require such an additional processing step.
Another useful property of exposed carbon foam produced by the dual-laser process is its high resistance to fouling: this can lead to enhanced sensitivity and extended lifespan of biosensors. Carbon foam can be used in applications where the accumulation of contaminants or residues may impair the performance or lifespan of components (e.g., filters, heating elements in e-cigarettes; electrodes); exposed carbon foam produced by the dual-laser process can be used in said components, resulting in enhanced performance or lifespan.
The performance of the carbon foam electrode produced using this dual-laser method has been explored by cyclic voltammetry (CV), as shown in Figure 15. Cyclic voltammetry plots of the well-characterized ferricyanide/ferrocyanide redox reaction were performed using electrodes prepared using the method described above and electrodes prepared using known conventional CO2 laser irradiation methods. Figure 15 shows CV curves obtained at scan rates of 10 mV/s, 25 mV/s, 50 mV/s, 75 mV/s, 100 mV/s, and 150 mV/s. Each curve shows data recorded using the carbon foam electrode produced using the dual-laser method of the present invention (light line) and the 3D graphene electrode produced using the known CO2 laser irradiation method (dark line). The peak at approximately 0.22 V in the cathode current direction corresponds to the reduction of ferricyanide to ferrocyanide; and the peak at approximately 0.28 V in the anodic current direction corresponds to the oxidation of ferrocyanide to ferricyanide.
Far from the prominent redox peaks, these graphs qualitatively show that the CV curves recorded using carbon foam electrodes produced using the dual-laser method disclosed in this specification are more rectangular than those recorded using 3D graphene electrodes produced by known methods. This is most evident at the high points of the voltage range (approximately 0.6 V) and at higher scan rates (see, for example, 100 mV/s). This increased rectangular appearance indicates increased capacitive behavior of the electrodes prepared using the dual-laser method of this invention, thus reflecting the very high surface area of the torsion or disordered multilayer carbon foam produced by this method.
The CV curves also clearly show that the voltage for separating the oxidation and reduction peaks is consistently lower for measurements using carbon foam electrodes produced by a dual-laser method compared to those using 3D graphene electrodes produced by conventional known methods. The peak separation ΔEp as a function of scan rate for CV measurements obtained using carbon foam electrodes produced by the method disclosed in this invention is plotted in Figure 16(a), and the peak separation ΔEp as a function of scan rate for CV measurements obtained using 3D graphene electrodes produced by known methods is plotted in Figure 16(b).
This data shows that ΔE<sub> p </sub> narrows when the electrode is prepared according to the dual-laser method. The theoretical peak separation parameter for reversible systems (such as ferricyanide/ferrocyanide reversible redox reactions) is 57 mV, but in practice this is sensitive to the influence of electrode structure on electrochemistry. Clearly, the voltage separation of the oxidation and reduction peaks in the cyclic voltammetry plots is close to the theoretical value. This demonstrates the quality of the electrodes produced by both known methods and the dual-laser method. Furthermore, results recorded using a carbon foam electrode produced by the dual-laser method show reduced separation, indicating improved porosity of the electrode produced in this manner compared to electrodes produced by conventional methods.
Figure 17 shows a comparison of electrochemical impedance spectroscopy results for a system comprising a carbon foam electrode produced using a dual-laser method (square) and a system comprising a 3D graphene electrode produced using a known method (circle). Bode plots show the change in phase angle as a function of frequency. The frequency responses of the two systems are significantly different. Specifically, measurements recorded using the carbon foam electrode produced using the dual-laser method lack the phase angle signal peak observed at approximately 1 kHz in measurements recorded using the 3D graphene electrode produced using a conventional method. The response from the electrode prepared using the dual-laser method indicates a rapid electron transfer response. These differences further clearly demonstrate that the carbon foam produced by the dual-laser method is distinct from and can be differentiated from 3D graphene produced by conventional methods.
Further details are clearly visible in Figure 18A. The Raman spectrum of the carbon foam fabricated using a dual-laser process is shown in Figure 18A, exhibiting three main peaks. Specifically, the D peak at approximately 1344 cm⁻¹ is characteristic of lattice defects, and the G peak at approximately 1577 cm⁻¹ is characteristic of sp² carbon hybridization, featuring distorted six-fold carbon rings. The 2D peak at approximately 2685 cm⁻¹ is characteristic of secondary transitions in 3D graphene, and the absence of a bimodal structure here indicates a lack of planar AB stacking found in multilayer 2D graphene or graphite. Fitting the 2D peak to a single Lorentzian peak centered at 2685 cm⁻¹ (with a full width at half maximum of 67 cm⁻¹ ) indicates the presence of only one or a few carbon foam sample layers in the 3D carbon formed using these two methods. Analysis of the D/G peak ratio (0.85) of the dual-laser process indicates a higher defect density compared to the conventional laser-induced graphene process using a single-laser step (0.67), as shown in Table 1 below.
| process | D/G | 2D/G | D/D’ |
| Dual laser | 0.85±0.1 | 0.95±0.12 | 3.7±1.3 |
| Conventional single laser | 0.67±0.13 | 0.75±0.05 | 2.6±0.22 |
Table 1
As we previously explained, Raman analysis of typical graphene foam revealed the following signature characteristics: absence of a D peak; a 2D peak higher than the G peak; and a D:G ratio close to zero. The carbon foam produced in this specific embodiment of the invention does not possess these characteristics; it is highly hydrophilic with a contact angle below 20°; it lacks the Raman signature characteristic indicative of graphene: Figure 18A shows the material produced via a dual-laser process: presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18B is another Raman analysis of carbon foam produced via a dual-laser process, again showing the presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18C is the Raman analysis of the carbon nano-onion material, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI: 10.1007/s00339-015-9315-9, and its similarity to the Raman analysis of carbon foam produced via a dual-laser process is evident. A plausible explanation is that the carbon foam produced by the dual-laser process is or contains carbon nanotube onion material. See also Figures 57A and 57B below.
Both dual-laser carbon foam and conventional graphene fabricated using a single-laser process exhibit microporous structures, as shown in the SEM images in Figure 19. Low-magnification images reveal significant differences in surface morphology. The single-laser surface shows a smoother, more textured surface with rougher edges, while the carbon foam fabricated using a dual-laser process displays a rougher surface. This region will be further described in the following section on characteristic R.
Key features
In this section, we outline the key features of specific embodiments of the invention. These features define the production of carbon fiber foam in the previously described dual-laser manufacturing process; this process offers numerous advantages over conventional CVD: we can compare the production of approximately 50 μm thick carbon foam at 1 cm² on plastic substrates (or virtually many other types of substrates) as shown in Table 2.
| process | Number of steps | time | temperature | pressure | cost |
| CVD | 6 | 300min | 800C | vacuum | $50 |
| Dual laser process | 1 | 2min | 20C | environment | Less than $1 |
Table 2
Features A-R define various aspects of the carbon foam manufacturing process, which is highly scalable, high-yield, highly reproducible, and easily adaptable to many different applications, all using the same process. For example, dual-laser carbon foam is particularly suitable for biosensors and electrochemical capacitors (e.g., supercapacitor and pseudocapacitor applications).
For biosensor applications, dual-laser carbon foam offers the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; higher wettability; and higher antifouling properties. One specific implementation of this biosensor is called Gii-Cap, which we will describe in more detail below.
For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; higher wettability; and better anti-fouling properties. One specific implementation of a supercapacitor is called Gii-Cap, which we will describe in more detail below.
Features A-R are organized into the following four groups:
Group 1: Subsurface carbon foam
Group 2: Dual Laser Processing
Group 3: Products
Group 4: Other aspects.
We can extend this organization as follows:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene material adhered to a substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual lasers operating in different frequency bands
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors in different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device
Feature M2: Screen-printed carbon foam supercapacitor layer
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Now let's look at Group 1:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
In the prior art section, we have described how earlier laser-induced graphene methods transformed the surface layer of a carbon precursor into 3D graphene. However, the resulting 3D graphene can be somewhat brittle, potentially peeling off from the underlying substrate, and is generally unsuitable for many real-world applications; furthermore, 3D graphene is typically relatively thin, with a depth of less than 50 μm.
In this specification, we describe an alternative method in which the surface of the carbon precursor is not converted into graphene at all; instead, only the subsurface region 14 of the carbon precursor is converted into carbon foam 16 by a focused laser beam 12; in one embodiment, the focused IR beam 12 generates a temperature above 500°C in the subsurface region or encapsulation region inside the polyimide film 14 for a very short time, between 1 ns and 10 μs (i.e., at a rate between approximately 5 × 10⁷ °C/s and 2 × 10¹² °C/s); this brief but intense heating is sufficient to form carbon foam 16 in this subsurface region or encapsulation region. This subsurface region or encapsulation region 16 has no substantial gas escape pathway; confining the gaseous products within the subsurface region or encapsulation region advantageously affects the structure of the carbon foam 16 formed in the subsurface region. The formation of carbon foam 16 only in the subsurface region was an unexpected discovery; the reasons for this unexpectedness include the extremely low absorptivity of the polyimide carbon precursor material to 1064 nm IR radiation, with a radiation absorptivity per centimeter (decimal) of less than 50 or as low as less than 10.
Under laser irradiation, the surface (e.g., the interface between the carbon precursor material perpendicular to and facing the laser and the gaseous environment surrounding the carbon precursor material) expands and transforms from the carbon precursor material into disordered amorphous non-graphene material 18. This disordered amorphous non-graphene material 18 forms a layer, which is typically at least 1% of the total thickness of the carbon precursor material; for a 500 μm thick polyimide film, the top 1 μm–10 μm is typically transformed into disordered amorphous non-graphene material 18; below this upper surface layer, within the bulk of the carbon precursor material, we obtain a region transformed into carbon foam 16.
The thickness of this carbon foam 16 is controlled by gradually moving the focus of the laser beam through the carbon precursor material; exceptionally thick carbon foam structures can be made using this process: carbon foam tracks with thicknesses of 50μm-200μm (approximately) have been achieved.
If a laser irradiates a carbon film precursor material, such as a polyimide film suspended in space (i.e., not mounted on a substrate) as shown in Figure 9-14B, after irradiation, as we gradually move through the material, we obtain disordered amorphous non-graphene material 18 on the upper surface (i.e., the surface facing the laser); then we obtain carbon foam regions 16. The laser beam 12 typically does not approach the lower surface of the carbon precursor material, such that the carbon foam regions 16 are located above the carbon precursor material that has not yet been converted into carbon foam. If the laser approaches the lower surface of the carbon precursor material, the carbon precursor near and located on the lower surface is converted into disordered amorphous non-graphene material.
Similarly, if a carbon precursor film, such as a polyimide (PI) film mounted on a substrate, is irradiated with a laser, as shown in Figures 1-6, we obtain the same material order; furthermore, the laser typically approaches the lower surface of the carbon precursor material resting on the substrate: the carbon precursor near and located on the lower surface is then transformed into a disordered amorphous non-graphene material 17. This disordered amorphous non-graphene material 17 adheres to the substrate 15; since the carbon foam region 16 is bonded to this disordered amorphous non-graphene material 17, the carbon foam region 16 itself is not directly bonded to the substrate 15, but is firmly attached to the substrate 15 via the intermediate disordered amorphous non-graphene material 17.
This method achieves carbon foam structures with significantly greater thickness than those achievable using previous methods that confine graphene foam formation to surface regions. Furthermore, this method enables carbon foam structures to adhere more robustly (but not directly) to the underlying substrate. It is important to note that with this method, carbon foam is not generated on any surface of the carbon precursor material; rather, it is generated only in the subsurface region within the carbon precursor material.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
In Feature A above, we define the region where carbon foam is generated by laser irradiation as the “under-surface” region. Another way to describe this region is to characterize it as “encapsulation”; this reflects the three-dimensional relationship between the carbon foam and its surrounding environment; the carbon foam 16 is “encapsulated” by the original carbon precursor material and by the disordered, amorphous, non-graphene material 18 generated by laser irradiation of the upper surface of the carbon precursor material 14.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of carbon precursor material, wherein said regions do not have substantial gas escape channels.
As we have seen above, the subsurface region or encapsulation region of the carbon precursor is transformed into carbon foam, and this subsurface region or encapsulation region has no substantial gas escape channel; confining the gaseous products within the subsurface region or encapsulation region affects the structure of the carbon foam 16 formed in the region.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to the substrate
As we have previously observed, when laser 11 irradiates the carbon film 14 mounted on substrate 15, the laser carbonizes the surface of the carbon film adjacent to substrate 15, forming a disordered amorphous non-graphene material 17 adjacent to substrate 15. This disordered amorphous non-graphene material 17 adheres to substrate 15. Because the internal, subsurface, or encapsulated carbon foam regions 16 are themselves bonded to this disordered amorphous non-graphene material 17, the carbon foam regions 16 themselves are not directly attached to substrate 15, but are firmly positioned on substrate 15 via the intermediate disordered amorphous non-graphene material 17. Compared to conventional laser-induced graphene, the carbon foam regions 16 adhere more firmly and are less likely to peel off even if the substrate is flexible, thus enabling applications such as biosensor applications where the substrate is typically a thin and flexible structure.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Previous features A-D covered the generation of carbon foam in the subsurface region or encapsulation region of the carbon precursor material. Because carbon foam does not form on exposed surfaces, and many applications require exposed carbon foam (e.g., for functionalization in biomedical sensing applications or supercapacitors), we can take additional steps to expose at least some of the carbon foam subsurface or encapsulate it.
We have previously seen the formation of disordered, amorphous, non-graphene material 18 beneath the surface or above the encapsulated carbon foam 16 by laser irradiation using an IR laser 11. We now use a laser (typically a long IR CO2 laser 20) to ablate or otherwise process this disordered, amorphous, non-graphene material 18, thus exposing the underlying carbon foam 16. Unlike the initial laser, this second laser 20 is typically defocused.
As mentioned earlier, we use standard 220mm × 180mm polyimide sheets (but other sizes of polyimide sheets can also be considered); this size is commonly used in standard laser scanning equipment, standard flatbed screen printing equipment, and standard conveyor belt dryers for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). Other sizes of polyimide sheets can be considered.
We have discovered that this secondary laser irradiation step alters the morphology and other characteristics of the underlying carbon foam in a surprising and advantageous manner, resulting in previously unobserved twisted or disordered multilayer carbon foams. Changing the parameters of the CO2 laser 20 can alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
This new exposed carbon foam possesses one or more of the following properties:
• Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
• Strong adhesion to any underlying flexible substrate
High porosity
High electrical conductivity
• Increase in capacitance or charge storage
• Rapid absorption of organic solvents and water-based solutions
• Higher hydrophilicity
High EMI shielding
• Electrode quality enhancement
High wettability
• Anti-fouling.
It should be noted that by changing the laser parameters of any one or both lasers used in the dual-laser process, one or more of these properties, as well as the size and extent of defects and the size (including relative size) of the Raman D and 2D peaks, can be altered. In this way, carbon foams tuned for or particularly suited to different applications can be produced. Surprisingly, the operation of the second ablation laser enables the production of usable exposed carbon foam regions, especially those with properties that can be adjusted by changing the parameters of the first and/or second lasers.
We can summarize it as follows:
A method for manufacturing a carbon foam material includes the following steps: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulated region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of it in the carbon foam.
Feature F: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
In the aforementioned feature E, we describe the formation of carbon foam 16 in the region by irradiating the encapsulated region or subsurface region of the carbon precursor with a laser 11 (e.g., an IR laser); the irradiation causes the upper (in the laser direction) carbon precursor material 14 to expand into a disordered, amorphous, non-graphene material 18; then, we expose or reveal the carbon foam 16 by ablating the upper disordered, amorphous, non-graphene material 18 with a second laser 20 (e.g., a CO2 laser). This second irradiation step not only ablates the upper disordered, amorphous, non-graphene material 18 and thus exposes the lower carbon foam 16, but also gives this lower carbon foam an unexpected and unusual surface morphology 21 with very desirable characteristics; such a carbon foam may be a torsion or disordered multilayer carbon foam.
However, because such foams may possess characteristics unrelated to graphene foams (such as a wide range of defects, appearance, wettability, and Raman spectra (see Feature R below), we explicitly describe such foams as “non-graphene carbon foams” in Feature F. Therefore, the term “non-graphene carbon foam” (as opposed to the term “carbon foam”) explicitly excludes graphene foams, including twisted or disordered multilayer graphene foams, but extends to foams covering any other 3D carbon material.
We can summarize it as follows:
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers in different wavelength bands
As we saw in features E and F above, we can use two separate laser irradiation steps. These steps are typically performed using two separate lasers: the first step, to generate subsurface or encapsulated carbon foam, is typically accomplished using a focused IR laser 11; and the second step involves irradiation using a defocused CO2 laser 20 at a longer wavelength, but other wavelengths (e.g., UV and visible light) can also be used.
The second laser 20 ablates the material 18 (e.g., disordered, amorphous, non-graphene material) located between the carbon foam 16 and the surface, exposing the underlying carbon foam 16. The exposure of the carbon foam 16 can also be altered by the second laser (e.g., in terms of its surface morphology 21); that is, the term 'exposure' should be broadly interpreted to include not only revealing at least some of the pre-existing carbon foam, but also transforming or altering at least some of the pre-existing carbon foam into a 3D carbon material foam with characteristics different from those of the pre-existing graphene foam.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
We have previously seen how we generate carbon foams, which can be twisted or multilayered: because of the special electrical properties of this material (e.g., conductivity, capacitance), we can attach or position one or more electrical contacts (including electrical objects such as flexible electronics, microprocessors, antennas, IoT devices, electrical interfaces, etc.) into the carbon foam. For printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate) and onto and inside a pre-existing 3D carbon material foam, such that the tracks form good electrical contacts with the foam and any structures formed on the foam, such as functionalized layers (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
In Feature H, we see that once the dual-laser process is complete, electrical contacts or circuitry are added to contact a pre-existing carbon foam; for example, simple silver electrical contacts can be screen-printed onto the carbon foam. In Feature I, we describe a process that begins by first screen-printing electrical contacts onto a polyimide film, and then completes the process by creating an exposed carbon foam through a second laser ablation step in the dual-laser process. This has several advantages because the screen-printing process can interfere with or destroy the carbon foam. We refer to this process as “PPC” (short for “post-printing conversion”), where the screen-printing step is performed prior to the dual-laser process to create the carbon foam. In Feature L5, we describe a biosensor fabricated using the PPC process.
Therefore, for screen-printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate), allowing carbon foam to subsequently form around one end of the printed tracks, thus providing a contact area with a large surface area and therefore very good electrical connectivity. Similar to the alternative processes described in Feature H above, the printed tracks also form good electrical contacts with any structures formed on the foam (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
An alternative sequence involves using a first laser beam to generate subsurface carbon foam, then screen printing electrical contacts, and then using a second laser beam to generate carbon foam to create good electrical contact with the electrical contacts.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed in the order of (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
We have previously observed that the thickness of the subsurface or encapsulated carbon foam region can far exceed that of conventional graphene foams confined to the surface layer: the laser focus of the first laser beam can be progressively moved downwards through the carbon precursor material to create a deep or thick subsurface or encapsulated carbon foam layer. Then, a second laser irradiation step is employed to ablate the material between the carbon foam and the surface of the carbon precursor material, resulting in an exposed region of the carbon foam. This now exposed carbon foam region has a thickness or depth of at least 50 μm; carbon foams with a thickness of 300 μm have been produced. The increased thickness is beneficial because it leads to better electrical conductivity, greater capacitance, and higher mechanical integrity.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
The specific properties or structure of the carbon foam produced by the second laser beam can be considered sensitive information because they define the characteristics of the final product. For the first laser beam process, it is desirable for the carbon foam supplier to perform the process at their manufacturing facility, then supply the carbon foam to the customer, who then uses the second laser beam for the final stage at their own manufacturing facility. As we explained earlier, by changing the parameters of the first and second lasers, it is possible to alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications. Typical parameters that can be changed or tuned in this way include: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface or encapsulation region.
By segmenting the manufacturing process in this way, suppliers do not need to know the specific manufacturing processes that customers use as part of the second laser ablation process (e.g., how they change the parameters of the second laser beam to give the exposed carbon foam the properties they need); customers can keep the details of how they produce the finished product confidential.
Therefore, the manufacturing process is a three-stage process involving the following steps: (a) irradiating the area below the surface of the carbon precursor material with the first laser beam at the manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Furthermore, this method enables the large-scale production (see feature P, for example) of carbon foam using only the first laser process, thereby reducing the cost of this material, which can be used in many different applications and for many different customers. The production volume of more specialized products using a second laser beam may be much lower than that of carbon foam produced using only the first laser process. Therefore, this method achieves more efficient and lower-cost manufacturing of the base material, namely carbon foam produced solely through the first laser process.
We can summarize it as follows:
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
For features A-K, the following optional features are particularly relevant. It should be noted that any one or more of the following optional features can each be combined with one or more other compatible optional features, as well as with one or more of features A-K:
We will cover the following areas:
Manufacturing process
First laser beam parameters and control scheme
Properties of the subsurface region or packaged region
carbon precursor materials
Substrate supporting carbon precursor materials
Carbonization at the surface where the laser beam is incident
ablation laser beam or second laser beam
Carbon foam.
It should be noted that any one or more of the following optional features may be combined with one or more other compatible optional features and with any one or more of the other “features” listed in this specification (e.g., features A-R):
The laser-based manufacturing process described above has many advantages over conventional CVD processes; these can be listed as the following optional features:
It is a room temperature process.
It is an environmental pressure process.
It can be done on plastic substrates (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
It takes about 2 minutes or less to create a 1 cm² carbon foam that is approximately 50 μm thick on a plastic substrate.
The formation of 3D carbon foam on a flexible substrate was achieved.
No graphene or graphene oxide precursors are required.
Carbon foam material is generated only in the encapsulation area or subsurface area of the carbon precursor material, and not on any surface of the carbon precursor material.
It uses a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
It is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
The parameters and control scheme of the first laser beam are crucial for the production of carbon foam; we define the relevant optional characteristics here:
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following:
Intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface or encapsulated region to form carbon foam.
• The laser beam generates temperatures exceeding approximately 500°C in the subsurface or encapsulated region to form carbon foam.
The pulse duration of the laser beam is between approximately 1 ns and 10 μs, resulting in a pulse speed of approximately 5 × 10⁷ °C/s.
Heating rate between 2 × 10¹² °C/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between approximately 50 kHz and 500 kHz.
• The laser pulse frequency is between approximately 1 kHz and 2 MHz.
• The laser wavelength is between approximately 0.7μm and 2.5μm.
The laser scans at speeds between approximately 9 cm/s and 40 cm/s.
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region through which the focal point passes.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region with a thickness of at least 50 μm.
• The focal point of the laser beam is moved through a depth of at least about 100 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region where the thickness of the carbon precursor is at least 100 μm.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scanning can result in a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm).
• The wavelength of the laser beam is not absorbed by the carbon precursor material.
• The carbon precursor material has extremely low absorption of the wavelength of the laser beam, with a radiation absorptivity per centimeter (decimal) of less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between approximately 0.7 μm and 2.5 μm.
The laser beam is an IR laser with a wavelength between approximately 0.75 μm and 1.40 μm.
The properties of the subsurface region or encapsulation region where carbon foam is generated can be defined using the following optional features:
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity and the choice of carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or more below the surface of the carbon precursor material.
• The thickness of the subsurface region or encapsulation region can be between approximately 10 μm and 200 μm.
• The subsurface region or encapsulation region is located at a certain distance below the surface of the carbon precursor material. This distance is a function of various factors, such as laser intensity, other laser parameters, and the selection of the carbon precursor material used. For example, the top of the subsurface region or encapsulation region may be at least 1%, 10%, 20%, 30%, or 40% below the total thickness of the surface carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the midpoint of the minimum cross-section of the first laser beam, and the volume is within 500 or 100 micrometers or 1 micrometer of this midpoint.
Carbon precursor materials can be defined by the following optional characteristics:
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam (see Group 3 below) is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300±50 cm⁻¹ .
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of a first and/or second laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
A substrate can be considered as a material having a surface on which carbon precursors are positioned; the specific material, thickness, and properties of the substrate are determined by the application: for example, for some sensors, the substrate may be a thin, flexible plastic film; for other applications, the substrate may be a rigid polyimide plate on which electronic circuitry can be mounted. An IR laser can directly irradiate the carbon source; alternatively, radiation from the IR laser can first pass through the substrate and then reach the carbon source, in which case there are two alternative scenarios: first, the substrate is substantially transparent to IR radiation, and the mechanism of carbon foam formation is as described above. In the second scenario, the substrate is substantially opaque to IR radiation: then, rapid heat transfer from the substrate to the carbon precursor material first generates a disordered, amorphous, non-graphene layer at the interface with the substrate, and then carbon foam forms in the subsurface region or encapsulation region within the carbon precursor material.
The carbon precursor material can be positioned and supported on a substrate, which can be defined by the following optional characteristics:
The substrate is a plastic body, film, or foil.
The substrate is flexible.
The substrate is a polyimide circuit board.
The substrate has an extremely low absorption rate of the first laser beam.
The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
The substrate has a high absorption rate for the first laser beam, absorbing more than 60% of the first laser beam.
The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
The substrate is formed from one or more of the following: silicon (Si), silicon dioxide (SiO2), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing silicon and silicon dioxide.
The substrate is a carbon source.
The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident can be defined by the following optional characteristics:
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by the first laser beam.
The disordered, amorphous, non-graphene material occupies a thickness below the surface of the adjacent carbon precursor material, which is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
The disordered, amorphous, non-graphene material extends to a distance below the surface of the carbon precursor material, said distance being at least 10 μm.
The disordered, amorphous, non-graphene material extends from the outer surface of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
The ablation laser beam or the second laser beam can be defined by the following optional characteristics:
The parameters of a laser beam include one or more of the following: intensity, wavelength, pulse duration, pulse profile, scanning speed, and heat generated in the subsurface region or packaged region.
Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
Changing laser parameters alters one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
The second laser beam alters the carbon foam as part of the process that exposes it.
The second laser beam alters the shape of the carbon foam as part of the process that exposes it.
The second laser beam is automatically controlled to scan on the same, and/or overlapping, and/or non-overlapping areas (e.g., raster scanning).
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
The carbon precursor material has an absorption coefficient for the second laser beam that is greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam that is greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300±50 cm⁻¹ .
The laser power is typically in the range of 8-20 watts, with 12W being optimal.
The typical working range of laser focal length is 50mm-400mm.
The second laser beam scans in a pattern that includes non-overlapping areas or lines.
The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam can be defined by the following optional characteristics:
The carbon foam has a thickness of at least 50 μm.
The thickness of the carbon foam ranges from 50 μm to 300 μm.
Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
Carbon foam is or includes carbon foam with a defective spatial distribution, resulting in high electrochemical reactivity.
Carbon foam is or includes carbon foam with vacancy basal defects, resulting in high electrochemical reactivity.
The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Carbon foam has one or more of the following properties:
Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
It has strong adhesion to the underlying flexible substrate.
High porosity
High electrical conductivity
Increase in capacitance or charge storage
Rapid absorption of organic solvents and water-based solutions.
ο Higher hydrophilicity
οEMI shielding high
Electrode quality enhancement
The contact angle is approximately 20° or less.
The properties of carbon foam can be selected by choosing specific laser parameters to generate carbon foam materials with one or more of the following desired properties or parameters: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
Group 3: Products
Feature L1: Biosensor
Carbon foams fabricated using the dual-laser method described above have wide applications in many different types of sensors. For simplicity, we will use the phrase "carbon foam" in this feature to refer to any carbon foam or 3D carbon material foam fabricated by the methods described in this specification. Appendix 1 includes further details on this field, describing in more detail a biosensor comprising a carbon foam functionalized by adding receptors specific to a target or analyte, and a connector enabling the receptors to attach indirectly to the carbon foam; (some receptors cannot attach directly to the carbon foam because of their poor stability in contact with a surface; instead, a connector must be used as an intermediary between the carbon foam and the receptor. During fabrication, the connector is first added to the carbon foam, and then the receptor is added to the connector.)
For biosensor applications, functionalized carbon foam has the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; enhanced wettability; and a contact angle of approximately 20° or less.
At a higher level, functionalized carbon foam can be used in sensors because it can generate detectable changes in state; its high sensitivity is a function of its large surface area. It can be used to detect specific chemicals, specific gases, mechanical stress, and temperature, among other variables. We will briefly look at each category.
First, chemical sensors: Chemical detection systems rely on detecting the electrical response of carbon foam when a target chemical substance is present; many different detection principles can be used, such as changes in capacitance, resistance, voltammetry, redox potential, and charge transfer resistance.
For example, the binding can be detected when a specific analyte or target binds to a carbon foam because it alters the surface of the carbon foam. Biomolecules, such as specific antibodies or aptamers (aptamers are short, single-stranded DNA or RNA molecules that can selectively bind to specific targets, including proteins, peptides, carbohydrates, small molecules, toxins, and living cells), are added to the carbon foam. When the target is present and binds to the aptamer, the morphology of the aptamer changes (e.g., by reducing surface area), and the capacitance of the combined carbon foam and aptamer system decreases in a measurable manner.
Using this principle, highly sensitive and selective sensors can be built; due to the quantitative reduction of measurable variables (e.g., capacitance), a LOC (lab-on-a-chip) can be built, which includes not only carbon foam and aptamer biosensors, but also power sources on the LOC, such as supercapacitors or other energy storage devices using carbon foam as their electrodes, as well as circuitry for measuring variables, calculating biosensor outputs, and displaying said outputs (e.g., the presence or absence of a target; the concentration of a target) on the LOC screen; this is further described in the feature O3 (Gii-Thru: HISLOC for Gii-Sens).
Carbon foam sensors can also measure the redox potential of a target; for example, a current peak can be detected when the oxidation of a target chemical is catalyzed by a specific catalyst added to the carbon foam; since the current is usually a function of the concentration of the target chemical, it is possible to quantitatively measure the target concentration.
Other technologies already applied to conventional graphene sensors, such as thermal conductivity measurements for detecting specific chemicals, resistance measurements for inferring temperature, physical deformation, or transitions in the presence of specific chemicals, and piezoresistive deformation for detecting motion, can all be applied to carbon foam sensors fabricated using the dual-laser method described above.
An important application of the large electrochemically effective region and fast electron transport rate of carbon foam generated by a dual-laser method is the implementation of an electroanalytical sensing electrode optimized for biosensing (called "Gii-Sens").
For example, the electroanalytical sensing electrode can be used in point-of-care diagnostic devices; the sensing electrode has extremely high sensitivity, reliability, purity, wettability and conductivity.
Figure 20A is a perspective view of a biosensor called Gii-Sens. The assembly consists of: a polyimide substrate 201; a working electrode 202 made of Gii carbon foam; a counter electrode 203 made of Gii carbon foam; a reference electrode 204 made of screen-printed silver-silver chloride; three screen-printed silver connection traces 205; and a screen-printed dielectric layer 206.
Figures 20B-20D show the four main manufacturing stages. Figure 20B shows step 1, in which the dual-laser process uses a polyimide substrate 201 as a precursor to produce a Gii carbon foam working electrode 202 (area of 18.94 mm² ) and a counter electrode 203 (area of 20.84 mm² ).
Figure 20C shows step 2, in which a silver-silver chloride reference electrode 204 (with an area of 8.99 mm² ) is screen-printed onto a polyimide substrate 201.
Figure 20D shows step 3, in which silver connection traces 205 are screen-printed onto the polyimide substrate 201; these overlap with the carbon foam electrodes at the electrical contact regions 207. The area of the silver traces is 1 x 18.85 mm² , and the area of the three silver traces is 3 x 56.55 mm² . The area overlapping with the underlying carbon foam electrodes is 1 x 2.21 mm² , and the area overlapping with the three carbon foam electrodes is 3 x 6.63 mm² .
Figure 20E shows step 4, in which the dielectric layer 206 is screen-printed over carbon foam electrodes 202, 203, 204 and silver connection traces 205. The active regions of the electrodes are as follows: working electrode 202: 12.64 mm² ; counter electrode 203: 14.18 mm² ; reference electrode 204: 2.59 mm² . The exposed areas of the silver connection traces 205 are 1 x 7.15 mm² and 2 x 21.45 mm² .
Figure 20F shows a single polyimide sheet on which an array of 100 carbon foam working and counter electrodes has been produced using the dual-laser process described in step 1 above. The sheet is a standard type of polyimide sheet, 220 mm × 180 mm, allowing it to be processed using standard screen printing and laser scanning equipment; it can be A5 size or any other suitable size.
Figures 20G and 20H show the final form of the sheet after step 4. 100 individual units can be cut and assembled into 100 finished Gii-Sens biosensors.
One specific use case for the Gii-Sens sensing electrode is a reversible polymer displacement sensor mechanism for electrochemical glucose monitoring. A graphene sensor for this use case has been proposed: see "Polymer indicator displacement assay: electrochemical glucose monitoring based on boronic acid receptors and graphene foam competitively binding with poly-nordihydroguaiaretic acid", Wikeley et al., DOI:10.1039/d1an01991k. This paper describes glucose... A pyrene-derived boric acid chemical acceptor was adsorbed onto a graphene foam electrode. The spontaneous oxidative polymerization of nordihydroguaiacol (NHG) onto the graphene foam electrode yielded a redox-active membrane (poly-NHG) covalently attached to the boric acid acceptor. Oxidation of the poly-NHG released the boric acid acceptor to interact with glucose in the solution phase, which was detected due to competitive binding upon recombination of the reduced poly-NHG with the boric acid functional groups. The sensor exhibited the expected boric acid selectivity for fructose-glucose. Glucose sensing was performed using the charge ratio at the voltammetric peaks of unbound and bound poly-NHG, with a substantially linear analytical range from 1 to 50 mM glucose in a pH 7 aqueous buffer.
The implementation of Gii-Sens sensing electrodes offers several advantages over current sensing electrodes, such as those used in graphene sensors:
It uses amplification-free, enzyme-free, and label-free electrochemical biosensor with a low detection limit.
Enhanced reproducibility.
Optimize the available dynamic range.
Minimize background noise.
Reduce planning time and operations.
It is scalable for low-cost manufacturing.
High sensitivity and selectivity.
Provide quantitative numerical results.
It can be printed into specific patterns, such as interdigitated patterns, to achieve miniaturized integrated devices.
Existing biometric and testing formats (e.g., ELISA, PCR, RT-PCR) can be translated into electrochemical microfluidic POCs without affecting performance quality.
It can perform impedance-based measurements with extremely high sensitivity, reliability, and extremely low background signal interference.
It replaces expensive, large-scale laboratory testing and low-sensitivity lateral flow testing.
It can be implemented in microfluidic analysis (single-objective or multi-objective) and lab-on-a-chip (LOC) devices.
It can be used in any sensor application where the user aims to immobilize (biological) molecules of interest (e.g., the carboxyl/n-hydroxysuccinimide moiety can be added to the sensor surface to provide a platform for subsequent immobilization and conjugation chemistry reactions).
It can be used for a variety of diagnostics: point-of-care (POC) human and animal health, food safety, in-situ environmental health and safety, and agricultural health and safety, all of which have enhanced biosensing sensitivity, selectivity, and reproducibility due to its purity and high specific surface area.
Enhanced wettability (e.g., contact angle below about 20°).
Enhanced stain resistance.
We can summarize it as follows:
A method of manufacturing a biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
L2: Fabricating carbon foam biosensors in a scalable and low-cost manner using screen printing technology.
We have already seen above how screen printing is widely used in manufacturing processes: it is a well-known, scalable, predictable, and low-cost technology. The detailed manufacturing process of the Gii-Sens carbon foam biosensor is shown in Figure 21.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric to at least partially cover the electrodes and connection traces.
Optional features include the following:
In the method defined above, in step 1, the dual-laser process uses a PI substrate as a precursor to generate a carbon foam working electrode and a counter electrode.
In the method defined above, in step 2, a reference electrode, such as a silver-silver chloride electrode, is screen-printed onto a PI substrate.
The method defined above, in step 3, involves screen printing connection traces, such as silver traces, onto a PI substrate to overlap with the carbon foam electrode. Note: The order of steps 2 and 3 can be reversed.
The method defined above, wherein in step 4, a dielectric layer is screen-printed over at least some of the carbon foam electrodes and silver connection traces.
Other aspects include:
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each sensor electrode comprising at least partially a carbon foam made by a method defined as any one of features A-K above, and each sensor electrode being electrically connected to a screen-printed track and also at least partially covered by a screen-printed electrolyte.
A point-of-care diagnostic device comprising a biosensor as defined above.
L3: Adding functional groups to biosensors at different manufacturing facilities
For Gii-Sens biosensors, the biosensors are manufactured in one facility, but customers add functional groups that biomolecules can attach to in another facility (usually their own). This accelerates the development and testing of these functional groups and also protects their trade secrets and proprietary technology in the final design of these functional groups and the biosensors.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in a different manufacturing facility.
L4: Adding functional groups to biosensors is part of the biosensor manufacturing process.
For the Gii-Sens+ biosensor, the manufacturing process includes adding functional groups. Figure 22 shows the detailed manufacturing process of Gii-Sens+.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
L5: Using PPC to manufacture biosensors: Post-printing conversion
A PPC variant of the Gii-Sens manufacturing process is shown in Figure 23. PPC is an abbreviation for "Post-Print Conversion," in which the screen printing step is completed before the dual-laser process to create carbon foam. The specific steps are as follows:
1. Screen printing a carbon layer onto a substrate (e.g., polyimide).
2. Screen-printed Ag/AgCl reference electrode
3. Screen printing Ag electrical connection traces
4. Screen-printed dielectric
4. Use a dual-laser process to generate carbon foam in the substrate.
All screen printing steps (1-3) can be completed using roll-to-roll or roll-to-sheet processes, followed by the use of a dual-laser process to generate carbon foam, and then the materials are kept flat and stacked.
Alternatively, only the first laser process (subsurface foam generation) can be completed in the facility, after which the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation). The customer can add functionalizing groups in their own manufacturing facility, different from the facility performing the first laser process step (or both laser process steps) in the dual-laser process. Alternatively, functionalization can be performed in the facility performing the dual-laser process.
Screen printing before manufacturing the carbon foam has advantages: because we don't dry the carbon foam, it's less hydrophobic. The carbon layer acts as a bridge between the carbon foam formed in the polyimide (e.g., carbon foam and non-graphene disordered amorphous foam) and the silver connectors.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode including at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on the substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon and the electrical connection trace and the reference electrode; and then (d) producing the carbon foam sensor electrode using a method as defined in any one of features A-K above.
Feature M1: Energy storage device: supercapacitor
Because carbon foam manufactured using any one of the characteristics A-K has a very large electrochemical active region and a fast electron transport rate, it is an ideal material for electrodes of capacitors, supercapacitors, or pseudocapacitors.
One important application is in supercapacitors (specifically implemented as "Gii-Cap") or other energy storage devices (e.g., lithium-ion batteries). For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; and higher wettability.
Carbon foam can be processed with metal oxides or other pseudocapacitive materials (variants of which we call Gii-Cap+) (e.g., to produce metal oxide layers or films), and the metal oxide films have extremely large surface areas and fast surface Faraday mechanisms.
It should be noted that when we use the term Gii-Cap, we include the Gii-Cap+ variant unless the context explicitly indicates that we specifically exclude the Gii-Cap+ variant. It should also be noted that we use the term "supercapacitor" to include (i) electrically double-layer (EDLC) capacitors, where charge is stored electrostatically with no interaction between the electrode and electrolyte ions, and (ii) pseudocapacitors, where there is electron charge transfer between the electrode and electrolyte, and in any energy storage device using a combination of electrically double-layer capacitors and pseudocapacitors. Finally, it should be noted that the term "supercapacitor" should be broadly interpreted to cover any electrochemical capacitor, including EDLC supercapacitors, pseudocapacitors, and mixtures of these. The Gii-Cap+ variant is primarily a pseudocapacitor, but we still refer to it as a "supercapacitor."
Compared to conventional supercapacitors, the carbon foam electrodes in the Gii-Cap supercapacitor enhance both electrostatic double-layer capacitance and electrochemical pseudocapacitance. Appendix 2 provides further details about the supercapacitor and describes a specific implementation in which an interdigitated carbon foam electrode in the active region is encapsulated by a hydrogel electrolyte (e.g., a salt with a high molar concentration) to generate an enhanced operating voltage window.
The implementations of EDLC supercapacitors Gii-Cap and pseudocapacitors Gii-Cap+ offer numerous advantages over conventional rechargeable batteries:
Fast charging
High power
Recyclable
Not easy to explode
Flexible forms and shapes
Solid gel electrolytes or polymeric electrolytes (e.g., ionogels or hydrogels) can be used, which are solid at room temperature and have a high transition temperature far exceeding the normal operating temperature (e.g., 90°C); this greatly reduces the risk of electrolyte leakage.
It can be used in a very wide range of devices and power storage needs, such as lab-on-a-chip (LOC), IoT devices, electric vehicles, UAVs, and EV applications.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
Figure 24 is an exploded perspective view of the Gii-Cap supercapacitor. It consists of a series of carbon foam electrodes 241 connected to a pair of screen-printed silver connectors 242, fabricated using the dual-laser process described above. A dielectric layer 243 is screen-printed over the carbon foam electrodes 241 and the screen-printed silver connectors 242. The carbon foam electrodes 241 are formed on a polyimide substrate 244. A pair of copper connector tabs 245 are connected to the pair of screen-printed silver connectors 242. An electrolyte layer 246 covers the carbon foam electrodes 241 (e.g., an ionogel electrolyte, such as a polymer hydrogel electrolyte, which is a gel or semi-solid at room temperature to minimize the risk of leakage and reversibly liquefies above 90°C, thus allowing application in liquid form during manufacturing). The assembly is sealed within an aluminum laminate heat-sealed bag 247.
Figure 25 is an exploded perspective view of a supercapacitor assembly: it consists of an interdigitated array of carbon foam electrodes 241 forming the supercapacitor; a screen-printed silver connector track 242 provides current to the carbon foam electrodes 241 and is covered by an electrically insulating dielectric layer 243. A polyimide sheet 244 forms the base of the assembly.
Figures 26A-H illustrate the manufacturing sequence. Figure 26A shows step 1, where interdigitated carbon foam electrodes are produced using a dual-laser process. The magnified area in Figure 26B shows the interdigitated carbon foam electrodes in more detail; group A electrodes form an electrode assembly, and group B electrodes form another electrode assembly; capacitive coupling between the two groups of electrodes stores energy. The carbon foam electrodes have a thickness of approximately 20-30 μm.
Figure 26C shows step 2, screen printing the silver collector electrodes. A silver connector A' supplies current to the A group of electrodes, and a silver connector B' supplies current to the B group of electrodes. The thickness of the silver layer is approximately 20-40 μm, and several layers can be applied.
We use a "common collector" layout: a typical interdigitated supercapacitor has two long silver collectors with graphene fingers extending from one side of each long silver collector. The long silver collectors have high resistance due to their length and require a significant amount of silver. Furthermore, printing the curved portions of the collectors is difficult. In the "common collector" method shown in Figure 26D, we have carbon foam fingers C extending from both sides of the shared collector 242: this maximizes the space utilization of the fingers and therefore maximizes the capacitance, reduces the amount of collector material required, and eliminates the difficult curved collector portions.
The region 250 of the carbon foam finger connected to the common collector electrode has rounded edges; these rounded edges reduce the chance of stress fracture and increase the reliability of the electrical connection.
Figure 26F shows step 3, in which the dielectric layer 243 is screen-printed over the silver collectors to make them electrically insulated; the thickness is approximately 10-30 μm.
Figure 26G shows step 4, adding copper connector tab 245 (made of conductive metal strip) to connect to the silver current collector 242. Figure 26H shows step 5, depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions. The electrolyte can be a combination of hydrogel and salt (see Appendix 2). Figure 26I shows step 6, packaging the entire assembly into an aluminum laminate heat-sealed bag 247, leaving only the copper connector tab 245 exposed. It should also be noted that step 4, adding the copper connector tab 245, can be performed before step 2 (screen printing the silver current collector) and after step 5 (depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions).
Figure 27 shows how a single polyimide sheet will accommodate six 220mm × 180mm Gii-Cap components; other sizes (e.g., A4, A5, A6, or sizes other than the standard A-series sizes) are also possible.
The detailed manufacturing process of Gii-Cap is shown in Figure 28.
The specifications for producing and operating Gii-Cap supercapacitors using hydrogel electrolytes in a single production run are shown in Table 3 below.
Table 3
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, the screen-printed electrical connection traces are formed above at least a portion of each electrode, and the screen-printed dielectric layer at least partially covers the electrodes and connection traces.
Feature M3: Carbon foam supercapacitor: common collector electrode
We saw how to use a "common collector electrode" above.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrodes comprise at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
PPC (Post-Printing Conversion) is shown in Figure 29. The steps are as follows:
1. Screen print the silver current collector onto a substrate (e.g., polyimide).
2. Print carbon screen printing over the silver current collector and then dry it.
3. Screen print the dielectric over the carbon layer and then dry it.
4. Carbon foam is generated in the carbon layer using a dual-laser process; the carbon foam is attached to the underlying polyimide substrate via a non-graphene interlayer.
5. Distribute electrolytes.
6. Add copper/aluminum inserts to make contact with the silver collector (or step 1).
7. Add a cap/small bag.
All screen printing steps (1-3) can be completed using a roll-to-roll process, followed by the generation of carbon foam using a dual-laser process, and then the material is kept flat and stacked. Alternatively, only the first laser process (generating carbon material foam under the surface) can be completed in the facility, and then the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation) and steps 5-7.
Screen printing before fabricating carbon foam has advantages: if carbon foam is made first, it may have sharp edges; the silver screen printing layer applied over these sharp edges may crack at these edges. However, by screen printing before creating the carbon foam, we avoid this problem. Additionally, because we don't dry the carbon foam, it is not hydrophobic.
We can summarize it as follows:
A method for manufacturing energy storage devices such as supercapacitors or pseudocapacitors;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
The Gii-Cap+ variant is produced using a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x ); its capacitance is much higher than that of the standard Gii-Cap device (see Table 4).
Table 4
This metal oxide electrochemical deposition process can be applied to both the Gii-Cap Supercap manufacturing process and the PPC process, and therefore all Gii-Cap products can also be Gii-Cap+ products. A detailed process flow diagram is shown in Figure 29.
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying a pseudocapacitive material, such as a metal oxide, to the energy storage electrode via an electrochemical deposition process.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
We use an ionic gel (an ionic liquid with fumed silica SiO2 ) that provides a voltage of 3V-6V. It is solid below 90°C, so it does not leak during transport and normal use, and is therefore particularly suitable for smart tags and IoT devices; above 90°C, it liquefies, and is therefore printable, with electrochemical printing occurring at temperatures above 90°C. Ionic gels are typically made from an ionic liquid (e.g., 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4)) plus a gel-forming agent (e.g., fumed silica SiO2 )).
Typically, manufacturing is carried out in an inert atmosphere (e.g., argon) because the presence of O2 and H2O can lead to a decrease in voltage and stability.
The optimal sites for achieving the best balance between increased capacitance and decreased voltage for O2 and H2O levels are described in more detail in Appendix 3 (GiiCap Iongel).
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
In the preceding sections covering features M1-M6, we focused on some general characteristics of Gii-Cap carbon foam supercapacitors. In the following sections covering features N-S, we focus on some more specific products that realize Gii-Cap.
Feature N1: Electrical conductor
For the biosensor devices described above, it is possible and desirable to fabricate electrical conductors providing measurement signal connections from carbon foam materials produced by a dual-laser method: because these conductors have extremely low resistance, sensitivity is maximized. Electrodes (e.g., functionalized biosensor working electrodes, and reference electrodes described above as being screen-printed; capacitor plate electrodes) are examples of electrical conductors covered by this feature N1. Additionally, this feature N1 also covers electrodes whose primary function is solely to carry signals and current, for example, to replace conventional silver connection traces, such as the screen-printed Ag electrical connection traces we described in the biosensors above.
We can summarize it as follows:
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
Features L1-L4 above describe biosensors using carbon foam fabricated by a dual-laser method in their sensor electrodes; features M1-M6 describe supercapacitors and pseudocapacitors using carbon foam fabricated by a dual-laser method in their electrodes.
A highly sensitive and selective biosensor can be established, and this biosensor and this supercapacitor can be combined into a single integrated device. The device also includes electronic circuitry for measuring the detected or measured variable, calculating the biosensor output and sending the output to a POC diagnostic device or displaying the output on the device's display screen (e.g., the presence or absence of the target; the concentration of the target).
Figure 30 is a schematic cross-section of this integrated LOC device: there are two separate polyimide membrane layers, the upper layer 301 comprising a functionalized carbon foam biosensor (Giii-Sens) 302, as described in feature L; and the lower layer 303 comprising a supercapacitor 304 (Giii-Cap), as described in feature M. Although the polyimide layers are shown back-to-back, they can also be arranged side-by-side; additionally, a single polyimide membrane can be used to integrate the biosensor 302 and the supercapacitor 304 together onto a single object.
A plastic component 305 with microchannels 306 provides a microfluidic system for dispensing test fluid over the biosensor 302; a subsurface carbon foam electrode or conventional connector track 307, as described in Feature O, guides the biosensor to a flexible electronics 308 (e.g., a microcontroller for measuring changes in the electrochemical properties of the biosensor in the presence of a target analyte; a display panel for displaying diagnostic results; a power management system for controlling power from the supercapacitor 304 to the electronics 308). The supercapacitor 304 (Gii-Cap) is charged (e.g., via a wireless sensing process (not shown) controlled by the microcontroller) and provides power for the biosensor measurement process and an integrated display showing the quantitative measurement results. Alternatively, a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) can charge the supercapacitor 304, which then provides power for the biosensor measurement process. Another variation uses a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) that charges the supercapacitor 304 and also provides power for the biosensor measurement process. The supercapacitor 304 is then reserved for powering high-power processes, such as wireless data transmission, enabling the LOC to function as a standalone LOC device capable of diagnostic processes and wirelessly transmitting result data without requiring the user to be near the LOC, which would be necessary if the LOC used conventional NFC (Near Field Communication). The electrical connector trace from the supercapacitor 304 to the flexible electronics 308 is not shown.
An exploded view of the fully integrated LoC device is shown in Figure 31. From the bottom up, we have (i) an induction power circuit 310; (ii) a Gii-Cap supercapacitor 312, which is wirelessly powered by the induction circuit 310; (iii) a Gii-Sens biosensor 313; (iv) a layer 314, which has electronics for the biosensor powered by the supercapacitor 312 and microfluidic channels; and (v) a top panel 315, which includes a display 316, also powered by the supercapacitor, and an annular aperture 317 into which samples are delivered.
Figure 32 shows the LOC (Local Occurrence) of the quantitative results displayed on its monitor.
Figure 33 shows an exploded view of an environmental monitoring device including a Gii-Sens sensor 330 configured to detect environmental parameters such as CO2 levels, volatile organic compounds, and other atmospheric pollutants. The Gii-Sens is not limited to being a biosensor and can also detect any molecule that can be functionalized to detect using a carbon foam sensor electrode. The environmental monitoring device includes the Gii-Sens sensor 330 and associated control and wireless transmission (e.g., LoRaWAN) electronics 331, as well as a PV solar cell 332 and a Gii-Cap supercapacitor 333. The electronics 331 include a secondary or primary battery (which may be a printed battery) and work in conjunction with the PV solar cell 332 to power those electronics and charge the Gii-Cap supercapacitor 333. The Gii-Sens sensor can also be configured to measure temperature, humidity, and pressure. The device has a back 334 that can be peeled off to expose an adhesive surface, allowing the device to be attached to a wall, etc. The PV solar cell, combined with a secondary or primary battery on electronic device 331, provides power to charge the Gii-Cap supercapacitor 333, which in turn provides the peak burst power required for data transmission. Unlike current environmental monitoring devices, this device can be permanently installed and maintained in place for many years without requiring battery replacement. It can detect atmospheric pollutants with a signal-to-noise ratio superior to conventional devices. The assembled device is shown in Figure 34.
Many other types of devices can be realized using a combination of carbon foam sensors and carbon foam supercapacitors; for example:
Any biosensor capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor, can benefit from wearable health monitoring devices such as continuous glucose monitors and other wearable monitors that sense electrolyte, potassium, sodium, and lactose levels.
This benefits from any sensor device capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor.
This benefits from any IoT device capable of transmitting data (e.g., wirelessly), where the data transmission is powered by a supercapacitor.
The device may include electronic components powered by a supercapacitor.
The device may include a battery to charge energy storage devices and/or power device electronics.
The device may include a PV battery to charge a secondary battery in an energy storage device and/or in a device and/or power device electronics.
We can summarize it as follows:
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
In this example, we combine two distinct power sources into a single device to form a combined or hybrid power source: the device has a battery (e.g., a printed battery or a conventional battery) and a supercapacitor, the supercapacitor using carbon foam made by a dual-laser method in its electrodes; they work together in a complementary manner. The battery can be a disposable, non-rechargeable battery (“primary” battery), or it can be a rechargeable battery (“secondary” battery).
The power sources serve complementary purposes: batteries can provide slow, long-term charging for supercapacitors or power relatively low-power-consuming electronic devices; supercapacitors can provide rapid, high-power discharging and power functions requiring higher power levels, such as wireless data connectivity and data payload transmission. It should be noted that the supercapacitor can be an EDL supercapacitor or a pseudocapacitor, or any other form of energy storage device. The device can be used in situations where high power is occasionally required (e.g., powering a transmitter to connect to a data network and send data payloads), but the device needs to be standalone and continuously used in the field for months or years: the device could be a high-value asset tracking tag that only occasionally needs to broadcast its information, but requires broadcasting at a higher power than conventional printed batteries can provide.
A schematic diagram is shown in Figure 35. There are two separate polyimide film layers: one layer 351 includes a supercapacitor (Gii-Cap) 352 as described in feature M, and the other layer 353 includes a cell 354, such as a printed cell; this can include electrodes made using carbon foam manufactured using a dual-laser process or conventional processes. It is also possible to fabricate the printed cell 354 and the supercapacitor 352 on the same sheet of polyimide, but yield may be affected because any defects in the printed flexible cell or supercapacitor will render the equipment unusable.
As described above, the subsurface carbon foam electrode (or conventional printed electrode) leads from the supercapacitor (Gii-Cap) 352 and the printed battery 354 to the BMS (Battery Management System) 355; the BMS 355 provides power to the flexible electronics 356; the subsurface carbon foam electrode or conventional connector track 357 connects different parts of the flexible electronics 356. The BMS 355 controls the flow of power from the battery 354 to the electronics 356; the battery 354 can trickle charge the supercapacitor 352. (The supercapacitor can also be the primary power source, designed to be charged once in the facility and then not need to be recharged.)
Battery 354 can be a printed battery, and can be a rechargeable secondary printed battery or a primary, non-rechargeable primary battery; battery 354 can trickle charge supercapacitor 352 and provide power to sensor or other device electronics 356; then, supercapacitor 352 provides power (e.g., instantaneous peak power) to circuits (such as data transmitters) that have short-term demands for relatively high burst power. As described above, the printed battery, supercapacitor, and electronics can all be part of a single integrated device, for example, all on a single substrate, or on a separate but attached substrate.
Although back-to-back polyimide layers are shown, they can also be side-by-side; in addition, there can be a single polyimide film that integrates the battery 354 and the supercapacitor 352 into a single object.
The battery 354, supercapacitor 352, and electronic device 356 can all be formed on one or more substrates as part of a continuous or batch manufacturing process (e.g., you don't use a previously manufactured battery and combine it with a supercapacitor). This allows the interconnects to be constructed as an integral part of the manufacturing process, resulting in lower costs, faster manufacturing, and higher performance (e.g., shorter interconnects).
The device can be used in smart tags (see below), or IoT environmental monitoring devices (e.g., temperature or humidity sensors), train seat occupancy sensors, or medical monitoring devices (e.g., continuous glucose monitors). More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
We can summarize it as follows:
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
One important application is the smart label, shown in Figure 36, with the bottom surface shown on the left and an exposed label surface 363 with human-readable text shown on the right. The label includes an adhesive release liner 364 to allow the bottom surface to be attached to packaging, components, etc. The label includes a thin, flexible battery 360 printed onto a polyimide film, and then a Gii-cap supercapacitor 361 formed on the same polyimide layer (or a different polyimide layer bonded to the printed battery polyimide film). The thin, flexible battery can be a non-rechargeable primary battery or a rechargeable secondary battery. The supercapacitor provides power to the data transmitter; the printed battery provides power to the smart label's electronics (including sensors) and power management electronics. Human-readable printed information 363 is included on one surface of the smart label; the back side...
The smart tag includes an electronics module 362 with power management, sensors (e.g., solid-state vibration, temperature, pressure, GPS, etc.) and data transmission electronics (e.g., an LTE transmitter or an ultra-low-cost LoRaWan transmitter). Once a data connection is established, the supercapacitor 361 provides sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in an "advertising" signal; instead, the smart tag can establish a data connection with a data receiver and then transmit the data payload once the connection is established; thus, it can be reasonably ensured that its data has been received. More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
For scalable manufacturing (e.g., producing millions of smart tags at low cost), roll-to-sheet manufacturing of smart tags is ideal (see Feature P: Gii 3 below).
We can summarize it as follows:
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics such as sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
The supercapacitor in the aforementioned example of feature M can provide power to the antenna but is not integrated with the battery: for example, it can provide power from a solar cell or draw power from local WiFi or a wireless charger (e.g., the Qi standard).
We can summarize it as follows:
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor
A useful feature is the combination of an energy harvester with a carbon foam supercapacitor. The energy harvester can be a solid-state energy harvester such as a solar cell, or a vibratory energy harvester (e.g., based on piezoelectric fibers), or a thermoelectric generator (e.g., a Seebeck generator). The supercapacitor can provide power (e.g., instantaneous power) to circuits with short-term demands for relatively high burst power (e.g., data transmitters and antennas). The device may also include a primary battery (e.g., a non-rechargeable printed battery) or a secondary rechargeable battery.
The energy harvester can be on the same substrate as the supercapacitor, or on a separate but connected substrate; the supercapacitor can be on the same side of the substrate as the energy harvester, or on opposite sides.
When the device includes a battery (e.g., a printed rechargeable secondary battery), the energy harvester charges the battery, and the battery provides power to low-power subsystems (e.g., sensors) and also charges the supercapacitor; the supercapacitor provides instantaneous high power for data transmission. Alternatively, the energy harvester can charge the supercapacitor directly.
This approach can be used in smart tags, or IoT environmental monitoring devices (such as temperature or humidity sensors), train seat occupancy sensors, wearable devices, and medical monitoring devices (such as continuous blood glucose monitors). This method is particularly useful in situations requiring continuous (or highly regular) power to the device, such as when continuous monitoring of the environment or an individual's health is necessary.
The device may include LoRaWan or other ultra-low power transmitters. Once a data connection is established, the supercapacitor can provide sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in the announcement signal; instead, the smart tag can establish a data connection with the data receiver and thus ensure that its data has been received.
More generally, the energy harvester can be a solid-state energy harvester, such as a solar cell, or a vibration energy harvester (e.g., based on piezoelectric fibers) or a thermoelectric generator (e.g., a Seebeck generator); the device can include one or more sensors powered by the energy harvester; the energy harvester can charge a supercapacitor; the device can include a primary or secondary battery; the device can be a smart tag, or an IoT environmental monitoring device (e.g., a temperature or humidity sensor), a train seat occupancy sensor, a wearable device, or a medical monitoring device.
We can summarize it as follows:
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
In an earlier chapter, we described the carbon foam in the Gii-Cap supercapacitor as a single planar interdigitated finger layer. In this section, we describe a three-dimensional structure of carbon foam that enables the carbon foam supercapacitor electrodes to be formed as a parallel-plate 3D structure with a greater energy storage potential than a single layer of interdigitated graphene foam fingers.
Figure 37 shows the basic layering of different materials in the core structure. Multiple screen printing steps are performed on the PI polyimide film 371 sheet. First, a conductor (such as a carbon ink or carbon paste layer 372) is screen-printed onto the lower surface of the polyimide film 371. Then, a current collector 373 (e.g., a screen-printed silver current collector) is screen-printed over the carbon layer 372. Finally, a dielectric layer 374 is screen-printed over the current collector.
Figure 38 shows the carbon foam layer formed in the polyimide film 371 using the dual-laser process described above: more specifically, an IR laser forms an encapsulated carbon foam layer 375 in the PI film 371; beneath this carbon foam layer is a disordered, amorphous, non-graphene layer 376 formed on the lower surface of the PI film 371. A CO2 ablation laser exposes the previously encapsulated carbon foam layer 370, thereby giving the exposed surface layer 377 a unique morphology.
This structure provides a conductive path from the current collector layer 373, through the conductive ink or paste layer 372, through the disordered amorphous non-graphene layer 376, and then to the carbon foam layer 375. In this way, the potential of the large-area carbon foam 375 can be increased, enabling it to act as a capacitor plate; the structure forms part of a half-cell.
Typical thicknesses are as follows: polyimide film 371: 127 μm; carbon ink layer: 20 μm; silver current collector layer 373: 30 μm; dielectric layer: 40 μm; carbon foam layer 375 and disordered amorphous non-graphene layer 376: 127 μm; unique surface morphology layer 377: 25 μm.
It should be noted that Gii-Cap+ (a variant that uses a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x , see Feature M2 above) and delivers significantly higher capacitance than the standard Gii-Cap device) can be used in Gii-Thru.
We can summarize it as
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising a carbon foam material made at least partially by a carbon precursor film as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Multiple structures as described in Figure 38 can be stacked together; since the surface area of the carbon foam layer can be very large (significantly larger than the surface area of the finger sites in the previously described planar interdigitated supercapacitor), this enables the production of high-performance supercapacitors.
The half-cell is illustrated in Figure 39. It comprises (gradually moving downwards through the structure): a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in a PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper tabs 395 for connection points; a screen-printed dielectric isolation layer 396; a second carbon foam layer 397 with a unique surface morphology in a PI film 398; and a hydrogel electrolyte layer 399 at the base of the stack. It may be helpful to associate this structure with the schematic diagram in Figure 38: in Figure 40A, we group the four main layers shown in Figure 38 at point A, i.e., moving downwards along the stack, the carbon foam layer, then the carbon ink layer, then the silver collector layer, and then the dielectric layer. Figure 40B is a cross-section of the structure of Figure 40A, showing the features of group A. Figure 40B is the same cross-section, but this time all the elements in Figure 39 are labeled.
The complete unit is shown in Figures 41A and 41B. In Figure 41A, we only label the features that are also present in Figure 39 (using the same numbering). So it includes: a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in the PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper inserts 395 for connection points; and a screen-printed dielectric isolation layer 396.
In Figure 41B, we now add an additional layer; moving down through the structure, we have a screen-printed dielectric insulating layer 400, followed by a screen-printed silver collector layer 401 with copper inserts 402, then a screen-printed carbon paste layer 403, and then a carbon foam layer 404 with a unique surface morphology in a PI film 405.
In Figure 41C, we group the four main layers shown in Figure 38 together at point A; the four top layers are grouped together at point B in the reverse order. Groups A and B are separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399, which is dispensed using a conventional electrolyte dispensing system.
Figure 41D is a cross-section of this structure, showing the A and B layers separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399. Figure 41E is the same cross-section, but this time the layers are numbered according to the schematic diagram in Figure 38.
Figure 41F is a perspective view of the assembled supercapacitor.
Figure 42 shows a stack of four full-cell supercapacitors; the carbon foam layer is shown in A, and the polymer hydrogel electrolyte is shown in B. Additional cells can be added to the stack to obtain the desired performance.
Figure 43A shows the detailed manufacturing process of the Gii-Thru supercapacitor, and Figure 43B shows the detailed manufacturing process of the Gii-Thru multi-stacked supercapacitor.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from the carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
The Gii-Thru structure described in Figure 38 can be used not only for supercapacitors but also for Gii-Sens sensors, such as biosensors.
For microfluidics, the Gii-Thru HISLOC (High Sensitivity, Low Cost) platform approach allows liquid and carbon foam sensors to be mounted on the upper surface of the biosensor device, with electrical connectors to the carbon foam sensor mounted on the lower surface. Microfluidics typically use functionalized gold electrodes, where all electrical connectors to these functionalized gold electrodes are coplanar; compared to these functionalized gold electrodes, Gii-Thru biosensors offer advantages in cost, yield, and performance. Furthermore, moving the electrical connectors to the bottom or base of the biosensor enables greater miniaturization and compatibility with point-of-care (POC) systems.
Figure 44A is a schematic cross-sectional view of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device. The top layer has three sample wells 440; the fluid to be analyzed flows into each of these samples 440. The wells 440 are formed as small pores in a laminated spacer layer 441 located above the polyimide film layer 442.
Three functionalized carbon foam regions are formed in the polyimide film layer 442, which form a reference electrode 448A, a working electrode 448B, and a counter electrode 448C; the upper surface of each electrode 448A-448C is exposed to the analytical flow present in the pore 440.
The base of the reference electrode 448A may include an Ag-AgCl layer (or a screen-printed carbon layer) 449; the base of the working electrode 448B is a screen-printed conductive carbon layer 443; and the base of the counter electrode 448C is another screen-printed conductive carbon layer 443. In this way, the reference electrode 448A is in electrical contact with the reference electrode connector 444A; the working electrode 448B is in electrical contact with the working electrode connector 444B; and the counter electrode 448C is in electrical contact with the counter electrode connector 444C.
The screen-printed dielectric layer 447 forms the base of the structure.
The interesting aspect of this structure is that the electrode connectors 444A-C are not coplanar with the functionalized carbon foam electrodes 448A-C, unlike conventional screen-printed sensors. Instead, they lie in the plane below the functionalized carbon foam electrodes 448A-C, on the opposite side of the aperture 440. This structure enables greater miniaturization and compatibility with POC (point-of-care) systems.
Figure 44B shows an isometric exploded view of the microfluidic diagnostic device of Figure 44A. Three sample wells 440 are located in a laminated spacer layer 441, which sits above a polyimide film layer 442. A reference electrode 448A, a working electrode 448B, and a counter electrode 448C are shown; the end of the reference electrode 448A is covered by an Ag-AgCl layer or a screen-printed carbon layer 449; the working electrode 448B and the counter electrode 448C are covered by a screen-printed conductive carbon layer 443. As noted above, the reference electrode 448A is in electrical contact with a reference electrode connector 444A; the working electrode 448B is in electrical contact with a working electrode connector 444B; and the counter electrode 448C is in electrical contact with a counter electrode connector 444C.
It should be noted that the three functionalized carbon foam regions 448A-C are shown as planar squares located on different planes; however, this is merely an artificial creation of the CAD drawing used to generate the figures, and the carbon foam regions 448A-C are better represented in Figure 44A. A screen-printed dielectric layer 447 forms the base of the structure.
Figures 44A and 44B above show a three-point array microfluidic diagnostic device. In Figures 45A and 45B, we present an eight-point array microfluidic diagnostic device. In isometric Figure 45A, the laminated pore spacer 451 includes an array of eight analyte holes 452 for the working electrode, plus holes 453 for the counter electrode and holes 454 for the reference electrode; the laminated pore spacer 451 is located above the polyimide layer 455. Gii carbon foam in the polyimide layer 456 forms eight working electrodes 457 and counter electrodes 458, and is fabricated using a dual-laser process. It should also be noted that the carbon foam electrodes 457, 458 are shown as planar squares located on three different planes; however, this is merely an artificial CAD design, and the carbon foam forms a continuous region within the polyimide layer 455.
The reference electrode 459 is covered with a thin screen-printed Ag-AgCl layer. A thin screen-printed carbon bonding interface layer 460 is located below the working electrode 457 and the counter electrode 458; screen-printed silver bonding traces 461 form electrical connections with all electrodes 457, 458, and 459. Then, a screen-printed dielectric layer 462 forms the housing of the device. Figure 45B is a pair of top views of the device of Figure 45A; the lower figure shows the path of the lower bonding traces.
Figure 46A shows a perspective view of the fully assembled multi-sample array microfluidic diagnostic device; Figure 46B is a top view.
We can summarize it as
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode, at least partially made of a carbon precursor film by means of any one of the features A-K above, in a layer below the sample orifice, and a reference electrode connector, a working electrode connector, and a counter electrode connector are also in the layer below the reference electrode, working electrode, and counter electrode.
Figure 47A shows an exploded view of a microfluidic diagnostic device comprising multiple laminated layers; it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. The top layer 470 of the device is a microfluidic foil; the middle layer 471 is a microfluidic foil with an adhesive and includes printed or molded microfluidic channels 472, and the bottom layer 473 is a microfluidic foil with an adhesive. The Gii-Thru sensor 474 is a three-point array (3SA) biosensor and includes a connector 475. Figure 47B is a top view showing the internal structure. The Gii-Thru sensor 473 can be replaced with different biosensors (e.g., 8SA) for greater flexibility.
Figure 48B shows an exploded view of a microfluidic diagnostic device comprising a printed or molded microfluidic card, and it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. This device includes a transparent resin barbed connector 481, a top foil 482, a transparent resin molded microfluidic card 483 with microfluidic channels 484, a perforated unit 485 made of microfluidic foil with an adhesive, and a Gii-Thru sensor 486. Similarly, the Gii-Thru sensor 486 can be replaced with different biosensors (e.g., 8SA) for greater flexibility, and the molded microfluidic card 483 can be replaced with designs featuring different microfluidic characteristics to allow for use on different assay platforms. Figure 45B is a top and side view.
Feature O4: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
The HISLOC manufacturing process can be summarized as follows:
1. Screen print the elastic layer onto the underside of the polyimide film.
2. Screen-printed silver connectors.
3. Screen printing silver/silver chloride reference electrode (steps 3 and 4 can be rearranged into 4 then 3).
4. Screen-printed dielectrics.
5. Gii carbon foam sensor electrodes are generated in a polyimide film using a dual-laser process.
The detailed manufacturing process is shown in Figure 49.
We can summarize it as follows:
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising a carbon foam material made at least partially from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Group 4
Feature P: Scalable manufacturing: G-ii 3
Gii-3 is a scalable manufacturing facility for roll-to-roll or roll-to-sheet production of all the Gii-based materials described above. A key commercial advantage is that Gii-3 manufacturing does not require custom equipment; it utilizes off-the-shelf computer-controlled lasers for dual-laser carbon foam manufacturing, along with conventional screen printing and drying techniques: these are well-known, easy-to-understand manufacturing processes and equipment that enable reproducibility and reliability.
Figure 50 is a schematic diagram of the overall manufacturing process, and Figure 51 shows the detailed process flow.
We can summarize it as follows:
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other Gii applications
The Gii carbon foam described in this specification can be used in a wide variety of applications, including many applications where conventional graphene foam is considered suitable.
We can summarize it as follows:
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, a tactile sensor for robots; a prototype sensor is shown that uses polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as the active layer in a piezoresistive pressure sensor for robotic touch sensing applications: several carbon foam layers are capable of exhibiting pressure sensitivity of 0.0418 mV/kPa in the range of 0 to >50 kPa. See DOI:10.4028/p-oy94hj. and DOI:1109/CDE52135.2021.9455738. These contents are incorporated herein by reference to the maximum extent permitted.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection. See DOI:10.1016/j.bios.2022.114954, the contents of which are incorporated herein by reference to the maximum extent permitted.
Continuous monitoring of chemical sensors.
Glucose Monitoring Sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring is shown; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competitively binding with polynordihydroguaiaric acid. See DOI:10.1039/D1AN01991K, the contents of which are incorporated herein by reference to the fullest extent permitted.
Lactic acid sensor: Employs a synthetic organic acceptor molecule based on attaching boric acid to a carbon foam to provide functionality and selectivity in competitive analyte binding, with surface redox polymer indicator substitution used. See DOI:10.1016/j.snb2022.133089, the contents of which are incorporated herein by reference to the maximum extent permitted.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1). See DOI:10.1016/j.elecom.2022.107394, the contents of which are incorporated herein by reference to the fullest extent permitted.
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
Under a scanning electron microscope, conventional graphene foam appears to have large open ring structures, typically 500 μm in size. Carbon foam generated using a dual-laser process looks very different; Figures 52–57A are SEM images of this Gii carbon foam.
Figure 57B is a SEM image of carbon nano-onions, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI:10.1007/s00339-015-9315-9 and "Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications", DOI:10.1016/j.ica.2017.07.021. Its similarity to Gii carbon foam is obvious.
As previously mentioned, graphene foam possesses several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature features: the absence of a D peak; a 2D peak higher than the G peak; and a D:G peak ratio close to zero. However, carbon foam produced using a dual-laser process does not exhibit these characteristics; it is hydrophilic with a contact angle below 20°; and it lacks the Raman spectral signature indicative of graphene: it displays a prominent D peak; a 2D peak significantly smaller than the G peak; and a D:G peak ratio significantly higher than zero. Figure 58 shows the Raman shifts of eight carbon foam sheets fabricated using a dual-laser process, demonstrating the consistency of the Raman signature. It also shows a prominent D peak; a 2D peak smaller than the G peak; and a D:G peak ratio significantly higher than zero. As we previously stated, this Raman spectrum shares many similarities with carbon nanotube onions. See also Figure 18C, also from “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9. The specific dual-laser parameters used to generate this low-resistivity carbon nano-onion variant of Gii carbon foam are shown in Table 5 below:
Table 5
We can summarize it as follows:
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
It should be noted that any of the devices described above, such as sensors, pressure sensors, biosensors, Hall effect sensors, supercapacitors, hydrogen fuel cells, and filters, can be characterized using these materials, and therefore we can summarize as follows:
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Appendix 2 Gii-Cap+ Hydrogel
Appendix 3 GiiCap Ion Gel
Appendix 4 Feasibility Study Recommendation (3 Months)
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Material via Connectors
Appendix 6 Baseline Experimental Conditions
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
It should be noted that Appendices 1-7 describe specific implementations of Gii carbon foam.
Appendix 8: Combined list of features and optional features
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
background
A supercapacitor is a device that stores electrical charge. Based on its structure and function, a supercapacitor falls between an electrolytic capacitor and a rechargeable battery.
The properties of supercapacitors make them superior to rechargeable batteries in applications requiring short charging times and those involving many charge/discharge cycles. However, compared to batteries, supercapacitors have disadvantages including a weaker ability to store energy over long periods.
The operational limitations of supercapacitors are determined by the material properties of their components. Specifically, the maximum voltage at which a supercapacitor can operate (i.e., can be charged) depends on the stability of the electrolyte and/or electrodes. The maximum voltage of a capacitor is an important parameter, especially since the energy stored in a capacitor is proportional to the square of the voltage. Supercapacitors with organic electrolytes typically support higher voltages than those with aqueous electrolytes. By utilizing organic electrolytes, supercapacitor designers can produce devices with an operating range of 2.5 to 2.7 V. In contrast, while aqueous electrolytes are often preferred due to their lower cost and lower toxicity, they typically result in devices with a lower operating voltage range. Known symmetrical aqueous supercapacitors generally cannot support voltages higher than 1.3–1.5 V. This voltage limitation can reach 1.8–2.0 V if electrodes made of different materials are used. The limitations of water-based supercapacitors are attributed to the electrolysis of water, which, in principle, occurs when water is exposed to a potential difference of 1.23 V. However, in practice, a larger potential difference is required before electrolysis occurs to overcome the effects of overpotential.
Carbon-based electrodes have been associated with supercapacitors since their early development. Initially, carbon attracted attention as an electrode material because it offered the possibility of fabricating electrodes with large surface areas. Later in the development of supercapacitor devices, the importance of the so-called double layer on the electrode surface was realized. This complex and often elusive phenomenon, related to the use of carbon as an electrode material, is central to the high capacitance values associated with supercapacitors. Supercapacitor devices incorporating carbon-based electrodes are thought to involve a double layer on the electrode surface, with energy stored electrostatically. Such supercapacitors are called electrostatic double-layer capacitors, or EDLCs.
Other types of supercapacitors also exist. Electrochemical pseudocapacitors utilize metal oxide electrodes or conductive polymer electrodes. Compared to the electrostatic charge storage mechanism of EDLCs, charge storage in pseudocapacitors is primarily electrochemical. A third type of supercapacitor is the hybrid capacitor. Hybrid capacitors have asymmetric electrodes. One electrode is typically made of carbon and exhibits electrostatic charge storage properties; the other electrode is typically a lithium-containing or lithium-doped material, which primarily exhibits electrochemical charge storage properties.
Conventionally, a supercapacitor can be considered and modeled as two capacitors connected in series, with each electrode associated with one capacitor. Each capacitor is located at the interface between the electrode and the electrolyte and is formed by the supercapacitor electrode, a dielectric layer (called the inner Helmholtz plane) formed by solvent molecules present in the electrolyte, and a charge carrier layer (called the outer Helmholtz plane) provided by the electrolyte as the opposite charge charging the electrode. This triple structure of the electrode, inner Helmholtz plane, and outer Helmholtz plane forming the capacitor system at each electrode is called a double layer or electrical double layer.
Summary of features in Appendix 1
A first aspect of the aforementioned features provides a symmetrical supercapacitor device comprising: two electrodes, each comprising a carbon foam as described in this specification (e.g., see features A-K in Appendix 8); and an ion gel or hydrogel electrolyte encapsulating the electrodes in active regions.
We have found that symmetrical supercapacitor devices, based on a combination of the characteristics described above, produce an enhanced operating voltage window. The term "symmetrical" refers to the fact that the electrodes comprise the same material and may be constructed from the same material.
The operating voltage window, or operating range, of a supercapacitor is a critical parameter of such a device and is determined by the breakdown voltage of the electrolyte. For supercapacitors based on aqueous electrolytes, water decomposition typically leads to limitations on the operating voltage window.
Although the reasons for the unexpectedly large operating window observed using the device disclosed in this invention are not yet fully understood, it is evident, without being bound by any theory, that the special property is a result of the combination of the carbon foam electrode and the electrolyte, and especially of the interface between these elements.
In electrochemistry, the large operating window of the device of this invention is equivalent to an unexpectedly large overpotential at the electrode. An overpotential is a potential difference exceeding the thermodynamic redox potential required for a specific reduction/oxidation reaction to occur. Overpotential is often a difficult phenomenon to understand, partly because many factors contribute to it. For example, overpotential depends on the electrode material, electrode morphology, and the properties of the electrolyte. In this invention, the large surface area provided to the electrolyte by the carbon foam electrode is considered likely to play a role in device performance. It is known that how ions diffuse from the electrolyte bulk to the electrode surface and the associated consumption of charge carriers on the electrode surface affect the overpotential. This may play a role in the device of this invention. The diffusion rate of charge carriers in the electrolyte may be affected by the presence of hydrated ions, which are larger than non-hydrated ions. The interaction between charge carriers and the morphology of the carbon foam electrode may also affect the overpotential. The presence of ion-gel or hydrogel polymers is also considered to influence the diffusion of charge carriers to the electrode surface, possibly due to spatial effects and related to the carbon foam morphology.
Hydrogels are gels whose liquid component is water and can be formed from a network of polymer chains. Supercapacitors with a hydrogel electrolyte forming the dielectric are expected to have performance characteristics associated with aqueous electrolyte-based supercapacitors. However, to this expectation, the inventors have found that the performance of a supercapacitor according to a first aspect (i.e., a symmetrical device in which the electrodes are made of the same material, including carbon foam and encapsulated in a hydrogel electrolyte) surpasses the expected performance of an aqueous device. The operating voltage window of the device is unexpectedly enhanced compared to aqueous electrolyte-based devices. The operating window is more similar to that of organic solvent-based supercapacitors.
Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), sodium polyacrylate, acrylate polymers, and copolymers, which have a large number of hydrophilic groups, are examples of polymers that can be utilized in hydrogels. Fluorinated hydrogels can also be used. The combination of hydrogels and ionic charge carriers helps to achieve a surprisingly large operating window through the system of the present invention.
The electrodes of the device disclosed in this invention are located on a substrate, and the electrolyte is present on top of the electrodes in a manner that seals at least a portion of the electrode structure, thus forming an active region. The active region of a supercapacitor is the region in a supercapacitor that stores charge, including the electrolyte and the electrodes.
The electrodes of the device can have an interdigitated geometry, meaning they can be interdigitated. This interdigitated electrode geometry helps maximize the capacitance of the supercapacitor. It also enables a device without a separator. Supercapacitors typically include separators between opposite electrodes to prevent short circuits. The absence of a separator facilitates the construction of supercapacitor devices. Separators can also negatively impact device performance, such as inhibiting charge flow and reducing charge/discharge rates. The absence of a separator avoids these negative performance effects.
Interdigitated electrode geometries are well-suited for symmetrical devices. Constructing an interdigitated electrode geometry with opposite electrodes made of different materials is significantly more complex than with electrodes made of the same material. If the electrodes are made of the same material, they can be fabricated in-situ in a single step. Using different electrode materials requires multiple fabrication steps, greatly increasing the complexity of the manufacturing process.
In addition, the absence of a separator eliminates any negative impact that a separator might have on device performance, such as inhibiting charge flow and causing a decrease in charge/discharge rate.
The hydrogel electrolyte can contain a sufficiently high charge carrier concentration to produce the enhanced operating voltage window.
An enhanced operating voltage window may depend on the concentration of charge carriers.
Charge carriers can have redox potentials that support an enhanced operating voltage window.
The charge carrier can be provided by aqueous solutions of acids, bases, or salts. Usable acids include sulfuric acid. Usable bases include potassium hydroxide.
Hydrogel electrolytes may comprise a mixture of hydrogel and salt. The electrolyte may be composed of a hydrogel polymer, such as PVA or PVP. The salt may be, for example, NaClO₄ , NaNO₃ , or Mg( ClO₄ ) ₂ . The molar concentration of the salt may be, for example, 0.5 M or greater, such as 1 M or greater, such as 2 M or greater, such as 2.5 M or greater, such as 3 M or greater, such as about 5 M. The molar concentration of the salt may be, for example, between 1 M and 10 M, or it may be, for example, between 2.5 M and 7.5 M.
Salts that can be used include phosphates, perchlorates, nitrates, and arsenates. Examples of salts include sodium sulfate, sodium bisulfate, sodium persulfate, sodium perchlorate, lithium perchlorate, magnesium perchlorate, sodium nitrate, and lithium hexafluoroarsenate. Aqueous solutions of these salts can be used in electrolytes to provide ion carriers.
Charge carriers can be ions. Charge carriers can be hydrated ions.
Hydrated ions are ions in an aqueous environment. Polar water molecules arrange themselves around the ions, forming hydrated spheres centered on the ions. The details of the mechanism behind the surprisingly wide enhanced operating voltage window observed with respect to the features of this invention are difficult to understand, and the inventors do not wish to be bound by theory. However, the surprisingly advantageous properties of the device of this invention are a result of the synergistic effect between the electrodes and the dielectric material. The enhanced performance is a lack of water splitting under voltage conditions under which electrolysis is expected to occur by those skilled in the art. The interface between the electrode and the electrolyte is expected to be the origin of its performance. There may be a synergistic interaction between the size of the charge carrier (possibly a hydrate) and the size of the pores present in the electrode. The hydrogel contains a network of polymer chains, and this chain network of the hydrogel may also have physical (spatial) effects that limit the exposure of water molecules to potential differences that could lead to their decomposition.
The increased size of hydrated ions is thought to combine with the porous structure of the carbon foam electrode to impede diffusion near the electrode surface, leading to an increase in overpotential.
The electrodes of a symmetrical supercapacitor device may include porous carbon foam. Optionally, the electrodes may not include additional adhesive material.
Porous carbon foam electrodes are thought to be combined with charge carriers in the electrolyte to increase overpotential, thereby enhancing the operating window of supercapacitors.
Carbon foam consists of one or more 2D carbon sheets (each sheet being a layer of sp2-bonded carbon) folded back-to-back to form a three-dimensional structure rather than planar sheets. Carbon foam lacks the regular AB stacking of planar carbon sheets found in graphite or multilayer 2D carbon. Carbon foam materials are typically porous. Carbon foam has a high surface area. By changing the parameters of the growth method, the porosity of the carbon foam can be controlled, and thus the surface area of the foam. This has the advantage of allowing control over the porosity of the device electrodes during the electrode fabrication process.
Carbon foam electrodes can be mounted on a substrate. Carbon foam electrodes can be mounted on a polyimide substrate. The polyimide substrate can be polyimide. The substrate can form the substrate of a supercapacitor device. The substrate can be thin enough to be flexible, thereby creating a flexible supercapacitor device. The substrate can contain one or more of the following materials (e.g., formed therefrom): polyimides (e.g., poly(4,4'-oxydiphenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde resins.
These substrate materials can be used as a carbon source and transformed into carbon foam using the dual-laser process described above. Carbon foam can be produced in this way by irradiating a polyimide substrate (e.g., with radiation, such as laser radiation). The resulting carbon foam is chemically and indirectly fixed to the substrate via an intermediate layer of amorphous, non-graphene material directly attached to the substrate (see earlier in this specification), resulting in a robust structure. Therefore, electrodes can be produced in situ by using a portion of the substrate as a carbon source, i.e., as a reagent for producing carbon foam. The structure is both robust and flexible. Flexible devices have advantages in many ways. Flexible devices can be conveniently packaged, for example, by rolling them up. For example, flexible devices can also be attached to the surface of curved structures.
The substrate can be substantially planar. The substrate can be a film, such as a thin film. The substrate thickness can be greater than 5 μm. The substrate thickness can be less than 120 μm. The substrate thickness can be between 5 μm and 120 μm. The substrate thickness can be substantially uniform across the substrate surface. The substrate can be flexible. The substrate can be tough.
The substrate may be a polyimide strip (e.g., a polyimide strip) having a first surface and a second surface.
Electrodes can be mass-balanced to optimize the operating voltage window.
A supercapacitor can be viewed as two capacitors connected in series. To maximize the capacitance of a supercapacitor, the capacitances of the two constituent capacitors should be equal. This can be engineered by adjusting the surface area of each electrode, thereby compensating for other factors affecting the capacitance, such as the properties of solvated ions. This process of adjusting the individual electrodes is called mass balancing. Electrode mass balancing has the advantages of maximizing the capacity of the superconducting device and extending the lifespan of the supercapacitor.
In a second aspect, there is a method for manufacturing a symmetrical supercapacitor device according to the first aspect, wherein:
Electrodes are formed on the substrate;
Electrolyte precursors containing charge carriers and hydrogels are applied to electrodes;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the active region.
Carbon foam electrodes can be fabricated by: converting a portion of a substrate (if the substrate is or includes a carbon source) into carbon foam; or by using chemical or physical deposition methods, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), sputtering, laser-induced growth, pulsed laser deposition, cathodic arc deposition, spin coating, dip coating, or sol-gel methods. In this way, electrodes are produced in situ on the substrate.
Electrolyte precursors can be prepared by preparing an aqueous solution of the charge carrier and then mixing this aqueous solution with a hydrogel. Electrodes can be formed using laser radiation.
When preparing the electrolyte precursor, it is important to remember that precipitation or crystallization of salts in the electrolyte is undesirable. Precipitation of salts or any solids in the electrolyte can lead to device breakage, or other defects in the device, or defects in its performance. This sets an upper limit on the concentration of the salt solution. Avoiding the use of supersaturated salt solutions may be advantageous. The precise upper limit of concentration may depend on the specific chemical composition present. For sodium perchlorate, the inventors have found that an electrolyte produced at a concentration of 5M avoids salt precipitation or crystallization, and, in combination with other features, allows the operating window of the supercapacitor device to extend beyond what would be expected based on considerations of the individual components. The electrolyte may include a salt solution with a concentration greater than 4M. The electrolyte may include a salt solution with a concentration greater than 3M, or greater than 2M, or greater than 1M, or greater than 0.5M.
At higher concentrations, salts were observed to precipitate readily from the electrolyte gel, and at such a rapid rate that the device became unusable. This precipitation may be caused by water evaporation. Hydrolysis and water loss could be another cause. In any case, the inventors found that although the electrolyte gel could be formed using sodium perchlorate at concentrations up to 16.5 M, precipitation problems were observed at all concentrations above 10 M.
High-molar salt solutions can be used when manufacturing hydrogel electrolytes.
For cost reasons, lower concentrations of salt solutions are generally advantageous.
The thickness of the carbon foam layer can be between 10 μm and 100 μm. This contributes to the flexibility of the device, allowing it to be rolled up for greater compactness.
A gap between 100 μm and 1000 μm can separate the electrodes from each other. The capacity of the device depends on the gap between the electrodes, and therefore adjusting this gap will affect the amount of charge that can be stored.
The operating window of the device of the present invention can be greater than 1.5V, or it can be greater than 2V, or it can be greater than 2.5V.
Any optional or preferred feature of any aspect of the system can be a feature of any other aspect of the system.
Appendix 1: Description of the Drawings
We have referenced the following attached figures, in which:
Figure 59 shows the carbon foam cyclic voltammetry measured at 25 mV/s for a positive voltage.
Figure 60 shows the carbon foam cyclic voltammetry measured at 25 mV/s for negative voltage.
Figure 61 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a positive voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a negative voltage window.
Figure 63 presents carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 presents carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 presents carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 1 Detailed Description
Dual-electrode supercapacitor
A typical carbon foam supercapacitor device based on this characteristic has interdigitated carbon foam electrodes, as shown in Figure 26. To summarize, a polyimide substrate supports the supercapacitor electrodes, which in this example are constructed of carbon foam and arranged in an interdigitated comb geometry, forming an interdigitated electrode structure. Silver current collectors extend along each side of the device, making each opposite electrode electrically integrated. The non-substrate side of the interdigitated electrode structure is encapsulated in a hydrogel. A polyimide cap can be added to contain the hydrogel, or the device can be packaged in other suitable ways.
As explained above, carbon foam electrodes can be formed on a polyimide substrate. Carbon foam is formed above a suitable substrate (i.e., a substrate providing the carbon source, in this example, a polyimide substrate) by exposing it to a laser beam. The carbon foam produced in this way grows from the substrate and indirectly adheres to it. The substrate and the carbon foam electrode formed in situ in this way form a single unit.
The carbon foam electrodes are manufactured using an infrared CO2 laser under ambient conditions. The substrate is a commercially available polyimide film with a nominal thickness of 127 micrometers. One example has eleven parallel carbon foam strips per electrode. This number can obviously vary. The carbon foam strips of the positive electrode are offset relative to the carbon foam strips of the second electrode, thus forming an interdigitated structure.
Electrode dimensions are shown in Table 6:
| <![CDATA[<u>mass balance ratio</u>]]> | 1.18 |
| <![CDATA[<u>Positive half-cell "electrode finger"</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.0472 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.20768 |
| <![CDATA[<u>Negative half-cell “electrode finger”</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.04 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.176 |
| Distance between fingers (cm) | 0.04 |
| <![CDATA[Total active electrode surface area (cm<sup>2</sup>)]]> | 0.38368 |
| <![CDATA[Total active electrode volume (cm<sup>3</sup>)]]> | 0.0019184 |
Table 6
Three-electrode device
In addition to the two-electrode supercapacitor device, a three-electrode testing device including a reference electrode was also fabricated. The three-electrode device comprises a working electrode, a counter electrode, and an Ag/AgCl reference electrode. Each of the working and counter electrodes is made of carbon foam, which in this specific embodiment is generated by dual-laser irradiation of a polyimide substrate, as previously described. This device is used to determine the stable voltage range of the NaClO4 hydrogel electrolyte. The three-electrode device is stabilized for at least one hour after fabrication before any measurements are performed.
Preparation of hydrogel electrolytes
Each of the disclosed two-electrode and three-electrode devices is based on a 5M sodium perchlorate solution, and the electrolyte is prepared as described herein. The 5M sodium perchlorate solution is prepared by dissolving sodium perchlorate (98% purity, from Sigma-Aldrich) in deionized water (dosage: 3.061 g NaClO₄ dissolved in 5 mL deionized H₂O ). The sodium perchlorate solution is then stirred with a magnetic stirrer on a hot plate at 120°C while polyvinyl alcohol (PVA, 99% hydrolyzed, Sigma-Aldrich) is added. 1.5 g of PVA is dissolved per 10 mL of solution. The mixture of sodium perchlorate solution and PVA is removed from the hot plate and allowed to cool, subsequently forming a white, opaque gel-like solution. The gel solution is then heated to 120°C until it liquefies and becomes transparent. It is then deposited onto a graphene electrode. After deposition onto the electrode surface, the liquefied hydrogel electrolyte material solidifies within approximately 5 minutes at room temperature. The amount of electrolyte deposited on the electrode depends on the surface area to be covered. For the test setup, deposit 150 μL of electrolyte.
Experimental results of the three-electrode device
The performance achievable from supercapacitors is ultimately limited by the stability of the electrolyte.
To test the electrolyte stability in the system of this invention, several experiments were performed using the three-electrode apparatus described herein. Differential pulse voltammetry (DPV) was initially used to select which voltage windows to investigate via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements.
i-Cyclic Voltmeter Method
Cyclic voltammetry measurements were performed to determine the stability of the electrolyte. In a standard three-electrode measurement, the potential between the working electrode and the reference electrode was scanned at a constant rate from the open-circuit potential (OCP; nominal 0V) to a predetermined upper limit, and then scanned downwards again. The current response of the working electrode was monitored during this period.
The results of these measurements are shown in Figures 59 and 60. Figure 59 shows the results of scanning the voltage from OCP in the positive direction.
The upper results set shows four voltammograms with maximum potentials of 1V, 1.2V, 1.3V, and 1.4V. The lower results set also includes a voltammogram with a maximum potential of 1.6V. As the upper voltage limit increases above 1.2V, the shape of the cyclic voltammograms becomes less "square." The tails become increasingly pronounced as the final scan voltage increases, indicating electrolyte degradation, which may be attributed to water electrolysis. These voltammograms indicate that the electrolyte is stable up to +1.2V.
Figure 60 shows a similar set of results, but for the negative electrode voltage. These data indicate that the electrolyte is stable up to -1.4V.
In summary, the data in Figures 59 and 60 provide an operating window of 2.6V for the device. This is significantly higher than expected when using an aqueous electrolyte.
ii. Constant Current Charge-Discharge (GCD) Data
Constant current charge-discharge (GCD) measurements were performed to determine coulombic efficiency based on charge and discharge times. In these measurements, a current was applied between the counter and the working electrode, and the voltage response of the working electrode (relative to the reference electrode) was measured. The GCD curves measured for the positive electrode voltage using a discharge current of 2 × 10⁻⁵ A (0.5 mA/ cm² ) for a selected voltage window are shown in Figure 61. The curves plateau above 1.2 V, indicating electrolyte degradation. The GCD curves for a selected negative electrode voltage window are shown in Figure 62.
A significant plateau was observed in the voltage windows up to -1.6V and -1.8V, indicating electrolyte degradation. The -1.4V voltage window exhibited a triangular GCD curve, indicating stability.
The results of cyclic voltammetry and constant current charge-discharge measurements of the three-electrode system are summarized in the table below.
The first table (Table 7) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the positive voltage window.
Table 7
The second table (Table 8) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the negative electrode voltage window.
Table 8
In these summary tables, coulombic efficiency is the ratio of stored energy to delivered energy measured in the second GCD cycle; areal capacitance in mF/ cm² is calculated using the following formula:
Area Capacitor
Furthermore, the discharge energy is the integral of the charging and discharging portions of the GCD curve over time.
The GCD curve indicates that +1.2V and -1.4V are the actual positive and negative voltage limits.
These voltage limits and areal capacitance values allow for the calculation of mass balance using the following formula:
Where, m + = mass of the positive electrode, m - = mass of the negative electrode, C + = capacitance of the positive electrode (F), C - = capacitance of the negative electrode (F), ΔE + = positive electrode voltage window limit, ΔE - = negative electrode voltage window limit.
Experimental Results of a Two-Electrode Device—Supercapacitor Performance
For the dual-electrode supercapacitor device, galvanostatic charge-discharge (GCD) data were collected within an applied current density range of 0.25 mA/ cm² to 30 mA/ cm² . Figure 63 plots the GCD results obtained from five different devices (CH1-CH5). These data were collected using a voltage window of 2.6 V, and greater electrolyte stability was observed at higher current densities. Further performance data for the dual-electrode supercapacitor are presented in Figure 64, showing cyclic voltammetry plots recorded from five different devices (devices #1 to #5) according to an embodiment of the invention at scan rates from 0.01 V/s to 5 V/s.
The cyclic voltammograms in the right column were recorded at low scan rates (0.01 V/s, 0.025 V/s, 0.05 V/s, 0.075 V/s, 0.1 V/s, 0.25 V/s, and 0.5 V/s), while the cyclic voltammograms in the left column were recorded at high scan rates (0.75 V/s, 1 V/s, 2 V/s, 3 V/s, 4 V/s, and 5 V/s). The trend shown in these data is that higher scan rates correlate with higher electrolyte stability. In each set of cyclic voltammograms shown in Figure 64, faster scan voltages resulted in larger differences in the current response between voltage rise and voltage fall.
In addition to the devices disclosed above, devices were also constructed in a similar manner but using hydrogel electrolytes comprising the following: (a) 3M NaClO 4 and PVA, (b) 1M NaClO 4 and PVA, (c) 2.5M NaNO 3 and PVA, (d) 3M Mg(ClO 4 ) 2 and PVA, and (e) 5M NaClO 4 and PVP.
The cyclic voltammetry results of these additional devices are shown in Figure [.]10. For each electrolyte, cyclic voltammetry was run between 0V and 0.7V, 0V and 0.8V, 0V and 0.9V, 0V and 1.0V, 0V and 1.2V, 0V and 1.3V, and 0V and 1.4V. Similarly, for each electrolyte, cyclic voltammetry was run between 0V and -0.7V, 0V and -0.8V, 0V and -0.9V, 0V and -1.0V, 0V and -1.2V, 0V and -1.3V, and 0V and -1.4V. These data are shown in Figure 65.
Data indicate that, in each device, for (d) 3M Mg(ClO 4 ) 2 and PVA and (e) 5M NaClO 4 and PVP, the electrolyte is stable up to the limits of -1.4V and +1.1V and up to +1.2V.
Further changes and modifications may be made within the scope of this disclosure.
Appendix 1 Concepts
1. A symmetrical supercapacitor device, comprising:
Two electrodes, each comprising a carbon foam material; and
Hydrogel electrolytes encapsulate electrodes in their active regions.
2. The symmetrical supercapacitor device according to Concept 1, wherein the hydrogel electrolyte comprises a mixture of hydrogel and salt.
3. A symmetrical supercapacitor device according to Concept 1 or Concept 2, comprising an ion charge carrier.
4. The symmetrical supercapacitor device according to Concept 3, wherein the ion charge carrier is hydrated.
5. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam.
6. The symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam material.
7. A symmetrical supercapacitor device according to any one of concepts 1, 5 and 6, wherein the carbon foam material is formed on a substrate.
8. The symmetrical supercapacitor device according to Concept 7, wherein the substrate is a polyimide substrate.
9. The symmetrical supercapacitor device according to Concept 7 or Concept 8, wherein the substrate forms the substrate of the device.
10. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the symmetrical supercapacitor device is flexible.
11. A method for manufacturing a symmetrical supercapacitor device according to any one of concepts 1 to 10, wherein:
Electrodes are formed on the substrate;
An electrolyte precursor containing charge carriers and hydrogels is applied to the electrode;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the effective region.
12. A method for manufacturing a symmetrical supercapacitor device according to Concept 11, wherein the electrolyte precursor is prepared by preparing an aqueous solution of a charge carrier and by mixing the aqueous solution with a hydrogel.
13. A method for manufacturing a symmetrical supercapacitor device according to Concept 11 or Concept 12, wherein the electrodes are formed in situ.
14. A method of manufacturing a symmetrical supercapacitor device according to any one of claims 11 to 13, wherein the electrodes are formed by irradiating the substrate with laser radiation.
Appendix 2: Gii-Cap+ Hydrogel
In this Appendix 2 section, we demonstrate the effectiveness of Gii carbon foam as an ideal substrate on which pseudocapacitive materials can be deposited, resulting in a significantly enhanced capacitance compared to using Gii carbon foam as the sole electrode material. For the context, these carbon foam-only devices exhibit full-cell specific capacitance in the 0.25–0.4 mF/ cm² region.
Sample preparation
Electrodeposition was performed on A7-sized Gii-Caps to cast a layer of pseudocapacitive material on them. Both v4 and v5 designs were suitable for electrodeposition, yielding similar performance. Results for the v4 sample will be detailed in this document.
First, the sheet containing six Gii-Cap devices (2 rows, 3 columns) was cut in half to obtain two 3-device half-sheets. The two half-sheets were then mounted on internally fabricated fixtures and placed inside the MiniPlant 3 electrodeposition tank. MnOx was deposited on the sample first, followed by rinsing with deionized water, and then FexOy was deposited. After FexOy deposition, the sample was rinsed again and dried in air at 40°C for at least 2 hours.
The deposition details are as follows. The manganese oxide precursor solution contained a mixture of manganese acetate tetrahydrate (40 mM) and surfactant (Tween 20, 0.1 wt%). Deposition was performed using constant current pulses. The on-time was 0.5 seconds, and the off-time was 2 seconds. The applied on-time current was 744 mA (19.14 mA/ cm² , based on the nominal geometry of the electrode). The off-time was 0 mA, i.e., the circuit was open. A total of 390 cycles of MnOx deposition were performed (3.7 C/ cm² per electrode). The FexOy precursor solution contained 40 mM MFe-TEA complex (TEA is triethanolamine). It contained FeCl₃ , TEA, and NaOH. Deposition was also performed using constant current pulses. The on-time was 1 s, and the off-time was 2 s. The applied on-time current was 233 mA (6 mA/ cm² ), and the off-time was set to 0 mA. The deposition process was repeated 1,000 times, yielding 6 C/ cm² for each electrode.
After deposition and sample drying, the samples are divided into individual devices. A quasi-reference electrode (RE) containing screen-printed Ag/AgCl ink is fixed along one edge of the device outside the working area (used to monitor the potential of each electrode during testing). The electrolyte is then applied to the working area of the device and extends onto the RE. The electrolyte used is an aqueous hydrogel containing NaClO₄ as the salt and PVA (polyvinyl alcohol) as the gelling agent. The hydrogel stock solution contains 199.5 g NaClO₄ monohydrate, 256.9 ml deionized water, and 42.4 g PVA. The mixture is solid at room temperature and becomes liquid at temperatures close to the boiling point of water. To dispense the hydrogel, it is heated to 94°C to liquefy it. Dispensing is performed by dropping the liquid electrolyte onto the working area and the RE, typically 3–4 ml per device. The hydrogel on the sample is then allowed to cool and re-solidify after approximately 10 minutes. After solidification, an imide film is applied to the device to prevent excessive electrolyte evaporation. Once capped, the device is ready for testing.
Electrochemical test parameters
Electrochemical tests were performed on the samples using a Biologic VMP-3 voltage/current regulator. Initial performance characterization was performed, followed by 500 charge-discharge cycles (conditioning protocol) for final characterization. The reported nominal values are those obtained in the second characterization step. The conditioning protocol was applied to further stabilize and consistent the sample performance.
During testing, the voltage was controlled at the battery level (the absolute difference between the positive and negative electrodes), with a minimum of 0V and a maximum of 2V. The potential difference between each electrode and the common RE was also measured, allowing for the calculation of individual electrode performance metrics.
These two characterization steps are called the Ragone test. They are identical and include the following:
a) Cyclic voltammetry (CV). Three scan rates were used: 50, 100, and 250 mV/s. Five cycles were performed at each scan rate.
b) Galvanic charge-discharge (GCD). Seven current densities were tested: 1, 2.5, 5, 7.5, 10, 20, and 30 mA/ cm² (based on a total device geometry of 12.96 cm² ). Five cycles were performed at each current density.
c) Electrochemical impedance spectroscopy (EIS). Voltage controlled, using a 1V DC applied voltage and a 10mV AC signal. Measurements were taken in the 1MHz–10mHz region.
The adjustment process was achieved by performing 500 GCDs at 10 mA/ cm² .
The nominal capacitance value is calculated based on the GCD after adjustment at 5 mA/ cm² . The ESR (Equivalent Series Resistance) is calculated based on the voltage drop at the start of the discharge half-cycle in the GCD. The reported ESR value is also derived from the final GCD at 5 mA/ cm² . The ESR can also be calculated from the Nyquist plot obtained from EIS. The results are almost identical.
Results and Conclusions
Average values were calculated for a total of 48 devices. Samples from batches 3258 and 3259 were used. Typical CV curves are shown in Figure 66. The full-cell response (left panel) shows a quasi-rectangular shape, indicating that the storage mechanism is not purely capacitive. This is expected, as both MnOx and FexOy are redox-active materials. Most of the capacitance of the device is concentrated above the cell voltage of 0.5V, as can be seen from the small envelope of the full-cell curve in the 0–0.5V region. The explanation for the smaller capacitance at lower cell voltages can be seen in the half-cell curve, shown in the right panel of Figure 66. This figure shows that MnOx is used as the positive electrode, while FexOy is the negative electrode. MnOx is a near-ideal pseudocapacitive material, as evidenced by its roughly rectangular CV (grey trajectory).
Meanwhile, the FexOy electrode exhibits a more asymmetric response to potential. Its capacitance is largely concentrated below 0V vs Ag/AgCl. When the potential is greater than 0V vs Ag/AgCl, FexOy displays a very small capacitance, as shown by the small envelope of the blue trace at these potentials. Therefore, this asymmetric FexOy response explains the smaller capacitance obtained at low voltages in a full cell.
Figure 66 shows the post-adjustment CV curves obtained at 100 mV/s from sample 3258-1#4. The left panel shows the full-cell CV, while the right panel shows the half-cell curves obtained during the full-cell measurement.
GCD curves were used for capacitance calculations because they provide more accurate values. Typical adjusted GCD curves are shown in Figure 67, displaying measurements for both full and half cells. The device exhibits a good capacitance response with quasi-triangular curves. The full cell exhibits linear discharge from maximum voltage down to approximately 0.5V, indicating that the pseudocapacitance of MnOx and FexOy achieves near-ideal capacitance behavior. As seen in the CV curves, FexOy exhibits an asymmetric capacitance-potential relationship, which explains the faster discharge below 0.5V of the battery voltage.
Figure 67 shows the post-adjustment GCD curves obtained at 5 mA/ cm² from sample 3258-1#4. The full-cell and corresponding half-cell responses are shown in the top, middle, and bottom lines, respectively.
In addition to different pseudocapacitive behaviors relative to potential, the MnOx and FexOy electrodes also exhibit different levels of capacitance. Both electrodes occupy the same geometric area in the device, but the MnOx electrode experiences a much smaller electrochemical window within the device (see the difference between the maximum and minimum electrode potentials in Figures 66 and 67). The smaller MnOx window (0.65 ± 0.06 V) is due to its larger specific capacitance compared to FexOy (1.35 ± 0.06 V window). For the device evaluated in this study, the regulated capacitance of the MnOx electrode reached 246.8 ± 36.0 mF/ cm² , while the regulated capacitance of the FexOy electrode was 171.4 ± 38.4 mF/ cm² . Therefore, these Gii-Cap+ devices are symmetrical in terms of electrode size but asymmetrical in terms of electrode composition and potential split.
Since a full cell is essentially two capacitors connected in series (formed by a double layer between the electrodes and the electrolyte counterions), the total cell capacitance will be lower than the capacitance of a single electrode. The adjusted average full cell capacitance is 52.5 ± 9.4 mF/ cm² . At the same current density (64.8 mA, 5 mA/ cm² , cell level) as the reported nominal capacitance, the ESR calculated based on the voltage drop at the start of discharge is 0.85 ± 0.12 Ω.
EIS measurements further confirmed the good capacitive response of these devices, as shown in Figure 68. The ESR can be estimated by locating the intersection of the Nyquist plot with the y-axis. For the sample shown in Figure 68, the ESR calculated by EIS is 0.78 Ω, which matches very well with the 0.73 Ω calculated by GCD for the same sample. The Bode plot provides information about the device's behavior at different frequencies. At high frequencies, such as 100–10000 Hz, the device functions essentially like a resistor with a phase angle of 0°. As the frequency decreases, the phase angle increases, indicating a greater contribution from capacitance (the phase angle of an ideal capacitor is -90°). When the phase angle exceeds the 45° mark, the device is considered to be essentially capacitive. Therefore, the time when the 45° phase shift occurs can be considered the characteristic time constant of the device. For the sample in this study, the average time constant is 4.48 ± 1.18 seconds. This time constant can be interpreted as the cycle time threshold for an effective capacitive response. When the cycle time is below the time constant, the device will not operate fully.
Figure 68 shows the regulated Nyquist (left) and Bode (right) curves obtained by electrostatic EIS at 1V DC (full cell) for sample 3258-1#4. The inset in the left figure shows a magnified view of the high-frequency response.
Considering that devices using Gii as the sole electrode material exhibit a specific capacitance of 0.25–0.4 mF/ cm² , adding pseudocapacitive materials enhances the energy storage capacity of these Gii-Caps by more than 100 times. Furthermore, adding these metal oxides does not significantly increase the ESR of these devices, thus maintaining their usefulness in high-power applications. The electrodeposition process is controllable, allowing for the fabrication of cells with less deposited material and consequently less total capacity, if desired. The resulting devices are inherently asymmetric, with MnOx as the dominant positive electrode and FexOy as the negative electrode.
Appendix 3 GiiCap Ion Gel
Objective: To demonstrate the specific capacitance and electrochemical stability window (ESW) of an electrolyte formulation comprising a room-temperature molten salt 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) and fumed silica, referred to as Iongel, in conjunction with an A7 apparatus, conducted in a “low” humidity and “airless” argon atmosphere.
Experimental conditions:
All electrochemical tests were performed in a “3-electrode” setup, in which regular interdigitated A7 devices were fabricated, the area ratio of the “working” electrode to the “counter” electrode was 1:2, and a third quasi-reference electrode comprised of screen-printed AgCl ink was used to monitor the potential of each electrode during the tests.
The electrolyte Iongel was prepared and stored in an airless environment.
Before applying the electrolyte to the A7 device for testing, heat Iongel to 90°C and then distribute a thin, uniform layer onto the A7 using a doctor blade. Allow the electrolyte to cool before preparing the device for testing and connection. For airless devices, testing is performed in the same airless environment where the electrolyte was stored and distributed, with the device connected to the electrochemical testing instrument: a Biologic VMP-3 regulator.
For low humidity environments, move the device to a humidity-controlled room with a relative humidity set to 20%, and seal and connect it to the instrument.
For each humidity level, a series of maximum electrode potentials (Emax) (in volts (V)) close to the nominal literature value 1 of the net electrolyte were tested. They are:
Positive electrode: 2.0, 1.9, 1.8, 1.7, 1.6, 1.5
Negative electrode: -2.0, -1.9, -1.8, -1.7, -1.6.
For each combination of humidity and electrode potential, N=8 samples are prepared from scratch.
Electrochemical test parameters:
A standard protocol was used, with a test window of 0.0-Emax V vs OCV. OCV quantification was 0.25 V vs AgClQref.
The electrochemical testing was divided into three stages: a) Ragone characterization; b) long-term (LT) cycling; c) Ragone characterization (post-).
Ragone characterization before and after LT cycling included: OCV, 1 hour; cyclic voltammetry (CV), 5 cycles each at 100 and 1000 mV/s; galvanostatic charge-discharge (GCD), 10 cycles each at 5 and 10 mA/cm²; and potentioelectric impedance spectroscopy (PEIS), between 10 MHz and 0.01 Hz.
The LT cycle includes: CV, 5000 cycles at 750mV/s.
Electrochemical stability was determined by post-hoc visual analysis of electrode damage and electrolyte discoloration, as well as by assessment of changes in coulombic efficiency across LT cycles. Device performance was determined based on the specific capacitance via GCD after 5000 LT cycles.
in conclusion:
ESW was determined by plotting the coulombic efficiency of the LT CV cycle against the number of cycles. When the coulombic efficiency remained consistent throughout the 5000 cycles, the cycle Emax was determined to be stable under given environmental conditions. Based on this analysis, the Iongel-A7 device was found to be stable in air with a relative humidity of 20% at negative and positive electrode potentials of -1.6 and +1.6 V, respectively. In the absence of air, the positive and negative ESWs were determined to be -1.8 and +1.7 V, respectively.
Regarding performance evaluation, the specific capacitance of the device at 20% relative humidity and in an airless environment was found to be 2.11 and 1.60 mF/ cm² , respectively, under the positive electrode window conditions. The specific capacitance of the negative electrode window was 1.55 and 2.11 mF/ cm² , respectively, under 20% relative humidity and in an airless environment.
Figures 69, 70, and 71 show the relevant results.
Figures 72, 73, and 74 show other relevant results.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Target:
The feasibility of the project was demonstrated using reagents that are critical to the Gii-Sens 3D carbon foam analysis system.
Phase 1: Surface Fixation
Objective: To maximize mAb(2) surface immobilization. To evaluate the most convenient surface chemistry for immobilizing mAb onto a surface.
Deliverables: Data supporting maximum surface coverage and the selected procedure.
Phase 3: Target Analyzer Sensing Range and LOD
Objective: To establish the electrochemical immunoassay procedure and results. To develop the electrochemical immunoassay procedure (incubation time, concentration, volume) and to establish parameters that produce the most sensitive analytical assay.
Deliverables: Data supporting the performance of electroanalytical immunoassays.
Experimental Section
Solution composition
Surface Chemistry
10 mM pyrene butyric acid in DMF
4mM EDC/10mM SulfoNHS
PBS 0.1M pH 7.2
Read aloud
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 0.02 M KCl.
0.02M PBS
Sensor modification program
10 μL of PyrBuOOH was applied to the sensor surface and incubated in a humid chamber for 2 hours, after which the solvent was allowed to evaporate spontaneously.
15 μL EDC/NHS, for 30 min
10 μL of A1 or C1 mAb in PBS for 1 hour
Electrochemical technology
Electrochemical impedance
Applied voltage = 0V
Amplitude = 0.01VRMS
Frequency range -5000 to 0.1Hz
Measurement Procedure
Direct determination: Unmarked: See Figures 75 and 76.
Direct determination: label-free and reagent-free: see Figures 77 and 78.
Calibration curve
Repeat at each point, n=5 (minimum) different disposable sensors (single readout, sensor disposed of).
Each calibration curve contains data (inter- and intra-assay variability) obtained by different operators over the following days.
Phase 1: Surface Chemistry
According to the scheme in Figure 79, the selected surface chemistry is Pyr-COOH modified graphene and EDC/NHS conjugates that capture mAb (A1 and C1), and the figure shows a schematic diagram of the surface immobilization reaction.
The concentrations of surface-fixed mAbs (A1 and C1) were screened using electrochemical impedance spectroscopy. (See Experimental Section). See Figure 80 (mAb A1 fixation on the surface. Inset normalized signal) and Figure 81 (mAb C1 fixation on the surface. Inset normalized signal).
Both A1 and C1 showed a logical trend in surface coverage. Based on the normalized curves, A1 showed a slightly larger surface coverage. The optimal coverage range selected was between 15 and 250 μg/mL. This concentration range was estimated to be sufficient to provide optimal sensor performance.
Phase 3: Determination and Target Analyte Investigation
Further evaluation of the potential and benefits of using it as a sensing electrochemical platform has been conducted in label-free assay formats.
Simultaneously, a reagent-free formulation was also explored, where the solution used for incubation and generating the readout signal was simply a buffer solution, as described in the experimental section. The dynamic range of the assay was also investigated at high concentrations, and the potential to extend this concentration range is expected to be identified.
Due to the interesting results obtained during the investigation described above and the general time constraints, the assay sensitivity was explored down to 10 pg/mL, and the aim was to explore the high concentration range up to 1000 ng/mL.
Label-free assay investigation
Label-free assays, as previously described, include assays that do not require secondary antibodies but use specific electrochemical readout solutions. In this study, the electrochemical solution was also used as the carrier solution, thus eliminating the need for a washing step or any other assay complications.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 82, which shows the label-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
To further investigate how to enhance measurement performance, the overall concentration range was divided, and the same data were used to explore different sensitivity ranges.
Label-free and reagent-free assay investigation
As mentioned earlier, label-free assays include assays that do not require secondary antibodies. In the absence of reagents, there is also no need for an electrochemical readout solution, as all incubation and measurement are performed solely in a buffer solution, which also acts as a carrier solution, further eliminating the need for additional washing steps.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 83, which shows the label-free and reagent-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Materials via Connectors
background
Sensors are analytical devices that detect changes or reactions and respond to some input from the environment. In recent years, their use has increased significantly due to their advantages such as high specificity and sensitivity, rapid and reliable results, ease of processing, and immediate diagnostics. Because of these advantages, sensors have entered various technological fields, such as chemical and medical diagnostics, environmental impact analysis, the food industry, and the marine sector.
Different forms of graphene and its derivatives have been used in the production and development of sensors, particularly biosensors. Graphene's electrochemical, physical, and chemical properties make it a material of interest for these applications. However, conventional graphene (e.g., 2D graphene) is difficult to handle in practical applications due to its ultrathin structure and flexibility, which makes it prone to curling, creases, and wrinkles. This significantly reduces the analytical performance of sensors, especially their sensitivity. To date, numerous strategies and techniques have been implemented to fabricate different types of graphene (e.g., different morphologies, different surface properties, and different functionalized derivatives, such as graphene quantum dots, graphene oxide, or reduced graphene oxide), and these have led to differences in sensing performance between sensors.
E.A.Obaje, G.Cummins, H.Schulze, S.Mahmood, M.P.Y.Desmulliez and T.T.Bachmann, Journal of Interdisciplinary Nanomedicine, 2016; 0(0), doi:10.1002/jin2.16 investigated the electrochemical properties of a newly fabricated sensor in relation to the function of its underlying composite material, and evaluated the selection of carbon and dielectric pastes by characterizing properties such as surface roughness, wettability, and susceptibility to nonspecific DNA binding.
L.H. Hess, A. Lyuleeva, B.M. Blaschke, M. Sachsenhauser, M. Seifert and J.A. Garrido, ACS Appl. Materials & Interfaces, 2014, 6, 9705-9710, describe a platform for biosensing applications based on polymer-modified CVD-grown graphene transistors.
C. Fenzl, P. Nayak, T. Hirsch, O.S. Wolfbeis, H.N. Alshareef and A.J. Baeumner, ACSSensors, 2017, 2, 616-620 describe laser-scribed graphene (LSG) electrodes as highly sensitive and reliable biosensor transducers in serum analysis.
S. Singal, A.K. Srivastava, S. Dhakate, A.M. Biradar and Rajesh, RSC Advances, 2015, 5, 74994-75003 describes an electroactive graphene-multi-walled carbon nanotube hybrid-loaded impedance immunosensor for the detection of human cardiac troponin-I.
Despite the existence of all existing technologies, there remains a need to improve the sensing activity of graphene-based sensors. Furthermore, it is still desirable to improve the sensitivity of these sensors without compromising at least one of their other aspects, such as their robustness, stability, durability, ease of functionalization, and/or ease of manufacture.
Summary of features in Appendix 5
In a first aspect, a sensor is provided comprising: (i) a carbon foam electrode, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam electrode via the connector. The carbon foam electrode is manufactured at least in part by a method defined by any one of the features A-K above.
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, comprising the following steps in sequence: (i) providing a carbon foam electrode as described in the first aspect; (ii) treating the carbon foam electrode with a connector; and (iii) treating the connector-modified carbon foam electrode obtained in step (ii) with a receptor.
In a third aspect, a method for sensing a target is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
Carbon foam materials typically possess a folded structure, which gives them a porous morphology and high specific surface area. Without being bound by any theoretical constraints, it is believed that the analytical performance of a sensor is influenced by the morphology of the carbon foam and its available surface area. The 3D structure leads to an increased usable surface area, allowing connectors and receptors (such as enzymes, proteins, nucleic acids, and antibodies) to bind efficiently to the carbon foam, thereby improving sensor performance and sensitivity.
Furthermore, it is desirable to construct the sensor using a very thick carbon foam layer. Preferably, the carbon foam layer thickness is greater than 50 μm. Since carbon foam can be porous, such a thick carbon foam layer is expected to provide a larger surface area, which is beneficial for enhancing analytical performance, especially sensing properties, compared to other conventional graphene-based sensors.
connector
In the context of the features of this invention, carbon foam is modified with a connector as part of the process for forming the desired sensor. The carbon foam described above (e.g., a thick porous carbon foam with a folded structure) provides an improved basis for modification because the increased surface area can be used for interaction with the connector, resulting in improved sensor sensitivity.
The modified carbon foam is then treated with an acceptor to obtain a sensor. Therefore, the adapter acts as an intermediate between the carbon foam and the acceptor. It is possible that at least a portion of the adapter is disposed (e.g., dispensed) within the carbon foam. It is also possible that the entire adapter is disposed (e.g., dispensed) within the carbon foam.
The connector can be selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof. Typically, the connector is selected from polymers (e.g., (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
Typically, the organic compounds described above comprise one or more functional groups independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymers, or mixtures thereof, optionally combined with linear, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. In the same embodiments, the optional structure may be a C1-C20 straight-chain, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residue, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. Still in the same embodiments, optionally, the organic compound having the functional groups described above may also comprise one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly linked to at least one of the functional groups, or the connector is a derivative of an ester or salt of such organic compound, or a compound that releases such organic compound in a reaction with the desired 3D carbon foam. Representatively, the connector is selected from the organic compounds described above in this paragraph.
Typically, the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
The joint can be covalently or non-covalently bonded to the carbon foam. For example, a diazo compound (e.g., a diazonium salt) can be covalently bonded to the carbon foam. For non-covalent bonding, the joint can be bonded to the carbon foam through at least one of the following: π-π interactions, ionic bonding, hydrogen bonding, hydrophobic or hydrophilic effects, electrostatic interactions, polymer encapsulation, adsorption, and grafting (e.g., photografting). For example, a joint containing one or more cyclic moieties as described above (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof) can be bonded to the carbon foam through π-π interactions.
In the context of this feature, the acceptor is bonded to the carbon foam via a linker. Therefore, the acceptor is indirectly bonded. When at least a portion or preferably the entire linker is disposed (e.g., dispersed) within the carbon foam, at least a portion or the entire acceptor may also be disposed (e.g., dispersed) within the carbon foam.
In this document, "receptor" refers to any molecule capable of responding to a target material (i.e., the target) present in the sample to be analyzed. The sample can be biological, chemical, optical, physical, or mechanical, but is typically biological. Therefore, "target" encompasses, but is not limited to, biological materials, chemical substances or mixtures, optical objects, physical or mechanical articles, etc., typically biological materials. The term "response" can include, but is not limited to, biological, and/or chemical, and/or optical, and/or physical, and/or mechanical interactions, typically biological and/or chemical interactions. These typical interactions can include, but are not limited to, binding or hybridization between the receptor and the target, or hydrophobic effects.
Therefore, receptors can include, but are not limited to, one of the following: electrochemical receptors, chemical receptors, biological receptors, optical receptors, physical or mechanical receptors. Receptors can be selected from, but are not limited to, crown ethers, ligands, catalysts, boric acids, carbohydrates, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof.
Typically, the receptor is a biological receptor (i.e., the sensor is a biosensor). Receptors are typically selected from aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles, or other cellular components, or mixtures thereof. More typically, receptors are selected from proteins (e.g., immunoproteins, non-immune proteins, immunoglobulin-binding proteins, glycoproteins), nucleic acids, antibodies, enzymes (e.g., oxidoreductases (preferably glucose oxidase, alcohol oxidase, or lactate oxidase), dehydrogenases) or mixtures thereof. Representatively, receptors are selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or mixtures thereof.
Typically, the target is biological material. Biological material can include, but is not limited to, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, protein complexes, nucleic acids, antibodies, antigens, lipids, fatty acids, fatty acid esters, vitamins, microorganisms, micelles, cells, organelles, or other cellular components, viruses, enzymes, or mixtures thereof. Typically, biological material is selected from deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, nucleic acids, antibodies, antigens, enzymes, or mixtures thereof. More typically, biological material is selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof. It should also be understood that, in the context of this feature, both biological receptors and biological materials can be naturally occurring or synthetically produced.
Receptors can attach to linkers. Receptors can be bonded to linkers by physical, biological, and/or chemical means. Typically, receptors are chemically bonded to linkers. Hereinafter, chemical bonds can include, but are not limited to, covalent bonds, non-covalent bonds (e.g., ionic bonds), metallic bonds, hydrogen bonds, chelate bonds, and non-covalent interactions such as van der Waals forces, π-π interactions, hydrophobic or hydrophilic effects, and electrostatic interactions. Typically, receptors (e.g., biological receptors) are covalently bonded to linkers. Typically, receptors (e.g., biological receptors) are bonded (e.g., covalently) to one or more functional groups contained in the linker (e.g., functional groups of organic compounds as previously described). For example, biological receptors can be covalently bonded to the carboxyl, amino, amine, or amide group of the linker (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide).
sensor
Sensors according to this feature typically comprise a carbon foam layer, which can be produced by a previously disclosed dual-laser processing method. Typically, the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm. Typically, at least a portion or all of the connector is disposed (e.g., dispersed) within the carbon foam. Optionally, at least a portion or all of the receptor is also disposed (e.g., dispersed) within the carbon foam (i.e., when at least a portion or preferably all of the connector is disposed (e.g., dispersed) within the carbon foam). Typically, at least a portion of the connector and optionally a portion of the receptor are disposed (e.g., dispersed) at a depth below the surface of the carbon foam (e.g., the carbon foam layer), said depth being greater than 1% of the total depth of said carbon foam, preferably greater than 5% of the total depth, more preferably greater than 10%, even more preferably greater than 15%, and even more preferably greater than 20%. Typically, at least a portion of the connector and optionally at least a portion of the acceptor are disposed (e.g., dispersed) at a depth greater than 1 μm below the surface of the carbon foam (e.g., a carbon foam layer), preferably greater than 5 μm, more preferably greater than 10 μm, even more preferably greater than 15 μm, and most preferably greater than 20 μm below the carbon foam surface. The entire connector and optionally the entire acceptor can be disposed (e.g., dispersed) at a depth greater than 1% of the total depth of the carbon foam. The thickness of the carbon foam layer can be any range described above (e.g., at least greater than 50 μm). "Dispersed" herein means that the connector (optionally, and acceptor) molecules, at least partially disposed within the carbon foam, are distributed therein to form multiple discrete domains other than a single cluster. These domains can be uniformly and/or continuously distributed (e.g., distributed as a uniform and/or continuous layer) within the carbon foam. Without being bound by any theory, it is believed that the replacement of the connector (optionally, and the acceptor) leads to the improved functionalization of the carbon foam, thereby enhancing the sensor's sensing activity (i.e., sensitivity).
Furthermore, and optionally, neither the connectors nor the acceptors are disposed (e.g., dispersed) throughout the entire depth of the carbon foam (e.g., carbon foam layers). In other words, the core of the carbon foam is not modified with connectors or acceptors.
The adapter may be selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof, and the receptor may be selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin or a mixture thereof.
The sensor may also include a substrate. In a first method of obtaining carbon foam, if a carbon source is provided on or adjacent to the substrate, the final sensor may include the substrate as a component. In a second method requiring the use of a substrate, the final sensor may also include the substrate as a component. Regardless of the method by which it is obtained, the carbon foam may optionally be adhered to the substrate within the sensor. Thus, the substrate included in the sensor may have one of the characteristics described previously for substrates used in the production of carbon foam and/or one possible combination of these characteristics. Alternatively, the sensor need not include a substrate. In other words, even if the carbon foam is produced to adhere to the substrate, it may be removed from the substrate as part of preparation for subsequent modifications.
Typically, the sensors characteristic of the present invention are chemical, physical or mechanical, biological or optical sensors, preferably biosensors (i.e., when the receptor is a biological receptor). Typically, the sensor (e.g., a biosensor) takes the form of an electrode or electrode device. The sensor (e.g., a biosensor) may include a multi-electrode platform, for example, a three-electrode platform including a counter electrode (CE), a working electrode (WE), and a reference electrode (E or RE). The electrode (e.g., WE) may be made of modified carbon foam (i.e., carbon foam modified with a receptor via a connector) characteristic of the present invention. Other electrodes (e.g., CE and/or RE) may also be carbon foam-based, preferably carbon foam-based, and more preferably based on the same carbon foam without any modification. All electrodes may have the same or different dimensions.
Sensors (e.g., biosensors) may be supplied as products, wherein the sensors are housed within packaging, and the products preferably include instructions for use. Typically, the packaging includes a primary package in which the sensor is housed. The sensor may be provided on an adapter housed within the primary package. Suitable examples of primary packaging are caps, pockets, folders, envelopes, boxes, containers, cartons, housings, etc. Optionally, the packaging may also include secondary packaging. Such secondary packaging is typically packaging that holds one or more sensors together. Suitable examples of secondary packaging are plastic cartons, cardboard boxes, blister packs, boxes (e.g., cardboard or plastic boxes), housings, containers, cardboard or plastic crates, pallets, bundles with or without one or more air bags, etc. Still optionally, the packaging may include tertiary packaging, which may be selected from boxes, housings, cartons, containers, etc. Suitably, at least one of the above-described packages may protect the sensor from light (e.g., direct sunlight), moisture, physical and/or chemical damage and contamination. The instructions may provide detailed steps for using the sensor according to its features. Instructions may be provided in printed form as labels, brochures, manuals, or leaflets. Instructions may also be printed on product packaging.
Sensor manufacturing
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, wherein the steps include: (i) providing carbon foam; (ii) treating the carbon foam with a connector; and (iii) treating the connector-modified carbon foam with a receptor.
The method may include the step of manufacturing the carbon foam before providing and processing it with a connector. Thus, the carbon foam is produced by one of the laser processing methods disclosed herein, typically the first or second method, but more typically the first method. The carbon foam thus produced may be adhered to, attached to, or provided on a substrate. Typically, the carbon foam can be removed from the substrate before processing the connector in step (ii). In other words, the carbon foam in step (i) is provided without a substrate. Alternatively, it is not necessary to remove the carbon foam (e.g., the carbon foam remains adhered to the substrate). In other words, the carbon foam in step (i) is provided with a substrate.
The carbon foam can be incubated together with the adapter. Incubation can occur in a buffer solution, preferably a buffer solution. Additionally or optionally, adapter modification may require at least one of the following conditions: light (ultraviolet, visible, or infrared radiation) or heat. After incubation, the adapter-modified carbon foam can be washed.
The adapter-modified carbon foam can be incubated with the receptor. After incubation, the sensor thus obtained can be cleaned before use. After cleaning, the sensor may be passivated. Passivation is understood as blocking any remaining activation sites that have not been functionalized by the receptor.
The receptor is used to process the connector-modified carbon foam in step (iii).
The sensor can be an electrode or an electrode device including a multi-electrode platform. Therefore, the manufacturing steps described above can be applied to the manufacture of electrodes. When the sensor is an electrode device including a multi-electrode platform, the manufacturing steps described above are applicable to the production of the working electrode (WE), and the method further includes the additional steps of producing a counter electrode (CE) and a reference electrode (E or RE).
Use of sensors
In a third aspect, a method of using a sensor is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing a target; (iii) measuring the response of the sensor; and (iv) optionally, correlating the response with the level of the target in the sample.
The target can be the target disclosed herein, and is usually the biological material disclosed herein. The sample can be the sample disclosed herein, and is usually the biological sample disclosed herein.
Before use, the sensor (e.g., a biosensor) can be appropriately stored under ambient conditions (e.g., room temperature of approximately 20°C and 1 atmosphere). Typically, the sensor is stored under dry conditions. After use, the sensor can be properly disposed of (i.e., the sensor is a disposable sensor).
The sensor can be immersed in a sample. The sample may contain phosphate-buffered saline (PBS). The concentration of the target in the sample may be at least 1 ppm. The equilibration time may be at least 0.5 minutes, or at least 1 minute, or at least 10 minutes, or at least 30 minutes, typically not exceeding 2 hours, or not exceeding 1 hour, or not exceeding 40 minutes. The sensor can be cleaned after contact with the sample, and then the response can be measured. The sensor can be cleaned by rinsing with PBS. The sensor can be dried after cleaning (e.g., by airflow, or by natural drying).
The response can be measured using differential pulse voltammetry and/or impedance spectroscopy. The measured response may be further correlated with the target level in the sample. The method may include steps (i), (ii), and (iii) as described above, and additionally includes the following steps in sequence: (iv) contacting the sensor with one or more samples (i.e., control samples) containing a known level of the target; (v) measuring the sensor's response to one or more control samples; (vi) comparing the response to a sample containing or suspected of containing the target with the response to one or more control samples; and (vii) correlating the response to a sample containing or suspected of containing the target with the level of the target in the sample.
Appendix 5 Concepts
1. A sensor comprising: (i) a carbon foam, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam via the connector.
2. The sensor according to Concept 1, wherein the carbon foam is obtained by a method of generating carbon foam at at least one location within a carbon source by concentrating infrared radiation at that location, and the infrared radiation is provided by a laser beam, wherein the laser beam is an infrared laser beam.
3. The sensor according to Concept 2, wherein the concentrated infrared radiation includes diffraction of the infrared radiation to form an interference pattern, each fringe of the interference pattern being located within the carbon source.
4. The sensor according to Concept 2 or Concept 3, wherein the at least one position is laterally moved inside the carbon source and/or the at least one position is moved within the depth of the carbon source.
5. The sensor according to any one of Concepts 2 to 4, wherein the infrared radiation directly irradiates the carbon source, or the infrared radiation passes through a substrate before irradiating the carbon source, wherein the carbon source is disposed on the surface of the substrate or adjacent to the surface of the substrate.
6. The sensor according to any one of Concepts 2 to 5, wherein the carbon source is additionally irradiated with additional radiation, and the additional radiation is performed before, simultaneously with or after the step of focusing infrared radiation at at least one location within the carbon source.
7. The sensor according to Concept 6, wherein the additional radiation is rasterized on the surface of the carbon source.
8. The sensor according to Concept 6 or Concept 7, wherein the additional radiation directly irradiates the carbon source or passes through a substrate as described in Concept 5 before irradiating the carbon source.
9. The sensor according to any one of the foregoing concepts, wherein at least a portion of the connector is disposed (preferably dispersed) within the carbon foam; and optionally, at least a portion of the receptor is disposed (preferably dispersed) within the carbon foam.
10. The sensor according to any one of Concepts 2 to 9, wherein the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm.
11. The sensor according to Concept 1, wherein the carbon foam is obtained by providing a carbon source on or adjacent to a substrate surface and exposing at least a portion of the carbon source, comprising a carbon-containing material, and/or at least a portion of the substrate to a laser beam, thereby converting at least a portion of the carbon source into the carbon foam.
12. The sensor according to Concepts 5, 8 or 11, wherein the substrate comprises one or more of the following: silicone, silicon dioxide, gallium nitride, gallium arsenide, zinc oxide; or alternatively, one or more polymers; or alternatively, one or more metals selected from aluminum, copper, gold or other metals, or oxides, nitrides or arsenides of said metals.
13. The sensor according to any one of the foregoing concepts, wherein the carbon foam contains less than 3% oxygen, preferably less than 1.5% atomic percentage, and/or less than 3% nitrogen atomic percentage.
14. The sensor according to any one of the foregoing concepts, wherein the connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
15. The sensor according to Concept 14, wherein the connector is selected from polymers (preferably (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
16. The sensor according to Concept 15, wherein the one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, optionally in combination with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
17. The sensor according to Concept 16, wherein the organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of an ester or salt of the organic compound, or a compound that releases the organic compound in a reaction with the carbon foam.
18. The sensor according to Concept 17, wherein the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
19. The sensor according to Concept 17 or Concept 18, wherein the connector is bonded to the carbon foam via π-π interactions.
20. The sensor according to any one of the foregoing concepts, wherein the receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
21. The sensor of claim 20, wherein the receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof.
22. The sensor according to Concept 21, wherein the receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
23. The sensor according to any one of the foregoing concepts, wherein the receptor is bonded to the connector in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
24. A method of manufacturing a sensor according to any one of the foregoing concepts, comprising the following steps in sequence: (i) providing a carbon foam as described in any one of concepts 1 to 13, 19; (ii) treating the carbon foam with a connector as described in any one of concepts 1, 14 to 19, 23; and (iii) treating the connector-modified carbon foam obtained in step (ii) with a receptor as described in any one of concepts 1, 20 to 23.
25. A method for sensing a target, comprising the following steps in sequence: (i) providing a sensor according to any one of Concepts 1 to 23; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
It should also be noted that the sensor described in Appendix 5 may be the Gii-Sens carbon foam sensor described earlier in this specification.
Appendix 6 Baseline Experimental Conditions
1 mM potassium ferrocyanide/potassium ferrocyanide was used in 0.1 M strontium nitrate, with at least five replicates randomly selected. Cyclic voltammetry was performed at scan rates of 25 and 200 mV/s as a comparative technique. Various characteristics were investigated and conclusions were drawn to evaluate the performance of the differential electrode materials.
Electrochemical impedance spectroscopy was performed at the equilibrium potential with an amplitude of 5 mV and a frequency range of 0.1 to 100 kHz.
Use a built-in or external silver/silver chloride reference electrode for the sensor.
Gii Sens carbon foam compared to conventional graphene electrode materials
The Gii Sens carbon foam sensor was evaluated and compared with other commercially available graphene-based sensors. See Figure 84.
The recorded reduction and oxidation peak currents show a 25% increase in efficiency per unit geometry in terms of current density. This clearly reflects the larger usable electrochemical area offered by the Gii Sens 3D carbon foam. See Figure 85.
According to cyclic voltammetry, the assessment of reduction-oxidation peak separation can be interpreted as a measure of the surface's electronic redox response to voltage scans and its ability to efficiently perform rapid redox reactions. The study showed that the reduction-oxidation peak separation remained below 70 mV, and no increase in separation was observed from 25 to 200 mV/s.
Other graphene electrode surfaces showed significant voltage separation from reduction to oxidation, indicating low efficiency of the redox Faraday reaction and pronounced detrimental effects associated with faster scan rates. See Figure 86.
The charge transfer resistance values for different surfaces show a significant improvement for the GiiSens sensor surface. This demonstrates the great potential of GiiSens for achieving reliable impedance-based measurements with minimal background signal interference.
Gii Sens compared to other carbon-based materials
Carbon-based electrode materials are very common in electroanalytical applications. Carbon paste electrodes are a common material for screen-printed sensors. They are the most widely used electrode surfaces in practical, immediate applications due to their fabrication flexibility and affordability. At the other end of the spectrum are glassy carbon surfaces, which are expected to offer better performance, but their availability is limited by fabrication flexibility and affordability. See Figure 87.
The Gii Sens carbon foam exhibits performance comparable to pure glassy carbon materials in terms of available electrochemically active area, while increasing the usable area by 50% for a carbon paste electrode of the same size. See Figure 88.
The separation of reduction-oxidation peaks obtained from cyclic voltammetry initially revealed the poor performance of the carbon paste material, which is highly dependent on slow scan rates to achieve a relatively acceptable redox reaction on its surface. The Gii Sens response outperformed pure glassy carbon even at any scan rate, demonstrating its significant potential for manufacturing flexibility and superior performance. See Figure 89.
The measurement of surface charge transfer resistance highlights the enormous potential of Gii Sens as an impedance-based sensing surface superior to glassy carbon, and opens up areas previously unreachable by carbon paste electrode materials.
Gii Sens compared to screen printing gold
Screen-printed gold sensors possess two crucial properties that enable the sensor material to be used in practical electrochemical sensing applications: flexible fabrication processes and excellent electrochemical reactivity. Two commercially available screen-printed gold samples were evaluated. See Figure 90. Gii Sens carbon foam was demonstrated to possess these properties as well, while also being affordable.
Recorded reduction and oxidation peak currents show that the available electrochemically effective region per geometric unit area has increased by at least 20%. See Figure 91.
As expected, screen-printed gold showed the most responsive electrode surface material in the evaluation batch; however, Gii-Sens matching further improved this performance, especially at fast scan rates. See Figure 92.
Comparing the charge transfer resistance of the electrode surfaces of screen-printed gold and Gii Sens also highlights the great potential of Gii carbon foam materials; in all cases, it exhibits low resistivity-related values.
The comparison between Gii Sens and screen-printed gold aims to demonstrate the superiority of Gii Sens in terms of ease of manufacture and superior performance, while affordability and scalability are undoubtedly beneficial inherent features of the Gii Sens sensor.
in conclusion
The Gii Sens sensor outperforms any other carbon-based or even graphene-based sensor on the market. It even surpasses screen-printed gold surfaces, eliminating any concerns about the overall convenience of using Gii Sens surfaces as the ultimate electrochemical sensing platform. Gii Sens demonstrates for the first time the perfect choice of fabrication and scalable materials for electroanalysis applications, while maintaining peak performance, ensuring maximum sensitivity and flexibility for high-throughput and point-of-care diagnostic applications.
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
Target:
Optimization of surface immobilization of anti-human calcitonin (cAb)
Summary of Results
Select a surface NHS production method. Match existing standard manufacturing processes.
Optimal cAb surface coverage was achieved using 100 μg/ml cAb.
For standard bare sensors, the typical %CV is 7%. For all sensors shown in the experiments presented in this report, the %CV for a 100 μg/ml cAb coating was 10%.
Using a 100 μg/ml cAb coating, 2000 pg/ml Ag was successfully detected by direct determination. The %CV of the signal output was 10%.
Experimental Section
Solution composition
Surface Chemistry
NHS modification
pyreneNHS
Capture antibody (cAb):
Product Name: Antih PCT 4004SPTN-5
Antigen (Ag):
Product Name: Recombinant PCT Antigen
Echem Readout Solution
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 20 mM KCl.
cAb fixation solution
Anti-hPCT in 1×PBS (pH 7.2)
Antigen (Ag) detection solution
In 20 mM KCl, 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ + Ag
Electrochemical technology
Electrochemical impedance
Applied voltage: OCP
Amplitude: 0.01V RMS
Frequency range: 100000-0.1Hz
Cyclic voltammetry
Scan rate: 25mV/s
Initial potential: -0.3V
High potential: 0.6V
Low potential: -0.3V
Measurement Procedure
NHS fixed
10 mM Pyr NHS prepared in DMF.
10 μL was drop-coated onto the working electrode of each sensor.
Place the sensor in an airtight box and incubate it for 12 to 18 hours.
It was confirmed that PyrNHS/DMF had been fully evaporated from the surface.
cAb fixation procedure
Place the NHS GiiSens+ sensor on a flat surface.
10 μL of cAb was drop-coated onto the working electrode of each sensor.
Place the sensor in a sealed container and bathe it in water for 2 hours.
Remove the sensor and gently rinse off the solution with DI water, then gently dry it with a stream of N2 gas.
Measurement procedure: Direct measurement 1 - see Figure 93
1) cAb readout: Apply the electrochemical readout solution to the sensor surface, and then perform EIS measurement.
2) Solution removal: Remove the electrochemical readout solution from the sensor surface.
3) t'1 readout: Apply the electrochemical readout solution containing the antigen to the sensor surface, followed by EIS measurement. There is approximately 1 minute between solution addition and measurement.
4) Read t'2 and perform EIS measurement. There is approximately 6 minutes between adding the solution and the measurement.
5) Read t'3 and perform EIS measurement. There is approximately 11 minutes between adding the solution and the measurement.
See the appendix for the electrochemical reading procedure.
1. Characterization curve graph
Each point is sampled repeatedly, with n = 5 (minimum) different disposable sensors (single readout, sensor is disposed of).
Phase 1: Surface Chemistry
The chosen surface chemistry is NHS-modified carbon foam, followed by conjugation of cAbs via amide bond formation. See Figure 94: Schematic diagram of the surface fixation reaction.
NHS generation on the carbon foam surface was monitored using electrochemical impedance spectroscopy and cyclic voltammetry. See Figure 95: Rct and ΔEp signal responses of the electrode for NHS functionalization.
The increases in Rct and ΔEp relative to the bare electrode confirm the NHS functionalization of the carbon foam electrode.
A range of cAb concentrations between 50 and 800 μg/ml were screened using electrochemical impedance spectroscopy. See Figure 96: cAb immobilization on the electrode.
For immobilization on the NHS-modified sensor, a logical increase in Rct was observed with increasing cAb concentration. The optimal coverage on the NHS electrode was estimated to be 100 μg/ml cAb, a concentration that provided the best sensor performance without wasting material for minimal gain. Excellent reproducibility (%CV 3%) was observed at this concentration.
Phase 2: Electrochemical Signals
The generated electrochemical signals were evaluated for direct assay, meaning that secondary antibodies are not required to assist antigen detection.
An antigen concentration of 2000 pg/ml was selected for the direct assay study. Based on the results of Phase 1 of this report, the surface antibody coating was fixed at 100 μg/ml. The Ag-Ab incubation time was selected as the initial assay parameter for the study. See Figure 97: Signal response from 2000 pg/ml in the direct assay using a 100 μg/ml cAb surface coating.
The 100 μg/ml cAb again showed a good level of reproducibility (%CV 8%). The difference in mean Rct between cAbs was significant, yielding different quantifiable signal outputs (ΔRct). The ΔRct signal output also showed an acceptable level of reproducibility, with %CV ≥ 10% at each readout time. The stability of the output signal between 1, 6, and 11 m indicated no additional Ab-Ag interactions after the first measurement. The 5-minute time interval between measurements is attributed to the time length required for EIS measurements. For 2000 pg/ml Ag samples, the optimal assay incubation time is as low as 1 minute.
Table 9: Key experimental and electrochemical parameters for cAb fixation
Table 10: Key experimental and electrochemical parameters for Ag detection
Appendix 8:
Combined list of features and optional features
Appendix 8 is a combined list of features and optional features. It should be noted that each of any one or more features A-R can be combined with one or more other compatible features A-R, as well as with any one or more optional features.
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene materials adhered to a substrate
Group 2: Dual-laser processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual Laser
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device: supercapacitor
Features M2: Details of Carbon Foam Supercapacitor
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate a subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the subsurface region.
An apparatus comprising a laser-induced carbon foam material produced by irradiating a subsurface region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an encapsulation region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the encapsulation region.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulation region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
A laser-induced carbon foam material is manufactured by means of a laser beam configured to irradiate an encapsulated, subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to a substrate
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between the graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between a graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing graphene material includes the following steps: (a) irradiating an encapsulation region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulation region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove at least some of the disordered amorphous non-graphene material and expose at least some of the carbon foam.
A laser-induced carbon foam is made by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
An apparatus comprising laser-induced carbon foam prepared by:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers operating in different frequency bands
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating a region of the carbon precursor material, below the surface of the material or a region below the surface of the material, with a laser beam operating in a first wavelength band to generate carbon foam in the region of encapsulation or the region below the surface, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
A laser-induced carbon foam material, which is made by the following:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of the carbon precursor material below the surface of the material using a laser beam operating in a first wavelength band, to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is carried out in one manufacturing facility, and step (b) is carried out in a different facility.
Feature L1: Biosensor
A method for manufacturing a biosensor, the biosensor comprising a sensing electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
A biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes a biosensor with sensing electrodes comprising carbon foam made at least in part by a method as defined in any one of features A-K above.
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric material to at least partially cover the electrodes and connection traces.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam made by a method defined as any one of features A-K above, and said biosensor includes (i) a screen-printed electrical connection trace over each electrode and (ii) a screen-printed dielectric that at least partially covers the electrodes and the connection trace.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and said method comprising an additional step of adding functionalized groups to at least the working electrode in a different manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam manufactured at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups added to at least the working electrode at different manufacturing facilities.
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least a portion of a carbon foam produced at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups that have been added to at least the working electrode at the same manufacturing facility.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon produced by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on a carbon precursor substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon layer, the electrical connection trace, and the reference electrode; and then (d) producing a carbon foam sensor electrode using a method as defined in any one of features A-K above.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, wherein the biosensor includes (a) a carbon layer screen-printed on a carbon precursor substrate; (b) screen-printed electrical connection traces and a screen-printed reference electrode; (c) a dielectric layer screen-printed over the carbon layer, the electrical connection traces, and the reference electrode; and (d) a carbon foam sensor electrode fabricated using a process as defined in any one of features A-K above.
Feature M1: Energy storage device
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
The method includes the steps of screen printing electrical connection traces over at least a portion of each electrode and screen printing a dielectric layer to at least partially cover the electrodes and connection traces.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Includes a screen-printed electrical connection trace formed above at least a portion of each electrode and a screen-printed dielectric layer that at least partially covers the electrode and the connection trace.
Feature M3: Carbon foam supercapacitor: common collector electrode
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
The method includes the step of screen printing electrical connection traces over at least a portion of each electrode, wherein a single electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrodes comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) a screen-printed electrical connector on a substrate; (b) a screen-printed carbon layer above the current collector; (c) a screen-printed dielectric over at least some of the carbon layer; and then (d) a carbon foam energy storage electrode produced at least in part by a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Supercapacitor: Metal Oxide Variant
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of electrochemically depositing a pseudocapacitive material, such as a metal oxide, onto the energy storage electrode.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) a pseudocapacitive material, such as a metal oxide, applied to said energy storage electrode.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel electrolyte in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) an ion-gel electrolyte having been applied in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in said environment are measured and controlled to optimize the capacitance of said energy storage device.
Feature N1: Electrical conductor
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
A method for manufacturing a smart tag includes the steps of combining or integrating a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as described in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor.
A method of manufacturing an integrated device includes the step of combining or integrating an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above.
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode formed at least partially in a layer below the sample orifice by means of a carbon precursor film formed by any one of the features A-K above, and a reference electrode connector, a working electrode connector, and a counter electrode connector in the layer below the reference electrode, the working electrode, and the counter electrode.
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
A method for manufacturing a lab-on-a-chip device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a conductive layer over the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) Screen printing a dielectric layer above the current collector layer;
(vi) The sensor electrode comprising carbon foam material is prepared from the carbon precursor film by at least part of the method defined in any one of features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Feature P: Scalable manufacturing of carbon foam: Gii 3
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other carbon foam applications
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, tactile sensors for robots; prototype sensors that use polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as an active layer in a piezoresistive pressure sensor for robotic touch sensing applications.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection.
Continuous monitoring of chemical sensors.
Glucose monitoring sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competing for binding with polynordihydroguaiaric acid.
Lactic acid sensor: Employs synthetic organic acceptor molecules based on attaching boric acid to carbon foam to provide functionality and selectivity in competitive analyte binding, using surface redox polymer indicator displacement.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1).
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material produced at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a prominent D peak; a 2D peak smaller than the G peak; and a D peak:G peak ratio greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Optional features
It should be noted that each of the following optional features can be combined with one or more other compatible optional features and with any one or more of the main features A-R.
Manufacturing process
The manufacturing process is a room temperature process.
The manufacturing process is an atmospheric pressure process.
It can be done on a plastic substrate (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
The manufacturing process requires approximately 2 minutes or less to create a 1 cm² carbon foam, which is about 50 μm thick, on a plastic substrate.
The manufacturing process enables the formation of 3D carbon foam on a flexible substrate.
The manufacturing process does not require graphene or graphene oxide precursors.
The manufacturing process generates carbon foam material only in the encapsulation and subsurface region of the carbon precursor material, and does not generate carbon foam material on any surface of the carbon precursor material.
The manufacturing process utilizes a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
The manufacturing process described herein is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
First laser beam parameters and control scheme
The first laser beam and the second laser beam are generated by different laser systems.
The first laser beam and the second laser beam are generated by the same laser system.
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface region or encapsulation region to form carbon foam.
• The laser beam generates temperatures exceeding 500°C in the subsurface region or encapsulated region to form carbon foam.
• The pulse duration of the laser beam is between 1 ns and 10 μs, resulting in a heating rate between approximately 5 × 10 7 ℃/s and 2 × 10 12 ℃/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between 50kHz and 500kHz.
• The laser pulse frequency is between 1 kHz and 2 MHz.
• The laser wavelength is between 0.7μm and 2.5μm.
• The laser is scanned at a speed between 9 cm/s and 40 cm/s (or ±50% of these ranges).
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The focal point of the laser beam is moved through a depth of at least 100 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scan can achieve a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm in size).
• The wavelength of the laser beam is not absorbed by the carbon precursor material, or the absorption rate is extremely low.
• Carbon precursor materials have extremely low absorption rates for the wavelengths of laser beams.
The radiation absorptivity per centimeter (decimal) is less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between 0.7μm and 2.5μm.
The laser beam is an IR laser with a wavelength between 0.75μm and 1.40μm.
Properties of the subsurface region or packaged region
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region is at least 10 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 20 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 30 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 40 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 50 μm below the surface of the carbon precursor material.
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
• The thickness of the subsurface region or encapsulation region is between 10 μm and 200 μm.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity or other laser parameters, and the selection of the carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, or more below the surface of the carbon precursor material.
• The distance between the subsurface region or encapsulation region and the surface of the carbon precursor material is at least 1% of the total thickness of the carbon precursor material, or at least 10% of the total thickness of the carbon precursor material, or at least 20% of the total thickness of the carbon precursor material, or at least 30% of the total thickness of the carbon precursor material, or at least 40% of the total thickness of the carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the center of the minimum cross-section of the first laser beam, and the volume is within 500 micrometers, 100 micrometers, or 1 micrometer of the center.
carbon precursor materials
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300 ± 50 cm⁻¹.
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of the laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
Substrate supporting carbon precursor materials
• The substrate is a plastic body, film, or foil.
• The substrate is flexible.
The substrate is a polyimide circuit board.
• The substrate has an extremely low absorption rate of the first laser beam.
• The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
• The substrate is formed of one or more of the following: silicon (Si), silicon dioxide (SiO 2 ), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing both silicon and silicon dioxide.
• The substrate is a carbon source.
• The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
• The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
• The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam.
• The thickness of the disordered, amorphous, non-graphene material occupying the surface of the adjacent carbon precursor material is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
• The disordered, amorphous, non-graphene material extends from its surface into the carbon precursor material matrix by at least 10 μm.
• The disordered, amorphous, non-graphene material extends from its outer surface into the body of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
Carbonization at the physical interface with the substrate supporting the carbon precursor material
• The carbon precursor material is transformed into a disordered, amorphous, non-graphene material at the physical interface with the substrate by the laser beam to a depth defined by the parameters of the laser beam.
The disordered, amorphous, non-graphene material adheres or otherwise attaches to one region of the carbon foam and to another region of the substrate, thus providing stability to the carbon foam.
• The thickness occupied by the disordered amorphous non-graphene material, as measured from the interface between the carbon precursor material and the substrate, is about 1%, less than about 1%, less than about 5%, or less than about 10% of the total thickness of the carbon precursor material.
• The thickness of the disordered, amorphous, non-graphene material occupying the interface between the carbon precursor material and the substrate is at least 10 μm.
• The disordered, amorphous, non-graphene material extends from the interface between the carbon precursor material and the substrate to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
ablation laser beam or second laser beam
The parameters of the laser beam include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the region below the surface or in the encapsulation region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
• A second laser beam alters the carbon foam as part of the process that exposes it.
• A second laser beam alters the shape of the carbon foam as part of the process that exposes it.
• The second laser beam is automatically controlled to scan in the same area, and/or overlapping area, and/or non-overlapping area.
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
• The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
• The carbon precursor material has an absorption coefficient for the second laser beam greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300± 50cm⁻¹ .
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The second laser beam scans in a pattern (e.g., a grating) that includes non-overlapping areas or lines.
• The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
• The second laser beam is the same as the laser beam that irradiates the encapsulation area or subsurface area of the carbon precursor material to generate carbon foam in the encapsulation area or subsurface area.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam
• The carbon foam is a multi-layered twisted or disordered carbon foam.
• The carbon foam is non-graphene carbon foam.
• Carbon foam includes carbon nanostructures such as carbon nano-onions, carbon nano-horns, carbon nanotubes, carbon nanodots, nanodiamonds and fullerenes, or any combination thereof.
• The thickness of the carbon foam is at least about 50 μm.
• The thickness of the carbon foam is between approximately 50 μm and 300 μm.
• Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
• Carbon foam is or includes carbon foam with a spatial distribution of defects that lead to high electrochemical reactivity.
• Carbon foam is or includes carbon foam with basal surface defects at vacant sites that lead to high electrochemical reactivity.
• The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Compared to conventional graphene foams produced using conventional laser processes, carbon foams possess one or more of the following properties: easier control over thickness or depth; greater flexibility compared to the highly brittle graphene produced using conventional laser processes; stronger adhesion to underlying flexible substrates; higher porosity; higher electrical conductivity; increased capacitance or charge storage; faster absorption of organic solvents and water-based solutions; higher hydrophilicity; contact angle less than approximately 20°; enhanced antifouling properties; higher EMI shielding; and improved electrode quality.
Biosensor Use Cases
• Carbon foam has been functionalized as a biosensor.
• Carbon foams are functionalized into biosensors by adding receptors that are specific to the target or analyte.
• Carbon foam has been functionalized into a biosensor with a reversible polymer displacement sensor mechanism for use in
Electrochemical glucose monitoring.
The reversible polymer displacement sensor includes a pyrene-derived boric acid chemical acceptor for glucose adsorbed onto an electrode comprising the carbon foam.
Carbon foams are functionalized as biosensors by adding receptors that are specific to a target or analyte and connectors that enable the receptors to attach to the carbon foam.
The connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
The connector is selected from polymers (preferably (meth)acrylate polymers), organic compounds containing one or more functional groups, carbodiimides, diazo compounds, or mixtures thereof.
• The one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, and optionally combined with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
The organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of the organic compound as an ester or salt, or a compound that releases the organic compound in a reaction with the carbon foam.
• The connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof.
The joint is bonded to the carbon foam via π-π interactions.
The receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
The receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes or mixtures thereof.
• The receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
The receptor is bonded to the adapter in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
Supercapacitor Use Cases
The carbon foam forms electrodes in an energy storage device, such as an electrochemical capacitor, supercapacitor, pseudocapacitor, or capacitor.
The carbon foam is treated with a metal oxide film to provide pseudocapacitance.
The carbon foam forms at least one electrode in the energy storage device, such as an electrochemical energy storage device.
A capacitor, supercapacitor, pseudocapacitor, or capacitor, and a hydrogel electrolyte encapsulates the electrode or each electrode in the active region to produce an enhanced operating voltage window.
The carbon foam forms the electrodes in the battery.
The carbon foam forms an electrical conductor.
Technical Field
This invention relates to laser-induced production of carbon nanostructures, including multilayer carbon foams with disordered layer twisting.
Background Technology
Carbon nanostructures are both highly attractive and a hot research topic. Carbon nano-onions (also known as multilayer fullerenes) exemplify this. See “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9 and “Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications”, DOI:10.1016/j.ica.2017.07.021, the contents of which are incorporated herein by reference.
As another carbon nanostructure, graphene has attracted widespread attention for many years due to its applications in biosensors, electrochemical sensing systems, supercapacitors, electrodes, and fuel cells. Known methods for producing 3D graphene include laser-induced graphene production as described in WO2019/038558; 3D graphene is formed on the surface of the exposed polyimide film when a suitable carbon precursor material (such as a polyimide film) is positioned on a supporting substrate and irradiated with a CO2 laser. Experience has shown that the thickness of 3D graphene produced by this method is less than 50 μm; furthermore, 3D graphene itself can be brittle and has poor adhesion to the underlying substrate, thus potentially peeling off. Therefore, 3D graphene is not suitable for many applications.
A note on terminology used in the field of carbon nanostructures: If we use only the term "graphene," there are many different forms of "graphene"; for example, the literature describes monolayer graphene, bilayer graphene, disordered graphene, graphene superlattices, graphene fibers, 3D graphene, graphene aerogels, wrinkled graphene, and many other forms. This presents a defining challenge, as using a specific term (e.g., "3D graphene") may imply limitation to only that specific form of graphene. Furthermore, IUPAC (International Union for Pure and Applied Chemistry) recommends using the name "graphite" for three-dimensional materials, and "graphene" only when discussing the reactions, structural relationships, or other properties of individual layers.
Therefore, in this specification, we use the term "carbon foam" as a general term, and this term should be broadly interpreted to cover any carbon nanostructure, such as 3D carbon material foam, including multilayer 3D carbon material foam with disordered layer twisting.
An example of the term "carbon foam" refers to a material manufactured using the methods described in this specification; such a material has slightly different properties from conventional graphene or conventional graphene foam. For example, graphene foam has several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature: the absence of a D peak; a 2D peak higher than the G peak; and a D peak:G peak ratio close to zero. As we will describe in more detail below, the carbon foam produced in specific embodiments of the invention does not possess these characteristics; it is hydrophilic with a contact angle less than 20°; it lacks the Raman signature indicative of graphene: it exhibits a prominent D peak; a 2D peak significantly smaller than the G peak; and a D peak:G peak ratio significantly higher than zero. In terms of appearance and Raman signature, it appears to be closer to carbon nanotube onion materials. Therefore, the term "carbon foam" in its scope also includes materials that are carbon nanostructures, such as carbon nanotube onions, carbon nanohorns, carbon nanotubes, carbon nanodots, nanodiamonds, and fullerenes, or any combination thereof.
Summary of the Invention
In this specification, we describe a method in which the surface of a carbon precursor is not converted into graphene at all; instead, the region beneath the surface of the carbon precursor, or the encapsulated region, is converted into carbon foam by a focused laser beam.
We summarize the invention as described in claim 1, namely a method for manufacturing carbon foam material, which includes the following steps:
(a) Using a first laser beam, an encapsulated or sub-surface region of the carbon precursor material is irradiated below the surface of the material to generate carbon foam in the sub-surface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Using a second laser beam to remove or ablate the disordered amorphous non-graphene material located above the carbon foam to expose at least some of the carbon foam.
The amorphous non-graphene material is positioned "above" the carbon foam because it is closer to the laser beam that generates the laser. One embodiment of the invention is described as a "dual-laser" process because two separate lasers are used in the production of the carbon foam material. The carbon foam material exhibits a significant D peak; the 2D peak is significantly smaller than the G peak; and the D peak:G peak ratio is significantly higher than zero. In terms of appearance and Raman signature, it appears more similar to carbon nanotube onion material. It can be used in biosensors, supercapacitors, and pseudocapacitors. In one embodiment, the carbon foam is referred to as "Gii" carbon foam.
Attached Figure Description
The invention will be described with reference to specific embodiments shown in the following figures.
Figures 1-6 schematically illustrate a dual-laser process for generating carbon foam when a polyimide (PI) film (which acts as a carbon precursor) is positioned on a substrate.
Figure 7 is a scanning electron image showing the unique surface morphology (x250) of carbon foam achieved using a dual-laser method.
Figure 8 is a scanning electron image showing the surface of conventional laser-induced graphene.
Figures 9-14B schematically illustrate a dual-laser process for generating carbon foam when the PI film (which acts as a carbon precursor) is not positioned on the substrate.
Figure 15 shows the cyclic voltammetry (CV) diagram of a carbon foam electrode produced using a dual-laser method.
Figure 16A is a graph showing the peak separation ΔE<sub>p</sub> of a carbon foam electrode produced using a dual-laser method as a function of the scan rate.
Figure 16B is a graph showing the peak separation ΔE<sub>p</sub> of a conventionally manufactured graphene electrode as a function of the scan rate.
Figure 17 compares the electrochemical impedance spectroscopy results of carbon foam electrodes produced using the dual-laser method with those of conventionally manufactured graphene electrodes.
Figures 18A and 18B show Raman analysis of carbon foam samples prepared using a dual-laser process.
Figure 18C shows the Raman analysis of carbon nanotube onion material.
Figure 19 is a scanning electron image showing dual-laser carbon foam and conventional graphene.
Figure 20 is a schematic image of a biosensor that includes dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Sens).
Figures 21-23 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Sens, Gii-Sens+, and PPC Gii-Sens variants).
Figures 24-27 are schematic images of a supercapacitor including dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Cap).
Figures 28 and 29 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Cap and Gii-Cap+ variants).
Figure 30 is a schematic cross-section of an integrated lab-on-a-chip (LoC) device that includes a biosensor and a supercapacitor made using dual-laser carbon foam.
Figure 31 is an exploded view of a fully integrated LoC device.
Figure 32 shows the LoC device displaying quantitative results on its monitor.
Figure 33 is an exploded view of an environmental monitoring device including the Gii-Sens sensor.
Figure 34 is a view of the assembled environmental monitoring device.
Figure 35 is a schematic cross-section of a device having a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 36 is a schematic diagram of a smart tag; it has a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 37 is a schematic cross-section showing the basic layering of different materials in the Gii-Thru variant, which is a three-dimensional structure of carbon foam.
Figures 38-42 are schematic diagrams of various Gii-Thru Gii-Cap/Gii-Cap+ three-dimensional supercapacitor devices.
Figures 43A and 43B are detailed process flow diagrams of the dual-laser carbon foam Gii-Thru Cap three-dimensional supercapacitor device.
Figures 44A and 44B are schematic diagrams of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device.
Figures 45A and 45B are schematic diagrams of the Gii-Thru sensor used in an eight-sample array microfluidic diagnostic device.
Figure 46A shows a perspective view of a fully assembled multi-sample array microfluidic diagnostic device.
Figure 46B is a top view of a multi-sample array microfluidic diagnostic device.
Figures 47 and 48 are views of a microfluidic diagnostic device.
Figure 49 shows the detailed manufacturing process of the high-sensitivity, low-cost Gii-Thru variant.
Figure 50 is a schematic diagram of a high-speed roll-to-roll or roll-to-sheet manufacturing system for Gii carbon foam.
Figure 51 shows the detailed process flow of the system in Figure 50.
Figures 52-57A show scanning electron images of dual-laser carbon foam at different magnifications.
Figure 57B is a scanning electron image of carbon nanotube onion material produced using conventional processes.
Figure 58 shows the Raman displacements of eight carbon foam sheets fabricated using a dual-laser process.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Figure 59 shows the carbon foam cyclic voltammogram measured at 25 mV/s for the anode voltage.
Figure 60 shows the carbon foam cyclic voltammogram for cathode voltage measured at 25 mV/s.
Figure 61 shows the galvanostatic charge-discharge (GCD) curves of carbon foam measured at 0.5 mA/ cm² for the anode voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves for the cathode voltage window, measured at 0.5 mA/ cm² .
Figure 63 shows carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 shows carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 shows carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 2: Gii-Cap+ Hydrogel
Figure 66 shows a typical CV curve for the Gii-Cap+ hydrogel device.
Figure 67 shows a typical GCD curve of the adjusted Gii-Cap+ hydrogel device.
Figure 68 shows the post-adjustment Nyquist (left) and Bode (right) curves of the Gii-Cap+ device.
Appendix 3 GiiCap Ion Gel
Figures 69-74 show the results of the GiiCap ionogel apparatus.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Figures 75-78 are schematic diagrams of the measurement procedure of the Gii-Sens 3D carbon foam measurement system.
Figures 79-81 show the surface chemistry of Gii-Sens 3D carbon foam.
Figures 82-83 show the label-free assay of Gii-Sens 3D carbon foam.
Appendix 6 Baseline Experimental Conditions
Figures 84-86 are graphs comparing the performance of Gii-Sens carbon foam and graphene electrode materials.
Figures 87-89 are graphs comparing the performance of Gii-Sens carbon foam and carbon-based electrode materials.
Figures 90-92 are graphs comparing the performance of Gii-Sens carbon foam and screen-printed gold.
Appendix 7: Optimization of surface immobilization of anti-human calcitonin (cAb)
Figure 93 shows an optimized direct assay procedure for surface immobilization of anti-human calcitonin (cAb).
Figure 94 is a schematic diagram of the surface fixation reaction.
Figure 95 shows the Rct and ΔEp signal responses of the Gii-Sens electrode with NHS functionalization.
Figure 96 shows cAb fixation on the GiiSens electrode.
Figure 97 shows the signal response from 2000 pg/ml in the direct determination form using a 100 μg/ml cAb surface coating.
It should be noted that Gii, Gii-Sens, Gii-Sens+, Gii-Cap, Gii-Cap+, Gii-Thru, and PPC Gii are trademarks of their respective owners. "Gii" generally refers to carbon foam produced using a dual-laser process. "Gii-Sens" refers to Gii carbon foam used in sensors (such as biosensors). "Gii-Cap" refers to Gii carbon foam used in supercapacitors. The "+" suffix indicates Gii carbon foam modified with a metal oxide layer or film. "Gii-Thru" refers to Gii carbon foam arranged in a specific three-dimensional structure. "PPC" refers to a specific manufacturing process, namely "post-printing conversion," in which Gii carbon foam is produced after various screen printing steps have been completed.
Figure Labels
Dual laser process
11 IR laser
12 IR laser beams
13. The interior of the PI film
14 PI film
15 substrate
16 Subsurface carbon foam region
17. Disordered amorphous non-graphene materials beneath the surface carbon foam region
18. Extended regions of disordered, amorphous, non-graphene material above the subsurface carbon foam region.
20CO2 laser
21 Unique surface morphology of exposed carbon foam regions
Biosensors
201 Polyimide substrate
202 Carbon Foam Working Electrode
203 Carbon foam counter electrode
204 carbon foam reference electrode
205 Screen Printed Silver Connecting Track
206 Dielectric Layer
The area where the 207 silver connection trajectory overlaps with the electrode
Gii-Cap Supercapacitor
Array of 241 carbon foam electrodes
242 Silkscreen Printed Silver Connector
243 Dielectric layer
244 Polyimide base layer
245 copper connector
246 Electrolyte layer
247 Aluminum Laminated Heat-Sealing Bag
250 carbon foam digits with rounded edges
Combined sensors and supercapacitors
301 Upper polyimide layer
302 Gii-Sens Biosensor
303 Lower polyimide layer
304 Supercapacitor
305 plastic parts
306 Microchannel
307 Connector Track
308 Flexible Electronic Devices
310 Induction Power Circuit
312 Gii-Cap Supercapacitor
313 Gii-Sens Biosensor
314 Device layer with microelectronic devices
315 Top Panel
316 monitor
317 Circular Analyte Well
Environmental monitors
330 Gii-Sens Carbon Foam Sensor
331 Control Electronic Devices
332 PV solar cells
333 Gii-Cap carbon foam supercapacitor
334 Peelable back
Combined supercapacitor and battery
351 First polyimide layer
352 Supercapacitor
353 Second polyimide layer
354 battery
355BMS (Battery Management System)
356 Flexible electronic devices
357 Electrical connectors
Smart Tags
360 Flexible Battery
361 Supercapacitor
362 Electronic Components Module
363 Exposed label surface; 364 Adhesive release liner; 364 Gii-Thru Cap
371PI membrane
372 Screen printing conductive ink or paste layer
373 Screen-printed collector
374 Dielectric Isolator
375 Encapsulated carbon foam layer; 376 Disordered, amorphous, non-graphene layer beneath the carbon foam layer; 377 Unique surface morphology layer.
390 Hydrogel Electrolyte Layer
391 Carbon foam layer with unique surface morphology
392 PI film
393 Screen Printing Carbon Paste Layer
394 Screen-printed silver connector layer
395 silver connector layer ketone insert
396 Distributed dielectric isolation layer
397 Second carbon foam layer with unique surface morphology
398 PI film
399 Hydrogel Electrolyte Layer
400 dielectric isolation layer
401 screen-printed silver current collector layer
402 copper insert
403 Screen Printing Carbon Paste Layer
404 carbon foam layer
405 PI film
Gii-Thru Sens
Three-point array microfluidic diagnostic device
440 Analyte Sample Wells
441 Laminated Hole Spacer Layer
442 Polyimide film
443 Screen-printed conductive carbon layer
444A Reference Electrode Connector
444B Working Electrode Connector
444C Counter electrode connector
447 Screen-printed dielectric layer
448A Reference Electrode
448B Working Electrode
448C counter electrode
449 Reference electrode screen-printed carbon layer
Eight-point array microfluidic diagnostic device
451 Laminated Hole Spacer
452 Array of eight analyte wells
453 Holes for the electrodes
454 Hole of the reference electrode
455 Polyimide layer
456 Polyimide layer
457 Eight working electrodes
458 pairs of electrodes
459 Reference Electrode
460 Screen-printed carbon bonding interface layer
461 Screen Printed Silver Connecting Track
462 Screen-printed dielectric layer
470 Top-layer microfluidic foil
471 Intermediate Layer Microfluidic Foil
472 Printed or molded microfluidic channels
473 Microfluidic foil with binder as the underlying layer
474Gii-Thru sensor
475 connector
481 Transparent Resin Barb Connector
482 Top Foil
483 Transparent Resin Molded Microfluidic Card
484 Microfluidic Channels
485-hole unit
486Gii-Thru sensor
Detailed Implementation
We will begin with a simplified, illustrative walkthrough of specific embodiments of the invention. We present two demonstrations; the first (Figures 1-6) will describe at a high level the carbon foam production process with a carbon precursor (e.g., a polyimide (PI) film, in this case, such as a membrane) mounted on a substrate; the second (Figures 9-14) covers the carbon foam production process without the polyimide film mounted on the substrate. In each case, we use a dual-laser process; the meaning of the terminology will be explained below.
In the first stage (see Figure 1), a laser 11 with wavelength λ uses a laser beam 12 to irradiate the interior 13 of a polyimide film 14, which is positioned on a substrate 15 suitable for end applications. This laser may be a pulsed IR laser that delivers IR radiation with a wavelength of 1064 nm.
As shown in Figure 2, a laser 11 with wavelength A is tuned so that the subsurface region 16 is transformed into carbon foam. The focus of laser A is gradually moved through the interior 13 of the polyimide film 14 to generate the entire carbon foam region 16. The depth or height of the carbon foam region 16 can be approximately 50 μm or greater, much higher than that achievable by other methods. Note that no carbon foam is generated at any time on the exposed surface of the polyimide film 14 (i.e., the surface on which the laser beam is incident). The region above the carbon foam 16 (i.e., closer to the laser than the carbon foam region 16) is not transformed into carbon foam. The region 17 below the carbon foam region 16 (i.e., the lower surface of the PI film) is also not transformed into carbon foam, but rather into disordered, amorphous, non-graphene material adhered to the underlying substrate 15.
Figure 3 shows that due to gas trapping, the laser 11 with wavelength λ causes physical expansion in region 18 above the internal carbon foam region 16 (i.e., closer to the laser than the carbon foam region 16). This region 18 is neither 3D graphene nor a polymer; it is a disordered amorphous material.
In the second stage, a laser 20 with wavelength B is now tuned to the disordered amorphous material region 18 above the carbon foam region 16, as shown in Figure 4. This can be a CO2 laser with a wavelength of 10.6 μm.
As shown in Figure 5, a laser 20 with wavelength B ablates some or all of the region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam region 16.
The laser 20 with wavelength B also reveals a lower carbon foam region with a unique surface morphology 21, as shown in Figure 6.
We refer to the process described in Figure 1-6 as the "dual-laser process".
Figure 7 is a scanning electron image showing the unique surface morphology (x250) achieved using a dual-laser method. In this case, the carbon source was first irradiated with IR radiation at a wavelength of 1064 nm from a pulsed IR laser, the radiation being focused into and gradually penetrating the carbon source. Then, the carbon source was irradiated with a laser beam at a wavelength of 10.6 μm from a CO2 laser. The thickness of the carbon foam layer in this image is approximately 220 μm.
As shown in Figure 8, the contrast with the surface morphology (x250) achieved using the conventional LIG method is striking: it features clear grating lines and less spiraling folds. The thickness of this carbon foam layer is less than 50 μm.
Based on the image in Figure 7, we can infer that the material produced using the dual-laser process does not have a surface morphology similar to conventional graphene foam; although it appears to be a multilayered, 3D carbon-based material with a chaotic, tortuous, foam-like structure, it is not necessarily a material commonly described as "graphene" in the conventional sense. More details are provided in Feature R below.
In the aforementioned demonstration (Figures 1-6), we investigated a dual-laser process for mounting a carbon precursor material (polyimide film) onto a substrate. In Figures 9-14 below, we will investigate a dual-laser process without mounting the polyimide film onto the substrate. We will later describe in detail the manufacturing processes for two specific implementations, referred to as Gii-Cap (supercapacitor) and Gii-Sens (sensor), which use a standard 220mm × 180mm sheet of polyimide film, which is not mounted onto the substrate; this size can be considered in standard laser scanning equipment, typically used for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). The manufacturing process also utilizes a standard flatbed screen printing apparatus and a standard conveyor belt dryer to easily accommodate thin PI films of different sizes. Other sizes of polyimide sheets can be considered.
As previously described, a laser 11 of wavelength Å (e.g., an IR laser) irradiates the interior 13 of the PI film 14; the film 14 is not currently mounted on the substrate, as shown in FIG9. It may be a sheet whose edges are supported or temporarily rested on a surface, or a sheet that forms part of a PI film roll when using a continuous manufacturing (e.g., roll-to-roll or roll-to-sheet) system (see Feature P below).
A laser 11 with wavelength λ is tuned to transform the subsurface region 16 into carbon foam, as shown in Figure 10. The focal point is gradually moved through the membrane 14 to create the entire carbon foam region 16. The height of the carbon foam region 16 can be approximately 50 μm or greater, much deeper or higher than could be achieved by other methods.
At no time does 3D graphene form on the exposed surface of the polymer film. The region above the carbon foam does not transform into 3D graphene.
As shown in Figure 11, due to gas retention, region 18 above the internal carbon foam region 16 undergoes physical expansion. This region is neither 3D graphene nor a polymer; it is a disordered amorphous material.
A laser 20 with wavelength B (e.g., CO2 ) is now tuned to region 18 above the carbon foam, as shown in Figure 12. The laser 20 with wavelength B ablates region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam 16, as shown in Figure 13.
Just as with the case where the polyimide film 14 is mounted on the substrate, the laser 20 with wavelength B also imparts a unique surface morphology 21 to the underlying carbon foam 16, as shown in Figure 14.
Some specific implementation details of this dual-laser method for producing carbon foam are as follows: In one example, the Nd:YAG solid-state laser is a wavelength A-wave laser, and it is positioned such that the IR laser radiation beam (wavelength 1064 nm) generated by the solid-state laser perpendicularly impacts the polyimide layer. Optics focus the IR laser radiation beam to a minimum beam convergence within a certain volume of the polyimide layer.
In the encapsulation region or subsurface region or location around the minimum beam convergence, the interaction between the laser and the polyimide leads to the carbonization of the carbon source. This carbonization results in the generation of carbon foams, such as twisted or disordered multilayer carbon foams, in the encapsulation region or subsurface region, and causes the formation of a disordered, amorphous, non-graphene material layer on the surface of the polyimide film.
While maintaining the laser beam focused at a specific depth within the polyimide layer, the laser scans laterally above the polyimide layer. In this way, the path entirely within the polyimide carbon source is traced and transformed into carbon foam. Thus, the polyimide is carbonized into carbon foam with a pattern corresponding to the path traced by the scanning, focused IR laser beam.
In one setup, the Nd:YAG IR laser pulsed at 80 kHz, and the laser beam scanned the surface at a speed of 9.4 cm/s. Other implementations utilized different parameters. For example, a pulse frequency of 50 kHz and a scanning speed of 35.5 cm/s were also successfully used to generate carbon foam. The laser power typically operated in the range of 8–20 watts, with an optimal value of 12 W; the laser focal length typically operated in the range of 50 mm–400 mm.
Once a predetermined area within the polyimide layer is irradiated by a focused IR laser beam in the manner described above, the depth of the encapsulated area or subsurface region or location within the polyimide is altered, and the IR laser beam scans the same predetermined area again. A standard computer-controlled laser scanning system can be used, which controls the X-Y position of the laser on the polyimide film. It may be necessary to pass the focused IR laser radiation through the same area more than once to generate carbon foam. In this specific implementation, the focused IR laser also irradiates adjacent but not substantially overlapping areas. This process of irradiating the carbon source with focused IR laser radiation at different focal depths is repeated until the desired depth of the polyimide layer is exposed to IR laser radiation and carbon foam is formed in the encapsulated area or subsurface region. However, the surface layer is a disordered, amorphous, non-graphene material.
In the second step, the polyimide layer is exposed to radiation from a CO2 laser for an ablation process, exposing at least some of the underlying carbon foam and obtaining exposed carbon foam with a specific surface morphology. The radiation from the CO2 laser scans the surface of the treated carbon source at a speed of 19 cm/s to match patterns or areas irradiated using an IR laser. Other embodiments utilize different parameters. For example, a pulse frequency of 50 kHz and a scan speed of 35.5 cm/s have also been used to successfully expose the underlying carbon foam. The laser power is typically in the range of 8–20 watts, with 12 W being optimal; the laser focal length is typically in the range of 50 mm–400 mm.
As described above, CO2 lasers ablate the disordered, amorphous, non-graphene material on the surface layer, thereby exposing the underlying carbon foam and altering the surface morphology of the carbon foam to produce exposed carbon foam with a greater number of defects compared to standard laser-induced graphene; as previously stated, this endows the carbon foam with extremely useful properties superior to standard laser-induced graphene.
Changing the laser parameters of one or two lasers (e.g., IR laser and CO2 laser), such as power, focus, wavelength, and scanning speed, alters the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
One useful property of exposed carbon foam fabricated using a dual-laser process is its high wettability: the contact angle can be less than 20°, making this carbon foam hydrophilic, compared to conventional graphene foams with contact angles between 70° and 150°, making them hydrophobic. This hydrophilicity of the carbon foam produced via the dual-laser process is highly relevant for two key applications: biosensors (a specific implementation called Gii-Sens) and supercapacitors (a specific implementation called Gii-Cap). For biosensors, high wettability allows the tested liquid (e.g., a liquid analyte) to spread rapidly and uniformly across the entire working electrode, resulting in higher sensitivity, consistency, and speed. For supercapacitors, high wettability means the electrolyte wets the supercapacitor electrodes better, leading to higher performance. While conventional graphene foams can be processed to make them more wettable, this carbon foam implementation does not require such an additional processing step.
Another useful property of exposed carbon foam produced by the dual-laser process is its high resistance to fouling: this can lead to enhanced sensitivity and extended lifespan of biosensors. Carbon foam can be used in applications where the accumulation of contaminants or residues may impair the performance or lifespan of components (e.g., filters, heating elements in e-cigarettes; electrodes); exposed carbon foam produced by the dual-laser process can be used in said components, resulting in enhanced performance or lifespan.
The performance of the carbon foam electrode produced using this dual-laser method has been explored by cyclic voltammetry (CV), as shown in Figure 15. Cyclic voltammetry plots of the well-characterized ferricyanide/ferrocyanide redox reaction were performed using electrodes prepared using the method described above and electrodes prepared using known conventional CO2 laser irradiation methods. Figure 15 shows CV curves obtained at scan rates of 10 mV/s, 25 mV/s, 50 mV/s, 75 mV/s, 100 mV/s, and 150 mV/s. Each curve shows data recorded using the carbon foam electrode produced using the dual-laser method of the present invention (light line) and the 3D graphene electrode produced using the known CO2 laser irradiation method (dark line). The peak at approximately 0.22 V in the cathode current direction corresponds to the reduction of ferricyanide to ferrocyanide; and the peak at approximately 0.28 V in the anodic current direction corresponds to the oxidation of ferrocyanide to ferricyanide.
Far from the prominent redox peaks, these graphs qualitatively show that the CV curves recorded using carbon foam electrodes produced using the dual-laser method disclosed in this specification are more rectangular than those recorded using 3D graphene electrodes produced by known methods. This is most evident at the high points of the voltage range (approximately 0.6 V) and at higher scan rates (see, for example, 100 mV/s). This increased rectangular appearance indicates increased capacitive behavior of the electrodes prepared using the dual-laser method of this invention, thus reflecting the very high surface area of the torsion or disordered multilayer carbon foam produced by this method.
The CV curves also clearly show that the voltage for separating the oxidation and reduction peaks is consistently lower for measurements using carbon foam electrodes produced by a dual-laser method compared to those using 3D graphene electrodes produced by conventional known methods. The peak separation ΔEp as a function of scan rate for CV measurements obtained using carbon foam electrodes produced by the method disclosed in this invention is plotted in Figure 16(a), and the peak separation ΔEp as a function of scan rate for CV measurements obtained using 3D graphene electrodes produced by known methods is plotted in Figure 16(b).
This data shows that ΔE<sub> p </sub> narrows when the electrode is prepared according to the dual-laser method. The theoretical peak separation parameter for reversible systems (such as ferricyanide/ferrocyanide reversible redox reactions) is 57 mV, but in practice this is sensitive to the influence of electrode structure on electrochemistry. Clearly, the voltage separation of the oxidation and reduction peaks in the cyclic voltammetry plots is close to the theoretical value. This demonstrates the quality of the electrodes produced by both known methods and the dual-laser method. Furthermore, results recorded using a carbon foam electrode produced by the dual-laser method show reduced separation, indicating improved porosity of the electrode produced in this manner compared to electrodes produced by conventional methods.
Figure 17 shows a comparison of electrochemical impedance spectroscopy results for a system comprising a carbon foam electrode produced using a dual-laser method (square) and a system comprising a 3D graphene electrode produced using a known method (circle). Bode plots show the change in phase angle as a function of frequency. The frequency responses of the two systems are significantly different. Specifically, measurements recorded using the carbon foam electrode produced using the dual-laser method lack the phase angle signal peak observed at approximately 1 kHz in measurements recorded using the 3D graphene electrode produced using a conventional method. The response from the electrode prepared using the dual-laser method indicates a rapid electron transfer response. These differences further clearly demonstrate that the carbon foam produced by the dual-laser method is distinct from and can be differentiated from 3D graphene produced by conventional methods.
Further details are clearly visible in Figure 18A. The Raman spectrum of the carbon foam fabricated using a dual-laser process is shown in Figure 18A, exhibiting three main peaks. Specifically, the D peak at approximately 1344 cm⁻¹ is characteristic of lattice defects, and the G peak at approximately 1577 cm⁻¹ is characteristic of sp² carbon hybridization, featuring distorted six-fold carbon rings. The 2D peak at approximately 2685 cm⁻¹ is characteristic of secondary transitions in 3D graphene, and the absence of a bimodal structure here indicates a lack of planar AB stacking found in multilayer 2D graphene or graphite. Fitting the 2D peak to a single Lorentzian peak centered at 2685 cm⁻¹ (with a full width at half maximum of 67 cm⁻¹ ) indicates the presence of only one or a few carbon foam sample layers in the 3D carbon formed using these two methods. Analysis of the D/G peak ratio (0.85) of the dual-laser process indicates a higher defect density compared to the conventional laser-induced graphene process using a single-laser step (0.67), as shown in Table 1 below.
| process | D/G | 2D/G | D/D’ |
| Dual laser | 0.85±0.1 | 0.95±0.12 | 3.7±1.3 |
| Conventional single laser | 0.67±0.13 | 0.75±0.05 | 2.6±0.22 |
Table 1
As we previously explained, Raman analysis of typical graphene foam revealed the following signature characteristics: absence of a D peak; a 2D peak higher than the G peak; and a D:G ratio close to zero. The carbon foam produced in this specific embodiment of the invention does not possess these characteristics; it is highly hydrophilic with a contact angle below 20°; it lacks the Raman signature characteristic indicative of graphene: Figure 18A shows the material produced via a dual-laser process: presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18B is another Raman analysis of carbon foam produced via a dual-laser process, again showing the presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18C is the Raman analysis of the carbon nano-onion material, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI: 10.1007/s00339-015-9315-9, and its similarity to the Raman analysis of carbon foam produced via a dual-laser process is evident. A plausible explanation is that the carbon foam produced by the dual-laser process is or contains carbon nanotube onion material. See also Figures 57A and 57B below.
Both dual-laser carbon foam and conventional graphene fabricated using a single-laser process exhibit microporous structures, as shown in the SEM images in Figure 19. Low-magnification images reveal significant differences in surface morphology. The single-laser surface shows a smoother, more textured surface with rougher edges, while the carbon foam fabricated using a dual-laser process displays a rougher surface. This region will be further described in the following section on characteristic R.
Key features
In this section, we outline the key features of specific embodiments of the invention. These features define the production of carbon fiber foam in the previously described dual-laser manufacturing process; this process offers numerous advantages over conventional CVD: we can compare the production of approximately 50 μm thick carbon foam at 1 cm² on plastic substrates (or virtually many other types of substrates) as shown in Table 2.
| process | Number of steps | time | temperature | pressure | cost |
| CVD | 6 | 300min | 800C | vacuum | $50 |
| Dual laser process | 1 | 2min | 20C | environment | Less than $1 |
Table 2
Features A-R define various aspects of the carbon foam manufacturing process, which is highly scalable, high-yield, highly reproducible, and easily adaptable to many different applications, all using the same process. For example, dual-laser carbon foam is particularly suitable for biosensors and electrochemical capacitors (e.g., supercapacitor and pseudocapacitor applications).
For biosensor applications, dual-laser carbon foam offers the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; higher wettability; and higher antifouling properties. One specific implementation of this biosensor is called Gii-Cap, which we will describe in more detail below.
For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; higher wettability; and better anti-fouling properties. One specific implementation of a supercapacitor is called Gii-Cap, which we will describe in more detail below.
Features A-R are organized into the following four groups:
Group 1: Subsurface carbon foam
Group 2: Dual Laser Processing
Group 3: Products
Group 4: Other aspects.
We can extend this organization as follows:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene material adhered to a substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual lasers operating in different frequency bands
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors in different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device
Feature M2: Screen-printed carbon foam supercapacitor layer
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Now let's look at Group 1:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
In the prior art section, we have described how earlier laser-induced graphene methods transformed the surface layer of a carbon precursor into 3D graphene. However, the resulting 3D graphene can be somewhat brittle, potentially peeling off from the underlying substrate, and is generally unsuitable for many real-world applications; furthermore, 3D graphene is typically relatively thin, with a depth of less than 50 μm.
In this specification, we describe an alternative method in which the surface of the carbon precursor is not converted into graphene at all; instead, only the subsurface region 14 of the carbon precursor is converted into carbon foam 16 by a focused laser beam 12; in one embodiment, the focused IR beam 12 generates a temperature above 500°C in the subsurface region or encapsulation region inside the polyimide film 14 for a very short time, between 1 ns and 10 μs (i.e., at a rate between approximately 5 × 10⁷ °C/s and 2 × 10¹² °C/s); this brief but intense heating is sufficient to form carbon foam 16 in this subsurface region or encapsulation region. This subsurface region or encapsulation region 16 has no substantial gas escape pathway; confining the gaseous products within the subsurface region or encapsulation region advantageously affects the structure of the carbon foam 16 formed in the subsurface region. The formation of carbon foam 16 only in the subsurface region was an unexpected discovery; the reasons for this unexpectedness include the extremely low absorptivity of the polyimide carbon precursor material to 1064 nm IR radiation, with a radiation absorptivity per centimeter (decimal) of less than 50 or as low as less than 10.
Under laser irradiation, the surface (e.g., the interface between the carbon precursor material perpendicular to and facing the laser and the gaseous environment surrounding the carbon precursor material) expands and transforms from the carbon precursor material into disordered amorphous non-graphene material 18. This disordered amorphous non-graphene material 18 forms a layer, which is typically at least 1% of the total thickness of the carbon precursor material; for a 500 μm thick polyimide film, the top 1 μm–10 μm is typically transformed into disordered amorphous non-graphene material 18; below this upper surface layer, within the bulk of the carbon precursor material, we obtain a region transformed into carbon foam 16.
The thickness of this carbon foam 16 is controlled by gradually moving the focus of the laser beam through the carbon precursor material; exceptionally thick carbon foam structures can be made using this process: carbon foam tracks with thicknesses of 50μm-200μm (approximately) have been achieved.
If a laser irradiates a carbon film precursor material, such as a polyimide film suspended in space (i.e., not mounted on a substrate) as shown in Figure 9-14B, after irradiation, as we gradually move through the material, we obtain disordered amorphous non-graphene material 18 on the upper surface (i.e., the surface facing the laser); then we obtain carbon foam regions 16. The laser beam 12 typically does not approach the lower surface of the carbon precursor material, such that the carbon foam regions 16 are located above the carbon precursor material that has not yet been converted into carbon foam. If the laser approaches the lower surface of the carbon precursor material, the carbon precursor near and located on the lower surface is converted into disordered amorphous non-graphene material.
Similarly, if a carbon precursor film, such as a polyimide (PI) film mounted on a substrate, is irradiated with a laser, as shown in Figures 1-6, we obtain the same material order; furthermore, the laser typically approaches the lower surface of the carbon precursor material resting on the substrate: the carbon precursor near and located on the lower surface is then transformed into a disordered amorphous non-graphene material 17. This disordered amorphous non-graphene material 17 adheres to the substrate 15; since the carbon foam region 16 is bonded to this disordered amorphous non-graphene material 17, the carbon foam region 16 itself is not directly bonded to the substrate 15, but is firmly attached to the substrate 15 via the intermediate disordered amorphous non-graphene material 17.
This method achieves carbon foam structures with significantly greater thickness than those achievable using previous methods that confine graphene foam formation to surface regions. Furthermore, this method enables carbon foam structures to adhere more robustly (but not directly) to the underlying substrate. It is important to note that with this method, carbon foam is not generated on any surface of the carbon precursor material; rather, it is generated only in the subsurface region within the carbon precursor material.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
In Feature A above, we define the region where carbon foam is generated by laser irradiation as the “under-surface” region. Another way to describe this region is to characterize it as “encapsulation”; this reflects the three-dimensional relationship between the carbon foam and its surrounding environment; the carbon foam 16 is “encapsulated” by the original carbon precursor material and by the disordered, amorphous, non-graphene material 18 generated by laser irradiation of the upper surface of the carbon precursor material 14.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of carbon precursor material, wherein said regions do not have substantial gas escape channels.
As we have seen above, the subsurface region or encapsulation region of the carbon precursor is transformed into carbon foam, and this subsurface region or encapsulation region has no substantial gas escape channel; confining the gaseous products within the subsurface region or encapsulation region affects the structure of the carbon foam 16 formed in the region.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to the substrate
As we have previously observed, when laser 11 irradiates the carbon film 14 mounted on substrate 15, the laser carbonizes the surface of the carbon film adjacent to substrate 15, forming a disordered amorphous non-graphene material 17 adjacent to substrate 15. This disordered amorphous non-graphene material 17 adheres to substrate 15. Because the internal, subsurface, or encapsulated carbon foam regions 16 are themselves bonded to this disordered amorphous non-graphene material 17, the carbon foam regions 16 themselves are not directly attached to substrate 15, but are firmly positioned on substrate 15 via the intermediate disordered amorphous non-graphene material 17. Compared to conventional laser-induced graphene, the carbon foam regions 16 adhere more firmly and are less likely to peel off even if the substrate is flexible, thus enabling applications such as biosensor applications where the substrate is typically a thin and flexible structure.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Previous features A-D covered the generation of carbon foam in the subsurface region or encapsulation region of the carbon precursor material. Because carbon foam does not form on exposed surfaces, and many applications require exposed carbon foam (e.g., for functionalization in biomedical sensing applications or supercapacitors), we can take additional steps to expose at least some of the carbon foam subsurface or encapsulate it.
We have previously seen the formation of disordered, amorphous, non-graphene material 18 beneath the surface or above the encapsulated carbon foam 16 by laser irradiation using an IR laser 11. We now use a laser (typically a long IR CO2 laser 20) to ablate or otherwise process this disordered, amorphous, non-graphene material 18, thus exposing the underlying carbon foam 16. Unlike the initial laser, this second laser 20 is typically defocused.
As mentioned earlier, we use standard 220mm × 180mm polyimide sheets (but other sizes of polyimide sheets can also be considered); this size is commonly used in standard laser scanning equipment, standard flatbed screen printing equipment, and standard conveyor belt dryers for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). Other sizes of polyimide sheets can be considered.
We have discovered that this secondary laser irradiation step alters the morphology and other characteristics of the underlying carbon foam in a surprising and advantageous manner, resulting in previously unobserved twisted or disordered multilayer carbon foams. Changing the parameters of the CO2 laser 20 can alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
This new exposed carbon foam possesses one or more of the following properties:
• Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
• Strong adhesion to any underlying flexible substrate
High porosity
High electrical conductivity
• Increase in capacitance or charge storage
• Rapid absorption of organic solvents and water-based solutions
• Higher hydrophilicity
High EMI shielding
• Electrode quality enhancement
High wettability
• Anti-fouling.
It should be noted that by changing the laser parameters of any one or both lasers used in the dual-laser process, one or more of these properties, as well as the size and extent of defects and the size (including relative size) of the Raman D and 2D peaks, can be altered. In this way, carbon foams tuned for or particularly suited to different applications can be produced. Surprisingly, the operation of the second ablation laser enables the production of usable exposed carbon foam regions, especially those with properties that can be adjusted by changing the parameters of the first and/or second lasers.
We can summarize it as follows:
A method for manufacturing a carbon foam material includes the following steps: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulated region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of it in the carbon foam.
Feature F: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
In the aforementioned feature E, we describe the formation of carbon foam 16 in the region by irradiating the encapsulated region or subsurface region of the carbon precursor with a laser 11 (e.g., an IR laser); the irradiation causes the upper (in the laser direction) carbon precursor material 14 to expand into a disordered, amorphous, non-graphene material 18; then, we expose or reveal the carbon foam 16 by ablating the upper disordered, amorphous, non-graphene material 18 with a second laser 20 (e.g., a CO2 laser). This second irradiation step not only ablates the upper disordered, amorphous, non-graphene material 18 and thus exposes the lower carbon foam 16, but also gives this lower carbon foam an unexpected and unusual surface morphology 21 with very desirable characteristics; such a carbon foam may be a torsion or disordered multilayer carbon foam.
However, because such foams may possess characteristics unrelated to graphene foams (such as a wide range of defects, appearance, wettability, and Raman spectra (see Feature R below), we explicitly describe such foams as “non-graphene carbon foams” in Feature F. Therefore, the term “non-graphene carbon foam” (as opposed to the term “carbon foam”) explicitly excludes graphene foams, including twisted or disordered multilayer graphene foams, but extends to foams covering any other 3D carbon material.
We can summarize it as follows:
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers in different wavelength bands
As we saw in features E and F above, we can use two separate laser irradiation steps. These steps are typically performed using two separate lasers: the first step, to generate subsurface or encapsulated carbon foam, is typically accomplished using a focused IR laser 11; and the second step involves irradiation using a defocused CO2 laser 20 at a longer wavelength, but other wavelengths (e.g., UV and visible light) can also be used.
The second laser 20 ablates the material 18 (e.g., disordered, amorphous, non-graphene material) located between the carbon foam 16 and the surface, exposing the underlying carbon foam 16. The exposure of the carbon foam 16 can also be altered by the second laser (e.g., in terms of its surface morphology 21); that is, the term 'exposure' should be broadly interpreted to include not only revealing at least some of the pre-existing carbon foam, but also transforming or altering at least some of the pre-existing carbon foam into a 3D carbon material foam with characteristics different from those of the pre-existing graphene foam.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
We have previously seen how we generate carbon foams, which can be twisted or multilayered: because of the special electrical properties of this material (e.g., conductivity, capacitance), we can attach or position one or more electrical contacts (including electrical objects such as flexible electronics, microprocessors, antennas, IoT devices, electrical interfaces, etc.) into the carbon foam. For printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate) and onto and inside a pre-existing 3D carbon material foam, such that the tracks form good electrical contacts with the foam and any structures formed on the foam, such as functionalized layers (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
In Feature H, we see that once the dual-laser process is complete, electrical contacts or circuitry are added to contact a pre-existing carbon foam; for example, simple silver electrical contacts can be screen-printed onto the carbon foam. In Feature I, we describe a process that begins by first screen-printing electrical contacts onto a polyimide film, and then completes the process by creating an exposed carbon foam through a second laser ablation step in the dual-laser process. This has several advantages because the screen-printing process can interfere with or destroy the carbon foam. We refer to this process as “PPC” (short for “post-printing conversion”), where the screen-printing step is performed prior to the dual-laser process to create the carbon foam. In Feature L5, we describe a biosensor fabricated using the PPC process.
Therefore, for screen-printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate), allowing carbon foam to subsequently form around one end of the printed tracks, thus providing a contact area with a large surface area and therefore very good electrical connectivity. Similar to the alternative processes described in Feature H above, the printed tracks also form good electrical contacts with any structures formed on the foam (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
An alternative sequence involves using a first laser beam to generate subsurface carbon foam, then screen printing electrical contacts, and then using a second laser beam to generate carbon foam to create good electrical contact with the electrical contacts.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed in the order of (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
We have previously observed that the thickness of the subsurface or encapsulated carbon foam region can far exceed that of conventional graphene foams confined to the surface layer: the laser focus of the first laser beam can be progressively moved downwards through the carbon precursor material to create a deep or thick subsurface or encapsulated carbon foam layer. Then, a second laser irradiation step is employed to ablate the material between the carbon foam and the surface of the carbon precursor material, resulting in an exposed region of the carbon foam. This now exposed carbon foam region has a thickness or depth of at least 50 μm; carbon foams with a thickness of 300 μm have been produced. The increased thickness is beneficial because it leads to better electrical conductivity, greater capacitance, and higher mechanical integrity.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
The specific properties or structure of the carbon foam produced by the second laser beam can be considered sensitive information because they define the characteristics of the final product. For the first laser beam process, it is desirable for the carbon foam supplier to perform the process at their manufacturing facility, then supply the carbon foam to the customer, who then uses the second laser beam for the final stage at their own manufacturing facility. As we explained earlier, by changing the parameters of the first and second lasers, it is possible to alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications. Typical parameters that can be changed or tuned in this way include: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface or encapsulation region.
By segmenting the manufacturing process in this way, suppliers do not need to know the specific manufacturing processes that customers use as part of the second laser ablation process (e.g., how they change the parameters of the second laser beam to give the exposed carbon foam the properties they need); customers can keep the details of how they produce the finished product confidential.
Therefore, the manufacturing process is a three-stage process involving the following steps: (a) irradiating the area below the surface of the carbon precursor material with the first laser beam at the manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Furthermore, this method enables the large-scale production (see feature P, for example) of carbon foam using only the first laser process, thereby reducing the cost of this material, which can be used in many different applications and for many different customers. The production volume of more specialized products using a second laser beam may be much lower than that of carbon foam produced using only the first laser process. Therefore, this method achieves more efficient and lower-cost manufacturing of the base material, namely carbon foam produced solely through the first laser process.
We can summarize it as follows:
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
For features A-K, the following optional features are particularly relevant. It should be noted that any one or more of the following optional features can each be combined with one or more other compatible optional features, as well as with one or more of features A-K:
We will cover the following areas:
Manufacturing process
First laser beam parameters and control scheme
Properties of the subsurface region or packaged region
carbon precursor materials
Substrate supporting carbon precursor materials
Carbonization at the surface where the laser beam is incident
ablation laser beam or second laser beam
Carbon foam.
It should be noted that any one or more of the following optional features may be combined with one or more other compatible optional features and with any one or more of the other “features” listed in this specification (e.g., features A-R):
The laser-based manufacturing process described above has many advantages over conventional CVD processes; these can be listed as the following optional features:
It is a room temperature process.
It is an environmental pressure process.
It can be done on plastic substrates (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
It takes about 2 minutes or less to create a 1 cm² carbon foam that is approximately 50 μm thick on a plastic substrate.
The formation of 3D carbon foam on a flexible substrate was achieved.
No graphene or graphene oxide precursors are required.
Carbon foam material is generated only in the encapsulation area or subsurface area of the carbon precursor material, and not on any surface of the carbon precursor material.
It uses a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
It is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
The parameters and control scheme of the first laser beam are crucial for the production of carbon foam; we define the relevant optional characteristics here:
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following:
Intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface or encapsulated region to form carbon foam.
• The laser beam generates temperatures exceeding approximately 500°C in the subsurface or encapsulated region to form carbon foam.
The pulse duration of the laser beam is between approximately 1 ns and 10 μs, resulting in a pulse speed of approximately 5 × 10⁷ °C/s.
Heating rate between 2 × 10¹² °C/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between approximately 50 kHz and 500 kHz.
• The laser pulse frequency is between approximately 1 kHz and 2 MHz.
• The laser wavelength is between approximately 0.7μm and 2.5μm.
The laser scans at speeds between approximately 9 cm/s and 40 cm/s.
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region through which the focal point passes.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region with a thickness of at least 50 μm.
• The focal point of the laser beam is moved through a depth of at least about 100 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region where the thickness of the carbon precursor is at least 100 μm.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scanning can result in a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm).
• The wavelength of the laser beam is not absorbed by the carbon precursor material.
• The carbon precursor material has extremely low absorption of the wavelength of the laser beam, with a radiation absorptivity per centimeter (decimal) of less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between approximately 0.7 μm and 2.5 μm.
The laser beam is an IR laser with a wavelength between approximately 0.75 μm and 1.40 μm.
The properties of the subsurface region or encapsulation region where carbon foam is generated can be defined using the following optional features:
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity and the choice of carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or more below the surface of the carbon precursor material.
• The thickness of the subsurface region or encapsulation region can be between approximately 10 μm and 200 μm.
• The subsurface region or encapsulation region is located at a certain distance below the surface of the carbon precursor material. This distance is a function of various factors, such as laser intensity, other laser parameters, and the selection of the carbon precursor material used. For example, the top of the subsurface region or encapsulation region may be at least 1%, 10%, 20%, 30%, or 40% below the total thickness of the surface carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the midpoint of the minimum cross-section of the first laser beam, and the volume is within 500 or 100 micrometers or 1 micrometer of this midpoint.
Carbon precursor materials can be defined by the following optional characteristics:
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam (see Group 3 below) is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300±50 cm⁻¹ .
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of a first and/or second laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
A substrate can be considered as a material having a surface on which carbon precursors are positioned; the specific material, thickness, and properties of the substrate are determined by the application: for example, for some sensors, the substrate may be a thin, flexible plastic film; for other applications, the substrate may be a rigid polyimide plate on which electronic circuitry can be mounted. An IR laser can directly irradiate the carbon source; alternatively, radiation from the IR laser can first pass through the substrate and then reach the carbon source, in which case there are two alternative scenarios: first, the substrate is substantially transparent to IR radiation, and the mechanism of carbon foam formation is as described above. In the second scenario, the substrate is substantially opaque to IR radiation: then, rapid heat transfer from the substrate to the carbon precursor material first generates a disordered, amorphous, non-graphene layer at the interface with the substrate, and then carbon foam forms in the subsurface region or encapsulation region within the carbon precursor material.
The carbon precursor material can be positioned and supported on a substrate, which can be defined by the following optional characteristics:
The substrate is a plastic body, film, or foil.
The substrate is flexible.
The substrate is a polyimide circuit board.
The substrate has an extremely low absorption rate of the first laser beam.
The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
The substrate has a high absorption rate for the first laser beam, absorbing more than 60% of the first laser beam.
The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
The substrate is formed from one or more of the following: silicon (Si), silicon dioxide (SiO2), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing silicon and silicon dioxide.
The substrate is a carbon source.
The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident can be defined by the following optional characteristics:
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by the first laser beam.
The disordered, amorphous, non-graphene material occupies a thickness below the surface of the adjacent carbon precursor material, which is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
The disordered, amorphous, non-graphene material extends to a distance below the surface of the carbon precursor material, said distance being at least 10 μm.
The disordered, amorphous, non-graphene material extends from the outer surface of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
The ablation laser beam or the second laser beam can be defined by the following optional characteristics:
The parameters of a laser beam include one or more of the following: intensity, wavelength, pulse duration, pulse profile, scanning speed, and heat generated in the subsurface region or packaged region.
Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
Changing laser parameters alters one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
The second laser beam alters the carbon foam as part of the process that exposes it.
The second laser beam alters the shape of the carbon foam as part of the process that exposes it.
The second laser beam is automatically controlled to scan on the same, and/or overlapping, and/or non-overlapping areas (e.g., raster scanning).
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
The carbon precursor material has an absorption coefficient for the second laser beam that is greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam that is greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300±50 cm⁻¹ .
The laser power is typically in the range of 8-20 watts, with 12W being optimal.
The typical working range of laser focal length is 50mm-400mm.
The second laser beam scans in a pattern that includes non-overlapping areas or lines.
The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam can be defined by the following optional characteristics:
The carbon foam has a thickness of at least 50 μm.
The thickness of the carbon foam ranges from 50 μm to 300 μm.
Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
Carbon foam is or includes carbon foam with a defective spatial distribution, resulting in high electrochemical reactivity.
Carbon foam is or includes carbon foam with vacancy basal defects, resulting in high electrochemical reactivity.
The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Carbon foam has one or more of the following properties:
Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
It has strong adhesion to the underlying flexible substrate.
High porosity
High electrical conductivity
Increase in capacitance or charge storage
Rapid absorption of organic solvents and water-based solutions.
ο Higher hydrophilicity
οEMI shielding high
Electrode quality enhancement
The contact angle is approximately 20° or less.
The properties of carbon foam can be selected by choosing specific laser parameters to generate carbon foam materials with one or more of the following desired properties or parameters: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
Group 3: Products
Feature L1: Biosensor
Carbon foams fabricated using the dual-laser method described above have wide applications in many different types of sensors. For simplicity, we will use the phrase "carbon foam" in this feature to refer to any carbon foam or 3D carbon material foam fabricated by the methods described in this specification. Appendix 1 includes further details on this field, describing in more detail a biosensor comprising a carbon foam functionalized by adding receptors specific to a target or analyte, and a connector enabling the receptors to attach indirectly to the carbon foam; (some receptors cannot attach directly to the carbon foam because of their poor stability in contact with a surface; instead, a connector must be used as an intermediary between the carbon foam and the receptor. During fabrication, the connector is first added to the carbon foam, and then the receptor is added to the connector.)
For biosensor applications, functionalized carbon foam has the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; enhanced wettability; and a contact angle of approximately 20° or less.
At a higher level, functionalized carbon foam can be used in sensors because it can generate detectable changes in state; its high sensitivity is a function of its large surface area. It can be used to detect specific chemicals, specific gases, mechanical stress, and temperature, among other variables. We will briefly look at each category.
First, chemical sensors: Chemical detection systems rely on detecting the electrical response of carbon foam when a target chemical substance is present; many different detection principles can be used, such as changes in capacitance, resistance, voltammetry, redox potential, and charge transfer resistance.
For example, the binding can be detected when a specific analyte or target binds to a carbon foam because it alters the surface of the carbon foam. Biomolecules, such as specific antibodies or aptamers (aptamers are short, single-stranded DNA or RNA molecules that can selectively bind to specific targets, including proteins, peptides, carbohydrates, small molecules, toxins, and living cells), are added to the carbon foam. When the target is present and binds to the aptamer, the morphology of the aptamer changes (e.g., by reducing surface area), and the capacitance of the combined carbon foam and aptamer system decreases in a measurable manner.
Using this principle, highly sensitive and selective sensors can be built; due to the quantitative reduction of measurable variables (e.g., capacitance), a LOC (lab-on-a-chip) can be built, which includes not only carbon foam and aptamer biosensors, but also power sources on the LOC, such as supercapacitors or other energy storage devices using carbon foam as their electrodes, as well as circuitry for measuring variables, calculating biosensor outputs, and displaying said outputs (e.g., the presence or absence of a target; the concentration of a target) on the LOC screen; this is further described in the feature O3 (Gii-Thru: HISLOC for Gii-Sens).
Carbon foam sensors can also measure the redox potential of a target; for example, a current peak can be detected when the oxidation of a target chemical is catalyzed by a specific catalyst added to the carbon foam; since the current is usually a function of the concentration of the target chemical, it is possible to quantitatively measure the target concentration.
Other technologies already applied to conventional graphene sensors, such as thermal conductivity measurements for detecting specific chemicals, resistance measurements for inferring temperature, physical deformation, or transitions in the presence of specific chemicals, and piezoresistive deformation for detecting motion, can all be applied to carbon foam sensors fabricated using the dual-laser method described above.
An important application of the large electrochemically effective region and fast electron transport rate of carbon foam generated by a dual-laser method is the implementation of an electroanalytical sensing electrode optimized for biosensing (called "Gii-Sens").
For example, the electroanalytical sensing electrode can be used in point-of-care diagnostic devices; the sensing electrode has extremely high sensitivity, reliability, purity, wettability and conductivity.
Figure 20A is a perspective view of a biosensor called Gii-Sens. The assembly consists of: a polyimide substrate 201; a working electrode 202 made of Gii carbon foam; a counter electrode 203 made of Gii carbon foam; a reference electrode 204 made of screen-printed silver-silver chloride; three screen-printed silver connection traces 205; and a screen-printed dielectric layer 206.
Figures 20B-20D show the four main manufacturing stages. Figure 20B shows step 1, in which the dual-laser process uses a polyimide substrate 201 as a precursor to produce a Gii carbon foam working electrode 202 (area of 18.94 mm² ) and a counter electrode 203 (area of 20.84 mm² ).
Figure 20C shows step 2, in which a silver-silver chloride reference electrode 204 (with an area of 8.99 mm² ) is screen-printed onto a polyimide substrate 201.
Figure 20D shows step 3, in which silver connection traces 205 are screen-printed onto the polyimide substrate 201; these overlap with the carbon foam electrodes at the electrical contact regions 207. The area of the silver traces is 1 x 18.85 mm² , and the area of the three silver traces is 3 x 56.55 mm² . The area overlapping with the underlying carbon foam electrodes is 1 x 2.21 mm² , and the area overlapping with the three carbon foam electrodes is 3 x 6.63 mm² .
Figure 20E shows step 4, in which the dielectric layer 206 is screen-printed over carbon foam electrodes 202, 203, 204 and silver connection traces 205. The active regions of the electrodes are as follows: working electrode 202: 12.64 mm² ; counter electrode 203: 14.18 mm² ; reference electrode 204: 2.59 mm² . The exposed areas of the silver connection traces 205 are 1 x 7.15 mm² and 2 x 21.45 mm² .
Figure 20F shows a single polyimide sheet on which an array of 100 carbon foam working and counter electrodes has been produced using the dual-laser process described in step 1 above. The sheet is a standard type of polyimide sheet, 220 mm × 180 mm, allowing it to be processed using standard screen printing and laser scanning equipment; it can be A5 size or any other suitable size.
Figures 20G and 20H show the final form of the sheet after step 4. 100 individual units can be cut and assembled into 100 finished Gii-Sens biosensors.
One specific use case for the Gii-Sens sensing electrode is a reversible polymer displacement sensor mechanism for electrochemical glucose monitoring. A graphene sensor for this use case has been proposed: see "Polymer indicator displacement assay: electrochemical glucose monitoring based on boronic acid receptors and graphene foam competitively binding with poly-nordihydroguaiaretic acid", Wikeley et al., DOI:10.1039/d1an01991k. This paper describes glucose... A pyrene-derived boric acid chemical acceptor was adsorbed onto a graphene foam electrode. The spontaneous oxidative polymerization of nordihydroguaiacol (NHG) onto the graphene foam electrode yielded a redox-active membrane (poly-NHG) covalently attached to the boric acid acceptor. Oxidation of the poly-NHG released the boric acid acceptor to interact with glucose in the solution phase, which was detected due to competitive binding upon recombination of the reduced poly-NHG with the boric acid functional groups. The sensor exhibited the expected boric acid selectivity for fructose-glucose. Glucose sensing was performed using the charge ratio at the voltammetric peaks of unbound and bound poly-NHG, with a substantially linear analytical range from 1 to 50 mM glucose in a pH 7 aqueous buffer.
The implementation of Gii-Sens sensing electrodes offers several advantages over current sensing electrodes, such as those used in graphene sensors:
It uses amplification-free, enzyme-free, and label-free electrochemical biosensor with a low detection limit.
Enhanced reproducibility.
Optimize the available dynamic range.
Minimize background noise.
Reduce planning time and operations.
It is scalable for low-cost manufacturing.
High sensitivity and selectivity.
Provide quantitative numerical results.
It can be printed into specific patterns, such as interdigitated patterns, to achieve miniaturized integrated devices.
Existing biometric and testing formats (e.g., ELISA, PCR, RT-PCR) can be translated into electrochemical microfluidic POCs without affecting performance quality.
It can perform impedance-based measurements with extremely high sensitivity, reliability, and extremely low background signal interference.
It replaces expensive, large-scale laboratory testing and low-sensitivity lateral flow testing.
It can be implemented in microfluidic analysis (single-objective or multi-objective) and lab-on-a-chip (LOC) devices.
It can be used in any sensor application where the user aims to immobilize (biological) molecules of interest (e.g., the carboxyl/n-hydroxysuccinimide moiety can be added to the sensor surface to provide a platform for subsequent immobilization and conjugation chemistry reactions).
It can be used for a variety of diagnostics: point-of-care (POC) human and animal health, food safety, in-situ environmental health and safety, and agricultural health and safety, all of which have enhanced biosensing sensitivity, selectivity, and reproducibility due to its purity and high specific surface area.
Enhanced wettability (e.g., contact angle below about 20°).
Enhanced stain resistance.
We can summarize it as follows:
A method of manufacturing a biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
L2: Fabricating carbon foam biosensors in a scalable and low-cost manner using screen printing technology.
We have already seen above how screen printing is widely used in manufacturing processes: it is a well-known, scalable, predictable, and low-cost technology. The detailed manufacturing process of the Gii-Sens carbon foam biosensor is shown in Figure 21.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric to at least partially cover the electrodes and connection traces.
Optional features include the following:
In the method defined above, in step 1, the dual-laser process uses a PI substrate as a precursor to generate a carbon foam working electrode and a counter electrode.
In the method defined above, in step 2, a reference electrode, such as a silver-silver chloride electrode, is screen-printed onto a PI substrate.
The method defined above, in step 3, involves screen printing connection traces, such as silver traces, onto a PI substrate to overlap with the carbon foam electrode. Note: The order of steps 2 and 3 can be reversed.
The method defined above, wherein in step 4, a dielectric layer is screen-printed over at least some of the carbon foam electrodes and silver connection traces.
Other aspects include:
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each sensor electrode comprising at least partially a carbon foam made by a method defined as any one of features A-K above, and each sensor electrode being electrically connected to a screen-printed track and also at least partially covered by a screen-printed electrolyte.
A point-of-care diagnostic device comprising a biosensor as defined above.
L3: Adding functional groups to biosensors at different manufacturing facilities
For Gii-Sens biosensors, the biosensors are manufactured in one facility, but customers add functional groups that biomolecules can attach to in another facility (usually their own). This accelerates the development and testing of these functional groups and also protects their trade secrets and proprietary technology in the final design of these functional groups and the biosensors.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in a different manufacturing facility.
L4: Adding functional groups to biosensors is part of the biosensor manufacturing process.
For the Gii-Sens+ biosensor, the manufacturing process includes adding functional groups. Figure 22 shows the detailed manufacturing process of Gii-Sens+.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
L5: Using PPC to manufacture biosensors: Post-printing conversion
A PPC variant of the Gii-Sens manufacturing process is shown in Figure 23. PPC is an abbreviation for "Post-Print Conversion," in which the screen printing step is completed before the dual-laser process to create carbon foam. The specific steps are as follows:
1. Screen printing a carbon layer onto a substrate (e.g., polyimide).
2. Screen-printed Ag/AgCl reference electrode
3. Screen printing Ag electrical connection traces
4. Screen-printed dielectric
4. Use a dual-laser process to generate carbon foam in the substrate.
All screen printing steps (1-3) can be completed using roll-to-roll or roll-to-sheet processes, followed by the use of a dual-laser process to generate carbon foam, and then the materials are kept flat and stacked.
Alternatively, only the first laser process (subsurface foam generation) can be completed in the facility, after which the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation). The customer can add functionalizing groups in their own manufacturing facility, different from the facility performing the first laser process step (or both laser process steps) in the dual-laser process. Alternatively, functionalization can be performed in the facility performing the dual-laser process.
Screen printing before manufacturing the carbon foam has advantages: because we don't dry the carbon foam, it's less hydrophobic. The carbon layer acts as a bridge between the carbon foam formed in the polyimide (e.g., carbon foam and non-graphene disordered amorphous foam) and the silver connectors.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode including at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on the substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon and the electrical connection trace and the reference electrode; and then (d) producing the carbon foam sensor electrode using a method as defined in any one of features A-K above.
Feature M1: Energy storage device: supercapacitor
Because carbon foam manufactured using any one of the characteristics A-K has a very large electrochemical active region and a fast electron transport rate, it is an ideal material for electrodes of capacitors, supercapacitors, or pseudocapacitors.
One important application is in supercapacitors (specifically implemented as "Gii-Cap") or other energy storage devices (e.g., lithium-ion batteries). For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; and higher wettability.
Carbon foam can be processed with metal oxides or other pseudocapacitive materials (variants of which we call Gii-Cap+) (e.g., to produce metal oxide layers or films), and the metal oxide films have extremely large surface areas and fast surface Faraday mechanisms.
It should be noted that when we use the term Gii-Cap, we include the Gii-Cap+ variant unless the context explicitly indicates that we specifically exclude the Gii-Cap+ variant. It should also be noted that we use the term "supercapacitor" to include (i) electrically double-layer (EDLC) capacitors, where charge is stored electrostatically with no interaction between the electrode and electrolyte ions, and (ii) pseudocapacitors, where there is electron charge transfer between the electrode and electrolyte, and in any energy storage device using a combination of electrically double-layer capacitors and pseudocapacitors. Finally, it should be noted that the term "supercapacitor" should be broadly interpreted to cover any electrochemical capacitor, including EDLC supercapacitors, pseudocapacitors, and mixtures of these. The Gii-Cap+ variant is primarily a pseudocapacitor, but we still refer to it as a "supercapacitor."
Compared to conventional supercapacitors, the carbon foam electrodes in the Gii-Cap supercapacitor enhance both electrostatic double-layer capacitance and electrochemical pseudocapacitance. Appendix 2 provides further details about the supercapacitor and describes a specific implementation in which an interdigitated carbon foam electrode in the active region is encapsulated by a hydrogel electrolyte (e.g., a salt with a high molar concentration) to generate an enhanced operating voltage window.
The implementations of EDLC supercapacitors Gii-Cap and pseudocapacitors Gii-Cap+ offer numerous advantages over conventional rechargeable batteries:
Fast charging
High power
Recyclable
Not easy to explode
Flexible forms and shapes
Solid gel electrolytes or polymeric electrolytes (e.g., ionogels or hydrogels) can be used, which are solid at room temperature and have a high transition temperature far exceeding the normal operating temperature (e.g., 90°C); this greatly reduces the risk of electrolyte leakage.
It can be used in a very wide range of devices and power storage needs, such as lab-on-a-chip (LOC), IoT devices, electric vehicles, UAVs, and EV applications.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
Figure 24 is an exploded perspective view of the Gii-Cap supercapacitor. It consists of a series of carbon foam electrodes 241 connected to a pair of screen-printed silver connectors 242, fabricated using the dual-laser process described above. A dielectric layer 243 is screen-printed over the carbon foam electrodes 241 and the screen-printed silver connectors 242. The carbon foam electrodes 241 are formed on a polyimide substrate 244. A pair of copper connector tabs 245 are connected to the pair of screen-printed silver connectors 242. An electrolyte layer 246 covers the carbon foam electrodes 241 (e.g., an ionogel electrolyte, such as a polymer hydrogel electrolyte, which is a gel or semi-solid at room temperature to minimize the risk of leakage and reversibly liquefies above 90°C, thus allowing application in liquid form during manufacturing). The assembly is sealed within an aluminum laminate heat-sealed bag 247.
Figure 25 is an exploded perspective view of a supercapacitor assembly: it consists of an interdigitated array of carbon foam electrodes 241 forming the supercapacitor; a screen-printed silver connector track 242 provides current to the carbon foam electrodes 241 and is covered by an electrically insulating dielectric layer 243. A polyimide sheet 244 forms the base of the assembly.
Figures 26A-H illustrate the manufacturing sequence. Figure 26A shows step 1, where interdigitated carbon foam electrodes are produced using a dual-laser process. The magnified area in Figure 26B shows the interdigitated carbon foam electrodes in more detail; group A electrodes form an electrode assembly, and group B electrodes form another electrode assembly; capacitive coupling between the two groups of electrodes stores energy. The carbon foam electrodes have a thickness of approximately 20-30 μm.
Figure 26C shows step 2, screen printing the silver collector electrodes. A silver connector A' supplies current to the A group of electrodes, and a silver connector B' supplies current to the B group of electrodes. The thickness of the silver layer is approximately 20-40 μm, and several layers can be applied.
We use a "common collector" layout: a typical interdigitated supercapacitor has two long silver collectors with graphene fingers extending from one side of each long silver collector. The long silver collectors have high resistance due to their length and require a significant amount of silver. Furthermore, printing the curved portions of the collectors is difficult. In the "common collector" method shown in Figure 26D, we have carbon foam fingers C extending from both sides of the shared collector 242: this maximizes the space utilization of the fingers and therefore maximizes the capacitance, reduces the amount of collector material required, and eliminates the difficult curved collector portions.
The region 250 of the carbon foam finger connected to the common collector electrode has rounded edges; these rounded edges reduce the chance of stress fracture and increase the reliability of the electrical connection.
Figure 26F shows step 3, in which the dielectric layer 243 is screen-printed over the silver collectors to make them electrically insulated; the thickness is approximately 10-30 μm.
Figure 26G shows step 4, adding copper connector tab 245 (made of conductive metal strip) to connect to the silver current collector 242. Figure 26H shows step 5, depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions. The electrolyte can be a combination of hydrogel and salt (see Appendix 2). Figure 26I shows step 6, packaging the entire assembly into an aluminum laminate heat-sealed bag 247, leaving only the copper connector tab 245 exposed. It should also be noted that step 4, adding the copper connector tab 245, can be performed before step 2 (screen printing the silver current collector) and after step 5 (depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions).
Figure 27 shows how a single polyimide sheet will accommodate six 220mm × 180mm Gii-Cap components; other sizes (e.g., A4, A5, A6, or sizes other than the standard A-series sizes) are also possible.
The detailed manufacturing process of Gii-Cap is shown in Figure 28.
The specifications for producing and operating Gii-Cap supercapacitors using hydrogel electrolytes in a single production run are shown in Table 3 below.
Table 3
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, the screen-printed electrical connection traces are formed above at least a portion of each electrode, and the screen-printed dielectric layer at least partially covers the electrodes and connection traces.
Feature M3: Carbon foam supercapacitor: common collector electrode
We saw how to use a "common collector electrode" above.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrodes comprise at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
PPC (Post-Printing Conversion) is shown in Figure 29. The steps are as follows:
1. Screen print the silver current collector onto a substrate (e.g., polyimide).
2. Print carbon screen printing over the silver current collector and then dry it.
3. Screen print the dielectric over the carbon layer and then dry it.
4. Carbon foam is generated in the carbon layer using a dual-laser process; the carbon foam is attached to the underlying polyimide substrate via a non-graphene interlayer.
5. Distribute electrolytes.
6. Add copper/aluminum inserts to make contact with the silver collector (or step 1).
7. Add a cap/small bag.
All screen printing steps (1-3) can be completed using a roll-to-roll process, followed by the generation of carbon foam using a dual-laser process, and then the material is kept flat and stacked. Alternatively, only the first laser process (generating carbon material foam under the surface) can be completed in the facility, and then the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation) and steps 5-7.
Screen printing before fabricating carbon foam has advantages: if carbon foam is made first, it may have sharp edges; the silver screen printing layer applied over these sharp edges may crack at these edges. However, by screen printing before creating the carbon foam, we avoid this problem. Additionally, because we don't dry the carbon foam, it is not hydrophobic.
We can summarize it as follows:
A method for manufacturing energy storage devices such as supercapacitors or pseudocapacitors;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
The Gii-Cap+ variant is produced using a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x ); its capacitance is much higher than that of the standard Gii-Cap device (see Table 4).
Table 4
This metal oxide electrochemical deposition process can be applied to both the Gii-Cap Supercap manufacturing process and the PPC process, and therefore all Gii-Cap products can also be Gii-Cap+ products. A detailed process flow diagram is shown in Figure 29.
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying a pseudocapacitive material, such as a metal oxide, to the energy storage electrode via an electrochemical deposition process.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
We use an ionic gel (an ionic liquid with fumed silica SiO2 ) that provides a voltage of 3V-6V. It is solid below 90°C, so it does not leak during transport and normal use, and is therefore particularly suitable for smart tags and IoT devices; above 90°C, it liquefies, and is therefore printable, with electrochemical printing occurring at temperatures above 90°C. Ionic gels are typically made from an ionic liquid (e.g., 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4)) plus a gel-forming agent (e.g., fumed silica SiO2 )).
Typically, manufacturing is carried out in an inert atmosphere (e.g., argon) because the presence of O2 and H2O can lead to a decrease in voltage and stability.
The optimal sites for achieving the best balance between increased capacitance and decreased voltage for O2 and H2O levels are described in more detail in Appendix 3 (GiiCap Iongel).
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
In the preceding sections covering features M1-M6, we focused on some general characteristics of Gii-Cap carbon foam supercapacitors. In the following sections covering features N-S, we focus on some more specific products that realize Gii-Cap.
Feature N1: Electrical conductor
For the biosensor devices described above, it is possible and desirable to fabricate electrical conductors providing measurement signal connections from carbon foam materials produced by a dual-laser method: because these conductors have extremely low resistance, sensitivity is maximized. Electrodes (e.g., functionalized biosensor working electrodes, and reference electrodes described above as being screen-printed; capacitor plate electrodes) are examples of electrical conductors covered by this feature N1. Additionally, this feature N1 also covers electrodes whose primary function is solely to carry signals and current, for example, to replace conventional silver connection traces, such as the screen-printed Ag electrical connection traces we described in the biosensors above.
We can summarize it as follows:
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
Features L1-L4 above describe biosensors using carbon foam fabricated by a dual-laser method in their sensor electrodes; features M1-M6 describe supercapacitors and pseudocapacitors using carbon foam fabricated by a dual-laser method in their electrodes.
A highly sensitive and selective biosensor can be established, and this biosensor and this supercapacitor can be combined into a single integrated device. The device also includes electronic circuitry for measuring the detected or measured variable, calculating the biosensor output and sending the output to a POC diagnostic device or displaying the output on the device's display screen (e.g., the presence or absence of the target; the concentration of the target).
Figure 30 is a schematic cross-section of this integrated LOC device: there are two separate polyimide membrane layers, the upper layer 301 comprising a functionalized carbon foam biosensor (Giii-Sens) 302, as described in feature L; and the lower layer 303 comprising a supercapacitor 304 (Giii-Cap), as described in feature M. Although the polyimide layers are shown back-to-back, they can also be arranged side-by-side; additionally, a single polyimide membrane can be used to integrate the biosensor 302 and the supercapacitor 304 together onto a single object.
A plastic component 305 with microchannels 306 provides a microfluidic system for dispensing test fluid over the biosensor 302; a subsurface carbon foam electrode or conventional connector track 307, as described in Feature O, guides the biosensor to a flexible electronics 308 (e.g., a microcontroller for measuring changes in the electrochemical properties of the biosensor in the presence of a target analyte; a display panel for displaying diagnostic results; a power management system for controlling power from the supercapacitor 304 to the electronics 308). The supercapacitor 304 (Gii-Cap) is charged (e.g., via a wireless sensing process (not shown) controlled by the microcontroller) and provides power for the biosensor measurement process and an integrated display showing the quantitative measurement results. Alternatively, a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) can charge the supercapacitor 304, which then provides power for the biosensor measurement process. Another variation uses a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) that charges the supercapacitor 304 and also provides power for the biosensor measurement process. The supercapacitor 304 is then reserved for powering high-power processes, such as wireless data transmission, enabling the LOC to function as a standalone LOC device capable of diagnostic processes and wirelessly transmitting result data without requiring the user to be near the LOC, which would be necessary if the LOC used conventional NFC (Near Field Communication). The electrical connector trace from the supercapacitor 304 to the flexible electronics 308 is not shown.
An exploded view of the fully integrated LoC device is shown in Figure 31. From the bottom up, we have (i) an induction power circuit 310; (ii) a Gii-Cap supercapacitor 312, which is wirelessly powered by the induction circuit 310; (iii) a Gii-Sens biosensor 313; (iv) a layer 314, which has electronics for the biosensor powered by the supercapacitor 312 and microfluidic channels; and (v) a top panel 315, which includes a display 316, also powered by the supercapacitor, and an annular aperture 317 into which samples are delivered.
Figure 32 shows the LOC (Local Occurrence) of the quantitative results displayed on its monitor.
Figure 33 shows an exploded view of an environmental monitoring device including a Gii-Sens sensor 330 configured to detect environmental parameters such as CO2 levels, volatile organic compounds, and other atmospheric pollutants. The Gii-Sens is not limited to being a biosensor and can also detect any molecule that can be functionalized to detect using a carbon foam sensor electrode. The environmental monitoring device includes the Gii-Sens sensor 330 and associated control and wireless transmission (e.g., LoRaWAN) electronics 331, as well as a PV solar cell 332 and a Gii-Cap supercapacitor 333. The electronics 331 include a secondary or primary battery (which may be a printed battery) and work in conjunction with the PV solar cell 332 to power those electronics and charge the Gii-Cap supercapacitor 333. The Gii-Sens sensor can also be configured to measure temperature, humidity, and pressure. The device has a back 334 that can be peeled off to expose an adhesive surface, allowing the device to be attached to a wall, etc. The PV solar cell, combined with a secondary or primary battery on electronic device 331, provides power to charge the Gii-Cap supercapacitor 333, which in turn provides the peak burst power required for data transmission. Unlike current environmental monitoring devices, this device can be permanently installed and maintained in place for many years without requiring battery replacement. It can detect atmospheric pollutants with a signal-to-noise ratio superior to conventional devices. The assembled device is shown in Figure 34.
Many other types of devices can be realized using a combination of carbon foam sensors and carbon foam supercapacitors; for example:
Any biosensor capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor, can benefit from wearable health monitoring devices such as continuous glucose monitors and other wearable monitors that sense electrolyte, potassium, sodium, and lactose levels.
This benefits from any sensor device capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor.
This benefits from any IoT device capable of transmitting data (e.g., wirelessly), where the data transmission is powered by a supercapacitor.
The device may include electronic components powered by a supercapacitor.
The device may include a battery to charge energy storage devices and/or power device electronics.
The device may include a PV battery to charge a secondary battery in an energy storage device and/or in a device and/or power device electronics.
We can summarize it as follows:
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
In this example, we combine two distinct power sources into a single device to form a combined or hybrid power source: the device has a battery (e.g., a printed battery or a conventional battery) and a supercapacitor, the supercapacitor using carbon foam made by a dual-laser method in its electrodes; they work together in a complementary manner. The battery can be a disposable, non-rechargeable battery (“primary” battery), or it can be a rechargeable battery (“secondary” battery).
The power sources serve complementary purposes: batteries can provide slow, long-term charging for supercapacitors or power relatively low-power-consuming electronic devices; supercapacitors can provide rapid, high-power discharging and power functions requiring higher power levels, such as wireless data connectivity and data payload transmission. It should be noted that the supercapacitor can be an EDL supercapacitor or a pseudocapacitor, or any other form of energy storage device. The device can be used in situations where high power is occasionally required (e.g., powering a transmitter to connect to a data network and send data payloads), but the device needs to be standalone and continuously used in the field for months or years: the device could be a high-value asset tracking tag that only occasionally needs to broadcast its information, but requires broadcasting at a higher power than conventional printed batteries can provide.
A schematic diagram is shown in Figure 35. There are two separate polyimide film layers: one layer 351 includes a supercapacitor (Gii-Cap) 352 as described in feature M, and the other layer 353 includes a cell 354, such as a printed cell; this can include electrodes made using carbon foam manufactured using a dual-laser process or conventional processes. It is also possible to fabricate the printed cell 354 and the supercapacitor 352 on the same sheet of polyimide, but yield may be affected because any defects in the printed flexible cell or supercapacitor will render the equipment unusable.
As described above, the subsurface carbon foam electrode (or conventional printed electrode) leads from the supercapacitor (Gii-Cap) 352 and the printed battery 354 to the BMS (Battery Management System) 355; the BMS 355 provides power to the flexible electronics 356; the subsurface carbon foam electrode or conventional connector track 357 connects different parts of the flexible electronics 356. The BMS 355 controls the flow of power from the battery 354 to the electronics 356; the battery 354 can trickle charge the supercapacitor 352. (The supercapacitor can also be the primary power source, designed to be charged once in the facility and then not need to be recharged.)
Battery 354 can be a printed battery, and can be a rechargeable secondary printed battery or a primary, non-rechargeable primary battery; battery 354 can trickle charge supercapacitor 352 and provide power to sensor or other device electronics 356; then, supercapacitor 352 provides power (e.g., instantaneous peak power) to circuits (such as data transmitters) that have short-term demands for relatively high burst power. As described above, the printed battery, supercapacitor, and electronics can all be part of a single integrated device, for example, all on a single substrate, or on a separate but attached substrate.
Although back-to-back polyimide layers are shown, they can also be side-by-side; in addition, there can be a single polyimide film that integrates the battery 354 and the supercapacitor 352 into a single object.
The battery 354, supercapacitor 352, and electronic device 356 can all be formed on one or more substrates as part of a continuous or batch manufacturing process (e.g., you don't use a previously manufactured battery and combine it with a supercapacitor). This allows the interconnects to be constructed as an integral part of the manufacturing process, resulting in lower costs, faster manufacturing, and higher performance (e.g., shorter interconnects).
The device can be used in smart tags (see below), or IoT environmental monitoring devices (e.g., temperature or humidity sensors), train seat occupancy sensors, or medical monitoring devices (e.g., continuous glucose monitors). More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
We can summarize it as follows:
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
One important application is the smart label, shown in Figure 36, with the bottom surface shown on the left and an exposed label surface 363 with human-readable text shown on the right. The label includes an adhesive release liner 364 to allow the bottom surface to be attached to packaging, components, etc. The label includes a thin, flexible battery 360 printed onto a polyimide film, and then a Gii-cap supercapacitor 361 formed on the same polyimide layer (or a different polyimide layer bonded to the printed battery polyimide film). The thin, flexible battery can be a non-rechargeable primary battery or a rechargeable secondary battery. The supercapacitor provides power to the data transmitter; the printed battery provides power to the smart label's electronics (including sensors) and power management electronics. Human-readable printed information 363 is included on one surface of the smart label; the back side...
The smart tag includes an electronics module 362 with power management, sensors (e.g., solid-state vibration, temperature, pressure, GPS, etc.) and data transmission electronics (e.g., an LTE transmitter or an ultra-low-cost LoRaWan transmitter). Once a data connection is established, the supercapacitor 361 provides sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in an "advertising" signal; instead, the smart tag can establish a data connection with a data receiver and then transmit the data payload once the connection is established; thus, it can be reasonably ensured that its data has been received. More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
For scalable manufacturing (e.g., producing millions of smart tags at low cost), roll-to-sheet manufacturing of smart tags is ideal (see Feature P: Gii 3 below).
We can summarize it as follows:
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics such as sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
The supercapacitor in the aforementioned example of feature M can provide power to the antenna but is not integrated with the battery: for example, it can provide power from a solar cell or draw power from local WiFi or a wireless charger (e.g., the Qi standard).
We can summarize it as follows:
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor
A useful feature is the combination of an energy harvester with a carbon foam supercapacitor. The energy harvester can be a solid-state energy harvester such as a solar cell, or a vibratory energy harvester (e.g., based on piezoelectric fibers), or a thermoelectric generator (e.g., a Seebeck generator). The supercapacitor can provide power (e.g., instantaneous power) to circuits with short-term demands for relatively high burst power (e.g., data transmitters and antennas). The device may also include a primary battery (e.g., a non-rechargeable printed battery) or a secondary rechargeable battery.
The energy harvester can be on the same substrate as the supercapacitor, or on a separate but connected substrate; the supercapacitor can be on the same side of the substrate as the energy harvester, or on opposite sides.
When the device includes a battery (e.g., a printed rechargeable secondary battery), the energy harvester charges the battery, and the battery provides power to low-power subsystems (e.g., sensors) and also charges the supercapacitor; the supercapacitor provides instantaneous high power for data transmission. Alternatively, the energy harvester can charge the supercapacitor directly.
This approach can be used in smart tags, or IoT environmental monitoring devices (such as temperature or humidity sensors), train seat occupancy sensors, wearable devices, and medical monitoring devices (such as continuous blood glucose monitors). This method is particularly useful in situations requiring continuous (or highly regular) power to the device, such as when continuous monitoring of the environment or an individual's health is necessary.
The device may include LoRaWan or other ultra-low power transmitters. Once a data connection is established, the supercapacitor can provide sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in the announcement signal; instead, the smart tag can establish a data connection with the data receiver and thus ensure that its data has been received.
More generally, the energy harvester can be a solid-state energy harvester, such as a solar cell, or a vibration energy harvester (e.g., based on piezoelectric fibers) or a thermoelectric generator (e.g., a Seebeck generator); the device can include one or more sensors powered by the energy harvester; the energy harvester can charge a supercapacitor; the device can include a primary or secondary battery; the device can be a smart tag, or an IoT environmental monitoring device (e.g., a temperature or humidity sensor), a train seat occupancy sensor, a wearable device, or a medical monitoring device.
We can summarize it as follows:
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
In an earlier chapter, we described the carbon foam in the Gii-Cap supercapacitor as a single planar interdigitated finger layer. In this section, we describe a three-dimensional structure of carbon foam that enables the carbon foam supercapacitor electrodes to be formed as a parallel-plate 3D structure with a greater energy storage potential than a single layer of interdigitated graphene foam fingers.
Figure 37 shows the basic layering of different materials in the core structure. Multiple screen printing steps are performed on the PI polyimide film 371 sheet. First, a conductor (such as a carbon ink or carbon paste layer 372) is screen-printed onto the lower surface of the polyimide film 371. Then, a current collector 373 (e.g., a screen-printed silver current collector) is screen-printed over the carbon layer 372. Finally, a dielectric layer 374 is screen-printed over the current collector.
Figure 38 shows the carbon foam layer formed in the polyimide film 371 using the dual-laser process described above: more specifically, an IR laser forms an encapsulated carbon foam layer 375 in the PI film 371; beneath this carbon foam layer is a disordered, amorphous, non-graphene layer 376 formed on the lower surface of the PI film 371. A CO2 ablation laser exposes the previously encapsulated carbon foam layer 370, thereby giving the exposed surface layer 377 a unique morphology.
This structure provides a conductive path from the current collector layer 373, through the conductive ink or paste layer 372, through the disordered amorphous non-graphene layer 376, and then to the carbon foam layer 375. In this way, the potential of the large-area carbon foam 375 can be increased, enabling it to act as a capacitor plate; the structure forms part of a half-cell.
Typical thicknesses are as follows: polyimide film 371: 127 μm; carbon ink layer: 20 μm; silver current collector layer 373: 30 μm; dielectric layer: 40 μm; carbon foam layer 375 and disordered amorphous non-graphene layer 376: 127 μm; unique surface morphology layer 377: 25 μm.
It should be noted that Gii-Cap+ (a variant that uses a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x , see Feature M2 above) and delivers significantly higher capacitance than the standard Gii-Cap device) can be used in Gii-Thru.
We can summarize it as
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising a carbon foam material made at least partially by a carbon precursor film as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Multiple structures as described in Figure 38 can be stacked together; since the surface area of the carbon foam layer can be very large (significantly larger than the surface area of the finger sites in the previously described planar interdigitated supercapacitor), this enables the production of high-performance supercapacitors.
The half-cell is illustrated in Figure 39. It comprises (gradually moving downwards through the structure): a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in a PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper tabs 395 for connection points; a screen-printed dielectric isolation layer 396; a second carbon foam layer 397 with a unique surface morphology in a PI film 398; and a hydrogel electrolyte layer 399 at the base of the stack. It may be helpful to associate this structure with the schematic diagram in Figure 38: in Figure 40A, we group the four main layers shown in Figure 38 at point A, i.e., moving downwards along the stack, the carbon foam layer, then the carbon ink layer, then the silver collector layer, and then the dielectric layer. Figure 40B is a cross-section of the structure of Figure 40A, showing the features of group A. Figure 40B is the same cross-section, but this time all the elements in Figure 39 are labeled.
The complete unit is shown in Figures 41A and 41B. In Figure 41A, we only label the features that are also present in Figure 39 (using the same numbering). So it includes: a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in the PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper inserts 395 for connection points; and a screen-printed dielectric isolation layer 396.
In Figure 41B, we now add an additional layer; moving down through the structure, we have a screen-printed dielectric insulating layer 400, followed by a screen-printed silver collector layer 401 with copper inserts 402, then a screen-printed carbon paste layer 403, and then a carbon foam layer 404 with a unique surface morphology in a PI film 405.
In Figure 41C, we group the four main layers shown in Figure 38 together at point A; the four top layers are grouped together at point B in the reverse order. Groups A and B are separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399, which is dispensed using a conventional electrolyte dispensing system.
Figure 41D is a cross-section of this structure, showing the A and B layers separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399. Figure 41E is the same cross-section, but this time the layers are numbered according to the schematic diagram in Figure 38.
Figure 41F is a perspective view of the assembled supercapacitor.
Figure 42 shows a stack of four full-cell supercapacitors; the carbon foam layer is shown in A, and the polymer hydrogel electrolyte is shown in B. Additional cells can be added to the stack to obtain the desired performance.
Figure 43A shows the detailed manufacturing process of the Gii-Thru supercapacitor, and Figure 43B shows the detailed manufacturing process of the Gii-Thru multi-stacked supercapacitor.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from the carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
The Gii-Thru structure described in Figure 38 can be used not only for supercapacitors but also for Gii-Sens sensors, such as biosensors.
For microfluidics, the Gii-Thru HISLOC (High Sensitivity, Low Cost) platform approach allows liquid and carbon foam sensors to be mounted on the upper surface of the biosensor device, with electrical connectors to the carbon foam sensor mounted on the lower surface. Microfluidics typically use functionalized gold electrodes, where all electrical connectors to these functionalized gold electrodes are coplanar; compared to these functionalized gold electrodes, Gii-Thru biosensors offer advantages in cost, yield, and performance. Furthermore, moving the electrical connectors to the bottom or base of the biosensor enables greater miniaturization and compatibility with point-of-care (POC) systems.
Figure 44A is a schematic cross-sectional view of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device. The top layer has three sample wells 440; the fluid to be analyzed flows into each of these samples 440. The wells 440 are formed as small pores in a laminated spacer layer 441 located above the polyimide film layer 442.
Three functionalized carbon foam regions are formed in the polyimide film layer 442, which form a reference electrode 448A, a working electrode 448B, and a counter electrode 448C; the upper surface of each electrode 448A-448C is exposed to the analytical flow present in the pore 440.
The base of the reference electrode 448A may include an Ag-AgCl layer (or a screen-printed carbon layer) 449; the base of the working electrode 448B is a screen-printed conductive carbon layer 443; and the base of the counter electrode 448C is another screen-printed conductive carbon layer 443. In this way, the reference electrode 448A is in electrical contact with the reference electrode connector 444A; the working electrode 448B is in electrical contact with the working electrode connector 444B; and the counter electrode 448C is in electrical contact with the counter electrode connector 444C.
The screen-printed dielectric layer 447 forms the base of the structure.
The interesting aspect of this structure is that the electrode connectors 444A-C are not coplanar with the functionalized carbon foam electrodes 448A-C, unlike conventional screen-printed sensors. Instead, they lie in the plane below the functionalized carbon foam electrodes 448A-C, on the opposite side of the aperture 440. This structure enables greater miniaturization and compatibility with POC (point-of-care) systems.
Figure 44B shows an isometric exploded view of the microfluidic diagnostic device of Figure 44A. Three sample wells 440 are located in a laminated spacer layer 441, which sits above a polyimide film layer 442. A reference electrode 448A, a working electrode 448B, and a counter electrode 448C are shown; the end of the reference electrode 448A is covered by an Ag-AgCl layer or a screen-printed carbon layer 449; the working electrode 448B and the counter electrode 448C are covered by a screen-printed conductive carbon layer 443. As noted above, the reference electrode 448A is in electrical contact with a reference electrode connector 444A; the working electrode 448B is in electrical contact with a working electrode connector 444B; and the counter electrode 448C is in electrical contact with a counter electrode connector 444C.
It should be noted that the three functionalized carbon foam regions 448A-C are shown as planar squares located on different planes; however, this is merely an artificial creation of the CAD drawing used to generate the figures, and the carbon foam regions 448A-C are better represented in Figure 44A. A screen-printed dielectric layer 447 forms the base of the structure.
Figures 44A and 44B above show a three-point array microfluidic diagnostic device. In Figures 45A and 45B, we present an eight-point array microfluidic diagnostic device. In isometric Figure 45A, the laminated pore spacer 451 includes an array of eight analyte holes 452 for the working electrode, plus holes 453 for the counter electrode and holes 454 for the reference electrode; the laminated pore spacer 451 is located above the polyimide layer 455. Gii carbon foam in the polyimide layer 456 forms eight working electrodes 457 and counter electrodes 458, and is fabricated using a dual-laser process. It should also be noted that the carbon foam electrodes 457, 458 are shown as planar squares located on three different planes; however, this is merely an artificial CAD design, and the carbon foam forms a continuous region within the polyimide layer 455.
The reference electrode 459 is covered with a thin screen-printed Ag-AgCl layer. A thin screen-printed carbon bonding interface layer 460 is located below the working electrode 457 and the counter electrode 458; screen-printed silver bonding traces 461 form electrical connections with all electrodes 457, 458, and 459. Then, a screen-printed dielectric layer 462 forms the housing of the device. Figure 45B is a pair of top views of the device of Figure 45A; the lower figure shows the path of the lower bonding traces.
Figure 46A shows a perspective view of the fully assembled multi-sample array microfluidic diagnostic device; Figure 46B is a top view.
We can summarize it as
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode, at least partially made of a carbon precursor film by means of any one of the features A-K above, in a layer below the sample orifice, and a reference electrode connector, a working electrode connector, and a counter electrode connector are also in the layer below the reference electrode, working electrode, and counter electrode.
Figure 47A shows an exploded view of a microfluidic diagnostic device comprising multiple laminated layers; it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. The top layer 470 of the device is a microfluidic foil; the middle layer 471 is a microfluidic foil with an adhesive and includes printed or molded microfluidic channels 472, and the bottom layer 473 is a microfluidic foil with an adhesive. The Gii-Thru sensor 474 is a three-point array (3SA) biosensor and includes a connector 475. Figure 47B is a top view showing the internal structure. The Gii-Thru sensor 473 can be replaced with different biosensors (e.g., 8SA) for greater flexibility.
Figure 48B shows an exploded view of a microfluidic diagnostic device comprising a printed or molded microfluidic card, and it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. This device includes a transparent resin barbed connector 481, a top foil 482, a transparent resin molded microfluidic card 483 with microfluidic channels 484, a perforated unit 485 made of microfluidic foil with an adhesive, and a Gii-Thru sensor 486. Similarly, the Gii-Thru sensor 486 can be replaced with different biosensors (e.g., 8SA) for greater flexibility, and the molded microfluidic card 483 can be replaced with designs featuring different microfluidic characteristics to allow for use on different assay platforms. Figure 45B is a top and side view.
Feature O4: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
The HISLOC manufacturing process can be summarized as follows:
1. Screen print the elastic layer onto the underside of the polyimide film.
2. Screen-printed silver connectors.
3. Screen printing silver/silver chloride reference electrode (steps 3 and 4 can be rearranged into 4 then 3).
4. Screen-printed dielectrics.
5. Gii carbon foam sensor electrodes are generated in a polyimide film using a dual-laser process.
The detailed manufacturing process is shown in Figure 49.
We can summarize it as follows:
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising a carbon foam material made at least partially from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Group 4
Feature P: Scalable manufacturing: G-ii 3
Gii-3 is a scalable manufacturing facility for roll-to-roll or roll-to-sheet production of all the Gii-based materials described above. A key commercial advantage is that Gii-3 manufacturing does not require custom equipment; it utilizes off-the-shelf computer-controlled lasers for dual-laser carbon foam manufacturing, along with conventional screen printing and drying techniques: these are well-known, easy-to-understand manufacturing processes and equipment that enable reproducibility and reliability.
Figure 50 is a schematic diagram of the overall manufacturing process, and Figure 51 shows the detailed process flow.
We can summarize it as follows:
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other Gii applications
The Gii carbon foam described in this specification can be used in a wide variety of applications, including many applications where conventional graphene foam is considered suitable.
We can summarize it as follows:
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, a tactile sensor for robots; a prototype sensor is shown that uses polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as the active layer in a piezoresistive pressure sensor for robotic touch sensing applications: several carbon foam layers are capable of exhibiting pressure sensitivity of 0.0418 mV/kPa in the range of 0 to >50 kPa. See DOI:10.4028/p-oy94hj. and DOI:1109/CDE52135.2021.9455738. These contents are incorporated herein by reference to the maximum extent permitted.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection. See DOI:10.1016/j.bios.2022.114954, the contents of which are incorporated herein by reference to the maximum extent permitted.
Continuous monitoring of chemical sensors.
Glucose Monitoring Sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring is shown; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competitively binding with polynordihydroguaiaric acid. See DOI:10.1039/D1AN01991K, the contents of which are incorporated herein by reference to the fullest extent permitted.
Lactic acid sensor: Employs a synthetic organic acceptor molecule based on attaching boric acid to a carbon foam to provide functionality and selectivity in competitive analyte binding, with surface redox polymer indicator substitution used. See DOI:10.1016/j.snb2022.133089, the contents of which are incorporated herein by reference to the maximum extent permitted.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1). See DOI:10.1016/j.elecom.2022.107394, the contents of which are incorporated herein by reference to the fullest extent permitted.
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
Under a scanning electron microscope, conventional graphene foam appears to have large open ring structures, typically 500 μm in size. Carbon foam generated using a dual-laser process looks very different; Figures 52–57A are SEM images of this Gii carbon foam.
Figure 57B is a SEM image of carbon nano-onions, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI:10.1007/s00339-015-9315-9 and "Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications", DOI:10.1016/j.ica.2017.07.021. Its similarity to Gii carbon foam is obvious.
As previously mentioned, graphene foam possesses several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature features: the absence of a D peak; a 2D peak higher than the G peak; and a D:G peak ratio close to zero. However, carbon foam produced using a dual-laser process does not exhibit these characteristics; it is hydrophilic with a contact angle below 20°; and it lacks the Raman spectral signature indicative of graphene: it displays a prominent D peak; a 2D peak significantly smaller than the G peak; and a D:G peak ratio significantly higher than zero. Figure 58 shows the Raman shifts of eight carbon foam sheets fabricated using a dual-laser process, demonstrating the consistency of the Raman signature. It also shows a prominent D peak; a 2D peak smaller than the G peak; and a D:G peak ratio significantly higher than zero. As we previously stated, this Raman spectrum shares many similarities with carbon nanotube onions. See also Figure 18C, also from “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9. The specific dual-laser parameters used to generate this low-resistivity carbon nano-onion variant of Gii carbon foam are shown in Table 5 below:
Table 5
We can summarize it as follows:
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
It should be noted that any of the devices described above, such as sensors, pressure sensors, biosensors, Hall effect sensors, supercapacitors, hydrogen fuel cells, and filters, can be characterized using these materials, and therefore we can summarize as follows:
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Appendix 2 Gii-Cap+ Hydrogel
Appendix 3 GiiCap Ion Gel
Appendix 4 Feasibility Study Recommendation (3 Months)
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Material via Connectors
Appendix 6 Baseline Experimental Conditions
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
It should be noted that Appendices 1-7 describe specific implementations of Gii carbon foam.
Appendix 8: Combined list of features and optional features
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
background
A supercapacitor is a device that stores electrical charge. Based on its structure and function, a supercapacitor falls between an electrolytic capacitor and a rechargeable battery.
The properties of supercapacitors make them superior to rechargeable batteries in applications requiring short charging times and those involving many charge/discharge cycles. However, compared to batteries, supercapacitors have disadvantages including a weaker ability to store energy over long periods.
The operational limitations of supercapacitors are determined by the material properties of their components. Specifically, the maximum voltage at which a supercapacitor can operate (i.e., can be charged) depends on the stability of the electrolyte and/or electrodes. The maximum voltage of a capacitor is an important parameter, especially since the energy stored in a capacitor is proportional to the square of the voltage. Supercapacitors with organic electrolytes typically support higher voltages than those with aqueous electrolytes. By utilizing organic electrolytes, supercapacitor designers can produce devices with an operating range of 2.5 to 2.7 V. In contrast, while aqueous electrolytes are often preferred due to their lower cost and lower toxicity, they typically result in devices with a lower operating voltage range. Known symmetrical aqueous supercapacitors generally cannot support voltages higher than 1.3–1.5 V. This voltage limitation can reach 1.8–2.0 V if electrodes made of different materials are used. The limitations of water-based supercapacitors are attributed to the electrolysis of water, which, in principle, occurs when water is exposed to a potential difference of 1.23 V. However, in practice, a larger potential difference is required before electrolysis occurs to overcome the effects of overpotential.
Carbon-based electrodes have been associated with supercapacitors since their early development. Initially, carbon attracted attention as an electrode material because it offered the possibility of fabricating electrodes with large surface areas. Later in the development of supercapacitor devices, the importance of the so-called double layer on the electrode surface was realized. This complex and often elusive phenomenon, related to the use of carbon as an electrode material, is central to the high capacitance values associated with supercapacitors. Supercapacitor devices incorporating carbon-based electrodes are thought to involve a double layer on the electrode surface, with energy stored electrostatically. Such supercapacitors are called electrostatic double-layer capacitors, or EDLCs.
Other types of supercapacitors also exist. Electrochemical pseudocapacitors utilize metal oxide electrodes or conductive polymer electrodes. Compared to the electrostatic charge storage mechanism of EDLCs, charge storage in pseudocapacitors is primarily electrochemical. A third type of supercapacitor is the hybrid capacitor. Hybrid capacitors have asymmetric electrodes. One electrode is typically made of carbon and exhibits electrostatic charge storage properties; the other electrode is typically a lithium-containing or lithium-doped material, which primarily exhibits electrochemical charge storage properties.
Conventionally, a supercapacitor can be considered and modeled as two capacitors connected in series, with each electrode associated with one capacitor. Each capacitor is located at the interface between the electrode and the electrolyte and is formed by the supercapacitor electrode, a dielectric layer (called the inner Helmholtz plane) formed by solvent molecules present in the electrolyte, and a charge carrier layer (called the outer Helmholtz plane) provided by the electrolyte as the opposite charge charging the electrode. This triple structure of the electrode, inner Helmholtz plane, and outer Helmholtz plane forming the capacitor system at each electrode is called a double layer or electrical double layer.
Summary of features in Appendix 1
A first aspect of the aforementioned features provides a symmetrical supercapacitor device comprising: two electrodes, each comprising a carbon foam as described in this specification (e.g., see features A-K in Appendix 8); and an ion gel or hydrogel electrolyte encapsulating the electrodes in active regions.
We have found that symmetrical supercapacitor devices, based on a combination of the characteristics described above, produce an enhanced operating voltage window. The term "symmetrical" refers to the fact that the electrodes comprise the same material and may be constructed from the same material.
The operating voltage window, or operating range, of a supercapacitor is a critical parameter of such a device and is determined by the breakdown voltage of the electrolyte. For supercapacitors based on aqueous electrolytes, water decomposition typically leads to limitations on the operating voltage window.
Although the reasons for the unexpectedly large operating window observed using the device disclosed in this invention are not yet fully understood, it is evident, without being bound by any theory, that the special property is a result of the combination of the carbon foam electrode and the electrolyte, and especially of the interface between these elements.
In electrochemistry, the large operating window of the device of this invention is equivalent to an unexpectedly large overpotential at the electrode. An overpotential is a potential difference exceeding the thermodynamic redox potential required for a specific reduction/oxidation reaction to occur. Overpotential is often a difficult phenomenon to understand, partly because many factors contribute to it. For example, overpotential depends on the electrode material, electrode morphology, and the properties of the electrolyte. In this invention, the large surface area provided to the electrolyte by the carbon foam electrode is considered likely to play a role in device performance. It is known that how ions diffuse from the electrolyte bulk to the electrode surface and the associated consumption of charge carriers on the electrode surface affect the overpotential. This may play a role in the device of this invention. The diffusion rate of charge carriers in the electrolyte may be affected by the presence of hydrated ions, which are larger than non-hydrated ions. The interaction between charge carriers and the morphology of the carbon foam electrode may also affect the overpotential. The presence of ion-gel or hydrogel polymers is also considered to influence the diffusion of charge carriers to the electrode surface, possibly due to spatial effects and related to the carbon foam morphology.
Hydrogels are gels whose liquid component is water and can be formed from a network of polymer chains. Supercapacitors with a hydrogel electrolyte forming the dielectric are expected to have performance characteristics associated with aqueous electrolyte-based supercapacitors. However, to this expectation, the inventors have found that the performance of a supercapacitor according to a first aspect (i.e., a symmetrical device in which the electrodes are made of the same material, including carbon foam and encapsulated in a hydrogel electrolyte) surpasses the expected performance of an aqueous device. The operating voltage window of the device is unexpectedly enhanced compared to aqueous electrolyte-based devices. The operating window is more similar to that of organic solvent-based supercapacitors.
Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), sodium polyacrylate, acrylate polymers, and copolymers, which have a large number of hydrophilic groups, are examples of polymers that can be utilized in hydrogels. Fluorinated hydrogels can also be used. The combination of hydrogels and ionic charge carriers helps to achieve a surprisingly large operating window through the system of the present invention.
The electrodes of the device disclosed in this invention are located on a substrate, and the electrolyte is present on top of the electrodes in a manner that seals at least a portion of the electrode structure, thus forming an active region. The active region of a supercapacitor is the region in a supercapacitor that stores charge, including the electrolyte and the electrodes.
The electrodes of the device can have an interdigitated geometry, meaning they can be interdigitated. This interdigitated electrode geometry helps maximize the capacitance of the supercapacitor. It also enables a device without a separator. Supercapacitors typically include separators between opposite electrodes to prevent short circuits. The absence of a separator facilitates the construction of supercapacitor devices. Separators can also negatively impact device performance, such as inhibiting charge flow and reducing charge/discharge rates. The absence of a separator avoids these negative performance effects.
Interdigitated electrode geometries are well-suited for symmetrical devices. Constructing an interdigitated electrode geometry with opposite electrodes made of different materials is significantly more complex than with electrodes made of the same material. If the electrodes are made of the same material, they can be fabricated in-situ in a single step. Using different electrode materials requires multiple fabrication steps, greatly increasing the complexity of the manufacturing process.
In addition, the absence of a separator eliminates any negative impact that a separator might have on device performance, such as inhibiting charge flow and causing a decrease in charge/discharge rate.
The hydrogel electrolyte can contain a sufficiently high charge carrier concentration to produce the enhanced operating voltage window.
An enhanced operating voltage window may depend on the concentration of charge carriers.
Charge carriers can have redox potentials that support an enhanced operating voltage window.
The charge carrier can be provided by aqueous solutions of acids, bases, or salts. Usable acids include sulfuric acid. Usable bases include potassium hydroxide.
Hydrogel electrolytes may comprise a mixture of hydrogel and salt. The electrolyte may be composed of a hydrogel polymer, such as PVA or PVP. The salt may be, for example, NaClO₄ , NaNO₃ , or Mg( ClO₄ ) ₂ . The molar concentration of the salt may be, for example, 0.5 M or greater, such as 1 M or greater, such as 2 M or greater, such as 2.5 M or greater, such as 3 M or greater, such as about 5 M. The molar concentration of the salt may be, for example, between 1 M and 10 M, or it may be, for example, between 2.5 M and 7.5 M.
Salts that can be used include phosphates, perchlorates, nitrates, and arsenates. Examples of salts include sodium sulfate, sodium bisulfate, sodium persulfate, sodium perchlorate, lithium perchlorate, magnesium perchlorate, sodium nitrate, and lithium hexafluoroarsenate. Aqueous solutions of these salts can be used in electrolytes to provide ion carriers.
Charge carriers can be ions. Charge carriers can be hydrated ions.
Hydrated ions are ions in an aqueous environment. Polar water molecules arrange themselves around the ions, forming hydrated spheres centered on the ions. The details of the mechanism behind the surprisingly wide enhanced operating voltage window observed with respect to the features of this invention are difficult to understand, and the inventors do not wish to be bound by theory. However, the surprisingly advantageous properties of the device of this invention are a result of the synergistic effect between the electrodes and the dielectric material. The enhanced performance is a lack of water splitting under voltage conditions under which electrolysis is expected to occur by those skilled in the art. The interface between the electrode and the electrolyte is expected to be the origin of its performance. There may be a synergistic interaction between the size of the charge carrier (possibly a hydrate) and the size of the pores present in the electrode. The hydrogel contains a network of polymer chains, and this chain network of the hydrogel may also have physical (spatial) effects that limit the exposure of water molecules to potential differences that could lead to their decomposition.
The increased size of hydrated ions is thought to combine with the porous structure of the carbon foam electrode to impede diffusion near the electrode surface, leading to an increase in overpotential.
The electrodes of a symmetrical supercapacitor device may include porous carbon foam. Optionally, the electrodes may not include additional adhesive material.
Porous carbon foam electrodes are thought to be combined with charge carriers in the electrolyte to increase overpotential, thereby enhancing the operating window of supercapacitors.
Carbon foam consists of one or more 2D carbon sheets (each sheet being a layer of sp2-bonded carbon) folded back-to-back to form a three-dimensional structure rather than planar sheets. Carbon foam lacks the regular AB stacking of planar carbon sheets found in graphite or multilayer 2D carbon. Carbon foam materials are typically porous. Carbon foam has a high surface area. By changing the parameters of the growth method, the porosity of the carbon foam can be controlled, and thus the surface area of the foam. This has the advantage of allowing control over the porosity of the device electrodes during the electrode fabrication process.
Carbon foam electrodes can be mounted on a substrate. Carbon foam electrodes can be mounted on a polyimide substrate. The polyimide substrate can be polyimide. The substrate can form the substrate of a supercapacitor device. The substrate can be thin enough to be flexible, thereby creating a flexible supercapacitor device. The substrate can contain one or more of the following materials (e.g., formed therefrom): polyimides (e.g., poly(4,4'-oxydiphenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde resins.
These substrate materials can be used as a carbon source and transformed into carbon foam using the dual-laser process described above. Carbon foam can be produced in this way by irradiating a polyimide substrate (e.g., with radiation, such as laser radiation). The resulting carbon foam is chemically and indirectly fixed to the substrate via an intermediate layer of amorphous, non-graphene material directly attached to the substrate (see earlier in this specification), resulting in a robust structure. Therefore, electrodes can be produced in situ by using a portion of the substrate as a carbon source, i.e., as a reagent for producing carbon foam. The structure is both robust and flexible. Flexible devices have advantages in many ways. Flexible devices can be conveniently packaged, for example, by rolling them up. For example, flexible devices can also be attached to the surface of curved structures.
The substrate can be substantially planar. The substrate can be a film, such as a thin film. The substrate thickness can be greater than 5 μm. The substrate thickness can be less than 120 μm. The substrate thickness can be between 5 μm and 120 μm. The substrate thickness can be substantially uniform across the substrate surface. The substrate can be flexible. The substrate can be tough.
The substrate may be a polyimide strip (e.g., a polyimide strip) having a first surface and a second surface.
Electrodes can be mass-balanced to optimize the operating voltage window.
A supercapacitor can be viewed as two capacitors connected in series. To maximize the capacitance of a supercapacitor, the capacitances of the two constituent capacitors should be equal. This can be engineered by adjusting the surface area of each electrode, thereby compensating for other factors affecting the capacitance, such as the properties of solvated ions. This process of adjusting the individual electrodes is called mass balancing. Electrode mass balancing has the advantages of maximizing the capacity of the superconducting device and extending the lifespan of the supercapacitor.
In a second aspect, there is a method for manufacturing a symmetrical supercapacitor device according to the first aspect, wherein:
Electrodes are formed on the substrate;
Electrolyte precursors containing charge carriers and hydrogels are applied to electrodes;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the active region.
Carbon foam electrodes can be fabricated by: converting a portion of a substrate (if the substrate is or includes a carbon source) into carbon foam; or by using chemical or physical deposition methods, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), sputtering, laser-induced growth, pulsed laser deposition, cathodic arc deposition, spin coating, dip coating, or sol-gel methods. In this way, electrodes are produced in situ on the substrate.
Electrolyte precursors can be prepared by preparing an aqueous solution of the charge carrier and then mixing this aqueous solution with a hydrogel. Electrodes can be formed using laser radiation.
When preparing the electrolyte precursor, it is important to remember that precipitation or crystallization of salts in the electrolyte is undesirable. Precipitation of salts or any solids in the electrolyte can lead to device breakage, or other defects in the device, or defects in its performance. This sets an upper limit on the concentration of the salt solution. Avoiding the use of supersaturated salt solutions may be advantageous. The precise upper limit of concentration may depend on the specific chemical composition present. For sodium perchlorate, the inventors have found that an electrolyte produced at a concentration of 5M avoids salt precipitation or crystallization, and, in combination with other features, allows the operating window of the supercapacitor device to extend beyond what would be expected based on considerations of the individual components. The electrolyte may include a salt solution with a concentration greater than 4M. The electrolyte may include a salt solution with a concentration greater than 3M, or greater than 2M, or greater than 1M, or greater than 0.5M.
At higher concentrations, salts were observed to precipitate readily from the electrolyte gel, and at such a rapid rate that the device became unusable. This precipitation may be caused by water evaporation. Hydrolysis and water loss could be another cause. In any case, the inventors found that although the electrolyte gel could be formed using sodium perchlorate at concentrations up to 16.5 M, precipitation problems were observed at all concentrations above 10 M.
High-molar salt solutions can be used when manufacturing hydrogel electrolytes.
For cost reasons, lower concentrations of salt solutions are generally advantageous.
The thickness of the carbon foam layer can be between 10 μm and 100 μm. This contributes to the flexibility of the device, allowing it to be rolled up for greater compactness.
A gap between 100 μm and 1000 μm can separate the electrodes from each other. The capacity of the device depends on the gap between the electrodes, and therefore adjusting this gap will affect the amount of charge that can be stored.
The operating window of the device of the present invention can be greater than 1.5V, or it can be greater than 2V, or it can be greater than 2.5V.
Any optional or preferred feature of any aspect of the system can be a feature of any other aspect of the system.
Appendix 1: Description of the Drawings
We have referenced the following attached figures, in which:
Figure 59 shows the carbon foam cyclic voltammetry measured at 25 mV/s for a positive voltage.
Figure 60 shows the carbon foam cyclic voltammetry measured at 25 mV/s for negative voltage.
Figure 61 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a positive voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a negative voltage window.
Figure 63 presents carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 presents carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 presents carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 1 Detailed Description
Dual-electrode supercapacitor
A typical carbon foam supercapacitor device based on this characteristic has interdigitated carbon foam electrodes, as shown in Figure 26. To summarize, a polyimide substrate supports the supercapacitor electrodes, which in this example are constructed of carbon foam and arranged in an interdigitated comb geometry, forming an interdigitated electrode structure. Silver current collectors extend along each side of the device, making each opposite electrode electrically integrated. The non-substrate side of the interdigitated electrode structure is encapsulated in a hydrogel. A polyimide cap can be added to contain the hydrogel, or the device can be packaged in other suitable ways.
As explained above, carbon foam electrodes can be formed on a polyimide substrate. Carbon foam is formed above a suitable substrate (i.e., a substrate providing the carbon source, in this example, a polyimide substrate) by exposing it to a laser beam. The carbon foam produced in this way grows from the substrate and indirectly adheres to it. The substrate and the carbon foam electrode formed in situ in this way form a single unit.
The carbon foam electrodes are manufactured using an infrared CO2 laser under ambient conditions. The substrate is a commercially available polyimide film with a nominal thickness of 127 micrometers. One example has eleven parallel carbon foam strips per electrode. This number can obviously vary. The carbon foam strips of the positive electrode are offset relative to the carbon foam strips of the second electrode, thus forming an interdigitated structure.
Electrode dimensions are shown in Table 6:
| <![CDATA[<u>mass balance ratio</u>]]> | 1.18 |
| <![CDATA[<u>Positive half-cell "electrode finger"</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.0472 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.20768 |
| <![CDATA[<u>Negative half-cell “electrode finger”</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.04 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.176 |
| Distance between fingers (cm) | 0.04 |
| <![CDATA[Total active electrode surface area (cm<sup>2</sup>)]]> | 0.38368 |
| <![CDATA[Total active electrode volume (cm<sup>3</sup>)]]> | 0.0019184 |
Table 6
Three-electrode device
In addition to the two-electrode supercapacitor device, a three-electrode testing device including a reference electrode was also fabricated. The three-electrode device comprises a working electrode, a counter electrode, and an Ag/AgCl reference electrode. Each of the working and counter electrodes is made of carbon foam, which in this specific embodiment is generated by dual-laser irradiation of a polyimide substrate, as previously described. This device is used to determine the stable voltage range of the NaClO4 hydrogel electrolyte. The three-electrode device is stabilized for at least one hour after fabrication before any measurements are performed.
Preparation of hydrogel electrolytes
Each of the disclosed two-electrode and three-electrode devices is based on a 5M sodium perchlorate solution, and the electrolyte is prepared as described herein. The 5M sodium perchlorate solution is prepared by dissolving sodium perchlorate (98% purity, from Sigma-Aldrich) in deionized water (dosage: 3.061 g NaClO₄ dissolved in 5 mL deionized H₂O ). The sodium perchlorate solution is then stirred with a magnetic stirrer on a hot plate at 120°C while polyvinyl alcohol (PVA, 99% hydrolyzed, Sigma-Aldrich) is added. 1.5 g of PVA is dissolved per 10 mL of solution. The mixture of sodium perchlorate solution and PVA is removed from the hot plate and allowed to cool, subsequently forming a white, opaque gel-like solution. The gel solution is then heated to 120°C until it liquefies and becomes transparent. It is then deposited onto a graphene electrode. After deposition onto the electrode surface, the liquefied hydrogel electrolyte material solidifies within approximately 5 minutes at room temperature. The amount of electrolyte deposited on the electrode depends on the surface area to be covered. For the test setup, deposit 150 μL of electrolyte.
Experimental results of the three-electrode device
The performance achievable from supercapacitors is ultimately limited by the stability of the electrolyte.
To test the electrolyte stability in the system of this invention, several experiments were performed using the three-electrode apparatus described herein. Differential pulse voltammetry (DPV) was initially used to select which voltage windows to investigate via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements.
i-Cyclic Voltmeter Method
Cyclic voltammetry measurements were performed to determine the stability of the electrolyte. In a standard three-electrode measurement, the potential between the working electrode and the reference electrode was scanned at a constant rate from the open-circuit potential (OCP; nominal 0V) to a predetermined upper limit, and then scanned downwards again. The current response of the working electrode was monitored during this period.
The results of these measurements are shown in Figures 59 and 60. Figure 59 shows the results of scanning the voltage from OCP in the positive direction.
The upper results set shows four voltammograms with maximum potentials of 1V, 1.2V, 1.3V, and 1.4V. The lower results set also includes a voltammogram with a maximum potential of 1.6V. As the upper voltage limit increases above 1.2V, the shape of the cyclic voltammograms becomes less "square." The tails become increasingly pronounced as the final scan voltage increases, indicating electrolyte degradation, which may be attributed to water electrolysis. These voltammograms indicate that the electrolyte is stable up to +1.2V.
Figure 60 shows a similar set of results, but for the negative electrode voltage. These data indicate that the electrolyte is stable up to -1.4V.
In summary, the data in Figures 59 and 60 provide an operating window of 2.6V for the device. This is significantly higher than expected when using an aqueous electrolyte.
ii. Constant Current Charge-Discharge (GCD) Data
Constant current charge-discharge (GCD) measurements were performed to determine coulombic efficiency based on charge and discharge times. In these measurements, a current was applied between the counter and the working electrode, and the voltage response of the working electrode (relative to the reference electrode) was measured. The GCD curves measured for the positive electrode voltage using a discharge current of 2 × 10⁻⁵ A (0.5 mA/ cm² ) for a selected voltage window are shown in Figure 61. The curves plateau above 1.2 V, indicating electrolyte degradation. The GCD curves for a selected negative electrode voltage window are shown in Figure 62.
A significant plateau was observed in the voltage windows up to -1.6V and -1.8V, indicating electrolyte degradation. The -1.4V voltage window exhibited a triangular GCD curve, indicating stability.
The results of cyclic voltammetry and constant current charge-discharge measurements of the three-electrode system are summarized in the table below.
The first table (Table 7) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the positive voltage window.
Table 7
The second table (Table 8) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the negative electrode voltage window.
Table 8
In these summary tables, coulombic efficiency is the ratio of stored energy to delivered energy measured in the second GCD cycle; areal capacitance in mF/ cm² is calculated using the following formula:
Area Capacitor
Furthermore, the discharge energy is the integral of the charging and discharging portions of the GCD curve over time.
The GCD curve indicates that +1.2V and -1.4V are the actual positive and negative voltage limits.
These voltage limits and areal capacitance values allow for the calculation of mass balance using the following formula:
Where, m + = mass of the positive electrode, m - = mass of the negative electrode, C + = capacitance of the positive electrode (F), C - = capacitance of the negative electrode (F), ΔE + = positive electrode voltage window limit, ΔE - = negative electrode voltage window limit.
Experimental Results of a Two-Electrode Device—Supercapacitor Performance
For the dual-electrode supercapacitor device, galvanostatic charge-discharge (GCD) data were collected within an applied current density range of 0.25 mA/ cm² to 30 mA/ cm² . Figure 63 plots the GCD results obtained from five different devices (CH1-CH5). These data were collected using a voltage window of 2.6 V, and greater electrolyte stability was observed at higher current densities. Further performance data for the dual-electrode supercapacitor are presented in Figure 64, showing cyclic voltammetry plots recorded from five different devices (devices #1 to #5) according to an embodiment of the invention at scan rates from 0.01 V/s to 5 V/s.
The cyclic voltammograms in the right column were recorded at low scan rates (0.01 V/s, 0.025 V/s, 0.05 V/s, 0.075 V/s, 0.1 V/s, 0.25 V/s, and 0.5 V/s), while the cyclic voltammograms in the left column were recorded at high scan rates (0.75 V/s, 1 V/s, 2 V/s, 3 V/s, 4 V/s, and 5 V/s). The trend shown in these data is that higher scan rates correlate with higher electrolyte stability. In each set of cyclic voltammograms shown in Figure 64, faster scan voltages resulted in larger differences in the current response between voltage rise and voltage fall.
In addition to the devices disclosed above, devices were also constructed in a similar manner but using hydrogel electrolytes comprising the following: (a) 3M NaClO 4 and PVA, (b) 1M NaClO 4 and PVA, (c) 2.5M NaNO 3 and PVA, (d) 3M Mg(ClO 4 ) 2 and PVA, and (e) 5M NaClO 4 and PVP.
The cyclic voltammetry results of these additional devices are shown in Figure [.]10. For each electrolyte, cyclic voltammetry was run between 0V and 0.7V, 0V and 0.8V, 0V and 0.9V, 0V and 1.0V, 0V and 1.2V, 0V and 1.3V, and 0V and 1.4V. Similarly, for each electrolyte, cyclic voltammetry was run between 0V and -0.7V, 0V and -0.8V, 0V and -0.9V, 0V and -1.0V, 0V and -1.2V, 0V and -1.3V, and 0V and -1.4V. These data are shown in Figure 65.
Data indicate that, in each device, for (d) 3M Mg(ClO 4 ) 2 and PVA and (e) 5M NaClO 4 and PVP, the electrolyte is stable up to the limits of -1.4V and +1.1V and up to +1.2V.
Further changes and modifications may be made within the scope of this disclosure.
Appendix 1 Concepts
1. A symmetrical supercapacitor device, comprising:
Two electrodes, each comprising a carbon foam material; and
Hydrogel electrolytes encapsulate electrodes in their active regions.
2. The symmetrical supercapacitor device according to Concept 1, wherein the hydrogel electrolyte comprises a mixture of hydrogel and salt.
3. A symmetrical supercapacitor device according to Concept 1 or Concept 2, comprising an ion charge carrier.
4. The symmetrical supercapacitor device according to Concept 3, wherein the ion charge carrier is hydrated.
5. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam.
6. The symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam material.
7. A symmetrical supercapacitor device according to any one of concepts 1, 5 and 6, wherein the carbon foam material is formed on a substrate.
8. The symmetrical supercapacitor device according to Concept 7, wherein the substrate is a polyimide substrate.
9. The symmetrical supercapacitor device according to Concept 7 or Concept 8, wherein the substrate forms the substrate of the device.
10. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the symmetrical supercapacitor device is flexible.
11. A method for manufacturing a symmetrical supercapacitor device according to any one of concepts 1 to 10, wherein:
Electrodes are formed on the substrate;
An electrolyte precursor containing charge carriers and hydrogels is applied to the electrode;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the effective region.
12. A method for manufacturing a symmetrical supercapacitor device according to Concept 11, wherein the electrolyte precursor is prepared by preparing an aqueous solution of a charge carrier and by mixing the aqueous solution with a hydrogel.
13. A method for manufacturing a symmetrical supercapacitor device according to Concept 11 or Concept 12, wherein the electrodes are formed in situ.
14. A method of manufacturing a symmetrical supercapacitor device according to any one of claims 11 to 13, wherein the electrodes are formed by irradiating the substrate with laser radiation.
Appendix 2: Gii-Cap+ Hydrogel
In this Appendix 2 section, we demonstrate the effectiveness of Gii carbon foam as an ideal substrate on which pseudocapacitive materials can be deposited, resulting in a significantly enhanced capacitance compared to using Gii carbon foam as the sole electrode material. For the context, these carbon foam-only devices exhibit full-cell specific capacitance in the 0.25–0.4 mF/ cm² region.
Sample preparation
Electrodeposition was performed on A7-sized Gii-Caps to cast a layer of pseudocapacitive material on them. Both v4 and v5 designs were suitable for electrodeposition, yielding similar performance. Results for the v4 sample will be detailed in this document.
First, the sheet containing six Gii-Cap devices (2 rows, 3 columns) was cut in half to obtain two 3-device half-sheets. The two half-sheets were then mounted on internally fabricated fixtures and placed inside the MiniPlant 3 electrodeposition tank. MnOx was deposited on the sample first, followed by rinsing with deionized water, and then FexOy was deposited. After FexOy deposition, the sample was rinsed again and dried in air at 40°C for at least 2 hours.
The deposition details are as follows. The manganese oxide precursor solution contained a mixture of manganese acetate tetrahydrate (40 mM) and surfactant (Tween 20, 0.1 wt%). Deposition was performed using constant current pulses. The on-time was 0.5 seconds, and the off-time was 2 seconds. The applied on-time current was 744 mA (19.14 mA/ cm² , based on the nominal geometry of the electrode). The off-time was 0 mA, i.e., the circuit was open. A total of 390 cycles of MnOx deposition were performed (3.7 C/ cm² per electrode). The FexOy precursor solution contained 40 mM MFe-TEA complex (TEA is triethanolamine). It contained FeCl₃ , TEA, and NaOH. Deposition was also performed using constant current pulses. The on-time was 1 s, and the off-time was 2 s. The applied on-time current was 233 mA (6 mA/ cm² ), and the off-time was set to 0 mA. The deposition process was repeated 1,000 times, yielding 6 C/ cm² for each electrode.
After deposition and sample drying, the samples are divided into individual devices. A quasi-reference electrode (RE) containing screen-printed Ag/AgCl ink is fixed along one edge of the device outside the working area (used to monitor the potential of each electrode during testing). The electrolyte is then applied to the working area of the device and extends onto the RE. The electrolyte used is an aqueous hydrogel containing NaClO₄ as the salt and PVA (polyvinyl alcohol) as the gelling agent. The hydrogel stock solution contains 199.5 g NaClO₄ monohydrate, 256.9 ml deionized water, and 42.4 g PVA. The mixture is solid at room temperature and becomes liquid at temperatures close to the boiling point of water. To dispense the hydrogel, it is heated to 94°C to liquefy it. Dispensing is performed by dropping the liquid electrolyte onto the working area and the RE, typically 3–4 ml per device. The hydrogel on the sample is then allowed to cool and re-solidify after approximately 10 minutes. After solidification, an imide film is applied to the device to prevent excessive electrolyte evaporation. Once capped, the device is ready for testing.
Electrochemical test parameters
Electrochemical tests were performed on the samples using a Biologic VMP-3 voltage/current regulator. Initial performance characterization was performed, followed by 500 charge-discharge cycles (conditioning protocol) for final characterization. The reported nominal values are those obtained in the second characterization step. The conditioning protocol was applied to further stabilize and consistent the sample performance.
During testing, the voltage was controlled at the battery level (the absolute difference between the positive and negative electrodes), with a minimum of 0V and a maximum of 2V. The potential difference between each electrode and the common RE was also measured, allowing for the calculation of individual electrode performance metrics.
These two characterization steps are called the Ragone test. They are identical and include the following:
a) Cyclic voltammetry (CV). Three scan rates were used: 50, 100, and 250 mV/s. Five cycles were performed at each scan rate.
b) Galvanic charge-discharge (GCD). Seven current densities were tested: 1, 2.5, 5, 7.5, 10, 20, and 30 mA/ cm² (based on a total device geometry of 12.96 cm² ). Five cycles were performed at each current density.
c) Electrochemical impedance spectroscopy (EIS). Voltage controlled, using a 1V DC applied voltage and a 10mV AC signal. Measurements were taken in the 1MHz–10mHz region.
The adjustment process was achieved by performing 500 GCDs at 10 mA/ cm² .
The nominal capacitance value is calculated based on the GCD after adjustment at 5 mA/ cm² . The ESR (Equivalent Series Resistance) is calculated based on the voltage drop at the start of the discharge half-cycle in the GCD. The reported ESR value is also derived from the final GCD at 5 mA/ cm² . The ESR can also be calculated from the Nyquist plot obtained from EIS. The results are almost identical.
Results and Conclusions
Average values were calculated for a total of 48 devices. Samples from batches 3258 and 3259 were used. Typical CV curves are shown in Figure 66. The full-cell response (left panel) shows a quasi-rectangular shape, indicating that the storage mechanism is not purely capacitive. This is expected, as both MnOx and FexOy are redox-active materials. Most of the capacitance of the device is concentrated above the cell voltage of 0.5V, as can be seen from the small envelope of the full-cell curve in the 0–0.5V region. The explanation for the smaller capacitance at lower cell voltages can be seen in the half-cell curve, shown in the right panel of Figure 66. This figure shows that MnOx is used as the positive electrode, while FexOy is the negative electrode. MnOx is a near-ideal pseudocapacitive material, as evidenced by its roughly rectangular CV (grey trajectory).
Meanwhile, the FexOy electrode exhibits a more asymmetric response to potential. Its capacitance is largely concentrated below 0V vs Ag/AgCl. When the potential is greater than 0V vs Ag/AgCl, FexOy displays a very small capacitance, as shown by the small envelope of the blue trace at these potentials. Therefore, this asymmetric FexOy response explains the smaller capacitance obtained at low voltages in a full cell.
Figure 66 shows the post-adjustment CV curves obtained at 100 mV/s from sample 3258-1#4. The left panel shows the full-cell CV, while the right panel shows the half-cell curves obtained during the full-cell measurement.
GCD curves were used for capacitance calculations because they provide more accurate values. Typical adjusted GCD curves are shown in Figure 67, displaying measurements for both full and half cells. The device exhibits a good capacitance response with quasi-triangular curves. The full cell exhibits linear discharge from maximum voltage down to approximately 0.5V, indicating that the pseudocapacitance of MnOx and FexOy achieves near-ideal capacitance behavior. As seen in the CV curves, FexOy exhibits an asymmetric capacitance-potential relationship, which explains the faster discharge below 0.5V of the battery voltage.
Figure 67 shows the post-adjustment GCD curves obtained at 5 mA/ cm² from sample 3258-1#4. The full-cell and corresponding half-cell responses are shown in the top, middle, and bottom lines, respectively.
In addition to different pseudocapacitive behaviors relative to potential, the MnOx and FexOy electrodes also exhibit different levels of capacitance. Both electrodes occupy the same geometric area in the device, but the MnOx electrode experiences a much smaller electrochemical window within the device (see the difference between the maximum and minimum electrode potentials in Figures 66 and 67). The smaller MnOx window (0.65 ± 0.06 V) is due to its larger specific capacitance compared to FexOy (1.35 ± 0.06 V window). For the device evaluated in this study, the regulated capacitance of the MnOx electrode reached 246.8 ± 36.0 mF/ cm² , while the regulated capacitance of the FexOy electrode was 171.4 ± 38.4 mF/ cm² . Therefore, these Gii-Cap+ devices are symmetrical in terms of electrode size but asymmetrical in terms of electrode composition and potential split.
Since a full cell is essentially two capacitors connected in series (formed by a double layer between the electrodes and the electrolyte counterions), the total cell capacitance will be lower than the capacitance of a single electrode. The adjusted average full cell capacitance is 52.5 ± 9.4 mF/ cm² . At the same current density (64.8 mA, 5 mA/ cm² , cell level) as the reported nominal capacitance, the ESR calculated based on the voltage drop at the start of discharge is 0.85 ± 0.12 Ω.
EIS measurements further confirmed the good capacitive response of these devices, as shown in Figure 68. The ESR can be estimated by locating the intersection of the Nyquist plot with the y-axis. For the sample shown in Figure 68, the ESR calculated by EIS is 0.78 Ω, which matches very well with the 0.73 Ω calculated by GCD for the same sample. The Bode plot provides information about the device's behavior at different frequencies. At high frequencies, such as 100–10000 Hz, the device functions essentially like a resistor with a phase angle of 0°. As the frequency decreases, the phase angle increases, indicating a greater contribution from capacitance (the phase angle of an ideal capacitor is -90°). When the phase angle exceeds the 45° mark, the device is considered to be essentially capacitive. Therefore, the time when the 45° phase shift occurs can be considered the characteristic time constant of the device. For the sample in this study, the average time constant is 4.48 ± 1.18 seconds. This time constant can be interpreted as the cycle time threshold for an effective capacitive response. When the cycle time is below the time constant, the device will not operate fully.
Figure 68 shows the regulated Nyquist (left) and Bode (right) curves obtained by electrostatic EIS at 1V DC (full cell) for sample 3258-1#4. The inset in the left figure shows a magnified view of the high-frequency response.
Considering that devices using Gii as the sole electrode material exhibit a specific capacitance of 0.25–0.4 mF/ cm² , adding pseudocapacitive materials enhances the energy storage capacity of these Gii-Caps by more than 100 times. Furthermore, adding these metal oxides does not significantly increase the ESR of these devices, thus maintaining their usefulness in high-power applications. The electrodeposition process is controllable, allowing for the fabrication of cells with less deposited material and consequently less total capacity, if desired. The resulting devices are inherently asymmetric, with MnOx as the dominant positive electrode and FexOy as the negative electrode.
Appendix 3 GiiCap Ion Gel
Objective: To demonstrate the specific capacitance and electrochemical stability window (ESW) of an electrolyte formulation comprising a room-temperature molten salt 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) and fumed silica, referred to as Iongel, in conjunction with an A7 apparatus, conducted in a “low” humidity and “airless” argon atmosphere.
Experimental conditions:
All electrochemical tests were performed in a “3-electrode” setup, in which regular interdigitated A7 devices were fabricated, the area ratio of the “working” electrode to the “counter” electrode was 1:2, and a third quasi-reference electrode comprised of screen-printed AgCl ink was used to monitor the potential of each electrode during the tests.
The electrolyte Iongel was prepared and stored in an airless environment.
Before applying the electrolyte to the A7 device for testing, heat Iongel to 90°C and then distribute a thin, uniform layer onto the A7 using a doctor blade. Allow the electrolyte to cool before preparing the device for testing and connection. For airless devices, testing is performed in the same airless environment where the electrolyte was stored and distributed, with the device connected to the electrochemical testing instrument: a Biologic VMP-3 regulator.
For low humidity environments, move the device to a humidity-controlled room with a relative humidity set to 20%, and seal and connect it to the instrument.
For each humidity level, a series of maximum electrode potentials (Emax) (in volts (V)) close to the nominal literature value 1 of the net electrolyte were tested. They are:
Positive electrode: 2.0, 1.9, 1.8, 1.7, 1.6, 1.5
Negative electrode: -2.0, -1.9, -1.8, -1.7, -1.6.
For each combination of humidity and electrode potential, N=8 samples are prepared from scratch.
Electrochemical test parameters:
A standard protocol was used, with a test window of 0.0-Emax V vs OCV. OCV quantification was 0.25 V vs AgClQref.
The electrochemical testing was divided into three stages: a) Ragone characterization; b) long-term (LT) cycling; c) Ragone characterization (post-).
Ragone characterization before and after LT cycling included: OCV, 1 hour; cyclic voltammetry (CV), 5 cycles each at 100 and 1000 mV/s; galvanostatic charge-discharge (GCD), 10 cycles each at 5 and 10 mA/cm²; and potentioelectric impedance spectroscopy (PEIS), between 10 MHz and 0.01 Hz.
The LT cycle includes: CV, 5000 cycles at 750mV/s.
Electrochemical stability was determined by post-hoc visual analysis of electrode damage and electrolyte discoloration, as well as by assessment of changes in coulombic efficiency across LT cycles. Device performance was determined based on the specific capacitance via GCD after 5000 LT cycles.
in conclusion:
ESW was determined by plotting the coulombic efficiency of the LT CV cycle against the number of cycles. When the coulombic efficiency remained consistent throughout the 5000 cycles, the cycle Emax was determined to be stable under given environmental conditions. Based on this analysis, the Iongel-A7 device was found to be stable in air with a relative humidity of 20% at negative and positive electrode potentials of -1.6 and +1.6 V, respectively. In the absence of air, the positive and negative ESWs were determined to be -1.8 and +1.7 V, respectively.
Regarding performance evaluation, the specific capacitance of the device at 20% relative humidity and in an airless environment was found to be 2.11 and 1.60 mF/ cm² , respectively, under the positive electrode window conditions. The specific capacitance of the negative electrode window was 1.55 and 2.11 mF/ cm² , respectively, under 20% relative humidity and in an airless environment.
Figures 69, 70, and 71 show the relevant results.
Figures 72, 73, and 74 show other relevant results.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Target:
The feasibility of the project was demonstrated using reagents that are critical to the Gii-Sens 3D carbon foam analysis system.
Phase 1: Surface Fixation
Objective: To maximize mAb(2) surface immobilization. To evaluate the most convenient surface chemistry for immobilizing mAb onto a surface.
Deliverables: Data supporting maximum surface coverage and the selected procedure.
Phase 3: Target Analyzer Sensing Range and LOD
Objective: To establish the electrochemical immunoassay procedure and results. To develop the electrochemical immunoassay procedure (incubation time, concentration, volume) and to establish parameters that produce the most sensitive analytical assay.
Deliverables: Data supporting the performance of electroanalytical immunoassays.
Experimental Section
Solution composition
Surface Chemistry
10 mM pyrene butyric acid in DMF
4mM EDC/10mM SulfoNHS
PBS 0.1M pH 7.2
Read aloud
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 0.02 M KCl.
0.02M PBS
Sensor modification program
10 μL of PyrBuOOH was applied to the sensor surface and incubated in a humid chamber for 2 hours, after which the solvent was allowed to evaporate spontaneously.
15 μL EDC/NHS, for 30 min
10 μL of A1 or C1 mAb in PBS for 1 hour
Electrochemical technology
Electrochemical impedance
Applied voltage = 0V
Amplitude = 0.01VRMS
Frequency range -5000 to 0.1Hz
Measurement Procedure
Direct determination: Unmarked: See Figures 75 and 76.
Direct determination: label-free and reagent-free: see Figures 77 and 78.
Calibration curve
Repeat at each point, n=5 (minimum) different disposable sensors (single readout, sensor disposed of).
Each calibration curve contains data (inter- and intra-assay variability) obtained by different operators over the following days.
Phase 1: Surface Chemistry
According to the scheme in Figure 79, the selected surface chemistry is Pyr-COOH modified graphene and EDC/NHS conjugates that capture mAb (A1 and C1), and the figure shows a schematic diagram of the surface immobilization reaction.
The concentrations of surface-fixed mAbs (A1 and C1) were screened using electrochemical impedance spectroscopy. (See Experimental Section). See Figure 80 (mAb A1 fixation on the surface. Inset normalized signal) and Figure 81 (mAb C1 fixation on the surface. Inset normalized signal).
Both A1 and C1 showed a logical trend in surface coverage. Based on the normalized curves, A1 showed a slightly larger surface coverage. The optimal coverage range selected was between 15 and 250 μg/mL. This concentration range was estimated to be sufficient to provide optimal sensor performance.
Phase 3: Determination and Target Analyte Investigation
Further evaluation of the potential and benefits of using it as a sensing electrochemical platform has been conducted in label-free assay formats.
Simultaneously, a reagent-free formulation was also explored, where the solution used for incubation and generating the readout signal was simply a buffer solution, as described in the experimental section. The dynamic range of the assay was also investigated at high concentrations, and the potential to extend this concentration range is expected to be identified.
Due to the interesting results obtained during the investigation described above and the general time constraints, the assay sensitivity was explored down to 10 pg/mL, and the aim was to explore the high concentration range up to 1000 ng/mL.
Label-free assay investigation
Label-free assays, as previously described, include assays that do not require secondary antibodies but use specific electrochemical readout solutions. In this study, the electrochemical solution was also used as the carrier solution, thus eliminating the need for a washing step or any other assay complications.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 82, which shows the label-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
To further investigate how to enhance measurement performance, the overall concentration range was divided, and the same data were used to explore different sensitivity ranges.
Label-free and reagent-free assay investigation
As mentioned earlier, label-free assays include assays that do not require secondary antibodies. In the absence of reagents, there is also no need for an electrochemical readout solution, as all incubation and measurement are performed solely in a buffer solution, which also acts as a carrier solution, further eliminating the need for additional washing steps.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 83, which shows the label-free and reagent-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Materials via Connectors
background
Sensors are analytical devices that detect changes or reactions and respond to some input from the environment. In recent years, their use has increased significantly due to their advantages such as high specificity and sensitivity, rapid and reliable results, ease of processing, and immediate diagnostics. Because of these advantages, sensors have entered various technological fields, such as chemical and medical diagnostics, environmental impact analysis, the food industry, and the marine sector.
Different forms of graphene and its derivatives have been used in the production and development of sensors, particularly biosensors. Graphene's electrochemical, physical, and chemical properties make it a material of interest for these applications. However, conventional graphene (e.g., 2D graphene) is difficult to handle in practical applications due to its ultrathin structure and flexibility, which makes it prone to curling, creases, and wrinkles. This significantly reduces the analytical performance of sensors, especially their sensitivity. To date, numerous strategies and techniques have been implemented to fabricate different types of graphene (e.g., different morphologies, different surface properties, and different functionalized derivatives, such as graphene quantum dots, graphene oxide, or reduced graphene oxide), and these have led to differences in sensing performance between sensors.
E.A.Obaje, G.Cummins, H.Schulze, S.Mahmood, M.P.Y.Desmulliez and T.T.Bachmann, Journal of Interdisciplinary Nanomedicine, 2016; 0(0), doi:10.1002/jin2.16 investigated the electrochemical properties of a newly fabricated sensor in relation to the function of its underlying composite material, and evaluated the selection of carbon and dielectric pastes by characterizing properties such as surface roughness, wettability, and susceptibility to nonspecific DNA binding.
L.H. Hess, A. Lyuleeva, B.M. Blaschke, M. Sachsenhauser, M. Seifert and J.A. Garrido, ACS Appl. Materials & Interfaces, 2014, 6, 9705-9710, describe a platform for biosensing applications based on polymer-modified CVD-grown graphene transistors.
C. Fenzl, P. Nayak, T. Hirsch, O.S. Wolfbeis, H.N. Alshareef and A.J. Baeumner, ACSSensors, 2017, 2, 616-620 describe laser-scribed graphene (LSG) electrodes as highly sensitive and reliable biosensor transducers in serum analysis.
S. Singal, A.K. Srivastava, S. Dhakate, A.M. Biradar and Rajesh, RSC Advances, 2015, 5, 74994-75003 describes an electroactive graphene-multi-walled carbon nanotube hybrid-loaded impedance immunosensor for the detection of human cardiac troponin-I.
Despite the existence of all existing technologies, there remains a need to improve the sensing activity of graphene-based sensors. Furthermore, it is still desirable to improve the sensitivity of these sensors without compromising at least one of their other aspects, such as their robustness, stability, durability, ease of functionalization, and/or ease of manufacture.
Summary of features in Appendix 5
In a first aspect, a sensor is provided comprising: (i) a carbon foam electrode, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam electrode via the connector. The carbon foam electrode is manufactured at least in part by a method defined by any one of the features A-K above.
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, comprising the following steps in sequence: (i) providing a carbon foam electrode as described in the first aspect; (ii) treating the carbon foam electrode with a connector; and (iii) treating the connector-modified carbon foam electrode obtained in step (ii) with a receptor.
In a third aspect, a method for sensing a target is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
Carbon foam materials typically possess a folded structure, which gives them a porous morphology and high specific surface area. Without being bound by any theoretical constraints, it is believed that the analytical performance of a sensor is influenced by the morphology of the carbon foam and its available surface area. The 3D structure leads to an increased usable surface area, allowing connectors and receptors (such as enzymes, proteins, nucleic acids, and antibodies) to bind efficiently to the carbon foam, thereby improving sensor performance and sensitivity.
Furthermore, it is desirable to construct the sensor using a very thick carbon foam layer. Preferably, the carbon foam layer thickness is greater than 50 μm. Since carbon foam can be porous, such a thick carbon foam layer is expected to provide a larger surface area, which is beneficial for enhancing analytical performance, especially sensing properties, compared to other conventional graphene-based sensors.
connector
In the context of the features of this invention, carbon foam is modified with a connector as part of the process for forming the desired sensor. The carbon foam described above (e.g., a thick porous carbon foam with a folded structure) provides an improved basis for modification because the increased surface area can be used for interaction with the connector, resulting in improved sensor sensitivity.
The modified carbon foam is then treated with an acceptor to obtain a sensor. Therefore, the adapter acts as an intermediate between the carbon foam and the acceptor. It is possible that at least a portion of the adapter is disposed (e.g., dispensed) within the carbon foam. It is also possible that the entire adapter is disposed (e.g., dispensed) within the carbon foam.
The connector can be selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof. Typically, the connector is selected from polymers (e.g., (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
Typically, the organic compounds described above comprise one or more functional groups independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymers, or mixtures thereof, optionally combined with linear, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. In the same embodiments, the optional structure may be a C1-C20 straight-chain, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residue, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. Still in the same embodiments, optionally, the organic compound having the functional groups described above may also comprise one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly linked to at least one of the functional groups, or the connector is a derivative of an ester or salt of such organic compound, or a compound that releases such organic compound in a reaction with the desired 3D carbon foam. Representatively, the connector is selected from the organic compounds described above in this paragraph.
Typically, the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
The joint can be covalently or non-covalently bonded to the carbon foam. For example, a diazo compound (e.g., a diazonium salt) can be covalently bonded to the carbon foam. For non-covalent bonding, the joint can be bonded to the carbon foam through at least one of the following: π-π interactions, ionic bonding, hydrogen bonding, hydrophobic or hydrophilic effects, electrostatic interactions, polymer encapsulation, adsorption, and grafting (e.g., photografting). For example, a joint containing one or more cyclic moieties as described above (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof) can be bonded to the carbon foam through π-π interactions.
In the context of this feature, the acceptor is bonded to the carbon foam via a linker. Therefore, the acceptor is indirectly bonded. When at least a portion or preferably the entire linker is disposed (e.g., dispersed) within the carbon foam, at least a portion or the entire acceptor may also be disposed (e.g., dispersed) within the carbon foam.
In this document, "receptor" refers to any molecule capable of responding to a target material (i.e., the target) present in the sample to be analyzed. The sample can be biological, chemical, optical, physical, or mechanical, but is typically biological. Therefore, "target" encompasses, but is not limited to, biological materials, chemical substances or mixtures, optical objects, physical or mechanical articles, etc., typically biological materials. The term "response" can include, but is not limited to, biological, and/or chemical, and/or optical, and/or physical, and/or mechanical interactions, typically biological and/or chemical interactions. These typical interactions can include, but are not limited to, binding or hybridization between the receptor and the target, or hydrophobic effects.
Therefore, receptors can include, but are not limited to, one of the following: electrochemical receptors, chemical receptors, biological receptors, optical receptors, physical or mechanical receptors. Receptors can be selected from, but are not limited to, crown ethers, ligands, catalysts, boric acids, carbohydrates, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof.
Typically, the receptor is a biological receptor (i.e., the sensor is a biosensor). Receptors are typically selected from aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles, or other cellular components, or mixtures thereof. More typically, receptors are selected from proteins (e.g., immunoproteins, non-immune proteins, immunoglobulin-binding proteins, glycoproteins), nucleic acids, antibodies, enzymes (e.g., oxidoreductases (preferably glucose oxidase, alcohol oxidase, or lactate oxidase), dehydrogenases) or mixtures thereof. Representatively, receptors are selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or mixtures thereof.
Typically, the target is biological material. Biological material can include, but is not limited to, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, protein complexes, nucleic acids, antibodies, antigens, lipids, fatty acids, fatty acid esters, vitamins, microorganisms, micelles, cells, organelles, or other cellular components, viruses, enzymes, or mixtures thereof. Typically, biological material is selected from deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, nucleic acids, antibodies, antigens, enzymes, or mixtures thereof. More typically, biological material is selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof. It should also be understood that, in the context of this feature, both biological receptors and biological materials can be naturally occurring or synthetically produced.
Receptors can attach to linkers. Receptors can be bonded to linkers by physical, biological, and/or chemical means. Typically, receptors are chemically bonded to linkers. Hereinafter, chemical bonds can include, but are not limited to, covalent bonds, non-covalent bonds (e.g., ionic bonds), metallic bonds, hydrogen bonds, chelate bonds, and non-covalent interactions such as van der Waals forces, π-π interactions, hydrophobic or hydrophilic effects, and electrostatic interactions. Typically, receptors (e.g., biological receptors) are covalently bonded to linkers. Typically, receptors (e.g., biological receptors) are bonded (e.g., covalently) to one or more functional groups contained in the linker (e.g., functional groups of organic compounds as previously described). For example, biological receptors can be covalently bonded to the carboxyl, amino, amine, or amide group of the linker (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide).
sensor
Sensors according to this feature typically comprise a carbon foam layer, which can be produced by a previously disclosed dual-laser processing method. Typically, the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm. Typically, at least a portion or all of the connector is disposed (e.g., dispersed) within the carbon foam. Optionally, at least a portion or all of the receptor is also disposed (e.g., dispersed) within the carbon foam (i.e., when at least a portion or preferably all of the connector is disposed (e.g., dispersed) within the carbon foam). Typically, at least a portion of the connector and optionally a portion of the receptor are disposed (e.g., dispersed) at a depth below the surface of the carbon foam (e.g., the carbon foam layer), said depth being greater than 1% of the total depth of said carbon foam, preferably greater than 5% of the total depth, more preferably greater than 10%, even more preferably greater than 15%, and even more preferably greater than 20%. Typically, at least a portion of the connector and optionally at least a portion of the acceptor are disposed (e.g., dispersed) at a depth greater than 1 μm below the surface of the carbon foam (e.g., a carbon foam layer), preferably greater than 5 μm, more preferably greater than 10 μm, even more preferably greater than 15 μm, and most preferably greater than 20 μm below the carbon foam surface. The entire connector and optionally the entire acceptor can be disposed (e.g., dispersed) at a depth greater than 1% of the total depth of the carbon foam. The thickness of the carbon foam layer can be any range described above (e.g., at least greater than 50 μm). "Dispersed" herein means that the connector (optionally, and acceptor) molecules, at least partially disposed within the carbon foam, are distributed therein to form multiple discrete domains other than a single cluster. These domains can be uniformly and/or continuously distributed (e.g., distributed as a uniform and/or continuous layer) within the carbon foam. Without being bound by any theory, it is believed that the replacement of the connector (optionally, and the acceptor) leads to the improved functionalization of the carbon foam, thereby enhancing the sensor's sensing activity (i.e., sensitivity).
Furthermore, and optionally, neither the connectors nor the acceptors are disposed (e.g., dispersed) throughout the entire depth of the carbon foam (e.g., carbon foam layers). In other words, the core of the carbon foam is not modified with connectors or acceptors.
The adapter may be selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof, and the receptor may be selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin or a mixture thereof.
The sensor may also include a substrate. In a first method of obtaining carbon foam, if a carbon source is provided on or adjacent to the substrate, the final sensor may include the substrate as a component. In a second method requiring the use of a substrate, the final sensor may also include the substrate as a component. Regardless of the method by which it is obtained, the carbon foam may optionally be adhered to the substrate within the sensor. Thus, the substrate included in the sensor may have one of the characteristics described previously for substrates used in the production of carbon foam and/or one possible combination of these characteristics. Alternatively, the sensor need not include a substrate. In other words, even if the carbon foam is produced to adhere to the substrate, it may be removed from the substrate as part of preparation for subsequent modifications.
Typically, the sensors characteristic of the present invention are chemical, physical or mechanical, biological or optical sensors, preferably biosensors (i.e., when the receptor is a biological receptor). Typically, the sensor (e.g., a biosensor) takes the form of an electrode or electrode device. The sensor (e.g., a biosensor) may include a multi-electrode platform, for example, a three-electrode platform including a counter electrode (CE), a working electrode (WE), and a reference electrode (E or RE). The electrode (e.g., WE) may be made of modified carbon foam (i.e., carbon foam modified with a receptor via a connector) characteristic of the present invention. Other electrodes (e.g., CE and/or RE) may also be carbon foam-based, preferably carbon foam-based, and more preferably based on the same carbon foam without any modification. All electrodes may have the same or different dimensions.
Sensors (e.g., biosensors) may be supplied as products, wherein the sensors are housed within packaging, and the products preferably include instructions for use. Typically, the packaging includes a primary package in which the sensor is housed. The sensor may be provided on an adapter housed within the primary package. Suitable examples of primary packaging are caps, pockets, folders, envelopes, boxes, containers, cartons, housings, etc. Optionally, the packaging may also include secondary packaging. Such secondary packaging is typically packaging that holds one or more sensors together. Suitable examples of secondary packaging are plastic cartons, cardboard boxes, blister packs, boxes (e.g., cardboard or plastic boxes), housings, containers, cardboard or plastic crates, pallets, bundles with or without one or more air bags, etc. Still optionally, the packaging may include tertiary packaging, which may be selected from boxes, housings, cartons, containers, etc. Suitably, at least one of the above-described packages may protect the sensor from light (e.g., direct sunlight), moisture, physical and/or chemical damage and contamination. The instructions may provide detailed steps for using the sensor according to its features. Instructions may be provided in printed form as labels, brochures, manuals, or leaflets. Instructions may also be printed on product packaging.
Sensor manufacturing
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, wherein the steps include: (i) providing carbon foam; (ii) treating the carbon foam with a connector; and (iii) treating the connector-modified carbon foam with a receptor.
The method may include the step of manufacturing the carbon foam before providing and processing it with a connector. Thus, the carbon foam is produced by one of the laser processing methods disclosed herein, typically the first or second method, but more typically the first method. The carbon foam thus produced may be adhered to, attached to, or provided on a substrate. Typically, the carbon foam can be removed from the substrate before processing the connector in step (ii). In other words, the carbon foam in step (i) is provided without a substrate. Alternatively, it is not necessary to remove the carbon foam (e.g., the carbon foam remains adhered to the substrate). In other words, the carbon foam in step (i) is provided with a substrate.
The carbon foam can be incubated together with the adapter. Incubation can occur in a buffer solution, preferably a buffer solution. Additionally or optionally, adapter modification may require at least one of the following conditions: light (ultraviolet, visible, or infrared radiation) or heat. After incubation, the adapter-modified carbon foam can be washed.
The adapter-modified carbon foam can be incubated with the receptor. After incubation, the sensor thus obtained can be cleaned before use. After cleaning, the sensor may be passivated. Passivation is understood as blocking any remaining activation sites that have not been functionalized by the receptor.
The receptor is used to process the connector-modified carbon foam in step (iii).
The sensor can be an electrode or an electrode device including a multi-electrode platform. Therefore, the manufacturing steps described above can be applied to the manufacture of electrodes. When the sensor is an electrode device including a multi-electrode platform, the manufacturing steps described above are applicable to the production of the working electrode (WE), and the method further includes the additional steps of producing a counter electrode (CE) and a reference electrode (E or RE).
Use of sensors
In a third aspect, a method of using a sensor is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing a target; (iii) measuring the response of the sensor; and (iv) optionally, correlating the response with the level of the target in the sample.
The target can be the target disclosed herein, and is usually the biological material disclosed herein. The sample can be the sample disclosed herein, and is usually the biological sample disclosed herein.
Before use, the sensor (e.g., a biosensor) can be appropriately stored under ambient conditions (e.g., room temperature of approximately 20°C and 1 atmosphere). Typically, the sensor is stored under dry conditions. After use, the sensor can be properly disposed of (i.e., the sensor is a disposable sensor).
The sensor can be immersed in a sample. The sample may contain phosphate-buffered saline (PBS). The concentration of the target in the sample may be at least 1 ppm. The equilibration time may be at least 0.5 minutes, or at least 1 minute, or at least 10 minutes, or at least 30 minutes, typically not exceeding 2 hours, or not exceeding 1 hour, or not exceeding 40 minutes. The sensor can be cleaned after contact with the sample, and then the response can be measured. The sensor can be cleaned by rinsing with PBS. The sensor can be dried after cleaning (e.g., by airflow, or by natural drying).
The response can be measured using differential pulse voltammetry and/or impedance spectroscopy. The measured response may be further correlated with the target level in the sample. The method may include steps (i), (ii), and (iii) as described above, and additionally includes the following steps in sequence: (iv) contacting the sensor with one or more samples (i.e., control samples) containing a known level of the target; (v) measuring the sensor's response to one or more control samples; (vi) comparing the response to a sample containing or suspected of containing the target with the response to one or more control samples; and (vii) correlating the response to a sample containing or suspected of containing the target with the level of the target in the sample.
Appendix 5 Concepts
1. A sensor comprising: (i) a carbon foam, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam via the connector.
2. The sensor according to Concept 1, wherein the carbon foam is obtained by a method of generating carbon foam at at least one location within a carbon source by concentrating infrared radiation at that location, and the infrared radiation is provided by a laser beam, wherein the laser beam is an infrared laser beam.
3. The sensor according to Concept 2, wherein the concentrated infrared radiation includes diffraction of the infrared radiation to form an interference pattern, each fringe of the interference pattern being located within the carbon source.
4. The sensor according to Concept 2 or Concept 3, wherein the at least one position is laterally moved inside the carbon source and/or the at least one position is moved within the depth of the carbon source.
5. The sensor according to any one of Concepts 2 to 4, wherein the infrared radiation directly irradiates the carbon source, or the infrared radiation passes through a substrate before irradiating the carbon source, wherein the carbon source is disposed on the surface of the substrate or adjacent to the surface of the substrate.
6. The sensor according to any one of Concepts 2 to 5, wherein the carbon source is additionally irradiated with additional radiation, and the additional radiation is performed before, simultaneously with or after the step of focusing infrared radiation at at least one location within the carbon source.
7. The sensor according to Concept 6, wherein the additional radiation is rasterized on the surface of the carbon source.
8. The sensor according to Concept 6 or Concept 7, wherein the additional radiation directly irradiates the carbon source or passes through a substrate as described in Concept 5 before irradiating the carbon source.
9. The sensor according to any one of the foregoing concepts, wherein at least a portion of the connector is disposed (preferably dispersed) within the carbon foam; and optionally, at least a portion of the receptor is disposed (preferably dispersed) within the carbon foam.
10. The sensor according to any one of Concepts 2 to 9, wherein the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm.
11. The sensor according to Concept 1, wherein the carbon foam is obtained by providing a carbon source on or adjacent to a substrate surface and exposing at least a portion of the carbon source, comprising a carbon-containing material, and/or at least a portion of the substrate to a laser beam, thereby converting at least a portion of the carbon source into the carbon foam.
12. The sensor according to Concepts 5, 8 or 11, wherein the substrate comprises one or more of the following: silicone, silicon dioxide, gallium nitride, gallium arsenide, zinc oxide; or alternatively, one or more polymers; or alternatively, one or more metals selected from aluminum, copper, gold or other metals, or oxides, nitrides or arsenides of said metals.
13. The sensor according to any one of the foregoing concepts, wherein the carbon foam contains less than 3% oxygen, preferably less than 1.5% atomic percentage, and/or less than 3% nitrogen atomic percentage.
14. The sensor according to any one of the foregoing concepts, wherein the connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
15. The sensor according to Concept 14, wherein the connector is selected from polymers (preferably (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
16. The sensor according to Concept 15, wherein the one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, optionally in combination with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
17. The sensor according to Concept 16, wherein the organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of an ester or salt of the organic compound, or a compound that releases the organic compound in a reaction with the carbon foam.
18. The sensor according to Concept 17, wherein the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
19. The sensor according to Concept 17 or Concept 18, wherein the connector is bonded to the carbon foam via π-π interactions.
20. The sensor according to any one of the foregoing concepts, wherein the receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
21. The sensor of claim 20, wherein the receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof.
22. The sensor according to Concept 21, wherein the receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
23. The sensor according to any one of the foregoing concepts, wherein the receptor is bonded to the connector in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
24. A method of manufacturing a sensor according to any one of the foregoing concepts, comprising the following steps in sequence: (i) providing a carbon foam as described in any one of concepts 1 to 13, 19; (ii) treating the carbon foam with a connector as described in any one of concepts 1, 14 to 19, 23; and (iii) treating the connector-modified carbon foam obtained in step (ii) with a receptor as described in any one of concepts 1, 20 to 23.
25. A method for sensing a target, comprising the following steps in sequence: (i) providing a sensor according to any one of Concepts 1 to 23; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
It should also be noted that the sensor described in Appendix 5 may be the Gii-Sens carbon foam sensor described earlier in this specification.
Appendix 6 Baseline Experimental Conditions
1 mM potassium ferrocyanide/potassium ferrocyanide was used in 0.1 M strontium nitrate, with at least five replicates randomly selected. Cyclic voltammetry was performed at scan rates of 25 and 200 mV/s as a comparative technique. Various characteristics were investigated and conclusions were drawn to evaluate the performance of the differential electrode materials.
Electrochemical impedance spectroscopy was performed at the equilibrium potential with an amplitude of 5 mV and a frequency range of 0.1 to 100 kHz.
Use a built-in or external silver/silver chloride reference electrode for the sensor.
Gii Sens carbon foam compared to conventional graphene electrode materials
The Gii Sens carbon foam sensor was evaluated and compared with other commercially available graphene-based sensors. See Figure 84.
The recorded reduction and oxidation peak currents show a 25% increase in efficiency per unit geometry in terms of current density. This clearly reflects the larger usable electrochemical area offered by the Gii Sens 3D carbon foam. See Figure 85.
According to cyclic voltammetry, the assessment of reduction-oxidation peak separation can be interpreted as a measure of the surface's electronic redox response to voltage scans and its ability to efficiently perform rapid redox reactions. The study showed that the reduction-oxidation peak separation remained below 70 mV, and no increase in separation was observed from 25 to 200 mV/s.
Other graphene electrode surfaces showed significant voltage separation from reduction to oxidation, indicating low efficiency of the redox Faraday reaction and pronounced detrimental effects associated with faster scan rates. See Figure 86.
The charge transfer resistance values for different surfaces show a significant improvement for the GiiSens sensor surface. This demonstrates the great potential of GiiSens for achieving reliable impedance-based measurements with minimal background signal interference.
Gii Sens compared to other carbon-based materials
Carbon-based electrode materials are very common in electroanalytical applications. Carbon paste electrodes are a common material for screen-printed sensors. They are the most widely used electrode surfaces in practical, immediate applications due to their fabrication flexibility and affordability. At the other end of the spectrum are glassy carbon surfaces, which are expected to offer better performance, but their availability is limited by fabrication flexibility and affordability. See Figure 87.
The Gii Sens carbon foam exhibits performance comparable to pure glassy carbon materials in terms of available electrochemically active area, while increasing the usable area by 50% for a carbon paste electrode of the same size. See Figure 88.
The separation of reduction-oxidation peaks obtained from cyclic voltammetry initially revealed the poor performance of the carbon paste material, which is highly dependent on slow scan rates to achieve a relatively acceptable redox reaction on its surface. The Gii Sens response outperformed pure glassy carbon even at any scan rate, demonstrating its significant potential for manufacturing flexibility and superior performance. See Figure 89.
The measurement of surface charge transfer resistance highlights the enormous potential of Gii Sens as an impedance-based sensing surface superior to glassy carbon, and opens up areas previously unreachable by carbon paste electrode materials.
Gii Sens compared to screen printing gold
Screen-printed gold sensors possess two crucial properties that enable the sensor material to be used in practical electrochemical sensing applications: flexible fabrication processes and excellent electrochemical reactivity. Two commercially available screen-printed gold samples were evaluated. See Figure 90. Gii Sens carbon foam was demonstrated to possess these properties as well, while also being affordable.
Recorded reduction and oxidation peak currents show that the available electrochemically effective region per geometric unit area has increased by at least 20%. See Figure 91.
As expected, screen-printed gold showed the most responsive electrode surface material in the evaluation batch; however, Gii-Sens matching further improved this performance, especially at fast scan rates. See Figure 92.
Comparing the charge transfer resistance of the electrode surfaces of screen-printed gold and Gii Sens also highlights the great potential of Gii carbon foam materials; in all cases, it exhibits low resistivity-related values.
The comparison between Gii Sens and screen-printed gold aims to demonstrate the superiority of Gii Sens in terms of ease of manufacture and superior performance, while affordability and scalability are undoubtedly beneficial inherent features of the Gii Sens sensor.
in conclusion
The Gii Sens sensor outperforms any other carbon-based or even graphene-based sensor on the market. It even surpasses screen-printed gold surfaces, eliminating any concerns about the overall convenience of using Gii Sens surfaces as the ultimate electrochemical sensing platform. Gii Sens demonstrates for the first time the perfect choice of fabrication and scalable materials for electroanalysis applications, while maintaining peak performance, ensuring maximum sensitivity and flexibility for high-throughput and point-of-care diagnostic applications.
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
Target:
Optimization of surface immobilization of anti-human calcitonin (cAb)
Summary of Results
Select a surface NHS production method. Match existing standard manufacturing processes.
Optimal cAb surface coverage was achieved using 100 μg/ml cAb.
For standard bare sensors, the typical %CV is 7%. For all sensors shown in the experiments presented in this report, the %CV for a 100 μg/ml cAb coating was 10%.
Using a 100 μg/ml cAb coating, 2000 pg/ml Ag was successfully detected by direct determination. The %CV of the signal output was 10%.
Experimental Section
Solution composition
Surface Chemistry
NHS modification
pyreneNHS
Capture antibody (cAb):
Product Name: Antih PCT 4004SPTN-5
Antigen (Ag):
Product Name: Recombinant PCT Antigen
Echem Readout Solution
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 20 mM KCl.
cAb fixation solution
Anti-hPCT in 1×PBS (pH 7.2)
Antigen (Ag) detection solution
In 20 mM KCl, 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ + Ag
Electrochemical technology
Electrochemical impedance
Applied voltage: OCP
Amplitude: 0.01V RMS
Frequency range: 100000-0.1Hz
Cyclic voltammetry
Scan rate: 25mV/s
Initial potential: -0.3V
High potential: 0.6V
Low potential: -0.3V
Measurement Procedure
NHS fixed
10 mM Pyr NHS prepared in DMF.
10 μL was drop-coated onto the working electrode of each sensor.
Place the sensor in an airtight box and incubate it for 12 to 18 hours.
It was confirmed that PyrNHS/DMF had been fully evaporated from the surface.
cAb fixation procedure
Place the NHS GiiSens+ sensor on a flat surface.
10 μL of cAb was drop-coated onto the working electrode of each sensor.
Place the sensor in a sealed container and bathe it in water for 2 hours.
Remove the sensor and gently rinse off the solution with DI water, then gently dry it with a stream of N2 gas.
Measurement procedure: Direct measurement 1 - see Figure 93
1) cAb readout: Apply the electrochemical readout solution to the sensor surface, and then perform EIS measurement.
2) Solution removal: Remove the electrochemical readout solution from the sensor surface.
3) t'1 readout: Apply the electrochemical readout solution containing the antigen to the sensor surface, followed by EIS measurement. There is approximately 1 minute between solution addition and measurement.
4) Read t'2 and perform EIS measurement. There is approximately 6 minutes between adding the solution and the measurement.
5) Read t'3 and perform EIS measurement. There is approximately 11 minutes between adding the solution and the measurement.
See the appendix for the electrochemical reading procedure.
1. Characterization curve graph
Each point is sampled repeatedly, with n = 5 (minimum) different disposable sensors (single readout, sensor is disposed of).
Phase 1: Surface Chemistry
The chosen surface chemistry is NHS-modified carbon foam, followed by conjugation of cAbs via amide bond formation. See Figure 94: Schematic diagram of the surface fixation reaction.
NHS generation on the carbon foam surface was monitored using electrochemical impedance spectroscopy and cyclic voltammetry. See Figure 95: Rct and ΔEp signal responses of the electrode for NHS functionalization.
The increases in Rct and ΔEp relative to the bare electrode confirm the NHS functionalization of the carbon foam electrode.
A range of cAb concentrations between 50 and 800 μg/ml were screened using electrochemical impedance spectroscopy. See Figure 96: cAb immobilization on the electrode.
For immobilization on the NHS-modified sensor, a logical increase in Rct was observed with increasing cAb concentration. The optimal coverage on the NHS electrode was estimated to be 100 μg/ml cAb, a concentration that provided the best sensor performance without wasting material for minimal gain. Excellent reproducibility (%CV 3%) was observed at this concentration.
Phase 2: Electrochemical Signals
The generated electrochemical signals were evaluated for direct assay, meaning that secondary antibodies are not required to assist antigen detection.
An antigen concentration of 2000 pg/ml was selected for the direct assay study. Based on the results of Phase 1 of this report, the surface antibody coating was fixed at 100 μg/ml. The Ag-Ab incubation time was selected as the initial assay parameter for the study. See Figure 97: Signal response from 2000 pg/ml in the direct assay using a 100 μg/ml cAb surface coating.
The 100 μg/ml cAb again showed a good level of reproducibility (%CV 8%). The difference in mean Rct between cAbs was significant, yielding different quantifiable signal outputs (ΔRct). The ΔRct signal output also showed an acceptable level of reproducibility, with %CV ≥ 10% at each readout time. The stability of the output signal between 1, 6, and 11 m indicated no additional Ab-Ag interactions after the first measurement. The 5-minute time interval between measurements is attributed to the time length required for EIS measurements. For 2000 pg/ml Ag samples, the optimal assay incubation time is as low as 1 minute.
Table 9: Key experimental and electrochemical parameters for cAb fixation
Table 10: Key experimental and electrochemical parameters for Ag detection
Appendix 8:
Combined list of features and optional features
Appendix 8 is a combined list of features and optional features. It should be noted that each of any one or more features A-R can be combined with one or more other compatible features A-R, as well as with any one or more optional features.
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene materials adhered to a substrate
Group 2: Dual-laser processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual Laser
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device: supercapacitor
Features M2: Details of Carbon Foam Supercapacitor
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate a subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the subsurface region.
An apparatus comprising a laser-induced carbon foam material produced by irradiating a subsurface region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an encapsulation region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the encapsulation region.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulation region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
A laser-induced carbon foam material is manufactured by means of a laser beam configured to irradiate an encapsulated, subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to a substrate
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between the graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between a graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing graphene material includes the following steps: (a) irradiating an encapsulation region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulation region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove at least some of the disordered amorphous non-graphene material and expose at least some of the carbon foam.
A laser-induced carbon foam is made by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
An apparatus comprising laser-induced carbon foam prepared by:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers operating in different frequency bands
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating a region of the carbon precursor material, below the surface of the material or a region below the surface of the material, with a laser beam operating in a first wavelength band to generate carbon foam in the region of encapsulation or the region below the surface, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
A laser-induced carbon foam material, which is made by the following:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of the carbon precursor material below the surface of the material using a laser beam operating in a first wavelength band, to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is carried out in one manufacturing facility, and step (b) is carried out in a different facility.
Feature L1: Biosensor
A method for manufacturing a biosensor, the biosensor comprising a sensing electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
A biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes a biosensor with sensing electrodes comprising carbon foam made at least in part by a method as defined in any one of features A-K above.
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric material to at least partially cover the electrodes and connection traces.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam made by a method defined as any one of features A-K above, and said biosensor includes (i) a screen-printed electrical connection trace over each electrode and (ii) a screen-printed dielectric that at least partially covers the electrodes and the connection trace.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and said method comprising an additional step of adding functionalized groups to at least the working electrode in a different manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam manufactured at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups added to at least the working electrode at different manufacturing facilities.
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least a portion of a carbon foam produced at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups that have been added to at least the working electrode at the same manufacturing facility.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon produced by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on a carbon precursor substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon layer, the electrical connection trace, and the reference electrode; and then (d) producing a carbon foam sensor electrode using a method as defined in any one of features A-K above.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, wherein the biosensor includes (a) a carbon layer screen-printed on a carbon precursor substrate; (b) screen-printed electrical connection traces and a screen-printed reference electrode; (c) a dielectric layer screen-printed over the carbon layer, the electrical connection traces, and the reference electrode; and (d) a carbon foam sensor electrode fabricated using a process as defined in any one of features A-K above.
Feature M1: Energy storage device
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
The method includes the steps of screen printing electrical connection traces over at least a portion of each electrode and screen printing a dielectric layer to at least partially cover the electrodes and connection traces.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Includes a screen-printed electrical connection trace formed above at least a portion of each electrode and a screen-printed dielectric layer that at least partially covers the electrode and the connection trace.
Feature M3: Carbon foam supercapacitor: common collector electrode
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
The method includes the step of screen printing electrical connection traces over at least a portion of each electrode, wherein a single electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrodes comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) a screen-printed electrical connector on a substrate; (b) a screen-printed carbon layer above the current collector; (c) a screen-printed dielectric over at least some of the carbon layer; and then (d) a carbon foam energy storage electrode produced at least in part by a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Supercapacitor: Metal Oxide Variant
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of electrochemically depositing a pseudocapacitive material, such as a metal oxide, onto the energy storage electrode.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) a pseudocapacitive material, such as a metal oxide, applied to said energy storage electrode.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel electrolyte in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) an ion-gel electrolyte having been applied in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in said environment are measured and controlled to optimize the capacitance of said energy storage device.
Feature N1: Electrical conductor
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
A method for manufacturing a smart tag includes the steps of combining or integrating a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as described in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor.
A method of manufacturing an integrated device includes the step of combining or integrating an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above.
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode formed at least partially in a layer below the sample orifice by means of a carbon precursor film formed by any one of the features A-K above, and a reference electrode connector, a working electrode connector, and a counter electrode connector in the layer below the reference electrode, the working electrode, and the counter electrode.
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
A method for manufacturing a lab-on-a-chip device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a conductive layer over the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) Screen printing a dielectric layer above the current collector layer;
(vi) The sensor electrode comprising carbon foam material is prepared from the carbon precursor film by at least part of the method defined in any one of features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Feature P: Scalable manufacturing of carbon foam: Gii 3
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other carbon foam applications
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, tactile sensors for robots; prototype sensors that use polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as an active layer in a piezoresistive pressure sensor for robotic touch sensing applications.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection.
Continuous monitoring of chemical sensors.
Glucose monitoring sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competing for binding with polynordihydroguaiaric acid.
Lactic acid sensor: Employs synthetic organic acceptor molecules based on attaching boric acid to carbon foam to provide functionality and selectivity in competitive analyte binding, using surface redox polymer indicator displacement.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1).
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material produced at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a prominent D peak; a 2D peak smaller than the G peak; and a D peak:G peak ratio greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Optional features
It should be noted that each of the following optional features can be combined with one or more other compatible optional features and with any one or more of the main features A-R.
Manufacturing process
The manufacturing process is a room temperature process.
The manufacturing process is an atmospheric pressure process.
It can be done on a plastic substrate (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
The manufacturing process requires approximately 2 minutes or less to create a 1 cm² carbon foam, which is about 50 μm thick, on a plastic substrate.
The manufacturing process enables the formation of 3D carbon foam on a flexible substrate.
The manufacturing process does not require graphene or graphene oxide precursors.
The manufacturing process generates carbon foam material only in the encapsulation and subsurface region of the carbon precursor material, and does not generate carbon foam material on any surface of the carbon precursor material.
The manufacturing process utilizes a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
The manufacturing process described herein is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
First laser beam parameters and control scheme
The first laser beam and the second laser beam are generated by different laser systems.
The first laser beam and the second laser beam are generated by the same laser system.
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface region or encapsulation region to form carbon foam.
• The laser beam generates temperatures exceeding 500°C in the subsurface region or encapsulated region to form carbon foam.
• The pulse duration of the laser beam is between 1 ns and 10 μs, resulting in a heating rate between approximately 5 × 10 7 ℃/s and 2 × 10 12 ℃/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between 50kHz and 500kHz.
• The laser pulse frequency is between 1 kHz and 2 MHz.
• The laser wavelength is between 0.7μm and 2.5μm.
• The laser is scanned at a speed between 9 cm/s and 40 cm/s (or ±50% of these ranges).
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The focal point of the laser beam is moved through a depth of at least 100 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scan can achieve a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm in size).
• The wavelength of the laser beam is not absorbed by the carbon precursor material, or the absorption rate is extremely low.
• Carbon precursor materials have extremely low absorption rates for the wavelengths of laser beams.
The radiation absorptivity per centimeter (decimal) is less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between 0.7μm and 2.5μm.
The laser beam is an IR laser with a wavelength between 0.75μm and 1.40μm.
Properties of the subsurface region or packaged region
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region is at least 10 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 20 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 30 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 40 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 50 μm below the surface of the carbon precursor material.
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
• The thickness of the subsurface region or encapsulation region is between 10 μm and 200 μm.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity or other laser parameters, and the selection of the carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, or more below the surface of the carbon precursor material.
• The distance between the subsurface region or encapsulation region and the surface of the carbon precursor material is at least 1% of the total thickness of the carbon precursor material, or at least 10% of the total thickness of the carbon precursor material, or at least 20% of the total thickness of the carbon precursor material, or at least 30% of the total thickness of the carbon precursor material, or at least 40% of the total thickness of the carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the center of the minimum cross-section of the first laser beam, and the volume is within 500 micrometers, 100 micrometers, or 1 micrometer of the center.
carbon precursor materials
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300 ± 50 cm⁻¹.
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of the laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
Substrate supporting carbon precursor materials
• The substrate is a plastic body, film, or foil.
• The substrate is flexible.
The substrate is a polyimide circuit board.
• The substrate has an extremely low absorption rate of the first laser beam.
• The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
• The substrate is formed of one or more of the following: silicon (Si), silicon dioxide (SiO 2 ), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing both silicon and silicon dioxide.
• The substrate is a carbon source.
• The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
• The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
• The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam.
• The thickness of the disordered, amorphous, non-graphene material occupying the surface of the adjacent carbon precursor material is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
• The disordered, amorphous, non-graphene material extends from its surface into the carbon precursor material matrix by at least 10 μm.
• The disordered, amorphous, non-graphene material extends from its outer surface into the body of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
Carbonization at the physical interface with the substrate supporting the carbon precursor material
• The carbon precursor material is transformed into a disordered, amorphous, non-graphene material at the physical interface with the substrate by the laser beam to a depth defined by the parameters of the laser beam.
The disordered, amorphous, non-graphene material adheres or otherwise attaches to one region of the carbon foam and to another region of the substrate, thus providing stability to the carbon foam.
• The thickness occupied by the disordered amorphous non-graphene material, as measured from the interface between the carbon precursor material and the substrate, is about 1%, less than about 1%, less than about 5%, or less than about 10% of the total thickness of the carbon precursor material.
• The thickness of the disordered, amorphous, non-graphene material occupying the interface between the carbon precursor material and the substrate is at least 10 μm.
• The disordered, amorphous, non-graphene material extends from the interface between the carbon precursor material and the substrate to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
ablation laser beam or second laser beam
The parameters of the laser beam include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the region below the surface or in the encapsulation region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
• A second laser beam alters the carbon foam as part of the process that exposes it.
• A second laser beam alters the shape of the carbon foam as part of the process that exposes it.
• The second laser beam is automatically controlled to scan in the same area, and/or overlapping area, and/or non-overlapping area.
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
• The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
• The carbon precursor material has an absorption coefficient for the second laser beam greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300± 50cm⁻¹ .
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The second laser beam scans in a pattern (e.g., a grating) that includes non-overlapping areas or lines.
• The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
• The second laser beam is the same as the laser beam that irradiates the encapsulation area or subsurface area of the carbon precursor material to generate carbon foam in the encapsulation area or subsurface area.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam
• The carbon foam is a multi-layered twisted or disordered carbon foam.
• The carbon foam is non-graphene carbon foam.
• Carbon foam includes carbon nanostructures such as carbon nano-onions, carbon nano-horns, carbon nanotubes, carbon nanodots, nanodiamonds and fullerenes, or any combination thereof.
• The thickness of the carbon foam is at least about 50 μm.
• The thickness of the carbon foam is between approximately 50 μm and 300 μm.
• Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
• Carbon foam is or includes carbon foam with a spatial distribution of defects that lead to high electrochemical reactivity.
• Carbon foam is or includes carbon foam with basal surface defects at vacant sites that lead to high electrochemical reactivity.
• The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Compared to conventional graphene foams produced using conventional laser processes, carbon foams possess one or more of the following properties: easier control over thickness or depth; greater flexibility compared to the highly brittle graphene produced using conventional laser processes; stronger adhesion to underlying flexible substrates; higher porosity; higher electrical conductivity; increased capacitance or charge storage; faster absorption of organic solvents and water-based solutions; higher hydrophilicity; contact angle less than approximately 20°; enhanced antifouling properties; higher EMI shielding; and improved electrode quality.
Biosensor Use Cases
• Carbon foam has been functionalized as a biosensor.
• Carbon foams are functionalized into biosensors by adding receptors that are specific to the target or analyte.
• Carbon foam has been functionalized into a biosensor with a reversible polymer displacement sensor mechanism for use in
Electrochemical glucose monitoring.
The reversible polymer displacement sensor includes a pyrene-derived boric acid chemical acceptor for glucose adsorbed onto an electrode comprising the carbon foam.
Carbon foams are functionalized as biosensors by adding receptors that are specific to a target or analyte and connectors that enable the receptors to attach to the carbon foam.
The connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
The connector is selected from polymers (preferably (meth)acrylate polymers), organic compounds containing one or more functional groups, carbodiimides, diazo compounds, or mixtures thereof.
• The one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, and optionally combined with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
The organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of the organic compound as an ester or salt, or a compound that releases the organic compound in a reaction with the carbon foam.
• The connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof.
The joint is bonded to the carbon foam via π-π interactions.
The receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
The receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes or mixtures thereof.
• The receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
The receptor is bonded to the adapter in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
Supercapacitor Use Cases
The carbon foam forms electrodes in an energy storage device, such as an electrochemical capacitor, supercapacitor, pseudocapacitor, or capacitor.
The carbon foam is treated with a metal oxide film to provide pseudocapacitance.
The carbon foam forms at least one electrode in the energy storage device, such as an electrochemical energy storage device.
A capacitor, supercapacitor, pseudocapacitor, or capacitor, and a hydrogel electrolyte encapsulates the electrode or each electrode in the active region to produce an enhanced operating voltage window.
The carbon foam forms the electrodes in the battery.
The carbon foam forms an electrical conductor.
Technical Field
This invention relates to laser-induced production of carbon nanostructures, including multilayer carbon foams with disordered layer twisting.
Background Technology
Carbon nanostructures are both highly attractive and a hot research topic. Carbon nano-onions (also known as multilayer fullerenes) exemplify this. See “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9 and “Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications”, DOI:10.1016/j.ica.2017.07.021, the contents of which are incorporated herein by reference.
As another carbon nanostructure, graphene has attracted widespread attention for many years due to its applications in biosensors, electrochemical sensing systems, supercapacitors, electrodes, and fuel cells. Known methods for producing 3D graphene include laser-induced graphene production as described in WO2019/038558; 3D graphene is formed on the surface of the exposed polyimide film when a suitable carbon precursor material (such as a polyimide film) is positioned on a supporting substrate and irradiated with a CO2 laser. Experience has shown that the thickness of 3D graphene produced by this method is less than 50 μm; furthermore, 3D graphene itself can be brittle and has poor adhesion to the underlying substrate, thus potentially peeling off. Therefore, 3D graphene is not suitable for many applications.
A note on terminology used in the field of carbon nanostructures: If we use only the term "graphene," there are many different forms of "graphene"; for example, the literature describes monolayer graphene, bilayer graphene, disordered graphene, graphene superlattices, graphene fibers, 3D graphene, graphene aerogels, wrinkled graphene, and many other forms. This presents a defining challenge, as using a specific term (e.g., "3D graphene") may imply limitation to only that specific form of graphene. Furthermore, IUPAC (International Union for Pure and Applied Chemistry) recommends using the name "graphite" for three-dimensional materials, and "graphene" only when discussing the reactions, structural relationships, or other properties of individual layers.
Therefore, in this specification, we use the term "carbon foam" as a general term, and this term should be broadly interpreted to cover any carbon nanostructure, such as 3D carbon material foam, including multilayer 3D carbon material foam with disordered layer twisting.
An example of the term "carbon foam" refers to a material manufactured using the methods described in this specification; such a material has slightly different properties from conventional graphene or conventional graphene foam. For example, graphene foam has several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature: the absence of a D peak; a 2D peak higher than the G peak; and a D peak:G peak ratio close to zero. As we will describe in more detail below, the carbon foam produced in specific embodiments of the invention does not possess these characteristics; it is hydrophilic with a contact angle less than 20°; it lacks the Raman signature indicative of graphene: it exhibits a prominent D peak; a 2D peak significantly smaller than the G peak; and a D peak:G peak ratio significantly higher than zero. In terms of appearance and Raman signature, it appears to be closer to carbon nanotube onion materials. Therefore, the term "carbon foam" in its scope also includes materials that are carbon nanostructures, such as carbon nanotube onions, carbon nanohorns, carbon nanotubes, carbon nanodots, nanodiamonds, and fullerenes, or any combination thereof.
Summary of the Invention
In this specification, we describe a method in which the surface of a carbon precursor is not converted into graphene at all; instead, the region beneath the surface of the carbon precursor, or the encapsulated region, is converted into carbon foam by a focused laser beam.
We summarize the invention as described in claim 1, namely a method for manufacturing carbon foam material, which includes the following steps:
(a) Using a first laser beam, an encapsulated or sub-surface region of the carbon precursor material is irradiated below the surface of the material to generate carbon foam in the sub-surface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Using a second laser beam to remove or ablate the disordered amorphous non-graphene material located above the carbon foam to expose at least some of the carbon foam.
The amorphous non-graphene material is positioned "above" the carbon foam because it is closer to the laser beam that generates the laser. One embodiment of the invention is described as a "dual-laser" process because two separate lasers are used in the production of the carbon foam material. The carbon foam material exhibits a significant D peak; the 2D peak is significantly smaller than the G peak; and the D peak:G peak ratio is significantly higher than zero. In terms of appearance and Raman signature, it appears more similar to carbon nanotube onion material. It can be used in biosensors, supercapacitors, and pseudocapacitors. In one embodiment, the carbon foam is referred to as "Gii" carbon foam.
Attached Figure Description
The invention will be described with reference to specific embodiments shown in the following figures.
Figures 1-6 schematically illustrate a dual-laser process for generating carbon foam when a polyimide (PI) film (which acts as a carbon precursor) is positioned on a substrate.
Figure 7 is a scanning electron image showing the unique surface morphology (x250) of carbon foam achieved using a dual-laser method.
Figure 8 is a scanning electron image showing the surface of conventional laser-induced graphene.
Figures 9-14B schematically illustrate a dual-laser process for generating carbon foam when the PI film (which acts as a carbon precursor) is not positioned on the substrate.
Figure 15 shows the cyclic voltammetry (CV) diagram of a carbon foam electrode produced using a dual-laser method.
Figure 16A is a graph showing the peak separation ΔE<sub>p</sub> of a carbon foam electrode produced using a dual-laser method as a function of the scan rate.
Figure 16B is a graph showing the peak separation ΔE<sub>p</sub> of a conventionally manufactured graphene electrode as a function of the scan rate.
Figure 17 compares the electrochemical impedance spectroscopy results of carbon foam electrodes produced using the dual-laser method with those of conventionally manufactured graphene electrodes.
Figures 18A and 18B show Raman analysis of carbon foam samples prepared using a dual-laser process.
Figure 18C shows the Raman analysis of carbon nanotube onion material.
Figure 19 is a scanning electron image showing dual-laser carbon foam and conventional graphene.
Figure 20 is a schematic image of a biosensor that includes dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Sens).
Figures 21-23 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Sens, Gii-Sens+, and PPC Gii-Sens variants).
Figures 24-27 are schematic images of a supercapacitor including dual-laser carbon foam (this specific implementation of carbon foam is called Gii-Cap).
Figures 28 and 29 are detailed process flow diagrams for dual-laser carbon foam (referred to as Gii-Cap and Gii-Cap+ variants).
Figure 30 is a schematic cross-section of an integrated lab-on-a-chip (LoC) device that includes a biosensor and a supercapacitor made using dual-laser carbon foam.
Figure 31 is an exploded view of a fully integrated LoC device.
Figure 32 shows the LoC device displaying quantitative results on its monitor.
Figure 33 is an exploded view of an environmental monitoring device including the Gii-Sens sensor.
Figure 34 is a view of the assembled environmental monitoring device.
Figure 35 is a schematic cross-section of a device having a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 36 is a schematic diagram of a smart tag; it has a battery (e.g., a printed battery or a conventional battery) and a Gii-Cap supercapacitor.
Figure 37 is a schematic cross-section showing the basic layering of different materials in the Gii-Thru variant, which is a three-dimensional structure of carbon foam.
Figures 38-42 are schematic diagrams of various Gii-Thru Gii-Cap/Gii-Cap+ three-dimensional supercapacitor devices.
Figures 43A and 43B are detailed process flow diagrams of the dual-laser carbon foam Gii-Thru Cap three-dimensional supercapacitor device.
Figures 44A and 44B are schematic diagrams of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device.
Figures 45A and 45B are schematic diagrams of the Gii-Thru sensor used in an eight-sample array microfluidic diagnostic device.
Figure 46A shows a perspective view of a fully assembled multi-sample array microfluidic diagnostic device.
Figure 46B is a top view of a multi-sample array microfluidic diagnostic device.
Figures 47 and 48 are views of a microfluidic diagnostic device.
Figure 49 shows the detailed manufacturing process of the high-sensitivity, low-cost Gii-Thru variant.
Figure 50 is a schematic diagram of a high-speed roll-to-roll or roll-to-sheet manufacturing system for Gii carbon foam.
Figure 51 shows the detailed process flow of the system in Figure 50.
Figures 52-57A show scanning electron images of dual-laser carbon foam at different magnifications.
Figure 57B is a scanning electron image of carbon nanotube onion material produced using conventional processes.
Figure 58 shows the Raman displacements of eight carbon foam sheets fabricated using a dual-laser process.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Figure 59 shows the carbon foam cyclic voltammogram measured at 25 mV/s for the anode voltage.
Figure 60 shows the carbon foam cyclic voltammogram for cathode voltage measured at 25 mV/s.
Figure 61 shows the galvanostatic charge-discharge (GCD) curves of carbon foam measured at 0.5 mA/ cm² for the anode voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves for the cathode voltage window, measured at 0.5 mA/ cm² .
Figure 63 shows carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 shows carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 shows carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 2: Gii-Cap+ Hydrogel
Figure 66 shows a typical CV curve for the Gii-Cap+ hydrogel device.
Figure 67 shows a typical GCD curve of the adjusted Gii-Cap+ hydrogel device.
Figure 68 shows the post-adjustment Nyquist (left) and Bode (right) curves of the Gii-Cap+ device.
Appendix 3 GiiCap Ion Gel
Figures 69-74 show the results of the GiiCap ionogel apparatus.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Figures 75-78 are schematic diagrams of the measurement procedure of the Gii-Sens 3D carbon foam measurement system.
Figures 79-81 show the surface chemistry of Gii-Sens 3D carbon foam.
Figures 82-83 show the label-free assay of Gii-Sens 3D carbon foam.
Appendix 6 Baseline Experimental Conditions
Figures 84-86 are graphs comparing the performance of Gii-Sens carbon foam and graphene electrode materials.
Figures 87-89 are graphs comparing the performance of Gii-Sens carbon foam and carbon-based electrode materials.
Figures 90-92 are graphs comparing the performance of Gii-Sens carbon foam and screen-printed gold.
Appendix 7: Optimization of surface immobilization of anti-human calcitonin (cAb)
Figure 93 shows an optimized direct assay procedure for surface immobilization of anti-human calcitonin (cAb).
Figure 94 is a schematic diagram of the surface fixation reaction.
Figure 95 shows the Rct and ΔEp signal responses of the Gii-Sens electrode with NHS functionalization.
Figure 96 shows cAb fixation on the GiiSens electrode.
Figure 97 shows the signal response from 2000 pg/ml in the direct determination form using a 100 μg/ml cAb surface coating.
It should be noted that Gii, Gii-Sens, Gii-Sens+, Gii-Cap, Gii-Cap+, Gii-Thru, and PPC Gii are trademarks of their respective owners. "Gii" generally refers to carbon foam produced using a dual-laser process. "Gii-Sens" refers to Gii carbon foam used in sensors (such as biosensors). "Gii-Cap" refers to Gii carbon foam used in supercapacitors. The "+" suffix indicates Gii carbon foam modified with a metal oxide layer or film. "Gii-Thru" refers to Gii carbon foam arranged in a specific three-dimensional structure. "PPC" refers to a specific manufacturing process, namely "post-printing conversion," in which Gii carbon foam is produced after various screen printing steps have been completed.
Figure Labels
Dual laser process
11 IR laser
12 IR laser beams
13. The interior of the PI film
14 PI film
15 substrate
16 Subsurface carbon foam region
17. Disordered amorphous non-graphene materials beneath the surface carbon foam region
18. Extended regions of disordered, amorphous, non-graphene material above the subsurface carbon foam region.
20CO2 laser
21 Unique surface morphology of exposed carbon foam regions
Biosensors
201 Polyimide substrate
202 Carbon Foam Working Electrode
203 Carbon foam counter electrode
204 carbon foam reference electrode
205 Screen Printed Silver Connecting Track
206 Dielectric Layer
The area where the 207 silver connection trajectory overlaps with the electrode
Gii-Cap Supercapacitor
Array of 241 carbon foam electrodes
242 Silkscreen Printed Silver Connector
243 Dielectric layer
244 Polyimide base layer
245 copper connector
246 Electrolyte layer
247 Aluminum Laminated Heat-Sealing Bag
250 carbon foam digits with rounded edges
Combined sensors and supercapacitors
301 Upper polyimide layer
302 Gii-Sens Biosensor
303 Lower polyimide layer
304 Supercapacitor
305 plastic parts
306 Microchannel
307 Connector Track
308 Flexible Electronic Devices
310 Induction Power Circuit
312 Gii-Cap Supercapacitor
313 Gii-Sens Biosensor
314 Device layer with microelectronic devices
315 Top Panel
316 monitor
317 Circular Analyte Well
Environmental monitors
330 Gii-Sens Carbon Foam Sensor
331 Control Electronic Devices
332 PV solar cells
333 Gii-Cap carbon foam supercapacitor
334 Peelable back
Combined supercapacitor and battery
351 First polyimide layer
352 Supercapacitor
353 Second polyimide layer
354 battery
355BMS (Battery Management System)
356 Flexible electronic devices
357 Electrical connectors
Smart Tags
360 Flexible Battery
361 Supercapacitor
362 Electronic Components Module
363 Exposed label surface; 364 Adhesive release liner; 364 Gii-Thru Cap
371PI membrane
372 Screen printing conductive ink or paste layer
373 Screen-printed collector
374 Dielectric Isolator
375 Encapsulated carbon foam layer; 376 Disordered, amorphous, non-graphene layer beneath the carbon foam layer; 377 Unique surface morphology layer.
390 Hydrogel Electrolyte Layer
391 Carbon foam layer with unique surface morphology
392 PI film
393 Screen Printing Carbon Paste Layer
394 Screen-printed silver connector layer
395 silver connector layer ketone insert
396 Distributed dielectric isolation layer
397 Second carbon foam layer with unique surface morphology
398 PI film
399 Hydrogel Electrolyte Layer
400 dielectric isolation layer
401 screen-printed silver current collector layer
402 copper insert
403 Screen Printing Carbon Paste Layer
404 carbon foam layer
405 PI film
Gii-Thru Sens
Three-point array microfluidic diagnostic device
440 Analyte Sample Wells
441 Laminated Hole Spacer Layer
442 Polyimide film
443 Screen-printed conductive carbon layer
444A Reference Electrode Connector
444B Working Electrode Connector
444C Counter electrode connector
447 Screen-printed dielectric layer
448A Reference Electrode
448B Working Electrode
448C counter electrode
449 Reference electrode screen-printed carbon layer
Eight-point array microfluidic diagnostic device
451 Laminated Hole Spacer
452 Array of eight analyte wells
453 Holes for the electrodes
454 Hole of the reference electrode
455 Polyimide layer
456 Polyimide layer
457 Eight working electrodes
458 pairs of electrodes
459 Reference Electrode
460 Screen-printed carbon bonding interface layer
461 Screen Printed Silver Connecting Track
462 Screen-printed dielectric layer
470 Top-layer microfluidic foil
471 Intermediate Layer Microfluidic Foil
472 Printed or molded microfluidic channels
473 Microfluidic foil with binder as the underlying layer
474Gii-Thru sensor
475 connector
481 Transparent Resin Barb Connector
482 Top Foil
483 Transparent Resin Molded Microfluidic Card
484 Microfluidic Channels
485-hole unit
486Gii-Thru sensor
Detailed Implementation
We will begin with a simplified, illustrative walkthrough of specific embodiments of the invention. We present two demonstrations; the first (Figures 1-6) will describe at a high level the carbon foam production process with a carbon precursor (e.g., a polyimide (PI) film, in this case, such as a membrane) mounted on a substrate; the second (Figures 9-14) covers the carbon foam production process without the polyimide film mounted on the substrate. In each case, we use a dual-laser process; the meaning of the terminology will be explained below.
In the first stage (see Figure 1), a laser 11 with wavelength λ uses a laser beam 12 to irradiate the interior 13 of a polyimide film 14, which is positioned on a substrate 15 suitable for end applications. This laser may be a pulsed IR laser that delivers IR radiation with a wavelength of 1064 nm.
As shown in Figure 2, a laser 11 with wavelength A is tuned so that the subsurface region 16 is transformed into carbon foam. The focus of laser A is gradually moved through the interior 13 of the polyimide film 14 to generate the entire carbon foam region 16. The depth or height of the carbon foam region 16 can be approximately 50 μm or greater, much higher than that achievable by other methods. Note that no carbon foam is generated at any time on the exposed surface of the polyimide film 14 (i.e., the surface on which the laser beam is incident). The region above the carbon foam 16 (i.e., closer to the laser than the carbon foam region 16) is not transformed into carbon foam. The region 17 below the carbon foam region 16 (i.e., the lower surface of the PI film) is also not transformed into carbon foam, but rather into disordered, amorphous, non-graphene material adhered to the underlying substrate 15.
Figure 3 shows that due to gas trapping, the laser 11 with wavelength λ causes physical expansion in region 18 above the internal carbon foam region 16 (i.e., closer to the laser than the carbon foam region 16). This region 18 is neither 3D graphene nor a polymer; it is a disordered amorphous material.
In the second stage, a laser 20 with wavelength B is now tuned to the disordered amorphous material region 18 above the carbon foam region 16, as shown in Figure 4. This can be a CO2 laser with a wavelength of 10.6 μm.
As shown in Figure 5, a laser 20 with wavelength B ablates some or all of the region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam region 16.
The laser 20 with wavelength B also reveals a lower carbon foam region with a unique surface morphology 21, as shown in Figure 6.
We refer to the process described in Figure 1-6 as the "dual-laser process".
Figure 7 is a scanning electron image showing the unique surface morphology (x250) achieved using a dual-laser method. In this case, the carbon source was first irradiated with IR radiation at a wavelength of 1064 nm from a pulsed IR laser, the radiation being focused into and gradually penetrating the carbon source. Then, the carbon source was irradiated with a laser beam at a wavelength of 10.6 μm from a CO2 laser. The thickness of the carbon foam layer in this image is approximately 220 μm.
As shown in Figure 8, the contrast with the surface morphology (x250) achieved using the conventional LIG method is striking: it features clear grating lines and less spiraling folds. The thickness of this carbon foam layer is less than 50 μm.
Based on the image in Figure 7, we can infer that the material produced using the dual-laser process does not have a surface morphology similar to conventional graphene foam; although it appears to be a multilayered, 3D carbon-based material with a chaotic, tortuous, foam-like structure, it is not necessarily a material commonly described as "graphene" in the conventional sense. More details are provided in Feature R below.
In the aforementioned demonstration (Figures 1-6), we investigated a dual-laser process for mounting a carbon precursor material (polyimide film) onto a substrate. In Figures 9-14 below, we will investigate a dual-laser process without mounting the polyimide film onto the substrate. We will later describe in detail the manufacturing processes for two specific implementations, referred to as Gii-Cap (supercapacitor) and Gii-Sens (sensor), which use a standard 220mm × 180mm sheet of polyimide film, which is not mounted onto the substrate; this size can be considered in standard laser scanning equipment, typically used for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). The manufacturing process also utilizes a standard flatbed screen printing apparatus and a standard conveyor belt dryer to easily accommodate thin PI films of different sizes. Other sizes of polyimide sheets can be considered.
As previously described, a laser 11 of wavelength Å (e.g., an IR laser) irradiates the interior 13 of the PI film 14; the film 14 is not currently mounted on the substrate, as shown in FIG9. It may be a sheet whose edges are supported or temporarily rested on a surface, or a sheet that forms part of a PI film roll when using a continuous manufacturing (e.g., roll-to-roll or roll-to-sheet) system (see Feature P below).
A laser 11 with wavelength λ is tuned to transform the subsurface region 16 into carbon foam, as shown in Figure 10. The focal point is gradually moved through the membrane 14 to create the entire carbon foam region 16. The height of the carbon foam region 16 can be approximately 50 μm or greater, much deeper or higher than could be achieved by other methods.
At no time does 3D graphene form on the exposed surface of the polymer film. The region above the carbon foam does not transform into 3D graphene.
As shown in Figure 11, due to gas retention, region 18 above the internal carbon foam region 16 undergoes physical expansion. This region is neither 3D graphene nor a polymer; it is a disordered amorphous material.
A laser 20 with wavelength B (e.g., CO2 ) is now tuned to region 18 above the carbon foam, as shown in Figure 12. The laser 20 with wavelength B ablates region 18 above the carbon foam region 16, exposing at least some of the underlying carbon foam 16, as shown in Figure 13.
Just as with the case where the polyimide film 14 is mounted on the substrate, the laser 20 with wavelength B also imparts a unique surface morphology 21 to the underlying carbon foam 16, as shown in Figure 14.
Some specific implementation details of this dual-laser method for producing carbon foam are as follows: In one example, the Nd:YAG solid-state laser is a wavelength A-wave laser, and it is positioned such that the IR laser radiation beam (wavelength 1064 nm) generated by the solid-state laser perpendicularly impacts the polyimide layer. Optics focus the IR laser radiation beam to a minimum beam convergence within a certain volume of the polyimide layer.
In the encapsulation region or subsurface region or location around the minimum beam convergence, the interaction between the laser and the polyimide leads to the carbonization of the carbon source. This carbonization results in the generation of carbon foams, such as twisted or disordered multilayer carbon foams, in the encapsulation region or subsurface region, and causes the formation of a disordered, amorphous, non-graphene material layer on the surface of the polyimide film.
While maintaining the laser beam focused at a specific depth within the polyimide layer, the laser scans laterally above the polyimide layer. In this way, the path entirely within the polyimide carbon source is traced and transformed into carbon foam. Thus, the polyimide is carbonized into carbon foam with a pattern corresponding to the path traced by the scanning, focused IR laser beam.
In one setup, the Nd:YAG IR laser pulsed at 80 kHz, and the laser beam scanned the surface at a speed of 9.4 cm/s. Other implementations utilized different parameters. For example, a pulse frequency of 50 kHz and a scanning speed of 35.5 cm/s were also successfully used to generate carbon foam. The laser power typically operated in the range of 8–20 watts, with an optimal value of 12 W; the laser focal length typically operated in the range of 50 mm–400 mm.
Once a predetermined area within the polyimide layer is irradiated by a focused IR laser beam in the manner described above, the depth of the encapsulated area or subsurface region or location within the polyimide is altered, and the IR laser beam scans the same predetermined area again. A standard computer-controlled laser scanning system can be used, which controls the X-Y position of the laser on the polyimide film. It may be necessary to pass the focused IR laser radiation through the same area more than once to generate carbon foam. In this specific implementation, the focused IR laser also irradiates adjacent but not substantially overlapping areas. This process of irradiating the carbon source with focused IR laser radiation at different focal depths is repeated until the desired depth of the polyimide layer is exposed to IR laser radiation and carbon foam is formed in the encapsulated area or subsurface region. However, the surface layer is a disordered, amorphous, non-graphene material.
In the second step, the polyimide layer is exposed to radiation from a CO2 laser for an ablation process, exposing at least some of the underlying carbon foam and obtaining exposed carbon foam with a specific surface morphology. The radiation from the CO2 laser scans the surface of the treated carbon source at a speed of 19 cm/s to match patterns or areas irradiated using an IR laser. Other embodiments utilize different parameters. For example, a pulse frequency of 50 kHz and a scan speed of 35.5 cm/s have also been used to successfully expose the underlying carbon foam. The laser power is typically in the range of 8–20 watts, with 12 W being optimal; the laser focal length is typically in the range of 50 mm–400 mm.
As described above, CO2 lasers ablate the disordered, amorphous, non-graphene material on the surface layer, thereby exposing the underlying carbon foam and altering the surface morphology of the carbon foam to produce exposed carbon foam with a greater number of defects compared to standard laser-induced graphene; as previously stated, this endows the carbon foam with extremely useful properties superior to standard laser-induced graphene.
Changing the laser parameters of one or two lasers (e.g., IR laser and CO2 laser), such as power, focus, wavelength, and scanning speed, alters the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
One useful property of exposed carbon foam fabricated using a dual-laser process is its high wettability: the contact angle can be less than 20°, making this carbon foam hydrophilic, compared to conventional graphene foams with contact angles between 70° and 150°, making them hydrophobic. This hydrophilicity of the carbon foam produced via the dual-laser process is highly relevant for two key applications: biosensors (a specific implementation called Gii-Sens) and supercapacitors (a specific implementation called Gii-Cap). For biosensors, high wettability allows the tested liquid (e.g., a liquid analyte) to spread rapidly and uniformly across the entire working electrode, resulting in higher sensitivity, consistency, and speed. For supercapacitors, high wettability means the electrolyte wets the supercapacitor electrodes better, leading to higher performance. While conventional graphene foams can be processed to make them more wettable, this carbon foam implementation does not require such an additional processing step.
Another useful property of exposed carbon foam produced by the dual-laser process is its high resistance to fouling: this can lead to enhanced sensitivity and extended lifespan of biosensors. Carbon foam can be used in applications where the accumulation of contaminants or residues may impair the performance or lifespan of components (e.g., filters, heating elements in e-cigarettes; electrodes); exposed carbon foam produced by the dual-laser process can be used in said components, resulting in enhanced performance or lifespan.
The performance of the carbon foam electrode produced using this dual-laser method has been explored by cyclic voltammetry (CV), as shown in Figure 15. Cyclic voltammetry plots of the well-characterized ferricyanide/ferrocyanide redox reaction were performed using electrodes prepared using the method described above and electrodes prepared using known conventional CO2 laser irradiation methods. Figure 15 shows CV curves obtained at scan rates of 10 mV/s, 25 mV/s, 50 mV/s, 75 mV/s, 100 mV/s, and 150 mV/s. Each curve shows data recorded using the carbon foam electrode produced using the dual-laser method of the present invention (light line) and the 3D graphene electrode produced using the known CO2 laser irradiation method (dark line). The peak at approximately 0.22 V in the cathode current direction corresponds to the reduction of ferricyanide to ferrocyanide; and the peak at approximately 0.28 V in the anodic current direction corresponds to the oxidation of ferrocyanide to ferricyanide.
Far from the prominent redox peaks, these graphs qualitatively show that the CV curves recorded using carbon foam electrodes produced using the dual-laser method disclosed in this specification are more rectangular than those recorded using 3D graphene electrodes produced by known methods. This is most evident at the high points of the voltage range (approximately 0.6 V) and at higher scan rates (see, for example, 100 mV/s). This increased rectangular appearance indicates increased capacitive behavior of the electrodes prepared using the dual-laser method of this invention, thus reflecting the very high surface area of the torsion or disordered multilayer carbon foam produced by this method.
The CV curves also clearly show that the voltage for separating the oxidation and reduction peaks is consistently lower for measurements using carbon foam electrodes produced by a dual-laser method compared to those using 3D graphene electrodes produced by conventional known methods. The peak separation ΔEp as a function of scan rate for CV measurements obtained using carbon foam electrodes produced by the method disclosed in this invention is plotted in Figure 16(a), and the peak separation ΔEp as a function of scan rate for CV measurements obtained using 3D graphene electrodes produced by known methods is plotted in Figure 16(b).
This data shows that ΔE<sub> p </sub> narrows when the electrode is prepared according to the dual-laser method. The theoretical peak separation parameter for reversible systems (such as ferricyanide/ferrocyanide reversible redox reactions) is 57 mV, but in practice this is sensitive to the influence of electrode structure on electrochemistry. Clearly, the voltage separation of the oxidation and reduction peaks in the cyclic voltammetry plots is close to the theoretical value. This demonstrates the quality of the electrodes produced by both known methods and the dual-laser method. Furthermore, results recorded using a carbon foam electrode produced by the dual-laser method show reduced separation, indicating improved porosity of the electrode produced in this manner compared to electrodes produced by conventional methods.
Figure 17 shows a comparison of electrochemical impedance spectroscopy results for a system comprising a carbon foam electrode produced using a dual-laser method (square) and a system comprising a 3D graphene electrode produced using a known method (circle). Bode plots show the change in phase angle as a function of frequency. The frequency responses of the two systems are significantly different. Specifically, measurements recorded using the carbon foam electrode produced using the dual-laser method lack the phase angle signal peak observed at approximately 1 kHz in measurements recorded using the 3D graphene electrode produced using a conventional method. The response from the electrode prepared using the dual-laser method indicates a rapid electron transfer response. These differences further clearly demonstrate that the carbon foam produced by the dual-laser method is distinct from and can be differentiated from 3D graphene produced by conventional methods.
Further details are clearly visible in Figure 18A. The Raman spectrum of the carbon foam fabricated using a dual-laser process is shown in Figure 18A, exhibiting three main peaks. Specifically, the D peak at approximately 1344 cm⁻¹ is characteristic of lattice defects, and the G peak at approximately 1577 cm⁻¹ is characteristic of sp² carbon hybridization, featuring distorted six-fold carbon rings. The 2D peak at approximately 2685 cm⁻¹ is characteristic of secondary transitions in 3D graphene, and the absence of a bimodal structure here indicates a lack of planar AB stacking found in multilayer 2D graphene or graphite. Fitting the 2D peak to a single Lorentzian peak centered at 2685 cm⁻¹ (with a full width at half maximum of 67 cm⁻¹ ) indicates the presence of only one or a few carbon foam sample layers in the 3D carbon formed using these two methods. Analysis of the D/G peak ratio (0.85) of the dual-laser process indicates a higher defect density compared to the conventional laser-induced graphene process using a single-laser step (0.67), as shown in Table 1 below.
| process | D/G | 2D/G | D/D’ |
| Dual laser | 0.85±0.1 | 0.95±0.12 | 3.7±1.3 |
| Conventional single laser | 0.67±0.13 | 0.75±0.05 | 2.6±0.22 |
Table 1
As we previously explained, Raman analysis of typical graphene foam revealed the following signature characteristics: absence of a D peak; a 2D peak higher than the G peak; and a D:G ratio close to zero. The carbon foam produced in this specific embodiment of the invention does not possess these characteristics; it is highly hydrophilic with a contact angle below 20°; it lacks the Raman signature characteristic indicative of graphene: Figure 18A shows the material produced via a dual-laser process: presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18B is another Raman analysis of carbon foam produced via a dual-laser process, again showing the presence of a D peak; a 2D peak lower than the G peak; and a D:G ratio higher than zero. Figure 18C is the Raman analysis of the carbon nano-onion material, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI: 10.1007/s00339-015-9315-9, and its similarity to the Raman analysis of carbon foam produced via a dual-laser process is evident. A plausible explanation is that the carbon foam produced by the dual-laser process is or contains carbon nanotube onion material. See also Figures 57A and 57B below.
Both dual-laser carbon foam and conventional graphene fabricated using a single-laser process exhibit microporous structures, as shown in the SEM images in Figure 19. Low-magnification images reveal significant differences in surface morphology. The single-laser surface shows a smoother, more textured surface with rougher edges, while the carbon foam fabricated using a dual-laser process displays a rougher surface. This region will be further described in the following section on characteristic R.
Key features
In this section, we outline the key features of specific embodiments of the invention. These features define the production of carbon fiber foam in the previously described dual-laser manufacturing process; this process offers numerous advantages over conventional CVD: we can compare the production of approximately 50 μm thick carbon foam at 1 cm² on plastic substrates (or virtually many other types of substrates) as shown in Table 2.
| process | Number of steps | time | temperature | pressure | cost |
| CVD | 6 | 300min | 800C | vacuum | $50 |
| Dual laser process | 1 | 2min | 20C | environment | Less than $1 |
Table 2
Features A-R define various aspects of the carbon foam manufacturing process, which is highly scalable, high-yield, highly reproducible, and easily adaptable to many different applications, all using the same process. For example, dual-laser carbon foam is particularly suitable for biosensors and electrochemical capacitors (e.g., supercapacitor and pseudocapacitor applications).
For biosensor applications, dual-laser carbon foam offers the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; higher wettability; and higher antifouling properties. One specific implementation of this biosensor is called Gii-Cap, which we will describe in more detail below.
For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; higher wettability; and better anti-fouling properties. One specific implementation of a supercapacitor is called Gii-Cap, which we will describe in more detail below.
Features A-R are organized into the following four groups:
Group 1: Subsurface carbon foam
Group 2: Dual Laser Processing
Group 3: Products
Group 4: Other aspects.
We can extend this organization as follows:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene material adhered to a substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual lasers operating in different frequency bands
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors in different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device
Feature M2: Screen-printed carbon foam supercapacitor layer
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Now let's look at Group 1:
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
In the prior art section, we have described how earlier laser-induced graphene methods transformed the surface layer of a carbon precursor into 3D graphene. However, the resulting 3D graphene can be somewhat brittle, potentially peeling off from the underlying substrate, and is generally unsuitable for many real-world applications; furthermore, 3D graphene is typically relatively thin, with a depth of less than 50 μm.
In this specification, we describe an alternative method in which the surface of the carbon precursor is not converted into graphene at all; instead, only the subsurface region 14 of the carbon precursor is converted into carbon foam 16 by a focused laser beam 12; in one embodiment, the focused IR beam 12 generates a temperature above 500°C in the subsurface region or encapsulation region inside the polyimide film 14 for a very short time, between 1 ns and 10 μs (i.e., at a rate between approximately 5 × 10⁷ °C/s and 2 × 10¹² °C/s); this brief but intense heating is sufficient to form carbon foam 16 in this subsurface region or encapsulation region. This subsurface region or encapsulation region 16 has no substantial gas escape pathway; confining the gaseous products within the subsurface region or encapsulation region advantageously affects the structure of the carbon foam 16 formed in the subsurface region. The formation of carbon foam 16 only in the subsurface region was an unexpected discovery; the reasons for this unexpectedness include the extremely low absorptivity of the polyimide carbon precursor material to 1064 nm IR radiation, with a radiation absorptivity per centimeter (decimal) of less than 50 or as low as less than 10.
Under laser irradiation, the surface (e.g., the interface between the carbon precursor material perpendicular to and facing the laser and the gaseous environment surrounding the carbon precursor material) expands and transforms from the carbon precursor material into disordered amorphous non-graphene material 18. This disordered amorphous non-graphene material 18 forms a layer, which is typically at least 1% of the total thickness of the carbon precursor material; for a 500 μm thick polyimide film, the top 1 μm–10 μm is typically transformed into disordered amorphous non-graphene material 18; below this upper surface layer, within the bulk of the carbon precursor material, we obtain a region transformed into carbon foam 16.
The thickness of this carbon foam 16 is controlled by gradually moving the focus of the laser beam through the carbon precursor material; exceptionally thick carbon foam structures can be made using this process: carbon foam tracks with thicknesses of 50μm-200μm (approximately) have been achieved.
If a laser irradiates a carbon film precursor material, such as a polyimide film suspended in space (i.e., not mounted on a substrate) as shown in Figure 9-14B, after irradiation, as we gradually move through the material, we obtain disordered amorphous non-graphene material 18 on the upper surface (i.e., the surface facing the laser); then we obtain carbon foam regions 16. The laser beam 12 typically does not approach the lower surface of the carbon precursor material, such that the carbon foam regions 16 are located above the carbon precursor material that has not yet been converted into carbon foam. If the laser approaches the lower surface of the carbon precursor material, the carbon precursor near and located on the lower surface is converted into disordered amorphous non-graphene material.
Similarly, if a carbon precursor film, such as a polyimide (PI) film mounted on a substrate, is irradiated with a laser, as shown in Figures 1-6, we obtain the same material order; furthermore, the laser typically approaches the lower surface of the carbon precursor material resting on the substrate: the carbon precursor near and located on the lower surface is then transformed into a disordered amorphous non-graphene material 17. This disordered amorphous non-graphene material 17 adheres to the substrate 15; since the carbon foam region 16 is bonded to this disordered amorphous non-graphene material 17, the carbon foam region 16 itself is not directly bonded to the substrate 15, but is firmly attached to the substrate 15 via the intermediate disordered amorphous non-graphene material 17.
This method achieves carbon foam structures with significantly greater thickness than those achievable using previous methods that confine graphene foam formation to surface regions. Furthermore, this method enables carbon foam structures to adhere more robustly (but not directly) to the underlying substrate. It is important to note that with this method, carbon foam is not generated on any surface of the carbon precursor material; rather, it is generated only in the subsurface region within the carbon precursor material.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
In Feature A above, we define the region where carbon foam is generated by laser irradiation as the “under-surface” region. Another way to describe this region is to characterize it as “encapsulation”; this reflects the three-dimensional relationship between the carbon foam and its surrounding environment; the carbon foam 16 is “encapsulated” by the original carbon precursor material and by the disordered, amorphous, non-graphene material 18 generated by laser irradiation of the upper surface of the carbon precursor material 14.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of carbon precursor material, wherein said regions do not have substantial gas escape channels.
As we have seen above, the subsurface region or encapsulation region of the carbon precursor is transformed into carbon foam, and this subsurface region or encapsulation region has no substantial gas escape channel; confining the gaseous products within the subsurface region or encapsulation region affects the structure of the carbon foam 16 formed in the region.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to the substrate
As we have previously observed, when laser 11 irradiates the carbon film 14 mounted on substrate 15, the laser carbonizes the surface of the carbon film adjacent to substrate 15, forming a disordered amorphous non-graphene material 17 adjacent to substrate 15. This disordered amorphous non-graphene material 17 adheres to substrate 15. Because the internal, subsurface, or encapsulated carbon foam regions 16 are themselves bonded to this disordered amorphous non-graphene material 17, the carbon foam regions 16 themselves are not directly attached to substrate 15, but are firmly positioned on substrate 15 via the intermediate disordered amorphous non-graphene material 17. Compared to conventional laser-induced graphene, the carbon foam regions 16 adhere more firmly and are less likely to peel off even if the substrate is flexible, thus enabling applications such as biosensor applications where the substrate is typically a thin and flexible structure.
We can summarize it as follows:
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
Group 2: Dual Laser Processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Previous features A-D covered the generation of carbon foam in the subsurface region or encapsulation region of the carbon precursor material. Because carbon foam does not form on exposed surfaces, and many applications require exposed carbon foam (e.g., for functionalization in biomedical sensing applications or supercapacitors), we can take additional steps to expose at least some of the carbon foam subsurface or encapsulate it.
We have previously seen the formation of disordered, amorphous, non-graphene material 18 beneath the surface or above the encapsulated carbon foam 16 by laser irradiation using an IR laser 11. We now use a laser (typically a long IR CO2 laser 20) to ablate or otherwise process this disordered, amorphous, non-graphene material 18, thus exposing the underlying carbon foam 16. Unlike the initial laser, this second laser 20 is typically defocused.
As mentioned earlier, we use standard 220mm × 180mm polyimide sheets (but other sizes of polyimide sheets can also be considered); this size is commonly used in standard laser scanning equipment, standard flatbed screen printing equipment, and standard conveyor belt dryers for laser engraving, laser cutting, and laser drawing (which can trace paths defined by standard CAD programs). Other sizes of polyimide sheets can be considered.
We have discovered that this secondary laser irradiation step alters the morphology and other characteristics of the underlying carbon foam in a surprising and advantageous manner, resulting in previously unobserved twisted or disordered multilayer carbon foams. Changing the parameters of the CO2 laser 20 can alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications.
This new exposed carbon foam possesses one or more of the following properties:
• Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
• Strong adhesion to any underlying flexible substrate
High porosity
High electrical conductivity
• Increase in capacitance or charge storage
• Rapid absorption of organic solvents and water-based solutions
• Higher hydrophilicity
High EMI shielding
• Electrode quality enhancement
High wettability
• Anti-fouling.
It should be noted that by changing the laser parameters of any one or both lasers used in the dual-laser process, one or more of these properties, as well as the size and extent of defects and the size (including relative size) of the Raman D and 2D peaks, can be altered. In this way, carbon foams tuned for or particularly suited to different applications can be produced. Surprisingly, the operation of the second ablation laser enables the production of usable exposed carbon foam regions, especially those with properties that can be adjusted by changing the parameters of the first and/or second lasers.
We can summarize it as follows:
A method for manufacturing a carbon foam material includes the following steps: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulated region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of it in the carbon foam.
Feature F: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
In the aforementioned feature E, we describe the formation of carbon foam 16 in the region by irradiating the encapsulated region or subsurface region of the carbon precursor with a laser 11 (e.g., an IR laser); the irradiation causes the upper (in the laser direction) carbon precursor material 14 to expand into a disordered, amorphous, non-graphene material 18; then, we expose or reveal the carbon foam 16 by ablating the upper disordered, amorphous, non-graphene material 18 with a second laser 20 (e.g., a CO2 laser). This second irradiation step not only ablates the upper disordered, amorphous, non-graphene material 18 and thus exposes the lower carbon foam 16, but also gives this lower carbon foam an unexpected and unusual surface morphology 21 with very desirable characteristics; such a carbon foam may be a torsion or disordered multilayer carbon foam.
However, because such foams may possess characteristics unrelated to graphene foams (such as a wide range of defects, appearance, wettability, and Raman spectra (see Feature R below), we explicitly describe such foams as “non-graphene carbon foams” in Feature F. Therefore, the term “non-graphene carbon foam” (as opposed to the term “carbon foam”) explicitly excludes graphene foams, including twisted or disordered multilayer graphene foams, but extends to foams covering any other 3D carbon material.
We can summarize it as follows:
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers in different wavelength bands
As we saw in features E and F above, we can use two separate laser irradiation steps. These steps are typically performed using two separate lasers: the first step, to generate subsurface or encapsulated carbon foam, is typically accomplished using a focused IR laser 11; and the second step involves irradiation using a defocused CO2 laser 20 at a longer wavelength, but other wavelengths (e.g., UV and visible light) can also be used.
The second laser 20 ablates the material 18 (e.g., disordered, amorphous, non-graphene material) located between the carbon foam 16 and the surface, exposing the underlying carbon foam 16. The exposure of the carbon foam 16 can also be altered by the second laser (e.g., in terms of its surface morphology 21); that is, the term 'exposure' should be broadly interpreted to include not only revealing at least some of the pre-existing carbon foam, but also transforming or altering at least some of the pre-existing carbon foam into a 3D carbon material foam with characteristics different from those of the pre-existing graphene foam.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
We have previously seen how we generate carbon foams, which can be twisted or multilayered: because of the special electrical properties of this material (e.g., conductivity, capacitance), we can attach or position one or more electrical contacts (including electrical objects such as flexible electronics, microprocessors, antennas, IoT devices, electrical interfaces, etc.) into the carbon foam. For printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate) and onto and inside a pre-existing 3D carbon material foam, such that the tracks form good electrical contacts with the foam and any structures formed on the foam, such as functionalized layers (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
In Feature H, we see that once the dual-laser process is complete, electrical contacts or circuitry are added to contact a pre-existing carbon foam; for example, simple silver electrical contacts can be screen-printed onto the carbon foam. In Feature I, we describe a process that begins by first screen-printing electrical contacts onto a polyimide film, and then completes the process by creating an exposed carbon foam through a second laser ablation step in the dual-laser process. This has several advantages because the screen-printing process can interfere with or destroy the carbon foam. We refer to this process as “PPC” (short for “post-printing conversion”), where the screen-printing step is performed prior to the dual-laser process to create the carbon foam. In Feature L5, we describe a biosensor fabricated using the PPC process.
Therefore, for screen-printed tracks (e.g., screen-printed silver tracks), these tracks are screen-printed onto a polyimide film (or other suitable substrate), allowing carbon foam to subsequently form around one end of the printed tracks, thus providing a contact area with a large surface area and therefore very good electrical connectivity. Similar to the alternative processes described in Feature H above, the printed tracks also form good electrical contacts with any structures formed on the foam (e.g., see Feature L below, where we describe how carbon foam can be functionalized to form a biosensor with an analyte-specific receptor layer).
An alternative sequence involves using a first laser beam to generate subsurface carbon foam, then screen printing electrical contacts, and then using a second laser beam to generate carbon foam to create good electrical contact with the electrical contacts.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed in the order of (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
We have previously observed that the thickness of the subsurface or encapsulated carbon foam region can far exceed that of conventional graphene foams confined to the surface layer: the laser focus of the first laser beam can be progressively moved downwards through the carbon precursor material to create a deep or thick subsurface or encapsulated carbon foam layer. Then, a second laser irradiation step is employed to ablate the material between the carbon foam and the surface of the carbon precursor material, resulting in an exposed region of the carbon foam. This now exposed carbon foam region has a thickness or depth of at least 50 μm; carbon foams with a thickness of 300 μm have been produced. The increased thickness is beneficial because it leads to better electrical conductivity, greater capacitance, and higher mechanical integrity.
We can summarize it as follows:
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
The specific properties or structure of the carbon foam produced by the second laser beam can be considered sensitive information because they define the characteristics of the final product. For the first laser beam process, it is desirable for the carbon foam supplier to perform the process at their manufacturing facility, then supply the carbon foam to the customer, who then uses the second laser beam for the final stage at their own manufacturing facility. As we explained earlier, by changing the parameters of the first and second lasers, it is possible to alter the properties of the carbon foam material, enabling the production of carbon foams with properties optimized for different applications. Typical parameters that can be changed or tuned in this way include: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface or encapsulation region.
By segmenting the manufacturing process in this way, suppliers do not need to know the specific manufacturing processes that customers use as part of the second laser ablation process (e.g., how they change the parameters of the second laser beam to give the exposed carbon foam the properties they need); customers can keep the details of how they produce the finished product confidential.
Therefore, the manufacturing process is a three-stage process involving the following steps: (a) irradiating the area below the surface of the carbon precursor material with the first laser beam at the manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Furthermore, this method enables the large-scale production (see feature P, for example) of carbon foam using only the first laser process, thereby reducing the cost of this material, which can be used in many different applications and for many different customers. The production volume of more specialized products using a second laser beam may be much lower than that of carbon foam produced using only the first laser process. Therefore, this method achieves more efficient and lower-cost manufacturing of the base material, namely carbon foam produced solely through the first laser process.
We can summarize it as follows:
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
For features A-K, the following optional features are particularly relevant. It should be noted that any one or more of the following optional features can each be combined with one or more other compatible optional features, as well as with one or more of features A-K:
We will cover the following areas:
Manufacturing process
First laser beam parameters and control scheme
Properties of the subsurface region or packaged region
carbon precursor materials
Substrate supporting carbon precursor materials
Carbonization at the surface where the laser beam is incident
ablation laser beam or second laser beam
Carbon foam.
It should be noted that any one or more of the following optional features may be combined with one or more other compatible optional features and with any one or more of the other “features” listed in this specification (e.g., features A-R):
The laser-based manufacturing process described above has many advantages over conventional CVD processes; these can be listed as the following optional features:
It is a room temperature process.
It is an environmental pressure process.
It can be done on plastic substrates (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
It takes about 2 minutes or less to create a 1 cm² carbon foam that is approximately 50 μm thick on a plastic substrate.
The formation of 3D carbon foam on a flexible substrate was achieved.
No graphene or graphene oxide precursors are required.
Carbon foam material is generated only in the encapsulation area or subsurface area of the carbon precursor material, and not on any surface of the carbon precursor material.
It uses a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
It is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
The parameters and control scheme of the first laser beam are crucial for the production of carbon foam; we define the relevant optional characteristics here:
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following:
Intensity, wavelength, pulse frequency, pulse duration, pulse profile, scan speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface or encapsulated region to form carbon foam.
• The laser beam generates temperatures exceeding approximately 500°C in the subsurface or encapsulated region to form carbon foam.
The pulse duration of the laser beam is between approximately 1 ns and 10 μs, resulting in a pulse speed of approximately 5 × 10⁷ °C/s.
Heating rate between 2 × 10¹² °C/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between approximately 50 kHz and 500 kHz.
• The laser pulse frequency is between approximately 1 kHz and 2 MHz.
• The laser wavelength is between approximately 0.7μm and 2.5μm.
The laser scans at speeds between approximately 9 cm/s and 40 cm/s.
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region through which the focal point passes.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region with a thickness of at least 50 μm.
• The focal point of the laser beam is moved through a depth of at least about 100 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region where the thickness of the carbon precursor is at least 100 μm.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scanning can result in a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm).
• The wavelength of the laser beam is not absorbed by the carbon precursor material.
• The carbon precursor material has extremely low absorption of the wavelength of the laser beam, with a radiation absorptivity per centimeter (decimal) of less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between approximately 0.7 μm and 2.5 μm.
The laser beam is an IR laser with a wavelength between approximately 0.75 μm and 1.40 μm.
The properties of the subsurface region or encapsulation region where carbon foam is generated can be defined using the following optional features:
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity and the choice of carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or more below the surface of the carbon precursor material.
• The thickness of the subsurface region or encapsulation region can be between approximately 10 μm and 200 μm.
• The subsurface region or encapsulation region is located at a certain distance below the surface of the carbon precursor material. This distance is a function of various factors, such as laser intensity, other laser parameters, and the selection of the carbon precursor material used. For example, the top of the subsurface region or encapsulation region may be at least 1%, 10%, 20%, 30%, or 40% below the total thickness of the surface carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the midpoint of the minimum cross-section of the first laser beam, and the volume is within 500 or 100 micrometers or 1 micrometer of this midpoint.
Carbon precursor materials can be defined by the following optional characteristics:
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam (see Group 3 below) is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300±50 cm⁻¹ .
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of a first and/or second laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
A substrate can be considered as a material having a surface on which carbon precursors are positioned; the specific material, thickness, and properties of the substrate are determined by the application: for example, for some sensors, the substrate may be a thin, flexible plastic film; for other applications, the substrate may be a rigid polyimide plate on which electronic circuitry can be mounted. An IR laser can directly irradiate the carbon source; alternatively, radiation from the IR laser can first pass through the substrate and then reach the carbon source, in which case there are two alternative scenarios: first, the substrate is substantially transparent to IR radiation, and the mechanism of carbon foam formation is as described above. In the second scenario, the substrate is substantially opaque to IR radiation: then, rapid heat transfer from the substrate to the carbon precursor material first generates a disordered, amorphous, non-graphene layer at the interface with the substrate, and then carbon foam forms in the subsurface region or encapsulation region within the carbon precursor material.
The carbon precursor material can be positioned and supported on a substrate, which can be defined by the following optional characteristics:
The substrate is a plastic body, film, or foil.
The substrate is flexible.
The substrate is a polyimide circuit board.
The substrate has an extremely low absorption rate of the first laser beam.
The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
The substrate has a high absorption rate for the first laser beam, absorbing more than 60% of the first laser beam.
The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
The substrate is formed from one or more of the following: silicon (Si), silicon dioxide (SiO2), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing silicon and silicon dioxide.
The substrate is a carbon source.
The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident can be defined by the following optional characteristics:
The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by the first laser beam.
The disordered, amorphous, non-graphene material occupies a thickness below the surface of the adjacent carbon precursor material, which is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
The disordered, amorphous, non-graphene material extends to a distance below the surface of the carbon precursor material, said distance being at least 10 μm.
The disordered, amorphous, non-graphene material extends from the outer surface of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
The ablation laser beam or the second laser beam can be defined by the following optional characteristics:
The parameters of a laser beam include one or more of the following: intensity, wavelength, pulse duration, pulse profile, scanning speed, and heat generated in the subsurface region or packaged region.
Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
Changing laser parameters alters one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
The second laser beam alters the carbon foam as part of the process that exposes it.
The second laser beam alters the shape of the carbon foam as part of the process that exposes it.
The second laser beam is automatically controlled to scan on the same, and/or overlapping, and/or non-overlapping areas (e.g., raster scanning).
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
The carbon precursor material has an absorption coefficient for the second laser beam that is greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam that is greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300±50 cm⁻¹ .
The laser power is typically in the range of 8-20 watts, with 12W being optimal.
The typical working range of laser focal length is 50mm-400mm.
The second laser beam scans in a pattern that includes non-overlapping areas or lines.
The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam can be defined by the following optional characteristics:
The carbon foam has a thickness of at least 50 μm.
The thickness of the carbon foam ranges from 50 μm to 300 μm.
Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
Carbon foam is or includes carbon foam with a defective spatial distribution, resulting in high electrochemical reactivity.
Carbon foam is or includes carbon foam with vacancy basal defects, resulting in high electrochemical reactivity.
The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Carbon foam has one or more of the following properties:
Thickness or depth is easy to control
It is more flexible than graphene produced using conventional laser processes, which is highly brittle.
It has strong adhesion to the underlying flexible substrate.
High porosity
High electrical conductivity
Increase in capacitance or charge storage
Rapid absorption of organic solvents and water-based solutions.
ο Higher hydrophilicity
οEMI shielding high
Electrode quality enhancement
The contact angle is approximately 20° or less.
The properties of carbon foam can be selected by choosing specific laser parameters to generate carbon foam materials with one or more of the following desired properties or parameters: defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption of organic solvents and water-based solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
Group 3: Products
Feature L1: Biosensor
Carbon foams fabricated using the dual-laser method described above have wide applications in many different types of sensors. For simplicity, we will use the phrase "carbon foam" in this feature to refer to any carbon foam or 3D carbon material foam fabricated by the methods described in this specification. Appendix 1 includes further details on this field, describing in more detail a biosensor comprising a carbon foam functionalized by adding receptors specific to a target or analyte, and a connector enabling the receptors to attach indirectly to the carbon foam; (some receptors cannot attach directly to the carbon foam because of their poor stability in contact with a surface; instead, a connector must be used as an intermediary between the carbon foam and the receptor. During fabrication, the connector is first added to the carbon foam, and then the receptor is added to the connector.)
For biosensor applications, functionalized carbon foam has the following advantages over conventional graphene foam: higher electron transport rate; higher detection sensitivity; larger electrochemical effective area; higher reproducibility; lower cost; enhanced wettability; and a contact angle of approximately 20° or less.
At a higher level, functionalized carbon foam can be used in sensors because it can generate detectable changes in state; its high sensitivity is a function of its large surface area. It can be used to detect specific chemicals, specific gases, mechanical stress, and temperature, among other variables. We will briefly look at each category.
First, chemical sensors: Chemical detection systems rely on detecting the electrical response of carbon foam when a target chemical substance is present; many different detection principles can be used, such as changes in capacitance, resistance, voltammetry, redox potential, and charge transfer resistance.
For example, the binding can be detected when a specific analyte or target binds to a carbon foam because it alters the surface of the carbon foam. Biomolecules, such as specific antibodies or aptamers (aptamers are short, single-stranded DNA or RNA molecules that can selectively bind to specific targets, including proteins, peptides, carbohydrates, small molecules, toxins, and living cells), are added to the carbon foam. When the target is present and binds to the aptamer, the morphology of the aptamer changes (e.g., by reducing surface area), and the capacitance of the combined carbon foam and aptamer system decreases in a measurable manner.
Using this principle, highly sensitive and selective sensors can be built; due to the quantitative reduction of measurable variables (e.g., capacitance), a LOC (lab-on-a-chip) can be built, which includes not only carbon foam and aptamer biosensors, but also power sources on the LOC, such as supercapacitors or other energy storage devices using carbon foam as their electrodes, as well as circuitry for measuring variables, calculating biosensor outputs, and displaying said outputs (e.g., the presence or absence of a target; the concentration of a target) on the LOC screen; this is further described in the feature O3 (Gii-Thru: HISLOC for Gii-Sens).
Carbon foam sensors can also measure the redox potential of a target; for example, a current peak can be detected when the oxidation of a target chemical is catalyzed by a specific catalyst added to the carbon foam; since the current is usually a function of the concentration of the target chemical, it is possible to quantitatively measure the target concentration.
Other technologies already applied to conventional graphene sensors, such as thermal conductivity measurements for detecting specific chemicals, resistance measurements for inferring temperature, physical deformation, or transitions in the presence of specific chemicals, and piezoresistive deformation for detecting motion, can all be applied to carbon foam sensors fabricated using the dual-laser method described above.
An important application of the large electrochemically effective region and fast electron transport rate of carbon foam generated by a dual-laser method is the implementation of an electroanalytical sensing electrode optimized for biosensing (called "Gii-Sens").
For example, the electroanalytical sensing electrode can be used in point-of-care diagnostic devices; the sensing electrode has extremely high sensitivity, reliability, purity, wettability and conductivity.
Figure 20A is a perspective view of a biosensor called Gii-Sens. The assembly consists of: a polyimide substrate 201; a working electrode 202 made of Gii carbon foam; a counter electrode 203 made of Gii carbon foam; a reference electrode 204 made of screen-printed silver-silver chloride; three screen-printed silver connection traces 205; and a screen-printed dielectric layer 206.
Figures 20B-20D show the four main manufacturing stages. Figure 20B shows step 1, in which the dual-laser process uses a polyimide substrate 201 as a precursor to produce a Gii carbon foam working electrode 202 (area of 18.94 mm² ) and a counter electrode 203 (area of 20.84 mm² ).
Figure 20C shows step 2, in which a silver-silver chloride reference electrode 204 (with an area of 8.99 mm² ) is screen-printed onto a polyimide substrate 201.
Figure 20D shows step 3, in which silver connection traces 205 are screen-printed onto the polyimide substrate 201; these overlap with the carbon foam electrodes at the electrical contact regions 207. The area of the silver traces is 1 x 18.85 mm² , and the area of the three silver traces is 3 x 56.55 mm² . The area overlapping with the underlying carbon foam electrodes is 1 x 2.21 mm² , and the area overlapping with the three carbon foam electrodes is 3 x 6.63 mm² .
Figure 20E shows step 4, in which the dielectric layer 206 is screen-printed over carbon foam electrodes 202, 203, 204 and silver connection traces 205. The active regions of the electrodes are as follows: working electrode 202: 12.64 mm² ; counter electrode 203: 14.18 mm² ; reference electrode 204: 2.59 mm² . The exposed areas of the silver connection traces 205 are 1 x 7.15 mm² and 2 x 21.45 mm² .
Figure 20F shows a single polyimide sheet on which an array of 100 carbon foam working and counter electrodes has been produced using the dual-laser process described in step 1 above. The sheet is a standard type of polyimide sheet, 220 mm × 180 mm, allowing it to be processed using standard screen printing and laser scanning equipment; it can be A5 size or any other suitable size.
Figures 20G and 20H show the final form of the sheet after step 4. 100 individual units can be cut and assembled into 100 finished Gii-Sens biosensors.
One specific use case for the Gii-Sens sensing electrode is a reversible polymer displacement sensor mechanism for electrochemical glucose monitoring. A graphene sensor for this use case has been proposed: see "Polymer indicator displacement assay: electrochemical glucose monitoring based on boronic acid receptors and graphene foam competitively binding with poly-nordihydroguaiaretic acid", Wikeley et al., DOI:10.1039/d1an01991k. This paper describes glucose... A pyrene-derived boric acid chemical acceptor was adsorbed onto a graphene foam electrode. The spontaneous oxidative polymerization of nordihydroguaiacol (NHG) onto the graphene foam electrode yielded a redox-active membrane (poly-NHG) covalently attached to the boric acid acceptor. Oxidation of the poly-NHG released the boric acid acceptor to interact with glucose in the solution phase, which was detected due to competitive binding upon recombination of the reduced poly-NHG with the boric acid functional groups. The sensor exhibited the expected boric acid selectivity for fructose-glucose. Glucose sensing was performed using the charge ratio at the voltammetric peaks of unbound and bound poly-NHG, with a substantially linear analytical range from 1 to 50 mM glucose in a pH 7 aqueous buffer.
The implementation of Gii-Sens sensing electrodes offers several advantages over current sensing electrodes, such as those used in graphene sensors:
It uses amplification-free, enzyme-free, and label-free electrochemical biosensor with a low detection limit.
Enhanced reproducibility.
Optimize the available dynamic range.
Minimize background noise.
Reduce planning time and operations.
It is scalable for low-cost manufacturing.
High sensitivity and selectivity.
Provide quantitative numerical results.
It can be printed into specific patterns, such as interdigitated patterns, to achieve miniaturized integrated devices.
Existing biometric and testing formats (e.g., ELISA, PCR, RT-PCR) can be translated into electrochemical microfluidic POCs without affecting performance quality.
It can perform impedance-based measurements with extremely high sensitivity, reliability, and extremely low background signal interference.
It replaces expensive, large-scale laboratory testing and low-sensitivity lateral flow testing.
It can be implemented in microfluidic analysis (single-objective or multi-objective) and lab-on-a-chip (LOC) devices.
It can be used in any sensor application where the user aims to immobilize (biological) molecules of interest (e.g., the carboxyl/n-hydroxysuccinimide moiety can be added to the sensor surface to provide a platform for subsequent immobilization and conjugation chemistry reactions).
It can be used for a variety of diagnostics: point-of-care (POC) human and animal health, food safety, in-situ environmental health and safety, and agricultural health and safety, all of which have enhanced biosensing sensitivity, selectivity, and reproducibility due to its purity and high specific surface area.
Enhanced wettability (e.g., contact angle below about 20°).
Enhanced stain resistance.
We can summarize it as follows:
A method of manufacturing a biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
L2: Fabricating carbon foam biosensors in a scalable and low-cost manner using screen printing technology.
We have already seen above how screen printing is widely used in manufacturing processes: it is a well-known, scalable, predictable, and low-cost technology. The detailed manufacturing process of the Gii-Sens carbon foam biosensor is shown in Figure 21.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric to at least partially cover the electrodes and connection traces.
Optional features include the following:
In the method defined above, in step 1, the dual-laser process uses a PI substrate as a precursor to generate a carbon foam working electrode and a counter electrode.
In the method defined above, in step 2, a reference electrode, such as a silver-silver chloride electrode, is screen-printed onto a PI substrate.
The method defined above, in step 3, involves screen printing connection traces, such as silver traces, onto a PI substrate to overlap with the carbon foam electrode. Note: The order of steps 2 and 3 can be reversed.
The method defined above, wherein in step 4, a dielectric layer is screen-printed over at least some of the carbon foam electrodes and silver connection traces.
Other aspects include:
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each sensor electrode comprising at least partially a carbon foam made by a method defined as any one of features A-K above, and each sensor electrode being electrically connected to a screen-printed track and also at least partially covered by a screen-printed electrolyte.
A point-of-care diagnostic device comprising a biosensor as defined above.
L3: Adding functional groups to biosensors at different manufacturing facilities
For Gii-Sens biosensors, the biosensors are manufactured in one facility, but customers add functional groups that biomolecules can attach to in another facility (usually their own). This accelerates the development and testing of these functional groups and also protects their trade secrets and proprietary technology in the final design of these functional groups and the biosensors.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in a different manufacturing facility.
L4: Adding functional groups to biosensors is part of the biosensor manufacturing process.
For the Gii-Sens+ biosensor, the manufacturing process includes adding functional groups. Figure 22 shows the detailed manufacturing process of Gii-Sens+.
We can summarize it as follows:
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
L5: Using PPC to manufacture biosensors: Post-printing conversion
A PPC variant of the Gii-Sens manufacturing process is shown in Figure 23. PPC is an abbreviation for "Post-Print Conversion," in which the screen printing step is completed before the dual-laser process to create carbon foam. The specific steps are as follows:
1. Screen printing a carbon layer onto a substrate (e.g., polyimide).
2. Screen-printed Ag/AgCl reference electrode
3. Screen printing Ag electrical connection traces
4. Screen-printed dielectric
4. Use a dual-laser process to generate carbon foam in the substrate.
All screen printing steps (1-3) can be completed using roll-to-roll or roll-to-sheet processes, followed by the use of a dual-laser process to generate carbon foam, and then the materials are kept flat and stacked.
Alternatively, only the first laser process (subsurface foam generation) can be completed in the facility, after which the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation). The customer can add functionalizing groups in their own manufacturing facility, different from the facility performing the first laser process step (or both laser process steps) in the dual-laser process. Alternatively, functionalization can be performed in the facility performing the dual-laser process.
Screen printing before manufacturing the carbon foam has advantages: because we don't dry the carbon foam, it's less hydrophobic. The carbon layer acts as a bridge between the carbon foam formed in the polyimide (e.g., carbon foam and non-graphene disordered amorphous foam) and the silver connectors.
We can summarize it as follows:
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode including at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on the substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon and the electrical connection trace and the reference electrode; and then (d) producing the carbon foam sensor electrode using a method as defined in any one of features A-K above.
Feature M1: Energy storage device: supercapacitor
Because carbon foam manufactured using any one of the characteristics A-K has a very large electrochemical active region and a fast electron transport rate, it is an ideal material for electrodes of capacitors, supercapacitors, or pseudocapacitors.
One important application is in supercapacitors (specifically implemented as "Gii-Cap") or other energy storage devices (e.g., lithium-ion batteries). For supercapacitors and other electronic applications, carbon foam offers the following advantages over conventional graphene foam: larger surface area; more porous structure; higher mass; lower sheet resistance; and higher wettability.
Carbon foam can be processed with metal oxides or other pseudocapacitive materials (variants of which we call Gii-Cap+) (e.g., to produce metal oxide layers or films), and the metal oxide films have extremely large surface areas and fast surface Faraday mechanisms.
It should be noted that when we use the term Gii-Cap, we include the Gii-Cap+ variant unless the context explicitly indicates that we specifically exclude the Gii-Cap+ variant. It should also be noted that we use the term "supercapacitor" to include (i) electrically double-layer (EDLC) capacitors, where charge is stored electrostatically with no interaction between the electrode and electrolyte ions, and (ii) pseudocapacitors, where there is electron charge transfer between the electrode and electrolyte, and in any energy storage device using a combination of electrically double-layer capacitors and pseudocapacitors. Finally, it should be noted that the term "supercapacitor" should be broadly interpreted to cover any electrochemical capacitor, including EDLC supercapacitors, pseudocapacitors, and mixtures of these. The Gii-Cap+ variant is primarily a pseudocapacitor, but we still refer to it as a "supercapacitor."
Compared to conventional supercapacitors, the carbon foam electrodes in the Gii-Cap supercapacitor enhance both electrostatic double-layer capacitance and electrochemical pseudocapacitance. Appendix 2 provides further details about the supercapacitor and describes a specific implementation in which an interdigitated carbon foam electrode in the active region is encapsulated by a hydrogel electrolyte (e.g., a salt with a high molar concentration) to generate an enhanced operating voltage window.
The implementations of EDLC supercapacitors Gii-Cap and pseudocapacitors Gii-Cap+ offer numerous advantages over conventional rechargeable batteries:
Fast charging
High power
Recyclable
Not easy to explode
Flexible forms and shapes
Solid gel electrolytes or polymeric electrolytes (e.g., ionogels or hydrogels) can be used, which are solid at room temperature and have a high transition temperature far exceeding the normal operating temperature (e.g., 90°C); this greatly reduces the risk of electrolyte leakage.
It can be used in a very wide range of devices and power storage needs, such as lab-on-a-chip (LOC), IoT devices, electric vehicles, UAVs, and EV applications.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
Figure 24 is an exploded perspective view of the Gii-Cap supercapacitor. It consists of a series of carbon foam electrodes 241 connected to a pair of screen-printed silver connectors 242, fabricated using the dual-laser process described above. A dielectric layer 243 is screen-printed over the carbon foam electrodes 241 and the screen-printed silver connectors 242. The carbon foam electrodes 241 are formed on a polyimide substrate 244. A pair of copper connector tabs 245 are connected to the pair of screen-printed silver connectors 242. An electrolyte layer 246 covers the carbon foam electrodes 241 (e.g., an ionogel electrolyte, such as a polymer hydrogel electrolyte, which is a gel or semi-solid at room temperature to minimize the risk of leakage and reversibly liquefies above 90°C, thus allowing application in liquid form during manufacturing). The assembly is sealed within an aluminum laminate heat-sealed bag 247.
Figure 25 is an exploded perspective view of a supercapacitor assembly: it consists of an interdigitated array of carbon foam electrodes 241 forming the supercapacitor; a screen-printed silver connector track 242 provides current to the carbon foam electrodes 241 and is covered by an electrically insulating dielectric layer 243. A polyimide sheet 244 forms the base of the assembly.
Figures 26A-H illustrate the manufacturing sequence. Figure 26A shows step 1, where interdigitated carbon foam electrodes are produced using a dual-laser process. The magnified area in Figure 26B shows the interdigitated carbon foam electrodes in more detail; group A electrodes form an electrode assembly, and group B electrodes form another electrode assembly; capacitive coupling between the two groups of electrodes stores energy. The carbon foam electrodes have a thickness of approximately 20-30 μm.
Figure 26C shows step 2, screen printing the silver collector electrodes. A silver connector A' supplies current to the A group of electrodes, and a silver connector B' supplies current to the B group of electrodes. The thickness of the silver layer is approximately 20-40 μm, and several layers can be applied.
We use a "common collector" layout: a typical interdigitated supercapacitor has two long silver collectors with graphene fingers extending from one side of each long silver collector. The long silver collectors have high resistance due to their length and require a significant amount of silver. Furthermore, printing the curved portions of the collectors is difficult. In the "common collector" method shown in Figure 26D, we have carbon foam fingers C extending from both sides of the shared collector 242: this maximizes the space utilization of the fingers and therefore maximizes the capacitance, reduces the amount of collector material required, and eliminates the difficult curved collector portions.
The region 250 of the carbon foam finger connected to the common collector electrode has rounded edges; these rounded edges reduce the chance of stress fracture and increase the reliability of the electrical connection.
Figure 26F shows step 3, in which the dielectric layer 243 is screen-printed over the silver collectors to make them electrically insulated; the thickness is approximately 10-30 μm.
Figure 26G shows step 4, adding copper connector tab 245 (made of conductive metal strip) to connect to the silver current collector 242. Figure 26H shows step 5, depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions. The electrolyte can be a combination of hydrogel and salt (see Appendix 2). Figure 26I shows step 6, packaging the entire assembly into an aluminum laminate heat-sealed bag 247, leaving only the copper connector tab 245 exposed. It should also be noted that step 4, adding the copper connector tab 245, can be performed before step 2 (screen printing the silver current collector) and after step 5 (depositing the electrolyte layer 246 over the interdigitated carbon foam finger positions).
Figure 27 shows how a single polyimide sheet will accommodate six 220mm × 180mm Gii-Cap components; other sizes (e.g., A4, A5, A6, or sizes other than the standard A-series sizes) are also possible.
The detailed manufacturing process of Gii-Cap is shown in Figure 28.
The specifications for producing and operating Gii-Cap supercapacitors using hydrogel electrolytes in a single production run are shown in Table 3 below.
Table 3
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, the screen-printed electrical connection traces are formed above at least a portion of each electrode, and the screen-printed dielectric layer at least partially covers the electrodes and connection traces.
Feature M3: Carbon foam supercapacitor: common collector electrode
We saw how to use a "common collector electrode" above.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, wherein the energy storage electrodes comprise at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
PPC (Post-Printing Conversion) is shown in Figure 29. The steps are as follows:
1. Screen print the silver current collector onto a substrate (e.g., polyimide).
2. Print carbon screen printing over the silver current collector and then dry it.
3. Screen print the dielectric over the carbon layer and then dry it.
4. Carbon foam is generated in the carbon layer using a dual-laser process; the carbon foam is attached to the underlying polyimide substrate via a non-graphene interlayer.
5. Distribute electrolytes.
6. Add copper/aluminum inserts to make contact with the silver collector (or step 1).
7. Add a cap/small bag.
All screen printing steps (1-3) can be completed using a roll-to-roll process, followed by the generation of carbon foam using a dual-laser process, and then the material is kept flat and stacked. Alternatively, only the first laser process (generating carbon material foam under the surface) can be completed in the facility, and then the sheet is shipped to the customer, who then performs the second stage of the dual-laser process (laser ablation) and steps 5-7.
Screen printing before fabricating carbon foam has advantages: if carbon foam is made first, it may have sharp edges; the silver screen printing layer applied over these sharp edges may crack at these edges. However, by screen printing before creating the carbon foam, we avoid this problem. Additionally, because we don't dry the carbon foam, it is not hydrophobic.
We can summarize it as follows:
A method for manufacturing energy storage devices such as supercapacitors or pseudocapacitors;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
The Gii-Cap+ variant is produced using a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x ); its capacitance is much higher than that of the standard Gii-Cap device (see Table 4).
Table 4
This metal oxide electrochemical deposition process can be applied to both the Gii-Cap Supercap manufacturing process and the PPC process, and therefore all Gii-Cap products can also be Gii-Cap+ products. A detailed process flow diagram is shown in Figure 29.
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying a pseudocapacitive material, such as a metal oxide, to the energy storage electrode via an electrochemical deposition process.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
We use an ionic gel (an ionic liquid with fumed silica SiO2 ) that provides a voltage of 3V-6V. It is solid below 90°C, so it does not leak during transport and normal use, and is therefore particularly suitable for smart tags and IoT devices; above 90°C, it liquefies, and is therefore printable, with electrochemical printing occurring at temperatures above 90°C. Ionic gels are typically made from an ionic liquid (e.g., 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4)) plus a gel-forming agent (e.g., fumed silica SiO2 )).
Typically, manufacturing is carried out in an inert atmosphere (e.g., argon) because the presence of O2 and H2O can lead to a decrease in voltage and stability.
The optimal sites for achieving the best balance between increased capacitance and decreased voltage for O2 and H2O levels are described in more detail in Appendix 3 (GiiCap Iongel).
We can summarize it as follows:
A method for manufacturing an energy storage device such as a supercapacitor, wherein the energy storage electrode comprises at least a portion of a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
In the preceding sections covering features M1-M6, we focused on some general characteristics of Gii-Cap carbon foam supercapacitors. In the following sections covering features N-S, we focus on some more specific products that realize Gii-Cap.
Feature N1: Electrical conductor
For the biosensor devices described above, it is possible and desirable to fabricate electrical conductors providing measurement signal connections from carbon foam materials produced by a dual-laser method: because these conductors have extremely low resistance, sensitivity is maximized. Electrodes (e.g., functionalized biosensor working electrodes, and reference electrodes described above as being screen-printed; capacitor plate electrodes) are examples of electrical conductors covered by this feature N1. Additionally, this feature N1 also covers electrodes whose primary function is solely to carry signals and current, for example, to replace conventional silver connection traces, such as the screen-printed Ag electrical connection traces we described in the biosensors above.
We can summarize it as follows:
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
Features L1-L4 above describe biosensors using carbon foam fabricated by a dual-laser method in their sensor electrodes; features M1-M6 describe supercapacitors and pseudocapacitors using carbon foam fabricated by a dual-laser method in their electrodes.
A highly sensitive and selective biosensor can be established, and this biosensor and this supercapacitor can be combined into a single integrated device. The device also includes electronic circuitry for measuring the detected or measured variable, calculating the biosensor output and sending the output to a POC diagnostic device or displaying the output on the device's display screen (e.g., the presence or absence of the target; the concentration of the target).
Figure 30 is a schematic cross-section of this integrated LOC device: there are two separate polyimide membrane layers, the upper layer 301 comprising a functionalized carbon foam biosensor (Giii-Sens) 302, as described in feature L; and the lower layer 303 comprising a supercapacitor 304 (Giii-Cap), as described in feature M. Although the polyimide layers are shown back-to-back, they can also be arranged side-by-side; additionally, a single polyimide membrane can be used to integrate the biosensor 302 and the supercapacitor 304 together onto a single object.
A plastic component 305 with microchannels 306 provides a microfluidic system for dispensing test fluid over the biosensor 302; a subsurface carbon foam electrode or conventional connector track 307, as described in Feature O, guides the biosensor to a flexible electronics 308 (e.g., a microcontroller for measuring changes in the electrochemical properties of the biosensor in the presence of a target analyte; a display panel for displaying diagnostic results; a power management system for controlling power from the supercapacitor 304 to the electronics 308). The supercapacitor 304 (Gii-Cap) is charged (e.g., via a wireless sensing process (not shown) controlled by the microcontroller) and provides power for the biosensor measurement process and an integrated display showing the quantitative measurement results. Alternatively, a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) can charge the supercapacitor 304, which then provides power for the biosensor measurement process. Another variation uses a rechargeable secondary battery (not shown) or a non-rechargeable primary battery (not shown) that charges the supercapacitor 304 and also provides power for the biosensor measurement process. The supercapacitor 304 is then reserved for powering high-power processes, such as wireless data transmission, enabling the LOC to function as a standalone LOC device capable of diagnostic processes and wirelessly transmitting result data without requiring the user to be near the LOC, which would be necessary if the LOC used conventional NFC (Near Field Communication). The electrical connector trace from the supercapacitor 304 to the flexible electronics 308 is not shown.
An exploded view of the fully integrated LoC device is shown in Figure 31. From the bottom up, we have (i) an induction power circuit 310; (ii) a Gii-Cap supercapacitor 312, which is wirelessly powered by the induction circuit 310; (iii) a Gii-Sens biosensor 313; (iv) a layer 314, which has electronics for the biosensor powered by the supercapacitor 312 and microfluidic channels; and (v) a top panel 315, which includes a display 316, also powered by the supercapacitor, and an annular aperture 317 into which samples are delivered.
Figure 32 shows the LOC (Local Occurrence) of the quantitative results displayed on its monitor.
Figure 33 shows an exploded view of an environmental monitoring device including a Gii-Sens sensor 330 configured to detect environmental parameters such as CO2 levels, volatile organic compounds, and other atmospheric pollutants. The Gii-Sens is not limited to being a biosensor and can also detect any molecule that can be functionalized to detect using a carbon foam sensor electrode. The environmental monitoring device includes the Gii-Sens sensor 330 and associated control and wireless transmission (e.g., LoRaWAN) electronics 331, as well as a PV solar cell 332 and a Gii-Cap supercapacitor 333. The electronics 331 include a secondary or primary battery (which may be a printed battery) and work in conjunction with the PV solar cell 332 to power those electronics and charge the Gii-Cap supercapacitor 333. The Gii-Sens sensor can also be configured to measure temperature, humidity, and pressure. The device has a back 334 that can be peeled off to expose an adhesive surface, allowing the device to be attached to a wall, etc. The PV solar cell, combined with a secondary or primary battery on electronic device 331, provides power to charge the Gii-Cap supercapacitor 333, which in turn provides the peak burst power required for data transmission. Unlike current environmental monitoring devices, this device can be permanently installed and maintained in place for many years without requiring battery replacement. It can detect atmospheric pollutants with a signal-to-noise ratio superior to conventional devices. The assembled device is shown in Figure 34.
Many other types of devices can be realized using a combination of carbon foam sensors and carbon foam supercapacitors; for example:
Any biosensor capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor, can benefit from wearable health monitoring devices such as continuous glucose monitors and other wearable monitors that sense electrolyte, potassium, sodium, and lactose levels.
This benefits from any sensor device capable of transmitting data (e.g., wirelessly), where data transmission is powered by a supercapacitor.
This benefits from any IoT device capable of transmitting data (e.g., wirelessly), where the data transmission is powered by a supercapacitor.
The device may include electronic components powered by a supercapacitor.
The device may include a battery to charge energy storage devices and/or power device electronics.
The device may include a PV battery to charge a secondary battery in an energy storage device and/or in a device and/or power device electronics.
We can summarize it as follows:
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
In this example, we combine two distinct power sources into a single device to form a combined or hybrid power source: the device has a battery (e.g., a printed battery or a conventional battery) and a supercapacitor, the supercapacitor using carbon foam made by a dual-laser method in its electrodes; they work together in a complementary manner. The battery can be a disposable, non-rechargeable battery (“primary” battery), or it can be a rechargeable battery (“secondary” battery).
The power sources serve complementary purposes: batteries can provide slow, long-term charging for supercapacitors or power relatively low-power-consuming electronic devices; supercapacitors can provide rapid, high-power discharging and power functions requiring higher power levels, such as wireless data connectivity and data payload transmission. It should be noted that the supercapacitor can be an EDL supercapacitor or a pseudocapacitor, or any other form of energy storage device. The device can be used in situations where high power is occasionally required (e.g., powering a transmitter to connect to a data network and send data payloads), but the device needs to be standalone and continuously used in the field for months or years: the device could be a high-value asset tracking tag that only occasionally needs to broadcast its information, but requires broadcasting at a higher power than conventional printed batteries can provide.
A schematic diagram is shown in Figure 35. There are two separate polyimide film layers: one layer 351 includes a supercapacitor (Gii-Cap) 352 as described in feature M, and the other layer 353 includes a cell 354, such as a printed cell; this can include electrodes made using carbon foam manufactured using a dual-laser process or conventional processes. It is also possible to fabricate the printed cell 354 and the supercapacitor 352 on the same sheet of polyimide, but yield may be affected because any defects in the printed flexible cell or supercapacitor will render the equipment unusable.
As described above, the subsurface carbon foam electrode (or conventional printed electrode) leads from the supercapacitor (Gii-Cap) 352 and the printed battery 354 to the BMS (Battery Management System) 355; the BMS 355 provides power to the flexible electronics 356; the subsurface carbon foam electrode or conventional connector track 357 connects different parts of the flexible electronics 356. The BMS 355 controls the flow of power from the battery 354 to the electronics 356; the battery 354 can trickle charge the supercapacitor 352. (The supercapacitor can also be the primary power source, designed to be charged once in the facility and then not need to be recharged.)
Battery 354 can be a printed battery, and can be a rechargeable secondary printed battery or a primary, non-rechargeable primary battery; battery 354 can trickle charge supercapacitor 352 and provide power to sensor or other device electronics 356; then, supercapacitor 352 provides power (e.g., instantaneous peak power) to circuits (such as data transmitters) that have short-term demands for relatively high burst power. As described above, the printed battery, supercapacitor, and electronics can all be part of a single integrated device, for example, all on a single substrate, or on a separate but attached substrate.
Although back-to-back polyimide layers are shown, they can also be side-by-side; in addition, there can be a single polyimide film that integrates the battery 354 and the supercapacitor 352 into a single object.
The battery 354, supercapacitor 352, and electronic device 356 can all be formed on one or more substrates as part of a continuous or batch manufacturing process (e.g., you don't use a previously manufactured battery and combine it with a supercapacitor). This allows the interconnects to be constructed as an integral part of the manufacturing process, resulting in lower costs, faster manufacturing, and higher performance (e.g., shorter interconnects).
The device can be used in smart tags (see below), or IoT environmental monitoring devices (e.g., temperature or humidity sensors), train seat occupancy sensors, or medical monitoring devices (e.g., continuous glucose monitors). More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
We can summarize it as follows:
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
One important application is the smart label, shown in Figure 36, with the bottom surface shown on the left and an exposed label surface 363 with human-readable text shown on the right. The label includes an adhesive release liner 364 to allow the bottom surface to be attached to packaging, components, etc. The label includes a thin, flexible battery 360 printed onto a polyimide film, and then a Gii-cap supercapacitor 361 formed on the same polyimide layer (or a different polyimide layer bonded to the printed battery polyimide film). The thin, flexible battery can be a non-rechargeable primary battery or a rechargeable secondary battery. The supercapacitor provides power to the data transmitter; the printed battery provides power to the smart label's electronics (including sensors) and power management electronics. Human-readable printed information 363 is included on one surface of the smart label; the back side...
The smart tag includes an electronics module 362 with power management, sensors (e.g., solid-state vibration, temperature, pressure, GPS, etc.) and data transmission electronics (e.g., an LTE transmitter or an ultra-low-cost LoRaWan transmitter). Once a data connection is established, the supercapacitor 361 provides sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in an "advertising" signal; instead, the smart tag can establish a data connection with a data receiver and then transmit the data payload once the connection is established; thus, it can be reasonably ensured that its data has been received. More generally, the device may include electronics powered by a battery; the device may include electronics powered by a supercapacitor; the device may include a data transmitter powered by a supercapacitor; the battery may be a printed battery; the battery may be a primary battery or a secondary battery.
For scalable manufacturing (e.g., producing millions of smart tags at low cost), roll-to-sheet manufacturing of smart tags is ideal (see Feature P: Gii 3 below).
We can summarize it as follows:
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics such as sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
The supercapacitor in the aforementioned example of feature M can provide power to the antenna but is not integrated with the battery: for example, it can provide power from a solar cell or draw power from local WiFi or a wireless charger (e.g., the Qi standard).
We can summarize it as follows:
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor
A useful feature is the combination of an energy harvester with a carbon foam supercapacitor. The energy harvester can be a solid-state energy harvester such as a solar cell, or a vibratory energy harvester (e.g., based on piezoelectric fibers), or a thermoelectric generator (e.g., a Seebeck generator). The supercapacitor can provide power (e.g., instantaneous power) to circuits with short-term demands for relatively high burst power (e.g., data transmitters and antennas). The device may also include a primary battery (e.g., a non-rechargeable printed battery) or a secondary rechargeable battery.
The energy harvester can be on the same substrate as the supercapacitor, or on a separate but connected substrate; the supercapacitor can be on the same side of the substrate as the energy harvester, or on opposite sides.
When the device includes a battery (e.g., a printed rechargeable secondary battery), the energy harvester charges the battery, and the battery provides power to low-power subsystems (e.g., sensors) and also charges the supercapacitor; the supercapacitor provides instantaneous high power for data transmission. Alternatively, the energy harvester can charge the supercapacitor directly.
This approach can be used in smart tags, or IoT environmental monitoring devices (such as temperature or humidity sensors), train seat occupancy sensors, wearable devices, and medical monitoring devices (such as continuous blood glucose monitors). This method is particularly useful in situations requiring continuous (or highly regular) power to the device, such as when continuous monitoring of the environment or an individual's health is necessary.
The device may include LoRaWan or other ultra-low power transmitters. Once a data connection is established, the supercapacitor can provide sufficient peak power to transmit useful data packets, so there is no need to simply include this data packet in the announcement signal; instead, the smart tag can establish a data connection with the data receiver and thus ensure that its data has been received.
More generally, the energy harvester can be a solid-state energy harvester, such as a solar cell, or a vibration energy harvester (e.g., based on piezoelectric fibers) or a thermoelectric generator (e.g., a Seebeck generator); the device can include one or more sensors powered by the energy harvester; the energy harvester can charge a supercapacitor; the device can include a primary or secondary battery; the device can be a smart tag, or an IoT environmental monitoring device (e.g., a temperature or humidity sensor), a train seat occupancy sensor, a wearable device, or a medical monitoring device.
We can summarize it as follows:
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
In an earlier chapter, we described the carbon foam in the Gii-Cap supercapacitor as a single planar interdigitated finger layer. In this section, we describe a three-dimensional structure of carbon foam that enables the carbon foam supercapacitor electrodes to be formed as a parallel-plate 3D structure with a greater energy storage potential than a single layer of interdigitated graphene foam fingers.
Figure 37 shows the basic layering of different materials in the core structure. Multiple screen printing steps are performed on the PI polyimide film 371 sheet. First, a conductor (such as a carbon ink or carbon paste layer 372) is screen-printed onto the lower surface of the polyimide film 371. Then, a current collector 373 (e.g., a screen-printed silver current collector) is screen-printed over the carbon layer 372. Finally, a dielectric layer 374 is screen-printed over the current collector.
Figure 38 shows the carbon foam layer formed in the polyimide film 371 using the dual-laser process described above: more specifically, an IR laser forms an encapsulated carbon foam layer 375 in the PI film 371; beneath this carbon foam layer is a disordered, amorphous, non-graphene layer 376 formed on the lower surface of the PI film 371. A CO2 ablation laser exposes the previously encapsulated carbon foam layer 370, thereby giving the exposed surface layer 377 a unique morphology.
This structure provides a conductive path from the current collector layer 373, through the conductive ink or paste layer 372, through the disordered amorphous non-graphene layer 376, and then to the carbon foam layer 375. In this way, the potential of the large-area carbon foam 375 can be increased, enabling it to act as a capacitor plate; the structure forms part of a half-cell.
Typical thicknesses are as follows: polyimide film 371: 127 μm; carbon ink layer: 20 μm; silver current collector layer 373: 30 μm; dielectric layer: 40 μm; carbon foam layer 375 and disordered amorphous non-graphene layer 376: 127 μm; unique surface morphology layer 377: 25 μm.
It should be noted that Gii-Cap+ (a variant that uses a metal oxide electrochemical deposition process (e.g., +ve is MnO x ; -ve is Fe x O x , see Feature M2 above) and delivers significantly higher capacitance than the standard Gii-Cap device) can be used in Gii-Thru.
We can summarize it as
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising a carbon foam material made at least partially by a carbon precursor film as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Multiple structures as described in Figure 38 can be stacked together; since the surface area of the carbon foam layer can be very large (significantly larger than the surface area of the finger sites in the previously described planar interdigitated supercapacitor), this enables the production of high-performance supercapacitors.
The half-cell is illustrated in Figure 39. It comprises (gradually moving downwards through the structure): a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in a PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper tabs 395 for connection points; a screen-printed dielectric isolation layer 396; a second carbon foam layer 397 with a unique surface morphology in a PI film 398; and a hydrogel electrolyte layer 399 at the base of the stack. It may be helpful to associate this structure with the schematic diagram in Figure 38: in Figure 40A, we group the four main layers shown in Figure 38 at point A, i.e., moving downwards along the stack, the carbon foam layer, then the carbon ink layer, then the silver collector layer, and then the dielectric layer. Figure 40B is a cross-section of the structure of Figure 40A, showing the features of group A. Figure 40B is the same cross-section, but this time all the elements in Figure 39 are labeled.
The complete unit is shown in Figures 41A and 41B. In Figure 41A, we only label the features that are also present in Figure 39 (using the same numbering). So it includes: a hydrogel electrolyte layer 390; a carbon foam layer 391 with a unique surface morphology in the PI film 392; a screen-printed carbon paste layer 393; a screen-printed silver connector layer 394 with external copper inserts 395 for connection points; and a screen-printed dielectric isolation layer 396.
In Figure 41B, we now add an additional layer; moving down through the structure, we have a screen-printed dielectric insulating layer 400, followed by a screen-printed silver collector layer 401 with copper inserts 402, then a screen-printed carbon paste layer 403, and then a carbon foam layer 404 with a unique surface morphology in a PI film 405.
In Figure 41C, we group the four main layers shown in Figure 38 together at point A; the four top layers are grouped together at point B in the reverse order. Groups A and B are separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399, which is dispensed using a conventional electrolyte dispensing system.
Figure 41D is a cross-section of this structure, showing the A and B layers separated by a hydrogel (e.g., polymer hydrogel) electrolyte layer 399. Figure 41E is the same cross-section, but this time the layers are numbered according to the schematic diagram in Figure 38.
Figure 41F is a perspective view of the assembled supercapacitor.
Figure 42 shows a stack of four full-cell supercapacitors; the carbon foam layer is shown in A, and the polymer hydrogel electrolyte is shown in B. Additional cells can be added to the stack to obtain the desired performance.
Figure 43A shows the detailed manufacturing process of the Gii-Thru supercapacitor, and Figure 43B shows the detailed manufacturing process of the Gii-Thru multi-stacked supercapacitor.
We can summarize it as follows:
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from the carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
The Gii-Thru structure described in Figure 38 can be used not only for supercapacitors but also for Gii-Sens sensors, such as biosensors.
For microfluidics, the Gii-Thru HISLOC (High Sensitivity, Low Cost) platform approach allows liquid and carbon foam sensors to be mounted on the upper surface of the biosensor device, with electrical connectors to the carbon foam sensor mounted on the lower surface. Microfluidics typically use functionalized gold electrodes, where all electrical connectors to these functionalized gold electrodes are coplanar; compared to these functionalized gold electrodes, Gii-Thru biosensors offer advantages in cost, yield, and performance. Furthermore, moving the electrical connectors to the bottom or base of the biosensor enables greater miniaturization and compatibility with point-of-care (POC) systems.
Figure 44A is a schematic cross-sectional view of the Gii-Thru sensor used in a three-sample array microfluidic diagnostic device. The top layer has three sample wells 440; the fluid to be analyzed flows into each of these samples 440. The wells 440 are formed as small pores in a laminated spacer layer 441 located above the polyimide film layer 442.
Three functionalized carbon foam regions are formed in the polyimide film layer 442, which form a reference electrode 448A, a working electrode 448B, and a counter electrode 448C; the upper surface of each electrode 448A-448C is exposed to the analytical flow present in the pore 440.
The base of the reference electrode 448A may include an Ag-AgCl layer (or a screen-printed carbon layer) 449; the base of the working electrode 448B is a screen-printed conductive carbon layer 443; and the base of the counter electrode 448C is another screen-printed conductive carbon layer 443. In this way, the reference electrode 448A is in electrical contact with the reference electrode connector 444A; the working electrode 448B is in electrical contact with the working electrode connector 444B; and the counter electrode 448C is in electrical contact with the counter electrode connector 444C.
The screen-printed dielectric layer 447 forms the base of the structure.
The interesting aspect of this structure is that the electrode connectors 444A-C are not coplanar with the functionalized carbon foam electrodes 448A-C, unlike conventional screen-printed sensors. Instead, they lie in the plane below the functionalized carbon foam electrodes 448A-C, on the opposite side of the aperture 440. This structure enables greater miniaturization and compatibility with POC (point-of-care) systems.
Figure 44B shows an isometric exploded view of the microfluidic diagnostic device of Figure 44A. Three sample wells 440 are located in a laminated spacer layer 441, which sits above a polyimide film layer 442. A reference electrode 448A, a working electrode 448B, and a counter electrode 448C are shown; the end of the reference electrode 448A is covered by an Ag-AgCl layer or a screen-printed carbon layer 449; the working electrode 448B and the counter electrode 448C are covered by a screen-printed conductive carbon layer 443. As noted above, the reference electrode 448A is in electrical contact with a reference electrode connector 444A; the working electrode 448B is in electrical contact with a working electrode connector 444B; and the counter electrode 448C is in electrical contact with a counter electrode connector 444C.
It should be noted that the three functionalized carbon foam regions 448A-C are shown as planar squares located on different planes; however, this is merely an artificial creation of the CAD drawing used to generate the figures, and the carbon foam regions 448A-C are better represented in Figure 44A. A screen-printed dielectric layer 447 forms the base of the structure.
Figures 44A and 44B above show a three-point array microfluidic diagnostic device. In Figures 45A and 45B, we present an eight-point array microfluidic diagnostic device. In isometric Figure 45A, the laminated pore spacer 451 includes an array of eight analyte holes 452 for the working electrode, plus holes 453 for the counter electrode and holes 454 for the reference electrode; the laminated pore spacer 451 is located above the polyimide layer 455. Gii carbon foam in the polyimide layer 456 forms eight working electrodes 457 and counter electrodes 458, and is fabricated using a dual-laser process. It should also be noted that the carbon foam electrodes 457, 458 are shown as planar squares located on three different planes; however, this is merely an artificial CAD design, and the carbon foam forms a continuous region within the polyimide layer 455.
The reference electrode 459 is covered with a thin screen-printed Ag-AgCl layer. A thin screen-printed carbon bonding interface layer 460 is located below the working electrode 457 and the counter electrode 458; screen-printed silver bonding traces 461 form electrical connections with all electrodes 457, 458, and 459. Then, a screen-printed dielectric layer 462 forms the housing of the device. Figure 45B is a pair of top views of the device of Figure 45A; the lower figure shows the path of the lower bonding traces.
Figure 46A shows a perspective view of the fully assembled multi-sample array microfluidic diagnostic device; Figure 46B is a top view.
We can summarize it as
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode, at least partially made of a carbon precursor film by means of any one of the features A-K above, in a layer below the sample orifice, and a reference electrode connector, a working electrode connector, and a counter electrode connector are also in the layer below the reference electrode, working electrode, and counter electrode.
Figure 47A shows an exploded view of a microfluidic diagnostic device comprising multiple laminated layers; it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. The top layer 470 of the device is a microfluidic foil; the middle layer 471 is a microfluidic foil with an adhesive and includes printed or molded microfluidic channels 472, and the bottom layer 473 is a microfluidic foil with an adhesive. The Gii-Thru sensor 474 is a three-point array (3SA) biosensor and includes a connector 475. Figure 47B is a top view showing the internal structure. The Gii-Thru sensor 473 can be replaced with different biosensors (e.g., 8SA) for greater flexibility.
Figure 48B shows an exploded view of a microfluidic diagnostic device comprising a printed or molded microfluidic card, and it includes a three-point array (3SA) microfluidic biosensor implementing Gii-Thru, as shown in Figure 44A. This device includes a transparent resin barbed connector 481, a top foil 482, a transparent resin molded microfluidic card 483 with microfluidic channels 484, a perforated unit 485 made of microfluidic foil with an adhesive, and a Gii-Thru sensor 486. Similarly, the Gii-Thru sensor 486 can be replaced with different biosensors (e.g., 8SA) for greater flexibility, and the molded microfluidic card 483 can be replaced with designs featuring different microfluidic characteristics to allow for use on different assay platforms. Figure 45B is a top and side view.
Feature O4: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
The HISLOC manufacturing process can be summarized as follows:
1. Screen print the elastic layer onto the underside of the polyimide film.
2. Screen-printed silver connectors.
3. Screen printing silver/silver chloride reference electrode (steps 3 and 4 can be rearranged into 4 then 3).
4. Screen-printed dielectrics.
5. Gii carbon foam sensor electrodes are generated in a polyimide film using a dual-laser process.
The detailed manufacturing process is shown in Figure 49.
We can summarize it as follows:
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising a carbon foam material made at least partially from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Group 4
Feature P: Scalable manufacturing: G-ii 3
Gii-3 is a scalable manufacturing facility for roll-to-roll or roll-to-sheet production of all the Gii-based materials described above. A key commercial advantage is that Gii-3 manufacturing does not require custom equipment; it utilizes off-the-shelf computer-controlled lasers for dual-laser carbon foam manufacturing, along with conventional screen printing and drying techniques: these are well-known, easy-to-understand manufacturing processes and equipment that enable reproducibility and reliability.
Figure 50 is a schematic diagram of the overall manufacturing process, and Figure 51 shows the detailed process flow.
We can summarize it as follows:
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other Gii applications
The Gii carbon foam described in this specification can be used in a wide variety of applications, including many applications where conventional graphene foam is considered suitable.
We can summarize it as follows:
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, a tactile sensor for robots; a prototype sensor is shown that uses polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as the active layer in a piezoresistive pressure sensor for robotic touch sensing applications: several carbon foam layers are capable of exhibiting pressure sensitivity of 0.0418 mV/kPa in the range of 0 to >50 kPa. See DOI:10.4028/p-oy94hj. and DOI:1109/CDE52135.2021.9455738. These contents are incorporated herein by reference to the maximum extent permitted.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection. See DOI:10.1016/j.bios.2022.114954, the contents of which are incorporated herein by reference to the maximum extent permitted.
Continuous monitoring of chemical sensors.
Glucose Monitoring Sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring is shown; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competitively binding with polynordihydroguaiaric acid. See DOI:10.1039/D1AN01991K, the contents of which are incorporated herein by reference to the fullest extent permitted.
Lactic acid sensor: Employs a synthetic organic acceptor molecule based on attaching boric acid to a carbon foam to provide functionality and selectivity in competitive analyte binding, with surface redox polymer indicator substitution used. See DOI:10.1016/j.snb2022.133089, the contents of which are incorporated herein by reference to the maximum extent permitted.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1). See DOI:10.1016/j.elecom.2022.107394, the contents of which are incorporated herein by reference to the fullest extent permitted.
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
Under a scanning electron microscope, conventional graphene foam appears to have large open ring structures, typically 500 μm in size. Carbon foam generated using a dual-laser process looks very different; Figures 52–57A are SEM images of this Gii carbon foam.
Figure 57B is a SEM image of carbon nano-onions, see "Raman spectroscopy of polyhedral carbon nano-onions", DOI:10.1007/s00339-015-9315-9 and "Carbon nano-onions: unique carbon nano-structures with fascinating properties and their potential applications", DOI:10.1016/j.ica.2017.07.021. Its similarity to Gii carbon foam is obvious.
As previously mentioned, graphene foam possesses several characteristics: it is hydrophobic and has low wettability. Raman analysis of typical graphene foam reveals the following signature features: the absence of a D peak; a 2D peak higher than the G peak; and a D:G peak ratio close to zero. However, carbon foam produced using a dual-laser process does not exhibit these characteristics; it is hydrophilic with a contact angle below 20°; and it lacks the Raman spectral signature indicative of graphene: it displays a prominent D peak; a 2D peak significantly smaller than the G peak; and a D:G peak ratio significantly higher than zero. Figure 58 shows the Raman shifts of eight carbon foam sheets fabricated using a dual-laser process, demonstrating the consistency of the Raman signature. It also shows a prominent D peak; a 2D peak smaller than the G peak; and a D:G peak ratio significantly higher than zero. As we previously stated, this Raman spectrum shares many similarities with carbon nanotube onions. See also Figure 18C, also from “Raman spectroscopy of polyhedral carbon nano-onions”, DOI:10.1007/s00339-015-9315-9. The specific dual-laser parameters used to generate this low-resistivity carbon nano-onion variant of Gii carbon foam are shown in Table 5 below:
Table 5
We can summarize it as follows:
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
It should be noted that any of the devices described above, such as sensors, pressure sensors, biosensors, Hall effect sensors, supercapacitors, hydrogen fuel cells, and filters, can be characterized using these materials, and therefore we can summarize as follows:
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
Appendix 2 Gii-Cap+ Hydrogel
Appendix 3 GiiCap Ion Gel
Appendix 4 Feasibility Study Recommendation (3 Months)
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Material via Connectors
Appendix 6 Baseline Experimental Conditions
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
It should be noted that Appendices 1-7 describe specific implementations of Gii carbon foam.
Appendix 8: Combined list of features and optional features
Appendix 1: Specific Implementation of Supercapacitors Using Hydrogel Electrolytes
background
A supercapacitor is a device that stores electrical charge. Based on its structure and function, a supercapacitor falls between an electrolytic capacitor and a rechargeable battery.
The properties of supercapacitors make them superior to rechargeable batteries in applications requiring short charging times and those involving many charge/discharge cycles. However, compared to batteries, supercapacitors have disadvantages including a weaker ability to store energy over long periods.
The operational limitations of supercapacitors are determined by the material properties of their components. Specifically, the maximum voltage at which a supercapacitor can operate (i.e., can be charged) depends on the stability of the electrolyte and/or electrodes. The maximum voltage of a capacitor is an important parameter, especially since the energy stored in a capacitor is proportional to the square of the voltage. Supercapacitors with organic electrolytes typically support higher voltages than those with aqueous electrolytes. By utilizing organic electrolytes, supercapacitor designers can produce devices with an operating range of 2.5 to 2.7 V. In contrast, while aqueous electrolytes are often preferred due to their lower cost and lower toxicity, they typically result in devices with a lower operating voltage range. Known symmetrical aqueous supercapacitors generally cannot support voltages higher than 1.3–1.5 V. This voltage limitation can reach 1.8–2.0 V if electrodes made of different materials are used. The limitations of water-based supercapacitors are attributed to the electrolysis of water, which, in principle, occurs when water is exposed to a potential difference of 1.23 V. However, in practice, a larger potential difference is required before electrolysis occurs to overcome the effects of overpotential.
Carbon-based electrodes have been associated with supercapacitors since their early development. Initially, carbon attracted attention as an electrode material because it offered the possibility of fabricating electrodes with large surface areas. Later in the development of supercapacitor devices, the importance of the so-called double layer on the electrode surface was realized. This complex and often elusive phenomenon, related to the use of carbon as an electrode material, is central to the high capacitance values associated with supercapacitors. Supercapacitor devices incorporating carbon-based electrodes are thought to involve a double layer on the electrode surface, with energy stored electrostatically. Such supercapacitors are called electrostatic double-layer capacitors, or EDLCs.
Other types of supercapacitors also exist. Electrochemical pseudocapacitors utilize metal oxide electrodes or conductive polymer electrodes. Compared to the electrostatic charge storage mechanism of EDLCs, charge storage in pseudocapacitors is primarily electrochemical. A third type of supercapacitor is the hybrid capacitor. Hybrid capacitors have asymmetric electrodes. One electrode is typically made of carbon and exhibits electrostatic charge storage properties; the other electrode is typically a lithium-containing or lithium-doped material, which primarily exhibits electrochemical charge storage properties.
Conventionally, a supercapacitor can be considered and modeled as two capacitors connected in series, with each electrode associated with one capacitor. Each capacitor is located at the interface between the electrode and the electrolyte and is formed by the supercapacitor electrode, a dielectric layer (called the inner Helmholtz plane) formed by solvent molecules present in the electrolyte, and a charge carrier layer (called the outer Helmholtz plane) provided by the electrolyte as the opposite charge charging the electrode. This triple structure of the electrode, inner Helmholtz plane, and outer Helmholtz plane forming the capacitor system at each electrode is called a double layer or electrical double layer.
Summary of features in Appendix 1
A first aspect of the aforementioned features provides a symmetrical supercapacitor device comprising: two electrodes, each comprising a carbon foam as described in this specification (e.g., see features A-K in Appendix 8); and an ion gel or hydrogel electrolyte encapsulating the electrodes in active regions.
We have found that symmetrical supercapacitor devices, based on a combination of the characteristics described above, produce an enhanced operating voltage window. The term "symmetrical" refers to the fact that the electrodes comprise the same material and may be constructed from the same material.
The operating voltage window, or operating range, of a supercapacitor is a critical parameter of such a device and is determined by the breakdown voltage of the electrolyte. For supercapacitors based on aqueous electrolytes, water decomposition typically leads to limitations on the operating voltage window.
Although the reasons for the unexpectedly large operating window observed using the device disclosed in this invention are not yet fully understood, it is evident, without being bound by any theory, that the special property is a result of the combination of the carbon foam electrode and the electrolyte, and especially of the interface between these elements.
In electrochemistry, the large operating window of the device of this invention is equivalent to an unexpectedly large overpotential at the electrode. An overpotential is a potential difference exceeding the thermodynamic redox potential required for a specific reduction/oxidation reaction to occur. Overpotential is often a difficult phenomenon to understand, partly because many factors contribute to it. For example, overpotential depends on the electrode material, electrode morphology, and the properties of the electrolyte. In this invention, the large surface area provided to the electrolyte by the carbon foam electrode is considered likely to play a role in device performance. It is known that how ions diffuse from the electrolyte bulk to the electrode surface and the associated consumption of charge carriers on the electrode surface affect the overpotential. This may play a role in the device of this invention. The diffusion rate of charge carriers in the electrolyte may be affected by the presence of hydrated ions, which are larger than non-hydrated ions. The interaction between charge carriers and the morphology of the carbon foam electrode may also affect the overpotential. The presence of ion-gel or hydrogel polymers is also considered to influence the diffusion of charge carriers to the electrode surface, possibly due to spatial effects and related to the carbon foam morphology.
Hydrogels are gels whose liquid component is water and can be formed from a network of polymer chains. Supercapacitors with a hydrogel electrolyte forming the dielectric are expected to have performance characteristics associated with aqueous electrolyte-based supercapacitors. However, to this expectation, the inventors have found that the performance of a supercapacitor according to a first aspect (i.e., a symmetrical device in which the electrodes are made of the same material, including carbon foam and encapsulated in a hydrogel electrolyte) surpasses the expected performance of an aqueous device. The operating voltage window of the device is unexpectedly enhanced compared to aqueous electrolyte-based devices. The operating window is more similar to that of organic solvent-based supercapacitors.
Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), sodium polyacrylate, acrylate polymers, and copolymers, which have a large number of hydrophilic groups, are examples of polymers that can be utilized in hydrogels. Fluorinated hydrogels can also be used. The combination of hydrogels and ionic charge carriers helps to achieve a surprisingly large operating window through the system of the present invention.
The electrodes of the device disclosed in this invention are located on a substrate, and the electrolyte is present on top of the electrodes in a manner that seals at least a portion of the electrode structure, thus forming an active region. The active region of a supercapacitor is the region in a supercapacitor that stores charge, including the electrolyte and the electrodes.
The electrodes of the device can have an interdigitated geometry, meaning they can be interdigitated. This interdigitated electrode geometry helps maximize the capacitance of the supercapacitor. It also enables a device without a separator. Supercapacitors typically include separators between opposite electrodes to prevent short circuits. The absence of a separator facilitates the construction of supercapacitor devices. Separators can also negatively impact device performance, such as inhibiting charge flow and reducing charge/discharge rates. The absence of a separator avoids these negative performance effects.
Interdigitated electrode geometries are well-suited for symmetrical devices. Constructing an interdigitated electrode geometry with opposite electrodes made of different materials is significantly more complex than with electrodes made of the same material. If the electrodes are made of the same material, they can be fabricated in-situ in a single step. Using different electrode materials requires multiple fabrication steps, greatly increasing the complexity of the manufacturing process.
In addition, the absence of a separator eliminates any negative impact that a separator might have on device performance, such as inhibiting charge flow and causing a decrease in charge/discharge rate.
The hydrogel electrolyte can contain a sufficiently high charge carrier concentration to produce the enhanced operating voltage window.
An enhanced operating voltage window may depend on the concentration of charge carriers.
Charge carriers can have redox potentials that support an enhanced operating voltage window.
The charge carrier can be provided by aqueous solutions of acids, bases, or salts. Usable acids include sulfuric acid. Usable bases include potassium hydroxide.
Hydrogel electrolytes may comprise a mixture of hydrogel and salt. The electrolyte may be composed of a hydrogel polymer, such as PVA or PVP. The salt may be, for example, NaClO₄ , NaNO₃ , or Mg( ClO₄ ) ₂ . The molar concentration of the salt may be, for example, 0.5 M or greater, such as 1 M or greater, such as 2 M or greater, such as 2.5 M or greater, such as 3 M or greater, such as about 5 M. The molar concentration of the salt may be, for example, between 1 M and 10 M, or it may be, for example, between 2.5 M and 7.5 M.
Salts that can be used include phosphates, perchlorates, nitrates, and arsenates. Examples of salts include sodium sulfate, sodium bisulfate, sodium persulfate, sodium perchlorate, lithium perchlorate, magnesium perchlorate, sodium nitrate, and lithium hexafluoroarsenate. Aqueous solutions of these salts can be used in electrolytes to provide ion carriers.
Charge carriers can be ions. Charge carriers can be hydrated ions.
Hydrated ions are ions in an aqueous environment. Polar water molecules arrange themselves around the ions, forming hydrated spheres centered on the ions. The details of the mechanism behind the surprisingly wide enhanced operating voltage window observed with respect to the features of this invention are difficult to understand, and the inventors do not wish to be bound by theory. However, the surprisingly advantageous properties of the device of this invention are a result of the synergistic effect between the electrodes and the dielectric material. The enhanced performance is a lack of water splitting under voltage conditions under which electrolysis is expected to occur by those skilled in the art. The interface between the electrode and the electrolyte is expected to be the origin of its performance. There may be a synergistic interaction between the size of the charge carrier (possibly a hydrate) and the size of the pores present in the electrode. The hydrogel contains a network of polymer chains, and this chain network of the hydrogel may also have physical (spatial) effects that limit the exposure of water molecules to potential differences that could lead to their decomposition.
The increased size of hydrated ions is thought to combine with the porous structure of the carbon foam electrode to impede diffusion near the electrode surface, leading to an increase in overpotential.
The electrodes of a symmetrical supercapacitor device may include porous carbon foam. Optionally, the electrodes may not include additional adhesive material.
Porous carbon foam electrodes are thought to be combined with charge carriers in the electrolyte to increase overpotential, thereby enhancing the operating window of supercapacitors.
Carbon foam consists of one or more 2D carbon sheets (each sheet being a layer of sp2-bonded carbon) folded back-to-back to form a three-dimensional structure rather than planar sheets. Carbon foam lacks the regular AB stacking of planar carbon sheets found in graphite or multilayer 2D carbon. Carbon foam materials are typically porous. Carbon foam has a high surface area. By changing the parameters of the growth method, the porosity of the carbon foam can be controlled, and thus the surface area of the foam. This has the advantage of allowing control over the porosity of the device electrodes during the electrode fabrication process.
Carbon foam electrodes can be mounted on a substrate. Carbon foam electrodes can be mounted on a polyimide substrate. The polyimide substrate can be polyimide. The substrate can form the substrate of a supercapacitor device. The substrate can be thin enough to be flexible, thereby creating a flexible supercapacitor device. The substrate can contain one or more of the following materials (e.g., formed therefrom): polyimides (e.g., poly(4,4'-oxydiphenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde resins.
These substrate materials can be used as a carbon source and transformed into carbon foam using the dual-laser process described above. Carbon foam can be produced in this way by irradiating a polyimide substrate (e.g., with radiation, such as laser radiation). The resulting carbon foam is chemically and indirectly fixed to the substrate via an intermediate layer of amorphous, non-graphene material directly attached to the substrate (see earlier in this specification), resulting in a robust structure. Therefore, electrodes can be produced in situ by using a portion of the substrate as a carbon source, i.e., as a reagent for producing carbon foam. The structure is both robust and flexible. Flexible devices have advantages in many ways. Flexible devices can be conveniently packaged, for example, by rolling them up. For example, flexible devices can also be attached to the surface of curved structures.
The substrate can be substantially planar. The substrate can be a film, such as a thin film. The substrate thickness can be greater than 5 μm. The substrate thickness can be less than 120 μm. The substrate thickness can be between 5 μm and 120 μm. The substrate thickness can be substantially uniform across the substrate surface. The substrate can be flexible. The substrate can be tough.
The substrate may be a polyimide strip (e.g., a polyimide strip) having a first surface and a second surface.
Electrodes can be mass-balanced to optimize the operating voltage window.
A supercapacitor can be viewed as two capacitors connected in series. To maximize the capacitance of a supercapacitor, the capacitances of the two constituent capacitors should be equal. This can be engineered by adjusting the surface area of each electrode, thereby compensating for other factors affecting the capacitance, such as the properties of solvated ions. This process of adjusting the individual electrodes is called mass balancing. Electrode mass balancing has the advantages of maximizing the capacity of the superconducting device and extending the lifespan of the supercapacitor.
In a second aspect, there is a method for manufacturing a symmetrical supercapacitor device according to the first aspect, wherein:
Electrodes are formed on the substrate;
Electrolyte precursors containing charge carriers and hydrogels are applied to electrodes;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the active region.
Carbon foam electrodes can be fabricated by: converting a portion of a substrate (if the substrate is or includes a carbon source) into carbon foam; or by using chemical or physical deposition methods, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), sputtering, laser-induced growth, pulsed laser deposition, cathodic arc deposition, spin coating, dip coating, or sol-gel methods. In this way, electrodes are produced in situ on the substrate.
Electrolyte precursors can be prepared by preparing an aqueous solution of the charge carrier and then mixing this aqueous solution with a hydrogel. Electrodes can be formed using laser radiation.
When preparing the electrolyte precursor, it is important to remember that precipitation or crystallization of salts in the electrolyte is undesirable. Precipitation of salts or any solids in the electrolyte can lead to device breakage, or other defects in the device, or defects in its performance. This sets an upper limit on the concentration of the salt solution. Avoiding the use of supersaturated salt solutions may be advantageous. The precise upper limit of concentration may depend on the specific chemical composition present. For sodium perchlorate, the inventors have found that an electrolyte produced at a concentration of 5M avoids salt precipitation or crystallization, and, in combination with other features, allows the operating window of the supercapacitor device to extend beyond what would be expected based on considerations of the individual components. The electrolyte may include a salt solution with a concentration greater than 4M. The electrolyte may include a salt solution with a concentration greater than 3M, or greater than 2M, or greater than 1M, or greater than 0.5M.
At higher concentrations, salts were observed to precipitate readily from the electrolyte gel, and at such a rapid rate that the device became unusable. This precipitation may be caused by water evaporation. Hydrolysis and water loss could be another cause. In any case, the inventors found that although the electrolyte gel could be formed using sodium perchlorate at concentrations up to 16.5 M, precipitation problems were observed at all concentrations above 10 M.
High-molar salt solutions can be used when manufacturing hydrogel electrolytes.
For cost reasons, lower concentrations of salt solutions are generally advantageous.
The thickness of the carbon foam layer can be between 10 μm and 100 μm. This contributes to the flexibility of the device, allowing it to be rolled up for greater compactness.
A gap between 100 μm and 1000 μm can separate the electrodes from each other. The capacity of the device depends on the gap between the electrodes, and therefore adjusting this gap will affect the amount of charge that can be stored.
The operating window of the device of the present invention can be greater than 1.5V, or it can be greater than 2V, or it can be greater than 2.5V.
Any optional or preferred feature of any aspect of the system can be a feature of any other aspect of the system.
Appendix 1: Description of the Drawings
We have referenced the following attached figures, in which:
Figure 59 shows the carbon foam cyclic voltammetry measured at 25 mV/s for a positive voltage.
Figure 60 shows the carbon foam cyclic voltammetry measured at 25 mV/s for negative voltage.
Figure 61 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a positive voltage window.
Figure 62 shows the carbon foam galvanostatic charge-discharge (GCD) curves measured at 0.5 mA/ cm² for a negative voltage window.
Figure 63 presents carbon foam galvanostatic charge-discharge (GCD) data obtained from five dual-electrode devices.
Figure 64 presents carbon foam cyclic voltammetry recorded from five different two-electrode setups at high (left) and low (right) scan rates.
Figure 65 presents carbon foam cyclic voltammogram data for five other systems, which differ due to the properties of the hydrogel electrolytes: (a) 3M NaClO4 and PVA; (b) 1M NaClO4 and PVA; (c) 2.5M NaNO3 and PVA; (d) 3M Mg( ClO4 ) 2 and PVA; and (e) 5M NaClO4 and PVP.
Appendix 1 Detailed Description
Dual-electrode supercapacitor
A typical carbon foam supercapacitor device based on this characteristic has interdigitated carbon foam electrodes, as shown in Figure 26. To summarize, a polyimide substrate supports the supercapacitor electrodes, which in this example are constructed of carbon foam and arranged in an interdigitated comb geometry, forming an interdigitated electrode structure. Silver current collectors extend along each side of the device, making each opposite electrode electrically integrated. The non-substrate side of the interdigitated electrode structure is encapsulated in a hydrogel. A polyimide cap can be added to contain the hydrogel, or the device can be packaged in other suitable ways.
As explained above, carbon foam electrodes can be formed on a polyimide substrate. Carbon foam is formed above a suitable substrate (i.e., a substrate providing the carbon source, in this example, a polyimide substrate) by exposing it to a laser beam. The carbon foam produced in this way grows from the substrate and indirectly adheres to it. The substrate and the carbon foam electrode formed in situ in this way form a single unit.
The carbon foam electrodes are manufactured using an infrared CO2 laser under ambient conditions. The substrate is a commercially available polyimide film with a nominal thickness of 127 micrometers. One example has eleven parallel carbon foam strips per electrode. This number can obviously vary. The carbon foam strips of the positive electrode are offset relative to the carbon foam strips of the second electrode, thus forming an interdigitated structure.
Electrode dimensions are shown in Table 6:
| <![CDATA[<u>mass balance ratio</u>]]> | 1.18 |
| <![CDATA[<u>Positive half-cell "electrode finger"</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.0472 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.20768 |
| <![CDATA[<u>Negative half-cell “electrode finger”</u>]]> | |
| Length (cm) | 0.4 |
| Width (cm) | 0.04 |
| Thickness (cm) | 0.005 |
| The number of | 11 |
| <![CDATA[Total exposed area (cm<sup>2</sup>)]]> | 0.176 |
| Distance between fingers (cm) | 0.04 |
| <![CDATA[Total active electrode surface area (cm<sup>2</sup>)]]> | 0.38368 |
| <![CDATA[Total active electrode volume (cm<sup>3</sup>)]]> | 0.0019184 |
Table 6
Three-electrode device
In addition to the two-electrode supercapacitor device, a three-electrode testing device including a reference electrode was also fabricated. The three-electrode device comprises a working electrode, a counter electrode, and an Ag/AgCl reference electrode. Each of the working and counter electrodes is made of carbon foam, which in this specific embodiment is generated by dual-laser irradiation of a polyimide substrate, as previously described. This device is used to determine the stable voltage range of the NaClO4 hydrogel electrolyte. The three-electrode device is stabilized for at least one hour after fabrication before any measurements are performed.
Preparation of hydrogel electrolytes
Each of the disclosed two-electrode and three-electrode devices is based on a 5M sodium perchlorate solution, and the electrolyte is prepared as described herein. The 5M sodium perchlorate solution is prepared by dissolving sodium perchlorate (98% purity, from Sigma-Aldrich) in deionized water (dosage: 3.061 g NaClO₄ dissolved in 5 mL deionized H₂O ). The sodium perchlorate solution is then stirred with a magnetic stirrer on a hot plate at 120°C while polyvinyl alcohol (PVA, 99% hydrolyzed, Sigma-Aldrich) is added. 1.5 g of PVA is dissolved per 10 mL of solution. The mixture of sodium perchlorate solution and PVA is removed from the hot plate and allowed to cool, subsequently forming a white, opaque gel-like solution. The gel solution is then heated to 120°C until it liquefies and becomes transparent. It is then deposited onto a graphene electrode. After deposition onto the electrode surface, the liquefied hydrogel electrolyte material solidifies within approximately 5 minutes at room temperature. The amount of electrolyte deposited on the electrode depends on the surface area to be covered. For the test setup, deposit 150 μL of electrolyte.
Experimental results of the three-electrode device
The performance achievable from supercapacitors is ultimately limited by the stability of the electrolyte.
To test the electrolyte stability in the system of this invention, several experiments were performed using the three-electrode apparatus described herein. Differential pulse voltammetry (DPV) was initially used to select which voltage windows to investigate via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements.
i-Cyclic Voltmeter Method
Cyclic voltammetry measurements were performed to determine the stability of the electrolyte. In a standard three-electrode measurement, the potential between the working electrode and the reference electrode was scanned at a constant rate from the open-circuit potential (OCP; nominal 0V) to a predetermined upper limit, and then scanned downwards again. The current response of the working electrode was monitored during this period.
The results of these measurements are shown in Figures 59 and 60. Figure 59 shows the results of scanning the voltage from OCP in the positive direction.
The upper results set shows four voltammograms with maximum potentials of 1V, 1.2V, 1.3V, and 1.4V. The lower results set also includes a voltammogram with a maximum potential of 1.6V. As the upper voltage limit increases above 1.2V, the shape of the cyclic voltammograms becomes less "square." The tails become increasingly pronounced as the final scan voltage increases, indicating electrolyte degradation, which may be attributed to water electrolysis. These voltammograms indicate that the electrolyte is stable up to +1.2V.
Figure 60 shows a similar set of results, but for the negative electrode voltage. These data indicate that the electrolyte is stable up to -1.4V.
In summary, the data in Figures 59 and 60 provide an operating window of 2.6V for the device. This is significantly higher than expected when using an aqueous electrolyte.
ii. Constant Current Charge-Discharge (GCD) Data
Constant current charge-discharge (GCD) measurements were performed to determine coulombic efficiency based on charge and discharge times. In these measurements, a current was applied between the counter and the working electrode, and the voltage response of the working electrode (relative to the reference electrode) was measured. The GCD curves measured for the positive electrode voltage using a discharge current of 2 × 10⁻⁵ A (0.5 mA/ cm² ) for a selected voltage window are shown in Figure 61. The curves plateau above 1.2 V, indicating electrolyte degradation. The GCD curves for a selected negative electrode voltage window are shown in Figure 62.
A significant plateau was observed in the voltage windows up to -1.6V and -1.8V, indicating electrolyte degradation. The -1.4V voltage window exhibited a triangular GCD curve, indicating stability.
The results of cyclic voltammetry and constant current charge-discharge measurements of the three-electrode system are summarized in the table below.
The first table (Table 7) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the positive voltage window.
Table 7
The second table (Table 8) summarizes the average coulombic efficiency, area discharge capacitance, and discharge energy data for the negative electrode voltage window.
Table 8
In these summary tables, coulombic efficiency is the ratio of stored energy to delivered energy measured in the second GCD cycle; areal capacitance in mF/ cm² is calculated using the following formula:
Area Capacitor
Furthermore, the discharge energy is the integral of the charging and discharging portions of the GCD curve over time.
The GCD curve indicates that +1.2V and -1.4V are the actual positive and negative voltage limits.
These voltage limits and areal capacitance values allow for the calculation of mass balance using the following formula:
Where, m + = mass of the positive electrode, m - = mass of the negative electrode, C + = capacitance of the positive electrode (F), C - = capacitance of the negative electrode (F), ΔE + = positive electrode voltage window limit, ΔE - = negative electrode voltage window limit.
Experimental Results of a Two-Electrode Device—Supercapacitor Performance
For the dual-electrode supercapacitor device, galvanostatic charge-discharge (GCD) data were collected within an applied current density range of 0.25 mA/ cm² to 30 mA/ cm² . Figure 63 plots the GCD results obtained from five different devices (CH1-CH5). These data were collected using a voltage window of 2.6 V, and greater electrolyte stability was observed at higher current densities. Further performance data for the dual-electrode supercapacitor are presented in Figure 64, showing cyclic voltammetry plots recorded from five different devices (devices #1 to #5) according to an embodiment of the invention at scan rates from 0.01 V/s to 5 V/s.
The cyclic voltammograms in the right column were recorded at low scan rates (0.01 V/s, 0.025 V/s, 0.05 V/s, 0.075 V/s, 0.1 V/s, 0.25 V/s, and 0.5 V/s), while the cyclic voltammograms in the left column were recorded at high scan rates (0.75 V/s, 1 V/s, 2 V/s, 3 V/s, 4 V/s, and 5 V/s). The trend shown in these data is that higher scan rates correlate with higher electrolyte stability. In each set of cyclic voltammograms shown in Figure 64, faster scan voltages resulted in larger differences in the current response between voltage rise and voltage fall.
In addition to the devices disclosed above, devices were also constructed in a similar manner but using hydrogel electrolytes comprising the following: (a) 3M NaClO 4 and PVA, (b) 1M NaClO 4 and PVA, (c) 2.5M NaNO 3 and PVA, (d) 3M Mg(ClO 4 ) 2 and PVA, and (e) 5M NaClO 4 and PVP.
The cyclic voltammetry results of these additional devices are shown in Figure [.]10. For each electrolyte, cyclic voltammetry was run between 0V and 0.7V, 0V and 0.8V, 0V and 0.9V, 0V and 1.0V, 0V and 1.2V, 0V and 1.3V, and 0V and 1.4V. Similarly, for each electrolyte, cyclic voltammetry was run between 0V and -0.7V, 0V and -0.8V, 0V and -0.9V, 0V and -1.0V, 0V and -1.2V, 0V and -1.3V, and 0V and -1.4V. These data are shown in Figure 65.
Data indicate that, in each device, for (d) 3M Mg(ClO 4 ) 2 and PVA and (e) 5M NaClO 4 and PVP, the electrolyte is stable up to the limits of -1.4V and +1.1V and up to +1.2V.
Further changes and modifications may be made within the scope of this disclosure.
Appendix 1 Concepts
1. A symmetrical supercapacitor device, comprising:
Two electrodes, each comprising a carbon foam material; and
Hydrogel electrolytes encapsulate electrodes in their active regions.
2. The symmetrical supercapacitor device according to Concept 1, wherein the hydrogel electrolyte comprises a mixture of hydrogel and salt.
3. A symmetrical supercapacitor device according to Concept 1 or Concept 2, comprising an ion charge carrier.
4. The symmetrical supercapacitor device according to Concept 3, wherein the ion charge carrier is hydrated.
5. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam.
6. The symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the electrodes comprise carbon foam material.
7. A symmetrical supercapacitor device according to any one of concepts 1, 5 and 6, wherein the carbon foam material is formed on a substrate.
8. The symmetrical supercapacitor device according to Concept 7, wherein the substrate is a polyimide substrate.
9. The symmetrical supercapacitor device according to Concept 7 or Concept 8, wherein the substrate forms the substrate of the device.
10. A symmetrical supercapacitor device according to any one of the foregoing concepts, wherein the symmetrical supercapacitor device is flexible.
11. A method for manufacturing a symmetrical supercapacitor device according to any one of concepts 1 to 10, wherein:
Electrodes are formed on the substrate;
An electrolyte precursor containing charge carriers and hydrogels is applied to the electrode;
The electrolyte is formed from the precursor, which allows the electrode to be embedded in the electrolyte within the effective region.
12. A method for manufacturing a symmetrical supercapacitor device according to Concept 11, wherein the electrolyte precursor is prepared by preparing an aqueous solution of a charge carrier and by mixing the aqueous solution with a hydrogel.
13. A method for manufacturing a symmetrical supercapacitor device according to Concept 11 or Concept 12, wherein the electrodes are formed in situ.
14. A method of manufacturing a symmetrical supercapacitor device according to any one of claims 11 to 13, wherein the electrodes are formed by irradiating the substrate with laser radiation.
Appendix 2: Gii-Cap+ Hydrogel
In this Appendix 2 section, we demonstrate the effectiveness of Gii carbon foam as an ideal substrate on which pseudocapacitive materials can be deposited, resulting in a significantly enhanced capacitance compared to using Gii carbon foam as the sole electrode material. For the context, these carbon foam-only devices exhibit full-cell specific capacitance in the 0.25–0.4 mF/ cm² region.
Sample preparation
Electrodeposition was performed on A7-sized Gii-Caps to cast a layer of pseudocapacitive material on them. Both v4 and v5 designs were suitable for electrodeposition, yielding similar performance. Results for the v4 sample will be detailed in this document.
First, the sheet containing six Gii-Cap devices (2 rows, 3 columns) was cut in half to obtain two 3-device half-sheets. The two half-sheets were then mounted on internally fabricated fixtures and placed inside the MiniPlant 3 electrodeposition tank. MnOx was deposited on the sample first, followed by rinsing with deionized water, and then FexOy was deposited. After FexOy deposition, the sample was rinsed again and dried in air at 40°C for at least 2 hours.
The deposition details are as follows. The manganese oxide precursor solution contained a mixture of manganese acetate tetrahydrate (40 mM) and surfactant (Tween 20, 0.1 wt%). Deposition was performed using constant current pulses. The on-time was 0.5 seconds, and the off-time was 2 seconds. The applied on-time current was 744 mA (19.14 mA/ cm² , based on the nominal geometry of the electrode). The off-time was 0 mA, i.e., the circuit was open. A total of 390 cycles of MnOx deposition were performed (3.7 C/ cm² per electrode). The FexOy precursor solution contained 40 mM MFe-TEA complex (TEA is triethanolamine). It contained FeCl₃ , TEA, and NaOH. Deposition was also performed using constant current pulses. The on-time was 1 s, and the off-time was 2 s. The applied on-time current was 233 mA (6 mA/ cm² ), and the off-time was set to 0 mA. The deposition process was repeated 1,000 times, yielding 6 C/ cm² for each electrode.
After deposition and sample drying, the samples are divided into individual devices. A quasi-reference electrode (RE) containing screen-printed Ag/AgCl ink is fixed along one edge of the device outside the working area (used to monitor the potential of each electrode during testing). The electrolyte is then applied to the working area of the device and extends onto the RE. The electrolyte used is an aqueous hydrogel containing NaClO₄ as the salt and PVA (polyvinyl alcohol) as the gelling agent. The hydrogel stock solution contains 199.5 g NaClO₄ monohydrate, 256.9 ml deionized water, and 42.4 g PVA. The mixture is solid at room temperature and becomes liquid at temperatures close to the boiling point of water. To dispense the hydrogel, it is heated to 94°C to liquefy it. Dispensing is performed by dropping the liquid electrolyte onto the working area and the RE, typically 3–4 ml per device. The hydrogel on the sample is then allowed to cool and re-solidify after approximately 10 minutes. After solidification, an imide film is applied to the device to prevent excessive electrolyte evaporation. Once capped, the device is ready for testing.
Electrochemical test parameters
Electrochemical tests were performed on the samples using a Biologic VMP-3 voltage/current regulator. Initial performance characterization was performed, followed by 500 charge-discharge cycles (conditioning protocol) for final characterization. The reported nominal values are those obtained in the second characterization step. The conditioning protocol was applied to further stabilize and consistent the sample performance.
During testing, the voltage was controlled at the battery level (the absolute difference between the positive and negative electrodes), with a minimum of 0V and a maximum of 2V. The potential difference between each electrode and the common RE was also measured, allowing for the calculation of individual electrode performance metrics.
These two characterization steps are called the Ragone test. They are identical and include the following:
a) Cyclic voltammetry (CV). Three scan rates were used: 50, 100, and 250 mV/s. Five cycles were performed at each scan rate.
b) Galvanic charge-discharge (GCD). Seven current densities were tested: 1, 2.5, 5, 7.5, 10, 20, and 30 mA/ cm² (based on a total device geometry of 12.96 cm² ). Five cycles were performed at each current density.
c) Electrochemical impedance spectroscopy (EIS). Voltage controlled, using a 1V DC applied voltage and a 10mV AC signal. Measurements were taken in the 1MHz–10mHz region.
The adjustment process was achieved by performing 500 GCDs at 10 mA/ cm² .
The nominal capacitance value is calculated based on the GCD after adjustment at 5 mA/ cm² . The ESR (Equivalent Series Resistance) is calculated based on the voltage drop at the start of the discharge half-cycle in the GCD. The reported ESR value is also derived from the final GCD at 5 mA/ cm² . The ESR can also be calculated from the Nyquist plot obtained from EIS. The results are almost identical.
Results and Conclusions
Average values were calculated for a total of 48 devices. Samples from batches 3258 and 3259 were used. Typical CV curves are shown in Figure 66. The full-cell response (left panel) shows a quasi-rectangular shape, indicating that the storage mechanism is not purely capacitive. This is expected, as both MnOx and FexOy are redox-active materials. Most of the capacitance of the device is concentrated above the cell voltage of 0.5V, as can be seen from the small envelope of the full-cell curve in the 0–0.5V region. The explanation for the smaller capacitance at lower cell voltages can be seen in the half-cell curve, shown in the right panel of Figure 66. This figure shows that MnOx is used as the positive electrode, while FexOy is the negative electrode. MnOx is a near-ideal pseudocapacitive material, as evidenced by its roughly rectangular CV (grey trajectory).
Meanwhile, the FexOy electrode exhibits a more asymmetric response to potential. Its capacitance is largely concentrated below 0V vs Ag/AgCl. When the potential is greater than 0V vs Ag/AgCl, FexOy displays a very small capacitance, as shown by the small envelope of the blue trace at these potentials. Therefore, this asymmetric FexOy response explains the smaller capacitance obtained at low voltages in a full cell.
Figure 66 shows the post-adjustment CV curves obtained at 100 mV/s from sample 3258-1#4. The left panel shows the full-cell CV, while the right panel shows the half-cell curves obtained during the full-cell measurement.
GCD curves were used for capacitance calculations because they provide more accurate values. Typical adjusted GCD curves are shown in Figure 67, displaying measurements for both full and half cells. The device exhibits a good capacitance response with quasi-triangular curves. The full cell exhibits linear discharge from maximum voltage down to approximately 0.5V, indicating that the pseudocapacitance of MnOx and FexOy achieves near-ideal capacitance behavior. As seen in the CV curves, FexOy exhibits an asymmetric capacitance-potential relationship, which explains the faster discharge below 0.5V of the battery voltage.
Figure 67 shows the post-adjustment GCD curves obtained at 5 mA/ cm² from sample 3258-1#4. The full-cell and corresponding half-cell responses are shown in the top, middle, and bottom lines, respectively.
In addition to different pseudocapacitive behaviors relative to potential, the MnOx and FexOy electrodes also exhibit different levels of capacitance. Both electrodes occupy the same geometric area in the device, but the MnOx electrode experiences a much smaller electrochemical window within the device (see the difference between the maximum and minimum electrode potentials in Figures 66 and 67). The smaller MnOx window (0.65 ± 0.06 V) is due to its larger specific capacitance compared to FexOy (1.35 ± 0.06 V window). For the device evaluated in this study, the regulated capacitance of the MnOx electrode reached 246.8 ± 36.0 mF/ cm² , while the regulated capacitance of the FexOy electrode was 171.4 ± 38.4 mF/ cm² . Therefore, these Gii-Cap+ devices are symmetrical in terms of electrode size but asymmetrical in terms of electrode composition and potential split.
Since a full cell is essentially two capacitors connected in series (formed by a double layer between the electrodes and the electrolyte counterions), the total cell capacitance will be lower than the capacitance of a single electrode. The adjusted average full cell capacitance is 52.5 ± 9.4 mF/ cm² . At the same current density (64.8 mA, 5 mA/ cm² , cell level) as the reported nominal capacitance, the ESR calculated based on the voltage drop at the start of discharge is 0.85 ± 0.12 Ω.
EIS measurements further confirmed the good capacitive response of these devices, as shown in Figure 68. The ESR can be estimated by locating the intersection of the Nyquist plot with the y-axis. For the sample shown in Figure 68, the ESR calculated by EIS is 0.78 Ω, which matches very well with the 0.73 Ω calculated by GCD for the same sample. The Bode plot provides information about the device's behavior at different frequencies. At high frequencies, such as 100–10000 Hz, the device functions essentially like a resistor with a phase angle of 0°. As the frequency decreases, the phase angle increases, indicating a greater contribution from capacitance (the phase angle of an ideal capacitor is -90°). When the phase angle exceeds the 45° mark, the device is considered to be essentially capacitive. Therefore, the time when the 45° phase shift occurs can be considered the characteristic time constant of the device. For the sample in this study, the average time constant is 4.48 ± 1.18 seconds. This time constant can be interpreted as the cycle time threshold for an effective capacitive response. When the cycle time is below the time constant, the device will not operate fully.
Figure 68 shows the regulated Nyquist (left) and Bode (right) curves obtained by electrostatic EIS at 1V DC (full cell) for sample 3258-1#4. The inset in the left figure shows a magnified view of the high-frequency response.
Considering that devices using Gii as the sole electrode material exhibit a specific capacitance of 0.25–0.4 mF/ cm² , adding pseudocapacitive materials enhances the energy storage capacity of these Gii-Caps by more than 100 times. Furthermore, adding these metal oxides does not significantly increase the ESR of these devices, thus maintaining their usefulness in high-power applications. The electrodeposition process is controllable, allowing for the fabrication of cells with less deposited material and consequently less total capacity, if desired. The resulting devices are inherently asymmetric, with MnOx as the dominant positive electrode and FexOy as the negative electrode.
Appendix 3 GiiCap Ion Gel
Objective: To demonstrate the specific capacitance and electrochemical stability window (ESW) of an electrolyte formulation comprising a room-temperature molten salt 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) and fumed silica, referred to as Iongel, in conjunction with an A7 apparatus, conducted in a “low” humidity and “airless” argon atmosphere.
Experimental conditions:
All electrochemical tests were performed in a “3-electrode” setup, in which regular interdigitated A7 devices were fabricated, the area ratio of the “working” electrode to the “counter” electrode was 1:2, and a third quasi-reference electrode comprised of screen-printed AgCl ink was used to monitor the potential of each electrode during the tests.
The electrolyte Iongel was prepared and stored in an airless environment.
Before applying the electrolyte to the A7 device for testing, heat Iongel to 90°C and then distribute a thin, uniform layer onto the A7 using a doctor blade. Allow the electrolyte to cool before preparing the device for testing and connection. For airless devices, testing is performed in the same airless environment where the electrolyte was stored and distributed, with the device connected to the electrochemical testing instrument: a Biologic VMP-3 regulator.
For low humidity environments, move the device to a humidity-controlled room with a relative humidity set to 20%, and seal and connect it to the instrument.
For each humidity level, a series of maximum electrode potentials (Emax) (in volts (V)) close to the nominal literature value 1 of the net electrolyte were tested. They are:
Positive electrode: 2.0, 1.9, 1.8, 1.7, 1.6, 1.5
Negative electrode: -2.0, -1.9, -1.8, -1.7, -1.6.
For each combination of humidity and electrode potential, N=8 samples are prepared from scratch.
Electrochemical test parameters:
A standard protocol was used, with a test window of 0.0-Emax V vs OCV. OCV quantification was 0.25 V vs AgClQref.
The electrochemical testing was divided into three stages: a) Ragone characterization; b) long-term (LT) cycling; c) Ragone characterization (post-).
Ragone characterization before and after LT cycling included: OCV, 1 hour; cyclic voltammetry (CV), 5 cycles each at 100 and 1000 mV/s; galvanostatic charge-discharge (GCD), 10 cycles each at 5 and 10 mA/cm²; and potentioelectric impedance spectroscopy (PEIS), between 10 MHz and 0.01 Hz.
The LT cycle includes: CV, 5000 cycles at 750mV/s.
Electrochemical stability was determined by post-hoc visual analysis of electrode damage and electrolyte discoloration, as well as by assessment of changes in coulombic efficiency across LT cycles. Device performance was determined based on the specific capacitance via GCD after 5000 LT cycles.
in conclusion:
ESW was determined by plotting the coulombic efficiency of the LT CV cycle against the number of cycles. When the coulombic efficiency remained consistent throughout the 5000 cycles, the cycle Emax was determined to be stable under given environmental conditions. Based on this analysis, the Iongel-A7 device was found to be stable in air with a relative humidity of 20% at negative and positive electrode potentials of -1.6 and +1.6 V, respectively. In the absence of air, the positive and negative ESWs were determined to be -1.8 and +1.7 V, respectively.
Regarding performance evaluation, the specific capacitance of the device at 20% relative humidity and in an airless environment was found to be 2.11 and 1.60 mF/ cm² , respectively, under the positive electrode window conditions. The specific capacitance of the negative electrode window was 1.55 and 2.11 mF/ cm² , respectively, under 20% relative humidity and in an airless environment.
Figures 69, 70, and 71 show the relevant results.
Figures 72, 73, and 74 show other relevant results.
Appendix 4 Feasibility Proposal for 3-Month Gii-Sens Measurement
Target:
The feasibility of the project was demonstrated using reagents that are critical to the Gii-Sens 3D carbon foam analysis system.
Phase 1: Surface Fixation
Objective: To maximize mAb(2) surface immobilization. To evaluate the most convenient surface chemistry for immobilizing mAb onto a surface.
Deliverables: Data supporting maximum surface coverage and the selected procedure.
Phase 3: Target Analyzer Sensing Range and LOD
Objective: To establish the electrochemical immunoassay procedure and results. To develop the electrochemical immunoassay procedure (incubation time, concentration, volume) and to establish parameters that produce the most sensitive analytical assay.
Deliverables: Data supporting the performance of electroanalytical immunoassays.
Experimental Section
Solution composition
Surface Chemistry
10 mM pyrene butyric acid in DMF
4mM EDC/10mM SulfoNHS
PBS 0.1M pH 7.2
Read aloud
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 0.02 M KCl.
0.02M PBS
Sensor modification program
10 μL of PyrBuOOH was applied to the sensor surface and incubated in a humid chamber for 2 hours, after which the solvent was allowed to evaporate spontaneously.
15 μL EDC/NHS, for 30 min
10 μL of A1 or C1 mAb in PBS for 1 hour
Electrochemical technology
Electrochemical impedance
Applied voltage = 0V
Amplitude = 0.01VRMS
Frequency range -5000 to 0.1Hz
Measurement Procedure
Direct determination: Unmarked: See Figures 75 and 76.
Direct determination: label-free and reagent-free: see Figures 77 and 78.
Calibration curve
Repeat at each point, n=5 (minimum) different disposable sensors (single readout, sensor disposed of).
Each calibration curve contains data (inter- and intra-assay variability) obtained by different operators over the following days.
Phase 1: Surface Chemistry
According to the scheme in Figure 79, the selected surface chemistry is Pyr-COOH modified graphene and EDC/NHS conjugates that capture mAb (A1 and C1), and the figure shows a schematic diagram of the surface immobilization reaction.
The concentrations of surface-fixed mAbs (A1 and C1) were screened using electrochemical impedance spectroscopy. (See Experimental Section). See Figure 80 (mAb A1 fixation on the surface. Inset normalized signal) and Figure 81 (mAb C1 fixation on the surface. Inset normalized signal).
Both A1 and C1 showed a logical trend in surface coverage. Based on the normalized curves, A1 showed a slightly larger surface coverage. The optimal coverage range selected was between 15 and 250 μg/mL. This concentration range was estimated to be sufficient to provide optimal sensor performance.
Phase 3: Determination and Target Analyte Investigation
Further evaluation of the potential and benefits of using it as a sensing electrochemical platform has been conducted in label-free assay formats.
Simultaneously, a reagent-free formulation was also explored, where the solution used for incubation and generating the readout signal was simply a buffer solution, as described in the experimental section. The dynamic range of the assay was also investigated at high concentrations, and the potential to extend this concentration range is expected to be identified.
Due to the interesting results obtained during the investigation described above and the general time constraints, the assay sensitivity was explored down to 10 pg/mL, and the aim was to explore the high concentration range up to 1000 ng/mL.
Label-free assay investigation
Label-free assays, as previously described, include assays that do not require secondary antibodies but use specific electrochemical readout solutions. In this study, the electrochemical solution was also used as the carrier solution, thus eliminating the need for a washing step or any other assay complications.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 82, which shows the label-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
To further investigate how to enhance measurement performance, the overall concentration range was divided, and the same data were used to explore different sensitivity ranges.
Label-free and reagent-free assay investigation
As mentioned earlier, label-free assays include assays that do not require secondary antibodies. In the absence of reagents, there is also no need for an electrochemical readout solution, as all incubation and measurement are performed solely in a buffer solution, which also acts as a carrier solution, further eliminating the need for additional washing steps.
For both A1 and C1 modified sensors, the first concentration range explored was 10 ng/mL to 10 pg/mL. See Figure 83, which shows the label-free and reagent-free dose-response curves of the A1 (top) and C1 (bottom) sensors compared to different N1 antigen concentrations. For all cases, the surface coating was >60 μg/mL, and the incubation time was 6 minutes.
For the concentration range studied, both A1 and C1 showed similar responses and achieved good initial dose-response curve characteristics.
Appendix 5 Specific Implementation of Sensors with Receptors Bonded to 3D Carbon Foam Materials via Connectors
background
Sensors are analytical devices that detect changes or reactions and respond to some input from the environment. In recent years, their use has increased significantly due to their advantages such as high specificity and sensitivity, rapid and reliable results, ease of processing, and immediate diagnostics. Because of these advantages, sensors have entered various technological fields, such as chemical and medical diagnostics, environmental impact analysis, the food industry, and the marine sector.
Different forms of graphene and its derivatives have been used in the production and development of sensors, particularly biosensors. Graphene's electrochemical, physical, and chemical properties make it a material of interest for these applications. However, conventional graphene (e.g., 2D graphene) is difficult to handle in practical applications due to its ultrathin structure and flexibility, which makes it prone to curling, creases, and wrinkles. This significantly reduces the analytical performance of sensors, especially their sensitivity. To date, numerous strategies and techniques have been implemented to fabricate different types of graphene (e.g., different morphologies, different surface properties, and different functionalized derivatives, such as graphene quantum dots, graphene oxide, or reduced graphene oxide), and these have led to differences in sensing performance between sensors.
E.A.Obaje, G.Cummins, H.Schulze, S.Mahmood, M.P.Y.Desmulliez and T.T.Bachmann, Journal of Interdisciplinary Nanomedicine, 2016; 0(0), doi:10.1002/jin2.16 investigated the electrochemical properties of a newly fabricated sensor in relation to the function of its underlying composite material, and evaluated the selection of carbon and dielectric pastes by characterizing properties such as surface roughness, wettability, and susceptibility to nonspecific DNA binding.
L.H. Hess, A. Lyuleeva, B.M. Blaschke, M. Sachsenhauser, M. Seifert and J.A. Garrido, ACS Appl. Materials & Interfaces, 2014, 6, 9705-9710, describe a platform for biosensing applications based on polymer-modified CVD-grown graphene transistors.
C. Fenzl, P. Nayak, T. Hirsch, O.S. Wolfbeis, H.N. Alshareef and A.J. Baeumner, ACSSensors, 2017, 2, 616-620 describe laser-scribed graphene (LSG) electrodes as highly sensitive and reliable biosensor transducers in serum analysis.
S. Singal, A.K. Srivastava, S. Dhakate, A.M. Biradar and Rajesh, RSC Advances, 2015, 5, 74994-75003 describes an electroactive graphene-multi-walled carbon nanotube hybrid-loaded impedance immunosensor for the detection of human cardiac troponin-I.
Despite the existence of all existing technologies, there remains a need to improve the sensing activity of graphene-based sensors. Furthermore, it is still desirable to improve the sensitivity of these sensors without compromising at least one of their other aspects, such as their robustness, stability, durability, ease of functionalization, and/or ease of manufacture.
Summary of features in Appendix 5
In a first aspect, a sensor is provided comprising: (i) a carbon foam electrode, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam electrode via the connector. The carbon foam electrode is manufactured at least in part by a method defined by any one of the features A-K above.
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, comprising the following steps in sequence: (i) providing a carbon foam electrode as described in the first aspect; (ii) treating the carbon foam electrode with a connector; and (iii) treating the connector-modified carbon foam electrode obtained in step (ii) with a receptor.
In a third aspect, a method for sensing a target is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
Carbon foam materials typically possess a folded structure, which gives them a porous morphology and high specific surface area. Without being bound by any theoretical constraints, it is believed that the analytical performance of a sensor is influenced by the morphology of the carbon foam and its available surface area. The 3D structure leads to an increased usable surface area, allowing connectors and receptors (such as enzymes, proteins, nucleic acids, and antibodies) to bind efficiently to the carbon foam, thereby improving sensor performance and sensitivity.
Furthermore, it is desirable to construct the sensor using a very thick carbon foam layer. Preferably, the carbon foam layer thickness is greater than 50 μm. Since carbon foam can be porous, such a thick carbon foam layer is expected to provide a larger surface area, which is beneficial for enhancing analytical performance, especially sensing properties, compared to other conventional graphene-based sensors.
connector
In the context of the features of this invention, carbon foam is modified with a connector as part of the process for forming the desired sensor. The carbon foam described above (e.g., a thick porous carbon foam with a folded structure) provides an improved basis for modification because the increased surface area can be used for interaction with the connector, resulting in improved sensor sensitivity.
The modified carbon foam is then treated with an acceptor to obtain a sensor. Therefore, the adapter acts as an intermediate between the carbon foam and the acceptor. It is possible that at least a portion of the adapter is disposed (e.g., dispensed) within the carbon foam. It is also possible that the entire adapter is disposed (e.g., dispensed) within the carbon foam.
The connector can be selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof. Typically, the connector is selected from polymers (e.g., (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
Typically, the organic compounds described above comprise one or more functional groups independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymers, or mixtures thereof, optionally combined with linear, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. In the same embodiments, the optional structure may be a C1-C20 straight-chain, branched, or cyclic alkyl, alkenyl, alkynyl, aryl residue, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy, or mixtures thereof. Still in the same embodiments, optionally, the organic compound having the functional groups described above may also comprise one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly linked to at least one of the functional groups, or the connector is a derivative of an ester or salt of such organic compound, or a compound that releases such organic compound in a reaction with the desired 3D carbon foam. Representatively, the connector is selected from the organic compounds described above in this paragraph.
Typically, the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
The joint can be covalently or non-covalently bonded to the carbon foam. For example, a diazo compound (e.g., a diazonium salt) can be covalently bonded to the carbon foam. For non-covalent bonding, the joint can be bonded to the carbon foam through at least one of the following: π-π interactions, ionic bonding, hydrogen bonding, hydrophobic or hydrophilic effects, electrostatic interactions, polymer encapsulation, adsorption, and grafting (e.g., photografting). For example, a joint containing one or more cyclic moieties as described above (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof) can be bonded to the carbon foam through π-π interactions.
In the context of this feature, the acceptor is bonded to the carbon foam via a linker. Therefore, the acceptor is indirectly bonded. When at least a portion or preferably the entire linker is disposed (e.g., dispersed) within the carbon foam, at least a portion or the entire acceptor may also be disposed (e.g., dispersed) within the carbon foam.
In this document, "receptor" refers to any molecule capable of responding to a target material (i.e., the target) present in the sample to be analyzed. The sample can be biological, chemical, optical, physical, or mechanical, but is typically biological. Therefore, "target" encompasses, but is not limited to, biological materials, chemical substances or mixtures, optical objects, physical or mechanical articles, etc., typically biological materials. The term "response" can include, but is not limited to, biological, and/or chemical, and/or optical, and/or physical, and/or mechanical interactions, typically biological and/or chemical interactions. These typical interactions can include, but are not limited to, binding or hybridization between the receptor and the target, or hydrophobic effects.
Therefore, receptors can include, but are not limited to, one of the following: electrochemical receptors, chemical receptors, biological receptors, optical receptors, physical or mechanical receptors. Receptors can be selected from, but are not limited to, crown ethers, ligands, catalysts, boric acids, carbohydrates, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof.
Typically, the receptor is a biological receptor (i.e., the sensor is a biosensor). Receptors are typically selected from aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles, or other cellular components, or mixtures thereof. More typically, receptors are selected from proteins (e.g., immunoproteins, non-immune proteins, immunoglobulin-binding proteins, glycoproteins), nucleic acids, antibodies, enzymes (e.g., oxidoreductases (preferably glucose oxidase, alcohol oxidase, or lactate oxidase), dehydrogenases) or mixtures thereof. Representatively, receptors are selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or mixtures thereof.
Typically, the target is biological material. Biological material can include, but is not limited to, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, protein complexes, nucleic acids, antibodies, antigens, lipids, fatty acids, fatty acid esters, vitamins, microorganisms, micelles, cells, organelles, or other cellular components, viruses, enzymes, or mixtures thereof. Typically, biological material is selected from deoxyribonucleic acid (DNA), ribonucleic acid (RNA), peptides, proteins, nucleic acids, antibodies, antigens, enzymes, or mixtures thereof. More typically, biological material is selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof. It should also be understood that, in the context of this feature, both biological receptors and biological materials can be naturally occurring or synthetically produced.
Receptors can attach to linkers. Receptors can be bonded to linkers by physical, biological, and/or chemical means. Typically, receptors are chemically bonded to linkers. Hereinafter, chemical bonds can include, but are not limited to, covalent bonds, non-covalent bonds (e.g., ionic bonds), metallic bonds, hydrogen bonds, chelate bonds, and non-covalent interactions such as van der Waals forces, π-π interactions, hydrophobic or hydrophilic effects, and electrostatic interactions. Typically, receptors (e.g., biological receptors) are covalently bonded to linkers. Typically, receptors (e.g., biological receptors) are bonded (e.g., covalently) to one or more functional groups contained in the linker (e.g., functional groups of organic compounds as previously described). For example, biological receptors can be covalently bonded to the carboxyl, amino, amine, or amide group of the linker (e.g., 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide).
sensor
Sensors according to this feature typically comprise a carbon foam layer, which can be produced by a previously disclosed dual-laser processing method. Typically, the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm. Typically, at least a portion or all of the connector is disposed (e.g., dispersed) within the carbon foam. Optionally, at least a portion or all of the receptor is also disposed (e.g., dispersed) within the carbon foam (i.e., when at least a portion or preferably all of the connector is disposed (e.g., dispersed) within the carbon foam). Typically, at least a portion of the connector and optionally a portion of the receptor are disposed (e.g., dispersed) at a depth below the surface of the carbon foam (e.g., the carbon foam layer), said depth being greater than 1% of the total depth of said carbon foam, preferably greater than 5% of the total depth, more preferably greater than 10%, even more preferably greater than 15%, and even more preferably greater than 20%. Typically, at least a portion of the connector and optionally at least a portion of the acceptor are disposed (e.g., dispersed) at a depth greater than 1 μm below the surface of the carbon foam (e.g., a carbon foam layer), preferably greater than 5 μm, more preferably greater than 10 μm, even more preferably greater than 15 μm, and most preferably greater than 20 μm below the carbon foam surface. The entire connector and optionally the entire acceptor can be disposed (e.g., dispersed) at a depth greater than 1% of the total depth of the carbon foam. The thickness of the carbon foam layer can be any range described above (e.g., at least greater than 50 μm). "Dispersed" herein means that the connector (optionally, and acceptor) molecules, at least partially disposed within the carbon foam, are distributed therein to form multiple discrete domains other than a single cluster. These domains can be uniformly and/or continuously distributed (e.g., distributed as a uniform and/or continuous layer) within the carbon foam. Without being bound by any theory, it is believed that the replacement of the connector (optionally, and the acceptor) leads to the improved functionalization of the carbon foam, thereby enhancing the sensor's sensing activity (i.e., sensitivity).
Furthermore, and optionally, neither the connectors nor the acceptors are disposed (e.g., dispersed) throughout the entire depth of the carbon foam (e.g., carbon foam layers). In other words, the core of the carbon foam is not modified with connectors or acceptors.
The adapter may be selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof, and the receptor may be selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin or a mixture thereof.
The sensor may also include a substrate. In a first method of obtaining carbon foam, if a carbon source is provided on or adjacent to the substrate, the final sensor may include the substrate as a component. In a second method requiring the use of a substrate, the final sensor may also include the substrate as a component. Regardless of the method by which it is obtained, the carbon foam may optionally be adhered to the substrate within the sensor. Thus, the substrate included in the sensor may have one of the characteristics described previously for substrates used in the production of carbon foam and/or one possible combination of these characteristics. Alternatively, the sensor need not include a substrate. In other words, even if the carbon foam is produced to adhere to the substrate, it may be removed from the substrate as part of preparation for subsequent modifications.
Typically, the sensors characteristic of the present invention are chemical, physical or mechanical, biological or optical sensors, preferably biosensors (i.e., when the receptor is a biological receptor). Typically, the sensor (e.g., a biosensor) takes the form of an electrode or electrode device. The sensor (e.g., a biosensor) may include a multi-electrode platform, for example, a three-electrode platform including a counter electrode (CE), a working electrode (WE), and a reference electrode (E or RE). The electrode (e.g., WE) may be made of modified carbon foam (i.e., carbon foam modified with a receptor via a connector) characteristic of the present invention. Other electrodes (e.g., CE and/or RE) may also be carbon foam-based, preferably carbon foam-based, and more preferably based on the same carbon foam without any modification. All electrodes may have the same or different dimensions.
Sensors (e.g., biosensors) may be supplied as products, wherein the sensors are housed within packaging, and the products preferably include instructions for use. Typically, the packaging includes a primary package in which the sensor is housed. The sensor may be provided on an adapter housed within the primary package. Suitable examples of primary packaging are caps, pockets, folders, envelopes, boxes, containers, cartons, housings, etc. Optionally, the packaging may also include secondary packaging. Such secondary packaging is typically packaging that holds one or more sensors together. Suitable examples of secondary packaging are plastic cartons, cardboard boxes, blister packs, boxes (e.g., cardboard or plastic boxes), housings, containers, cardboard or plastic crates, pallets, bundles with or without one or more air bags, etc. Still optionally, the packaging may include tertiary packaging, which may be selected from boxes, housings, cartons, containers, etc. Suitably, at least one of the above-described packages may protect the sensor from light (e.g., direct sunlight), moisture, physical and/or chemical damage and contamination. The instructions may provide detailed steps for using the sensor according to its features. Instructions may be provided in printed form as labels, brochures, manuals, or leaflets. Instructions may also be printed on product packaging.
Sensor manufacturing
In a second aspect, a method for manufacturing a sensor according to the first aspect is provided, wherein the steps include: (i) providing carbon foam; (ii) treating the carbon foam with a connector; and (iii) treating the connector-modified carbon foam with a receptor.
The method may include the step of manufacturing the carbon foam before providing and processing it with a connector. Thus, the carbon foam is produced by one of the laser processing methods disclosed herein, typically the first or second method, but more typically the first method. The carbon foam thus produced may be adhered to, attached to, or provided on a substrate. Typically, the carbon foam can be removed from the substrate before processing the connector in step (ii). In other words, the carbon foam in step (i) is provided without a substrate. Alternatively, it is not necessary to remove the carbon foam (e.g., the carbon foam remains adhered to the substrate). In other words, the carbon foam in step (i) is provided with a substrate.
The carbon foam can be incubated together with the adapter. Incubation can occur in a buffer solution, preferably a buffer solution. Additionally or optionally, adapter modification may require at least one of the following conditions: light (ultraviolet, visible, or infrared radiation) or heat. After incubation, the adapter-modified carbon foam can be washed.
The adapter-modified carbon foam can be incubated with the receptor. After incubation, the sensor thus obtained can be cleaned before use. After cleaning, the sensor may be passivated. Passivation is understood as blocking any remaining activation sites that have not been functionalized by the receptor.
The receptor is used to process the connector-modified carbon foam in step (iii).
The sensor can be an electrode or an electrode device including a multi-electrode platform. Therefore, the manufacturing steps described above can be applied to the manufacture of electrodes. When the sensor is an electrode device including a multi-electrode platform, the manufacturing steps described above are applicable to the production of the working electrode (WE), and the method further includes the additional steps of producing a counter electrode (CE) and a reference electrode (E or RE).
Use of sensors
In a third aspect, a method of using a sensor is provided, comprising the following steps in sequence: (i) providing a sensor according to the first aspect; (ii) contacting the sensor with a sample containing or suspected of containing a target; (iii) measuring the response of the sensor; and (iv) optionally, correlating the response with the level of the target in the sample.
The target can be the target disclosed herein, and is usually the biological material disclosed herein. The sample can be the sample disclosed herein, and is usually the biological sample disclosed herein.
Before use, the sensor (e.g., a biosensor) can be appropriately stored under ambient conditions (e.g., room temperature of approximately 20°C and 1 atmosphere). Typically, the sensor is stored under dry conditions. After use, the sensor can be properly disposed of (i.e., the sensor is a disposable sensor).
The sensor can be immersed in a sample. The sample may contain phosphate-buffered saline (PBS). The concentration of the target in the sample may be at least 1 ppm. The equilibration time may be at least 0.5 minutes, or at least 1 minute, or at least 10 minutes, or at least 30 minutes, typically not exceeding 2 hours, or not exceeding 1 hour, or not exceeding 40 minutes. The sensor can be cleaned after contact with the sample, and then the response can be measured. The sensor can be cleaned by rinsing with PBS. The sensor can be dried after cleaning (e.g., by airflow, or by natural drying).
The response can be measured using differential pulse voltammetry and/or impedance spectroscopy. The measured response may be further correlated with the target level in the sample. The method may include steps (i), (ii), and (iii) as described above, and additionally includes the following steps in sequence: (iv) contacting the sensor with one or more samples (i.e., control samples) containing a known level of the target; (v) measuring the sensor's response to one or more control samples; (vi) comparing the response to a sample containing or suspected of containing the target with the response to one or more control samples; and (vii) correlating the response to a sample containing or suspected of containing the target with the level of the target in the sample.
Appendix 5 Concepts
1. A sensor comprising: (i) a carbon foam, (ii) a connector, and (iii) a receptor, wherein the receptor is bonded to the carbon foam via the connector.
2. The sensor according to Concept 1, wherein the carbon foam is obtained by a method of generating carbon foam at at least one location within a carbon source by concentrating infrared radiation at that location, and the infrared radiation is provided by a laser beam, wherein the laser beam is an infrared laser beam.
3. The sensor according to Concept 2, wherein the concentrated infrared radiation includes diffraction of the infrared radiation to form an interference pattern, each fringe of the interference pattern being located within the carbon source.
4. The sensor according to Concept 2 or Concept 3, wherein the at least one position is laterally moved inside the carbon source and/or the at least one position is moved within the depth of the carbon source.
5. The sensor according to any one of Concepts 2 to 4, wherein the infrared radiation directly irradiates the carbon source, or the infrared radiation passes through a substrate before irradiating the carbon source, wherein the carbon source is disposed on the surface of the substrate or adjacent to the surface of the substrate.
6. The sensor according to any one of Concepts 2 to 5, wherein the carbon source is additionally irradiated with additional radiation, and the additional radiation is performed before, simultaneously with or after the step of focusing infrared radiation at at least one location within the carbon source.
7. The sensor according to Concept 6, wherein the additional radiation is rasterized on the surface of the carbon source.
8. The sensor according to Concept 6 or Concept 7, wherein the additional radiation directly irradiates the carbon source or passes through a substrate as described in Concept 5 before irradiating the carbon source.
9. The sensor according to any one of the foregoing concepts, wherein at least a portion of the connector is disposed (preferably dispersed) within the carbon foam; and optionally, at least a portion of the receptor is disposed (preferably dispersed) within the carbon foam.
10. The sensor according to any one of Concepts 2 to 9, wherein the carbon foam layer thickness is greater than 50 μm, preferably greater than 100 μm, more preferably greater than 200 μm, and even more preferably greater than 300 μm.
11. The sensor according to Concept 1, wherein the carbon foam is obtained by providing a carbon source on or adjacent to a substrate surface and exposing at least a portion of the carbon source, comprising a carbon-containing material, and/or at least a portion of the substrate to a laser beam, thereby converting at least a portion of the carbon source into the carbon foam.
12. The sensor according to Concepts 5, 8 or 11, wherein the substrate comprises one or more of the following: silicone, silicon dioxide, gallium nitride, gallium arsenide, zinc oxide; or alternatively, one or more polymers; or alternatively, one or more metals selected from aluminum, copper, gold or other metals, or oxides, nitrides or arsenides of said metals.
13. The sensor according to any one of the foregoing concepts, wherein the carbon foam contains less than 3% oxygen, preferably less than 1.5% atomic percentage, and/or less than 3% nitrogen atomic percentage.
14. The sensor according to any one of the foregoing concepts, wherein the connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
15. The sensor according to Concept 14, wherein the connector is selected from polymers (preferably (meth)acrylate polymers); organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
16. The sensor according to Concept 15, wherein the one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, optionally in combination with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
17. The sensor according to Concept 16, wherein the organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of an ester or salt of the organic compound, or a compound that releases the organic compound in a reaction with the carbon foam.
18. The sensor according to Concept 17, wherein the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or mixtures thereof.
19. The sensor according to Concept 17 or Concept 18, wherein the connector is bonded to the carbon foam via π-π interactions.
20. The sensor according to any one of the foregoing concepts, wherein the receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
21. The sensor of claim 20, wherein the receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components, or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes, or mixtures thereof.
22. The sensor according to Concept 21, wherein the receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
23. The sensor according to any one of the foregoing concepts, wherein the receptor is bonded to the connector in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
24. A method of manufacturing a sensor according to any one of the foregoing concepts, comprising the following steps in sequence: (i) providing a carbon foam as described in any one of concepts 1 to 13, 19; (ii) treating the carbon foam with a connector as described in any one of concepts 1, 14 to 19, 23; and (iii) treating the connector-modified carbon foam obtained in step (ii) with a receptor as described in any one of concepts 1, 20 to 23.
25. A method for sensing a target, comprising the following steps in sequence: (i) providing a sensor according to any one of Concepts 1 to 23; (ii) contacting the sensor with a sample containing or suspected of containing the target; (iii) measuring the response of the sensor; and optionally (iv) correlating the response with the level of the target in the sample.
It should also be noted that the sensor described in Appendix 5 may be the Gii-Sens carbon foam sensor described earlier in this specification.
Appendix 6 Baseline Experimental Conditions
1 mM potassium ferrocyanide/potassium ferrocyanide was used in 0.1 M strontium nitrate, with at least five replicates randomly selected. Cyclic voltammetry was performed at scan rates of 25 and 200 mV/s as a comparative technique. Various characteristics were investigated and conclusions were drawn to evaluate the performance of the differential electrode materials.
Electrochemical impedance spectroscopy was performed at the equilibrium potential with an amplitude of 5 mV and a frequency range of 0.1 to 100 kHz.
Use a built-in or external silver/silver chloride reference electrode for the sensor.
Gii Sens carbon foam compared to conventional graphene electrode materials
The Gii Sens carbon foam sensor was evaluated and compared with other commercially available graphene-based sensors. See Figure 84.
The recorded reduction and oxidation peak currents show a 25% increase in efficiency per unit geometry in terms of current density. This clearly reflects the larger usable electrochemical area offered by the Gii Sens 3D carbon foam. See Figure 85.
According to cyclic voltammetry, the assessment of reduction-oxidation peak separation can be interpreted as a measure of the surface's electronic redox response to voltage scans and its ability to efficiently perform rapid redox reactions. The study showed that the reduction-oxidation peak separation remained below 70 mV, and no increase in separation was observed from 25 to 200 mV/s.
Other graphene electrode surfaces showed significant voltage separation from reduction to oxidation, indicating low efficiency of the redox Faraday reaction and pronounced detrimental effects associated with faster scan rates. See Figure 86.
The charge transfer resistance values for different surfaces show a significant improvement for the GiiSens sensor surface. This demonstrates the great potential of GiiSens for achieving reliable impedance-based measurements with minimal background signal interference.
Gii Sens compared to other carbon-based materials
Carbon-based electrode materials are very common in electroanalytical applications. Carbon paste electrodes are a common material for screen-printed sensors. They are the most widely used electrode surfaces in practical, immediate applications due to their fabrication flexibility and affordability. At the other end of the spectrum are glassy carbon surfaces, which are expected to offer better performance, but their availability is limited by fabrication flexibility and affordability. See Figure 87.
The Gii Sens carbon foam exhibits performance comparable to pure glassy carbon materials in terms of available electrochemically active area, while increasing the usable area by 50% for a carbon paste electrode of the same size. See Figure 88.
The separation of reduction-oxidation peaks obtained from cyclic voltammetry initially revealed the poor performance of the carbon paste material, which is highly dependent on slow scan rates to achieve a relatively acceptable redox reaction on its surface. The Gii Sens response outperformed pure glassy carbon even at any scan rate, demonstrating its significant potential for manufacturing flexibility and superior performance. See Figure 89.
The measurement of surface charge transfer resistance highlights the enormous potential of Gii Sens as an impedance-based sensing surface superior to glassy carbon, and opens up areas previously unreachable by carbon paste electrode materials.
Gii Sens compared to screen printing gold
Screen-printed gold sensors possess two crucial properties that enable the sensor material to be used in practical electrochemical sensing applications: flexible fabrication processes and excellent electrochemical reactivity. Two commercially available screen-printed gold samples were evaluated. See Figure 90. Gii Sens carbon foam was demonstrated to possess these properties as well, while also being affordable.
Recorded reduction and oxidation peak currents show that the available electrochemically effective region per geometric unit area has increased by at least 20%. See Figure 91.
As expected, screen-printed gold showed the most responsive electrode surface material in the evaluation batch; however, Gii-Sens matching further improved this performance, especially at fast scan rates. See Figure 92.
Comparing the charge transfer resistance of the electrode surfaces of screen-printed gold and Gii Sens also highlights the great potential of Gii carbon foam materials; in all cases, it exhibits low resistivity-related values.
The comparison between Gii Sens and screen-printed gold aims to demonstrate the superiority of Gii Sens in terms of ease of manufacture and superior performance, while affordability and scalability are undoubtedly beneficial inherent features of the Gii Sens sensor.
in conclusion
The Gii Sens sensor outperforms any other carbon-based or even graphene-based sensor on the market. It even surpasses screen-printed gold surfaces, eliminating any concerns about the overall convenience of using Gii Sens surfaces as the ultimate electrochemical sensing platform. Gii Sens demonstrates for the first time the perfect choice of fabrication and scalable materials for electroanalysis applications, while maintaining peak performance, ensuring maximum sensitivity and flexibility for high-throughput and point-of-care diagnostic applications.
Appendix 7 Optimization of surface immobilization of anti-human calcitonin (cAb)
Target:
Optimization of surface immobilization of anti-human calcitonin (cAb)
Summary of Results
Select a surface NHS production method. Match existing standard manufacturing processes.
Optimal cAb surface coverage was achieved using 100 μg/ml cAb.
For standard bare sensors, the typical %CV is 7%. For all sensors shown in the experiments presented in this report, the %CV for a 100 μg/ml cAb coating was 10%.
Using a 100 μg/ml cAb coating, 2000 pg/ml Ag was successfully detected by direct determination. The %CV of the signal output was 10%.
Experimental Section
Solution composition
Surface Chemistry
NHS modification
pyreneNHS
Capture antibody (cAb):
Product Name: Antih PCT 4004SPTN-5
Antigen (Ag):
Product Name: Recombinant PCT Antigen
Echem Readout Solution
The reaction is: 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ in 20 mM KCl.
cAb fixation solution
Anti-hPCT in 1×PBS (pH 7.2)
Antigen (Ag) detection solution
In 20 mM KCl, 1 mM K₃Fe(CN) ₆ + 1 mM K₄Fe(CN) ₆ + Ag
Electrochemical technology
Electrochemical impedance
Applied voltage: OCP
Amplitude: 0.01V RMS
Frequency range: 100000-0.1Hz
Cyclic voltammetry
Scan rate: 25mV/s
Initial potential: -0.3V
High potential: 0.6V
Low potential: -0.3V
Measurement Procedure
NHS fixed
10 mM Pyr NHS prepared in DMF.
10 μL was drop-coated onto the working electrode of each sensor.
Place the sensor in an airtight box and incubate it for 12 to 18 hours.
It was confirmed that PyrNHS/DMF had been fully evaporated from the surface.
cAb fixation procedure
Place the NHS GiiSens+ sensor on a flat surface.
10 μL of cAb was drop-coated onto the working electrode of each sensor.
Place the sensor in a sealed container and bathe it in water for 2 hours.
Remove the sensor and gently rinse off the solution with DI water, then gently dry it with a stream of N2 gas.
Measurement procedure: Direct measurement 1 - see Figure 93
1) cAb readout: Apply the electrochemical readout solution to the sensor surface, and then perform EIS measurement.
2) Solution removal: Remove the electrochemical readout solution from the sensor surface.
3) t'1 readout: Apply the electrochemical readout solution containing the antigen to the sensor surface, followed by EIS measurement. There is approximately 1 minute between solution addition and measurement.
4) Read t'2 and perform EIS measurement. There is approximately 6 minutes between adding the solution and the measurement.
5) Read t'3 and perform EIS measurement. There is approximately 11 minutes between adding the solution and the measurement.
See the appendix for the electrochemical reading procedure.
1. Characterization curve graph
Each point is sampled repeatedly, with n = 5 (minimum) different disposable sensors (single readout, sensor is disposed of).
Phase 1: Surface Chemistry
The chosen surface chemistry is NHS-modified carbon foam, followed by conjugation of cAbs via amide bond formation. See Figure 94: Schematic diagram of the surface fixation reaction.
NHS generation on the carbon foam surface was monitored using electrochemical impedance spectroscopy and cyclic voltammetry. See Figure 95: Rct and ΔEp signal responses of the electrode for NHS functionalization.
The increases in Rct and ΔEp relative to the bare electrode confirm the NHS functionalization of the carbon foam electrode.
A range of cAb concentrations between 50 and 800 μg/ml were screened using electrochemical impedance spectroscopy. See Figure 96: cAb immobilization on the electrode.
For immobilization on the NHS-modified sensor, a logical increase in Rct was observed with increasing cAb concentration. The optimal coverage on the NHS electrode was estimated to be 100 μg/ml cAb, a concentration that provided the best sensor performance without wasting material for minimal gain. Excellent reproducibility (%CV 3%) was observed at this concentration.
Phase 2: Electrochemical Signals
The generated electrochemical signals were evaluated for direct assay, meaning that secondary antibodies are not required to assist antigen detection.
An antigen concentration of 2000 pg/ml was selected for the direct assay study. Based on the results of Phase 1 of this report, the surface antibody coating was fixed at 100 μg/ml. The Ag-Ab incubation time was selected as the initial assay parameter for the study. See Figure 97: Signal response from 2000 pg/ml in the direct assay using a 100 μg/ml cAb surface coating.
The 100 μg/ml cAb again showed a good level of reproducibility (%CV 8%). The difference in mean Rct between cAbs was significant, yielding different quantifiable signal outputs (ΔRct). The ΔRct signal output also showed an acceptable level of reproducibility, with %CV ≥ 10% at each readout time. The stability of the output signal between 1, 6, and 11 m indicated no additional Ab-Ag interactions after the first measurement. The 5-minute time interval between measurements is attributed to the time length required for EIS measurements. For 2000 pg/ml Ag samples, the optimal assay incubation time is as low as 1 minute.
Table 9: Key experimental and electrochemical parameters for cAb fixation
Table 10: Key experimental and electrochemical parameters for Ag detection
Appendix 8:
Combined list of features and optional features
Appendix 8 is a combined list of features and optional features. It should be noted that each of any one or more features A-R can be combined with one or more other compatible features A-R, as well as with any one or more optional features.
Group 1: Subsurface carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
Feature D: Amorphous non-graphene materials adhered to a substrate
Group 2: Dual-laser processing
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature G: Dual Laser
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
Feature I: Electrical contacts are printed on a polyimide film, and then exposed carbon foam is produced.
Feature J: High trajectory formed in carbon foam
Feature K: Application of first and second lasers in different manufacturing facilities
Group 3: Products
Feature L1: Biosensor
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
Feature M1: Energy storage device: supercapacitor
Features M2: Details of Carbon Foam Supercapacitor
Feature M3: Carbon foam supercapacitor: common collector electrode
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
Feature M5: Carbon Foam Pseudocapacitor: Metal Oxide Variant
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
Feature N1: Electrical conductor
Feature N2: A combination of sensor and supercapacitor
Feature N3: A combination of supercapacitor and battery
Feature N4: Smart Tag
Feature N5: Combined supercapacitor and antenna
Feature N6: Combined Energy Scavenger + Supercapacitor.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
Group 4: Other Aspects
Feature P: Scalable manufacturing of carbon foam: Gii 3
Feature Q: Various other carbon foam applications
Feature R: Non-graphene carbon foam
Feature A: Carbon foam generated in the region below the surface of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating a subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the subsurface region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate a subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the subsurface region.
An apparatus comprising a laser-induced carbon foam material produced by irradiating a subsurface region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the subsurface region.
Feature B: Carbon foam generated in the encapsulation region of the carbon precursor material.
A method for manufacturing carbon foam material includes the following steps: irradiating an encapsulation region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the encapsulation region.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an encapsulation region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the encapsulation region.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulation region of a carbon precursor material, wherein parameters of the laser beam are selected to generate carbon foam in the encapsulation region.
Feature C: Carbon foam generated in regions of the carbon precursor material, wherein said regions do not have substantial gas escape channels.
A method for manufacturing carbon foam material includes the steps of: irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not generate substantial gas escape channels leading to the surface of the precursor material.
A laser-induced carbon foam material is manufactured by means of a laser beam configured to irradiate an encapsulated, subsurface region of a carbon precursor material, the parameters of which are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an encapsulated, subsurface region of a carbon precursor material, wherein parameters of a laser beam are selected to generate carbon foam in the region, and wherein the laser beam does not create substantial gas escape channels leading to the surface of the precursor material.
Feature D: Amorphous non-graphene materials adhered to a substrate
A method for manufacturing carbon foam material includes the following steps: irradiating an internal region of a carbon precursor material positioned on a substrate, wherein parameters of a laser beam are selected to generate carbon foam in the region and generate disordered amorphous non-graphene material between the carbon foam region and the substrate; wherein the disordered amorphous non-graphene material is adhered to or otherwise directly attached to the substrate.
A laser-induced carbon foam material is produced by means of a laser beam configured to irradiate an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between the graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
An apparatus comprising a laser-induced carbon foam material manufactured by irradiating an internal region of a carbon precursor material positioned on a substrate, the parameters of the laser beam being selected to generate carbon foam in the region and to generate disordered amorphous non-graphene material between a graphene region and the substrate, the disordered amorphous non-graphene material being adhered to or otherwise directly attached to the substrate.
Feature E: Carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing graphene material includes the following steps: (a) irradiating an encapsulation region or subsurface region of a carbon precursor material with a laser beam to generate carbon foam in the encapsulation region or subsurface region and generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove at least some of the disordered amorphous non-graphene material and expose at least some of the carbon foam.
A laser-induced carbon foam is made by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by: (a) irradiating an encapsulated region or subsurface region of a carbon precursor material with a laser beam to generate a carbon foam in the encapsulated region or subsurface region and to generate disordered amorphous non-graphene material above the carbon foam, and then (b) performing laser ablation or treatment to remove the disordered amorphous non-graphene material and expose at least some of the carbon foam.
Feature F: Non-graphene carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing non-graphene carbon foam, comprising the following steps:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
An apparatus comprising laser-induced carbon foam prepared by:
(a) A laser beam irradiates the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region and to generate disordered, amorphous, non-graphene material above the carbon foam, then...
(b) Perform laser ablation or treatment to remove disordered, amorphous, non-graphene material and expose at least some of the underlying carbon foam, and transform at least some of the underlying carbon foam into non-graphene carbon foam.
Feature G: Dual lasers operating in different frequency bands
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating a region of the carbon precursor material, below the surface of the material or a region below the surface of the material, with a laser beam operating in a first wavelength band to generate carbon foam in the region of encapsulation or the region below the surface, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam.
Feature H: Electrical contacts positioned within carbon foam generated by laser ablation of the carbon foam region beneath the surface.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
A laser-induced carbon foam, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam; and
(c) Attaching, printing or positioning one or more electrical contacts into carbon foam.
Feature I: Electrical contacts are printed on a polyimide film and then exposed carbon foam is produced.
A method for manufacturing carbon foam material, comprising the following steps:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
A laser-induced carbon foam material, which is made by the following:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Screen printing electrical contacts onto or into a carbon precursor material;
(b) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed sequentially (a) then (b) or (b) then (a); and
(c) Using a laser beam operating in the second band to remove or ablate the material above the carbon foam to expose at least some of the carbon foam that is connected to the electrical contacts.
Feature J: High trajectory formed in carbon foam
A method for manufacturing carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of the carbon precursor material below the surface of the material using a laser beam operating in a first wavelength band, to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Furthermore, the thickness or depth of the carbon foam is at least 50 μm.
Feature K: Application of first and second lasers in different manufacturing facilities
A method for manufacturing an apparatus, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
A laser-induced carbon foam material, which is made by the following:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is performed in one manufacturing facility, and step (b) is performed in a different manufacturing facility.
An apparatus comprising a laser-induced carbon foam material manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the encapsulation region or subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material located above the carbon foam to expose at least some of the carbon foam;
Step (a) is carried out in one manufacturing facility, and step (b) is carried out in a different facility.
Feature L1: Biosensor
A method for manufacturing a biosensor, the biosensor comprising a sensing electrode comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
A biosensor includes a sensing electrode comprising a carbon foam made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes a biosensor with sensing electrodes comprising carbon foam made at least in part by a method as defined in any one of features A-K above.
Feature L2: Utilizing screen printing technology to manufacture carbon foam biosensors in a scalable and low-cost manner.
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric material to at least partially cover the electrodes and connection traces.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam made by a method defined as any one of features A-K above, and said biosensor includes (i) a screen-printed electrical connection trace over each electrode and (ii) a screen-printed dielectric that at least partially covers the electrodes and the connection trace.
Feature L3: Adding functional groups to biosensors at different manufacturing facilities
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and said method comprising an additional step of adding functionalized groups to at least the working electrode in a different manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least partially a carbon foam manufactured at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups added to at least the working electrode at different manufacturing facilities.
Feature L4: Adding functional groups to biosensors as part of the biosensor manufacturing process.
A method for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each sensor electrode comprising at least partially a carbon foam made by a method as defined in any one of features A-K above, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, each electrode including at least a portion of a carbon foam produced at a manufacturing facility by a method defined as any one of features A-K above, and wherein the biosensor includes functionalized groups that have been added to at least the working electrode at the same manufacturing facility.
Feature L5: Biosensors manufactured using PPC: post-printing conversion
A method for manufacturing a biosensor including sensor electrodes such as a working electrode and a counter electrode, each sensor electrode comprising at least partially carbon produced by a method as defined in any one of features A-K above, and the method comprising the steps of: (a) screen printing a carbon layer on a carbon precursor substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon layer, the electrical connection trace, and the reference electrode; and then (d) producing a carbon foam sensor electrode using a method as defined in any one of features A-K above.
A biosensor includes sensor electrodes, such as a working electrode and a counter electrode, wherein the biosensor includes (a) a carbon layer screen-printed on a carbon precursor substrate; (b) screen-printed electrical connection traces and a screen-printed reference electrode; (c) a dielectric layer screen-printed over the carbon layer, the electrical connection traces, and the reference electrode; and (d) a carbon foam sensor electrode fabricated using a process as defined in any one of features A-K above.
Feature M1: Energy storage device
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature M2: Screen-printed carbon foam supercapacitor layer
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
The method includes the steps of screen printing electrical connection traces over at least a portion of each electrode and screen printing a dielectric layer to at least partially cover the electrodes and connection traces.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Includes a screen-printed electrical connection trace formed above at least a portion of each electrode and a screen-printed dielectric layer that at least partially covers the electrode and the connection trace.
Feature M3: Carbon foam supercapacitor: common collector electrode
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least part of a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
The method includes the step of screen printing electrical connection traces over at least a portion of each electrode, wherein a single electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
An energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrodes comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above and arranged in an interdigitated pattern;
Furthermore, screen-printed electrical connection traces are formed above at least a portion of each electrode, and each electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
Feature M4: Carbon Foam Supercapacitor: PPC Manufacturing Process
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by means of a method as defined in any one of features A-K above.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) a screen-printed electrical connector on a substrate; (b) a screen-printed carbon layer above the current collector; (c) a screen-printed dielectric over at least some of the carbon layer; and then (d) a carbon foam energy storage electrode produced at least in part by a method as defined in any one of features A-K above.
Feature M5: Carbon Foam Supercapacitor: Metal Oxide Variant
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of electrochemically depositing a pseudocapacitive material, such as a metal oxide, onto the energy storage electrode.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) a pseudocapacitive material, such as a metal oxide, applied to said energy storage electrode.
Feature M6: Carbon Foam Supercapacitor: Uses ionogel in low humidity environments
A method for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
The method includes the step of applying an ion gel electrolyte in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
An energy storage device, such as a supercapacitor or a pseudocapacitor;
It includes (a) an energy storage electrode comprising a carbon foam material, said carbon foam material being made at least in part by a method as defined in any one of features A-K above; and (b) an ion-gel electrolyte having been applied in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in said environment are measured and controlled to optimize the capacitance of said energy storage device.
Feature N1: Electrical conductor
A method for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part a carbon foam made by a method as defined in any one of features A-K above.
An electrical conductor comprising at least in part a carbon foam made by a method as defined in any one of features A-K above.
Feature N2: A combination of sensor and supercapacitor
A method for manufacturing an apparatus comprising both a sensor and an energy storage device such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A sensor device, such as a biosensor, includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
A point-of-care diagnostic device includes (a) a sensing electrode comprising a carbon foam material made at least in part by a method as defined in any one of features A-K above, and (b) an energy storage device, such as a supercapacitor, wherein the energy storage device comprises a carbon foam material made at least in part by a method as defined in any one of features A-K above.
Feature N3: A combination of supercapacitor and battery
A method for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N4: Smart Tag
A method for manufacturing a smart tag includes the steps of combining or integrating a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as described in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
A smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above;
Furthermore, smart tags include battery-powered electronics, sensor electronics, and data transmitters powered by supercapacitors.
Feature N5: Combined supercapacitor and antenna
A method for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
An integrated device includes an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature N6: Combined energy harvester + supercapacitor.
A method of manufacturing an integrated device includes the step of combining or integrating an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and comprises at least in part a carbon foam material made by a method as defined in any one of features A-K above.
A data recording device includes an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and includes at least in part a carbon foam material made by a method as defined in any one of features A-K above.
Feature O1: 3D carbon foam structure: Gii-Thru for Gii-Cap
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above.
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
An energy storage device, such as a supercapacitor, includes:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
Features O2: 3D carbon foam structure: Gii-Thru stackable Gii-Cap/Gii-Cap+
A method for manufacturing an energy storage device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a current collector layer over the screen-printed conductive paste or ink layer;
(iv) Screen printing a dielectric layer over the current collector layer;
(v) The energy storage electrode comprising carbon foam material is prepared from the carbon precursor membrane by at least part of the method defined by any one of the features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
An energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
Features O3: 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC
A microfluidic diagnostic device includes a sample orifice positioned on the upper surface of the device, a reference electrode, a working electrode, and a counter electrode formed at least partially in a layer below the sample orifice by means of a carbon precursor film formed by any one of the features A-K above, and a reference electrode connector, a working electrode connector, and a counter electrode connector in the layer below the reference electrode, the working electrode, and the counter electrode.
Features O4 3D carbon foam structure: Gii-Thru for Gii-Sens: HISLOC manufacturing process
A method for manufacturing a lab-on-a-chip device includes the following steps:
(i) Provide carbon precursor membranes;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film.
(iii) Screen printing a conductive layer over the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) Screen printing a dielectric layer above the current collector layer;
(vi) The sensor electrode comprising carbon foam material is prepared from the carbon precursor film by at least part of the method defined in any one of features A-K above;
Furthermore, a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
A lab-on-a-chip device includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising at least in part a carbon foam material made from a carbon precursor film by a method as defined in any one of features A-K above, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
Feature P: Scalable manufacturing of carbon foam: Gii 3
A method for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the features A-K above.
Feature Q: Various other carbon foam applications
An apparatus comprising at least a portion of a carbon foam material produced by a method as defined in any one of features A-K above, wherein the apparatus is one of the following types of apparatuses:
Hall effect sensor: Carbon foam exhibits a response to a magnetic field.
For example, tactile sensors for robots; prototype sensors that use polydimethylsiloxane (PDMS) embedded in and above Gii carbon foam as an active layer in a piezoresistive pressure sensor for robotic touch sensing applications.
Sensors for infectious diseases.
A biosensor in which Gii carbon foam is π-π non-covalently functionalized with pyrene carboxylic acid (PCA) for interleukin-10 impedance detection.
Continuous monitoring of chemical sensors.
Glucose monitoring sensor: A reversible polymer displacement sensor mechanism for electrochemical glucose monitoring; a pyrene-derived boric acid chemical acceptor for glucose is adsorbed onto a carbon foam electrode, competing for binding with polynordihydroguaiaric acid.
Lactic acid sensor: Employs synthetic organic acceptor molecules based on attaching boric acid to carbon foam to provide functionality and selectivity in competitive analyte binding, using surface redox polymer indicator displacement.
Gas detection sensors, such as those for hydrogen peroxide and oxygen detection, utilize Gii carbon foam immersed in a phosphate buffer solution at pH 7 and a self-contained microporous nanoparticle polymer (PIM-1).
Optical detector.
Self-charging hybrid energy generator.
Green gases are transformed into useful chemical substances.
Fuel cells, such as hydrogen fuel cells.
Filters, including breathable filters.
Heating device.
Feature R: Non-graphene carbon material foam
A carbon foam material, which is made at least in part by a method as defined in any one of the features A-K above, and which is hydrophilic with a contact angle of less than 20°.
A carbon foam material, which is at least partially made by means of any one of the characteristics A-K above, and whose Raman spectrum exhibits a significant D peak; the 2D peak is smaller than the G peak; and the ratio of the D peak to the G peak is greater than zero.
A carbon nanotube onion material, which is at least partially made by a method as defined in any one of features A-K above.
An apparatus comprising at least partially a carbon foam material produced by a method as defined in any one of features A-K above, wherein the carbon foam material is hydrophilic and has a contact angle of less than 20°.
An apparatus comprising a carbon foam material produced at least in part by a method as defined in any one of features A-K above, wherein the Raman spectrum of the carbon foam material exhibits a prominent D peak; a 2D peak smaller than the G peak; and a D peak:G peak ratio greater than zero.
An apparatus comprising a carbon nanoparticle onion material, which is at least partially produced by a method as defined in any one of features A-K above.
Optional features
It should be noted that each of the following optional features can be combined with one or more other compatible optional features and with any one or more of the main features A-R.
Manufacturing process
The manufacturing process is a room temperature process.
The manufacturing process is an atmospheric pressure process.
It can be done on a plastic substrate (compatible with any manufacturing process, not just silicon chip manufacturing).
It can be done without a catalyst.
The manufacturing process requires approximately 2 minutes or less to create a 1 cm² carbon foam, which is about 50 μm thick, on a plastic substrate.
The manufacturing process enables the formation of 3D carbon foam on a flexible substrate.
The manufacturing process does not require graphene or graphene oxide precursors.
The manufacturing process generates carbon foam material only in the encapsulation and subsurface region of the carbon precursor material, and does not generate carbon foam material on any surface of the carbon precursor material.
The manufacturing process utilizes a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
The manufacturing process described herein is suitable for high-speed, high-volume roll-to-roll or roll-to-sheet production.
First laser beam parameters and control scheme
The first laser beam and the second laser beam are generated by different laser systems.
The first laser beam and the second laser beam are generated by the same laser system.
The parameters of the laser beam irradiating the subsurface region or packaged region include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the subsurface region or packaged region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
• The laser beam generates temperatures above 500°C in the subsurface region or encapsulation region to form carbon foam.
• The laser beam generates temperatures exceeding 500°C in the subsurface region or encapsulated region to form carbon foam.
• The pulse duration of the laser beam is between 1 ns and 10 μs, resulting in a heating rate between approximately 5 × 10 7 ℃/s and 2 × 10 12 ℃/s.
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The laser pulse frequency is between 50kHz and 500kHz.
• The laser pulse frequency is between 1 kHz and 2 MHz.
• The laser wavelength is between 0.7μm and 2.5μm.
• The laser is scanned at a speed between 9 cm/s and 40 cm/s (or ±50% of these ranges).
The parameters of the laser beam include the focal point parameters.
The parameters of the laser beam include diffraction parameters.
The parameters of the laser beam include the interference pattern parameters.
• The focal point of the laser beam moves through the depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region.
• The focal point of the laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The focal point of the laser beam is moved through a depth of at least 100 μm through the carbon precursor material to generate carbon foam in the subsurface region or encapsulation region of the carbon precursor.
• The laser beam scans (e.g., raster scanning) or moves laterally on the carbon precursor material to form the desired pattern.
• A laser beam scans or moves laterally across a carbon precursor material to form a desired pattern that includes non-overlapping areas or lines.
• A laser beam is repeatedly scanned (e.g., raster scan) or moved laterally on a carbon precursor material, with its focal point or maximum intensity arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
• The laser beam scans at a rate between 1.7 mm/s and 3550 m/s, or more typically between 35 mm/s and 350 mm/s, and the scan can achieve a pulses per inch (PPI) between 100 and 10000 (related to the production of individual polyimide sheets approximately 220 mm × 180 mm in size).
• The wavelength of the laser beam is not absorbed by the carbon precursor material, or the absorption rate is extremely low.
• Carbon precursor materials have extremely low absorption rates for the wavelengths of laser beams.
The radiation absorptivity per centimeter (decimal) is less than 50, or less than 20, or less than 10.
The laser beam is an IR laser.
The laser beam is an IR laser with a wavelength between 0.7μm and 2.5μm.
The laser beam is an IR laser with a wavelength between 0.75μm and 1.40μm.
Properties of the subsurface region or packaged region
The desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
• The subsurface region or encapsulation region is at least 10 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 20 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 30 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 40 μm below the surface of the carbon precursor material.
• The subsurface region or encapsulation region is at least 50 μm below the surface of the carbon precursor material.
Unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed approximately 50 μm.
• The thickness of the subsurface region or encapsulation region is between 10 μm and 200 μm.
• The subsurface region or encapsulation region can be positioned at different depths below the surface of the carbon precursor material, oriented towards the incident laser; and the exact depth of the subsurface region or encapsulation region is a function of various factors, such as laser intensity or other laser parameters, and the selection of the carbon precursor material used. For example, the subsurface region or encapsulation region can be at least about 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, or more below the surface of the carbon precursor material.
• The distance between the subsurface region or encapsulation region and the surface of the carbon precursor material is at least 1% of the total thickness of the carbon precursor material, or at least 10% of the total thickness of the carbon precursor material, or at least 20% of the total thickness of the carbon precursor material, or at least 30% of the total thickness of the carbon precursor material, or at least 40% of the total thickness of the carbon precursor material.
• The subsurface region or encapsulation region is a space of a certain volume centered on the center of the minimum cross-section of the first laser beam, and the volume is within 500 micrometers, 100 micrometers, or 1 micrometer of the center.
carbon precursor materials
Carbon precursor materials are basically made of thermosetting materials.
Carbon precursor materials are primarily made of non-thermoplastic materials.
• The carbon precursor material is a thermosetting film.
Thermosetting film is a polyimide film.
The carbon precursor is a polyimide film.
The carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
• The carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
• The carbon precursor is a membrane or sheet.
• Carbon precursor materials are flexible.
• Carbon precursor materials are printed layers, such as screen-printed layers.
• The thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
• The carbon precursor material is substantially planar or flat and is perpendicular to the orientation of the first laser beam.
• The carbon precursor material is homogeneous.
• Carbon precursor materials are heterogeneous and contain several different materials.
• The carbon precursor is supported on a substrate, which is not made of the carbon precursor.
• Carbon precursor materials have a low absorption coefficient at the wavelength of the first laser beam.
• The carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
• The absorption coefficient of the carbon precursor material to the second or ablation laser beam is less than 300 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second or ablation laser beam is 300 ± 50 cm⁻¹.
• The thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
• The thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
• A carbon precursor material is mounted on a substrate that is substantially optically transparent at one or more wavelengths of the laser beam.
• The carbon source of the carbon precursor material comprises or is formed from one or more polymers.
• Carbon precursor materials include one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde.
The carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also known as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
The carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); and heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
• Carbon precursors contain materials containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonded bonds (e.g., imide bonds).
Substrate supporting carbon precursor materials
• The substrate is a plastic body, film, or foil.
• The substrate is flexible.
The substrate is a polyimide circuit board.
• The substrate has an extremely low absorption rate of the first laser beam.
• The substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam.
• The substrate has a high absorption rate of the first laser beam, absorbing more than 60% of the first laser beam, and its thermal conductivity is at least 10 W/mK.
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam, and the disordered, amorphous, non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
• The substrate is formed of one or more of the following: silicon (Si), silicon dioxide (SiO 2 ), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
The substrate is a silicon wafer.
The substrate is a silicon dioxide wafer.
The substrate is a wafer containing both silicon and silicon dioxide.
• The substrate is a carbon source.
• The substrate is not a carbon source; for example, it is a metal, a dielectric material, or a screen-printed dielectric material.
• The carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
• The carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
Carbonization at the surface where the laser beam is incident
• The surface of the carbon precursor material is transformed into disordered, amorphous, non-graphene material by a laser beam.
• The thickness of the disordered, amorphous, non-graphene material occupying the surface of the adjacent carbon precursor material is approximately 1%, less than 1%, less than 5%, or less than 10% of the total thickness of the carbon precursor material.
• The disordered, amorphous, non-graphene material extends from its surface into the carbon precursor material matrix by at least 10 μm.
• The disordered, amorphous, non-graphene material extends from its outer surface into the body of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
Carbonization at the physical interface with the substrate supporting the carbon precursor material
• The carbon precursor material is transformed into a disordered, amorphous, non-graphene material at the physical interface with the substrate by the laser beam to a depth defined by the parameters of the laser beam.
The disordered, amorphous, non-graphene material adheres or otherwise attaches to one region of the carbon foam and to another region of the substrate, thus providing stability to the carbon foam.
• The thickness occupied by the disordered amorphous non-graphene material, as measured from the interface between the carbon precursor material and the substrate, is about 1%, less than about 1%, less than about 5%, or less than about 10% of the total thickness of the carbon precursor material.
• The thickness of the disordered, amorphous, non-graphene material occupying the interface between the carbon precursor material and the substrate is at least 10 μm.
• The disordered, amorphous, non-graphene material extends from the interface between the carbon precursor material and the substrate to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
ablation laser beam or second laser beam
The parameters of the laser beam include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the region below the surface or in the encapsulation region.
• Changing the laser parameters alters the properties of carbon foam materials, enabling the production of carbon foams with properties optimized for different applications.
• Changing laser parameters can alter one or more of the following properties or parameters of carbon foam materials: the type of carbon nanostructure present (e.g., carbon nano-onion), defect size, defect distribution, defect degree, defect type, Raman D and 2D peaks, relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
The laser beam (“second laser beam”) that ablates the amorphous non-graphene material formed above the encapsulated region or subsurface region in the carbon precursor is a CO2 laser.
• A second laser beam alters the carbon foam as part of the process that exposes it.
• A second laser beam alters the shape of the carbon foam as part of the process that exposes it.
• The second laser beam is automatically controlled to scan in the same area, and/or overlapping area, and/or non-overlapping area.
The wavelength of the laser beam used to ablate amorphous non-graphene materials is between 8 μm and 15 μm.
• The second laser beam is a long IR laser, a UV laser, or a visible light laser.
The pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
• The carbon precursor material has an absorption coefficient for the second laser beam greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam greater than 200 cm⁻¹ .
The absorption coefficient of the carbon precursor material for the second laser beam is 300± 50cm⁻¹ .
• The laser power is typically in the range of 8-20 watts, with 12W being optimal.
• The typical working range of laser focal length is 50mm-400mm.
• The second laser beam scans in a pattern (e.g., a grating) that includes non-overlapping areas or lines.
• The second laser beam scans with a pattern that matches the scanning pattern of the first laser beam.
The second laser beam is defocused.
• The second laser beam is the same as the laser beam that irradiates the encapsulation area or subsurface area of the carbon precursor material to generate carbon foam in the encapsulation area or subsurface area.
The manufacturing process is a three-stage process involving the following steps: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing the laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam
• The carbon foam is a multi-layered twisted or disordered carbon foam.
• The carbon foam is non-graphene carbon foam.
• Carbon foam includes carbon nanostructures such as carbon nano-onions, carbon nano-horns, carbon nanotubes, carbon nanodots, nanodiamonds and fullerenes, or any combination thereof.
• The thickness of the carbon foam is at least about 50 μm.
• The thickness of the carbon foam is between approximately 50 μm and 300 μm.
• Carbon foam is or includes multi-layered twisted or disordered multi-layered foam.
• Carbon foam is or includes carbon foam with a spatial distribution of defects that lead to high electrochemical reactivity.
• Carbon foam is or includes carbon foam with basal surface defects at vacant sites that lead to high electrochemical reactivity.
• The carbon:oxygen ratio of carbon foam is between 25:1 and 50:1.
Carbon foam has a fast electron transfer constant.
Compared to conventional graphene foams produced using conventional laser processes, carbon foams possess one or more of the following properties: easier control over thickness or depth; greater flexibility compared to the highly brittle graphene produced using conventional laser processes; stronger adhesion to underlying flexible substrates; higher porosity; higher electrical conductivity; increased capacitance or charge storage; faster absorption of organic solvents and water-based solutions; higher hydrophilicity; contact angle less than approximately 20°; enhanced antifouling properties; higher EMI shielding; and improved electrode quality.
Biosensor Use Cases
• Carbon foam has been functionalized as a biosensor.
• Carbon foams are functionalized into biosensors by adding receptors that are specific to the target or analyte.
• Carbon foam has been functionalized into a biosensor with a reversible polymer displacement sensor mechanism for use in
Electrochemical glucose monitoring.
The reversible polymer displacement sensor includes a pyrene-derived boric acid chemical acceptor for glucose adsorbed onto an electrode comprising the carbon foam.
Carbon foams are functionalized as biosensors by adding receptors that are specific to a target or analyte and connectors that enable the receptors to attach to the carbon foam.
The connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
The connector is selected from polymers (preferably (meth)acrylate polymers), organic compounds containing one or more functional groups, carbodiimides, diazo compounds, or mixtures thereof.
• The one or more functional groups are independently selected from oxygen, nitrogen, sulfur, halides, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, and optionally combined with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residues, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
The organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of the organic compound as an ester or salt, or a compound that releases the organic compound in a reaction with the carbon foam.
• The connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide or a mixture thereof.
The joint is bonded to the carbon foam via π-π interactions.
The receptor is one of the following: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
The receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes or mixtures thereof.
• The receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
The receptor is bonded to the adapter in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
Supercapacitor Use Cases
The carbon foam forms electrodes in an energy storage device, such as an electrochemical capacitor, supercapacitor, pseudocapacitor, or capacitor.
The carbon foam is treated with a metal oxide film to provide pseudocapacitance.
The carbon foam forms at least one electrode in the energy storage device, such as an electrochemical energy storage device.
A capacitor, supercapacitor, pseudocapacitor, or capacitor, and a hydrogel electrolyte encapsulates the electrode or each electrode in the active region to produce an enhanced operating voltage window.
The carbon foam forms the electrodes in the battery.
The carbon foam forms an electrical conductor.
Claims (186)
1. A method for manufacturing a carbon foam material, comprising the following steps:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a first laser beam to generate a carbon foam in the subsurface region and generate disordered, amorphous, non-graphene material above the carbon foam, then
(b) Using a second laser beam to remove or ablate the disordered, amorphous, non-graphene material located above the carbon foam to expose at least some of the carbon foam.
First laser beam parameters and control scheme
2. The method of claim 1, wherein the first laser beam operates in a first wavelength band and the second laser beam operates in a second wavelength band.
3. The method as described in any of the preceding claims, wherein the first laser beam and the second laser beam are generated by different laser systems.
4. The method as described in any of the preceding claims, wherein the first laser beam and the second laser beam are generated by the same laser system.
5. The method of any of the preceding claims, wherein the parameters of the first laser beam irradiating the subsurface region or encapsulation region include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the subsurface region or encapsulation region.
6. The method as claimed in any of the preceding claims, wherein changing the laser parameters of the first laser beam alters the properties of the carbon foam material, thereby enabling the production of carbon foam with properties optimized for different applications.
7. The method as described in any of the preceding claims, wherein changing the laser parameters of the first laser beam alters one or more of the following carbon foam material properties or parameters: the type of carbon nanostructures present, the size of defects, the distribution of defects, the degree of defects, the type of defects, Raman D and 2D peaks, the relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
8. The method as described in any of the preceding claims, wherein no substantial gas escape channel is generated by the first laser beam leading to the surface of the precursor material.
9. The method of any of the preceding claims, wherein the first laser beam generates a temperature above 500°C in the subsurface region or encapsulation region to form carbon foam.
10. The method as claimed in any of the preceding claims, wherein the pulse duration of the first laser beam is between 1 ns and 10 μs, thereby providing a heating rate between approximately 5 × 10⁷ °C/s and 2 × 10¹² °C/s.
11. The method as claimed in any of the preceding claims, wherein the power of the first laser beam is in a typical operating range of 8 watts to 20 watts, preferably 12W.
12. The method as claimed in any of the preceding claims, wherein the focal length of the first laser beam is in a typical operating range of 50 mm to 400 mm.
13. The method of any of the preceding claims, wherein the pulse frequency of the first laser beam is between 50 kHz and 500 kHz.
14. The method of any of the preceding claims, wherein the pulse frequency of the first laser beam is between 1 kHz and 2 MHz.
15. The method of any of the preceding claims, wherein the wavelength of the first laser beam is between 0.7 μm and 2.5 μm.
16. The method of any of the preceding claims, wherein the first laser is scanned in a range between 9 cm/s and 40 cm/s or ±50% of these ranges.
17. The method of any of the preceding claims, wherein the parameters of the first laser beam include focus parameters.
18. The method of any of the preceding claims, wherein the parameters of the first laser beam include diffraction parameters.
19. The method as claimed in any of the preceding claims, wherein the parameters of the first laser beam include interference pattern parameters.
20. The method of any of the preceding claims, wherein the focus of the first laser beam is moved through a depth of the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region.
21. The method of any of the preceding claims, wherein the focal point of the first laser beam is moved through a depth of at least about 50 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region.
22. The method of any of the preceding claims, wherein the focal point of the first laser beam is moved through a depth of at least 100 μm through the carbon precursor material to generate carbon foam in the region below the surface of the carbon precursor or in the encapsulation region.
23. The method of any of the preceding claims, wherein the first laser beam scans, for example, raster scans, or moves laterally on the carbon precursor material to form a desired pattern.
24. The method of any of the preceding claims, wherein the first laser beam scans or moves laterally on the carbon precursor material to form a desired pattern including non-overlapping regions or lines.
25. The method of any of the preceding claims, wherein the first laser beam is repeatedly scanned (e.g., raster scanned) or moved laterally on the carbon precursor material, wherein the focal point or maximum intensity is arranged at multiple different depths within the carbon precursor material until a carbon foam with the desired pattern and depth is produced.
26. The method of any of the preceding claims, wherein the first laser beam is scanned at a scan rate between 1.7 mm/s and 3550 m/s or more typically between 35 mm/s and 350 mm/s, and the scan can result in a pulses per inch (PPI) between 100 and 10000 (in relation to the production of individual polyimide sheets approximately 220 mm × 180 mm in size).
27. The method of any of the preceding claims, wherein the first laser beam has a wavelength that is substantially not absorbed by the carbon precursor material or is absorbed by the carbon precursor material at a very low absorption rate.
28. The method of any of the preceding claims, wherein the first laser beam has a wavelength that is absorbed by the carbon precursor material at an extremely low absorptivity.
29. The method of any of the preceding claims, wherein the radiation absorptivity per centimeter (decimal) of the carbon precursor material is less than 50, less than 20, or less than 10.
30. The method as claimed in any of the preceding claims, wherein the first laser beam is an IR laser.
31. The method of any of the preceding claims, wherein the first laser beam is an IR laser having a wavelength between 0.7 μm and 2.5 μm.
32. The method of any of the preceding claims, wherein the first laser beam is an IR laser having a wavelength between 0.75 μm and 1.40 μm.
Properties of the subsurface region or packaged region
33. The method of any of the preceding claims, wherein the desired depth of the subsurface region or encapsulation region in the carbon precursor material is achieved by moving the focus of the first laser beam through the depth.
34. The method of any of the preceding claims, wherein the subsurface region or encapsulation region is at least 10 μm below the surface of the carbon precursor material.
35. The method of any of the preceding claims, wherein the subsurface region or encapsulation region is at least 20 μm below the surface of the carbon precursor material.
36. The method of any of the preceding claims, wherein the subsurface region or encapsulation region is at least 30 μm below the surface of the carbon precursor material.
37. The method of any of the preceding claims, wherein the subsurface region or encapsulation region is at least 40 μm below the surface of the carbon precursor material.
38. The method of any of the preceding claims, wherein the subsurface region or encapsulation region is at least 50 μm below the surface of the carbon precursor material.
39. The method as described in any of the preceding claims, wherein, unlike conventional graphene foam, the thickness of the subsurface region or encapsulated region can exceed about 50 μm.
40. The method of any of the preceding claims, wherein the subsurface region or encapsulation region has a thickness between 10 μm and 200 μm.
41. The method of any of the preceding claims, wherein the subsurface region or encapsulation region is oriented toward different depths below the surface of the carbon precursor material where the incident laser is located; and the exact depth of the subsurface region or encapsulation region is a function of various factors such as laser intensity or other laser parameters and the selection of the carbon precursor material used.
42. The method of any of the preceding claims, wherein the distance between the subsurface region or encapsulation region and the surface of the carbon precursor material is at least 1% of the total thickness of the carbon precursor material, or at least 10% of the total thickness of the carbon precursor material, or at least 20% of the total thickness of the carbon precursor material, or at least 30% of the total thickness of the carbon precursor material, or at least 40% of the total thickness of the carbon precursor material.
43. The method of any of the preceding claims, wherein the subsurface region or encapsulation region is a space of a certain volume centered on the center of the minimum cross-section of the first laser beam, and the volume is within 500 micrometers of the center, or within 100 micrometers of the center, or within 1 micrometer of the center.
carbon precursor materials
44. The method of any of the preceding claims, wherein the carbon precursor material is made substantially of a thermosetting material.
45. The method of any of the preceding claims, wherein the carbon precursor material is made substantially of a non-thermoplastic material.
46. The method of any of the preceding claims, wherein the carbon precursor material is a thermosetting film.
47. The method of any of the preceding claims, wherein the thermosetting film is a polyimide film.
48. The method of any of the preceding claims, wherein the carbon precursor is a polyimide film.
49. The method of any of the preceding claims, wherein the carbon precursor is a polyimide film, and the wavelength of the first laser is in the range of 0.7 μm to 2.5 μm.
50. The method of any of the preceding claims, wherein the carbon precursor is at least 50% by mass of carbon, or at least 75% by mass of carbon, or at least 90% by mass of carbon.
51. The method of any of the preceding claims, wherein the carbon precursor is a film or sheet.
52. The method as described in any of the preceding claims, wherein the carbon precursor material is flexible.
53. The method of any of the preceding claims, wherein the carbon precursor material is a printed layer, such as a screen-printed layer.
54. The method of any of the preceding claims, wherein the thickness of the carbon precursor material is greater than 5 μm, or between 5 μm and 120 μm, or greater than 120 μm.
55. The method of any of the preceding claims, wherein the carbon precursor material is substantially planar or flat and oriented perpendicular to the first laser beam.
56. The method of any of the preceding claims, wherein the carbon precursor material is homogeneous.
57. The method of any of the preceding claims, wherein the carbon precursor material is heterogeneous and comprises several different materials.
58. The method of any of the preceding claims, wherein the carbon precursor is supported on a substrate, the substrate being not made of the carbon precursor.
59. The method of any of the preceding claims, wherein the carbon precursor material has a low absorption coefficient at the wavelength of the first laser beam.
60. The method of any of the preceding claims, wherein the carbon precursor material has an absorption coefficient for the first laser beam of less than 50 cm⁻¹ , or less than 20 cm⁻¹ , or less than 10 cm⁻¹ .
61. The method of any of the preceding claims, wherein the carbon precursor material has an absorption coefficient of less than 300 cm⁻¹ for the second or ablation laser beam.
62. The method as described in any of the preceding claims, wherein the carbon precursor material has an absorption coefficient of 300 ± 50 cm⁻¹ for the second or ablation laser beam.
63. The method of any of the preceding claims, wherein the thermal conductivity of the carbon precursor material is less than 1.0 W/mK (using the method according to ASTM D5470).
64. The method of any of the preceding claims, wherein the thermal conductivity of the carbon precursor material is less than 0.5 W/mK (using the method according to ASTM D5470).
65. The method of any of the preceding claims, wherein the carbon precursor material is mounted on a substrate, the substrate being substantially optically transparent at one or more wavelengths of the laser beam.
66. The method of any of the preceding claims, wherein the carbon source of the carbon precursor material comprises or is formed from one or more polymers.
67. The method of any of the preceding claims, wherein the carbon precursor material comprises one or more of the following materials: polyimides (e.g., poly(4,4'-oxophenylene-pyromellitic acid diamine), also known as polyimide), polyetherimides (PEI), poly(methyl methacrylate) (PMMA) (e.g., sprayed PMMA), polyurethanes (PU), polyesters, vinyl polymers, carbonized polymers, photoresist polymers, alkyd resins, and urea-formaldehyde resins.
68. The method of any of the preceding claims, wherein the carbon precursor comprises one or more of the following materials: poly(amic acid) (e.g., aryl-containing poly(amic acid)) (e.g., poly(pyromellitic dianhydride-co-4,4'-oxodiphenylamine), amic acid, also referred to as polyamic acid); dianhydrides (e.g., aryl dianhydrides) (e.g., pyromellitic dianhydride); derivatives of said poly(amic acid); derivatives of said dianhydrides (e.g., derivatives of pyromellitic dianhydride).
69. The method of any of the preceding claims, wherein the carbon precursor comprises one or more of the following materials: aromatic materials (e.g., aromatic polymers); heteroaromatic materials (e.g., heteroaromatic polymers); polymers containing aromatic moieties; cyclic materials (e.g., polymers containing cyclic moieties); heterocyclic materials (e.g., polymers containing heterocyclic moieties); heteroaromatic materials (e.g., polymers containing heteroaromatic moieties).
70. The method of any of the preceding claims, wherein the carbon precursor comprises a material containing one or more of aromatic bonds, heteroaromatic bonds, or heterobonds (e.g., imide bonds).
Substrate supporting carbon precursor materials
71. The method of any of the preceding claims, wherein the carbon precursor is positioned on or adjacent to the substrate.
72. The method of any of the preceding claims, wherein the carbon precursor is positioned "above" the substrate (e.g., the carbon precursor is positioned closer to the laser source than the substrate).
73. The method of any of the preceding claims, wherein the carbon precursor is positioned "below" the substrate (e.g., the carbon precursor is positioned further away from the laser source than the substrate).
74. The method of any of the preceding claims, wherein the substrate is a plastic body, film, or foil.
75. The method of any of the preceding claims, wherein the substrate is flexible.
76. The method of any of the preceding claims, wherein the substrate is a polyimide circuit board.
77. The method of any of the preceding claims, wherein the substrate has an extremely low absorption rate to the first laser beam.
78. The method of any of the preceding claims, wherein the substrate is substantially optically transparent at one or more wavelengths of the first laser beam.
79. The method of any of the preceding claims, wherein the substrate has a high absorptivity to the first laser beam, absorbing more than 60% of the first laser beam.
80. The method of any of the preceding claims, wherein the substrate has a high absorptivity to the first laser beam, absorbs more than 60% of the first laser beam, and has a thermal conductivity of at least 10 W/mK.
81. The method of any of the preceding claims, wherein the surface of the carbon precursor material is transformed into a disordered amorphous non-graphene material by the laser beam, and the disordered amorphous non-graphene material adheres or bonds to the substrate, thereby indirectly attaching the 3D carbon material foam to the substrate.
82. The method of any of the preceding claims, wherein the substrate is formed of one or more of the following: silicon (Si), silicon dioxide ( SiO2 ), gallium nitride (GaN), gallium arsenide (GaAs), and zinc oxide (ZnO).
83. The method of any of the preceding claims, wherein the substrate is a silicon wafer.
84. The method of any of the preceding claims, wherein the substrate is a silicon dioxide wafer.
85. The method of any of the preceding claims, wherein the substrate is a wafer comprising both silicon and silicon dioxide.
86. The method of any of the preceding claims, wherein the substrate is a carbon source.
87. The method of any of the preceding claims, wherein the substrate is not a carbon source, for example, a metal, a dielectric material, or a screen-printed dielectric material.
Carbonization at the surface where the laser beam is incident
88. The method of any of the preceding claims, wherein the surface of the carbon precursor material is transformed into a disordered, amorphous, non-graphene material by the first laser beam.
89. The method of any of the preceding claims, wherein the disordered amorphous non-graphene material occupies about 1%, or less than about 1%, or less than about 5%, or less than about 10% of the total thickness of the carbon precursor material from the surface of the carbon precursor material.
90. The method of any of the preceding claims, wherein the disordered amorphous non-graphene material occupies a thickness of at least 10 μm from the surface of the carbon precursor material.
91. The method of any of the preceding claims, wherein the disordered amorphous non-graphene material extends from its outer surface toward the body of the carbon precursor material to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
Carbonization at the physical interface with the substrate supporting the carbon precursor material
92. The method of any of the preceding claims, wherein the carbon precursor is positioned on or adjacent to the substrate.
93. The method of any of the preceding claims, wherein the carbon precursor material is transformed by the laser beam at the physical interface with the substrate into a disordered, amorphous, non-graphene material to a depth defined by the parameters of the laser beam.
94. The method of any of the preceding claims, wherein the disordered amorphous non-graphene material is located in one region adhered to or otherwise attached to the carbon foam and in another region adhered to or otherwise attached to the substrate, thereby providing stability to the carbon foam.
95. The method of any of the preceding claims, wherein the thickness of the disordered amorphous non-graphene material occupied by the material, as measured from the interface between the carbon precursor material and the substrate, is about 1%, less than about 1%, less than about 5%, or less than about 10% of the total thickness of the carbon precursor material.
96. The method of any of the preceding claims, wherein the thickness of the disordered amorphous non-graphene material occupying the substrate from the interface between the carbon precursor material and the substrate is at least 10 μm.
97. The method of any of the preceding claims, wherein the disordered amorphous non-graphene material extends from the interface between the carbon precursor material and the substrate to a depth of 10 μm or less, or 20 μm or less, or 30 μm or less, or 40 μm or less, or 50 μm or less, or 100 μm or less.
ablation laser beam or second laser beam
98. The method of any of the preceding claims, wherein the parameters of the second laser beam include one or more of the following: intensity, wavelength, pulse frequency, pulse duration, pulse profile, scanning speed, focal length, and heat generated in the subsurface region or encapsulation region.
99. The method as claimed in any of the preceding claims, wherein changing the second laser parameters alters the properties of the carbon foam material, thereby enabling the production of carbon foam with properties optimized for different applications.
100. The method as claimed in any of the preceding claims, wherein changing the laser parameters of the second laser beam alters one or more of the following properties or parameters of the carbon foam material: the type of carbon nanostructure present, the size of defects, the distribution of defects, the degree of defects, the type of defects, Raman D and 2D peaks, the relative size of Raman D and 2D peaks, thickness or depth, flexibility, adhesion, porosity, conductivity, capacitance, absorption by organic solvents and aqueous solutions, hydrophilicity, EMI shielding, electrode quality, wettability, contact angle, and antifouling properties.
101. The method as claimed in any of the preceding claims, wherein the second laser beam is a CO2 laser.
102. The method as described in any of the preceding claims, wherein the second laser beam alters the carbon foam as part of a process that exposes it.
103. The method as claimed in any of the preceding claims, wherein the second laser beam alters the morphology of the carbon foam as part of the process of exposing it.
104. The method of any of the preceding claims, wherein the second laser beam is automatically controlled to scan over the same region, and/or overlapping region, and/or non-overlapping region.
105. The method as claimed in any of the preceding claims, wherein the wavelength of the second laser beam ablating the amorphous non-graphene material is between 8 μm and 15 μm.
106. The method of any of the preceding claims, wherein the second laser beam is a long IR laser, or a UV laser, or a visible laser.
107. The method as claimed in any of the preceding claims, wherein the pulse frequency of the second laser beam is between 50 kHz and 500 kHz, and the scanning speed is between 9 cm/s and 40 cm/s.
108. The method of any of the preceding claims, wherein the carbon precursor material has an absorption coefficient for the second laser beam greater than 100 cm⁻¹ , or an absorption coefficient for the second laser beam greater than 200 cm⁻¹ .
109. The method as claimed in any of the preceding claims, wherein the carbon precursor material has an absorption coefficient of 300 ± 50 cm⁻¹ for the second laser beam.
110. The method as claimed in any of the preceding claims, wherein the laser power is in a typical operating range of 8 watts to 20 watts, preferably 12W.
111. The method as claimed in any of the preceding claims, wherein the second laser focal length is in a typical operating range of 50 mm to 400 mm.
112. The method of any of the preceding claims, wherein the second laser beam scans in a pattern (e.g., a grating) that includes non-overlapping regions or lines.
113. The method of any of the preceding claims, wherein the second laser beam scans with a pattern matching the scanning pattern of the first laser beam.
114. The method of any of the preceding claims, wherein the second laser beam is defocused.
115. The method of any of the preceding claims, wherein the second laser beam is the same as the laser beam irradiating the encapsulation region or subsurface region of the carbon precursor material to generate carbon foam in the encapsulation region or subsurface region.
116. The method of any of the preceding claims, wherein the manufacturing process is a three-stage process comprising the steps of: (a) irradiating a region below the surface of a carbon precursor material with a first laser beam at a manufacturing site to produce an unfinished carbon foam product; (b) transferring the unfinished carbon foam product to a customer-controlled manufacturing site; and (c) performing laser ablation or treatment at the customer-controlled manufacturing site.
Carbon foam
117. The method of any of the preceding claims, wherein the carbon foam is a multilayer torsion or disordered carbon foam, or comprises a multilayer torsion or disordered carbon foam.
118. The method of any of the preceding claims, wherein the carbon foam is a non-graphene carbon foam, or comprises a non-graphene carbon foam.
119. The method of any of the preceding claims, wherein the carbon foam comprises carbon nanostructures such as carbon nano-onions, carbon nano-angles, carbon nanotubes, carbon nanodots, nanodiamonds and fullerenes, or any combination thereof.
120. The method of any of the preceding claims, wherein the thickness of the carbon foam is at least about 50 μm.
121. The method of any of the preceding claims, wherein the thickness of the carbon foam is between about 50 μm and 300 μm.
122. The method of any of the preceding claims, wherein the carbon foam is or comprises a carbon foam having a spatial distribution of defects that result in high electrochemical reactivity.
123. The method of any of the preceding claims, wherein the carbon foam is or comprises a carbon foam having vacancy basal surface defects that result in high electrochemical reactivity.
124. The method of any of the preceding claims, wherein the carbon foam has a carbon:oxygen ratio between 25:1 and 50:1.
125. The method as described in any of the preceding claims, wherein the carbon foam has a fast electron transfer constant.
126. The method as claimed in any of the preceding claims, wherein the carbon foam, compared to conventional graphene foam produced using conventional laser processes, has one or more of the following properties: greater control over thickness or depth; greater flexibility compared to highly brittle graphene produced using conventional laser processes; stronger adhesion to the underlying flexible substrate; higher porosity; higher conductivity; increased capacitance or charge storage; faster absorption of organic solvents and water-based solutions; higher hydrophilicity; contact angle less than about 20°; enhanced antifouling properties; higher EMI shielding; and enhanced electrode quality.
Biosensor Use Cases
127. The method of any of the preceding claims, wherein the carbon foam is functionalized as a biosensor.
128. The method of any of the preceding claims, wherein the carbon foam is functionalized as a biosensor by adding a receptor specific to the target or analyte.
129. The method of any of the preceding claims, wherein the carbon foam is functionalized as a biosensor having a reversible polymer displacement sensor mechanism for electrochemical glucose monitoring.
130. The method of any of the preceding claims, wherein the reversible polymer displacement sensor comprises a pyrene-derived boric acid chemical acceptor for glucose adsorbed onto an electrode comprising the carbon foam.
131. The method of any of the preceding claims, wherein the carbon foam is functionalized as a biosensor by adding a receptor specific to a target or analyte and a connector that enables the receptor to attach to the carbon foam.
132. The method of any of the preceding claims, wherein the connector is selected from nanoparticles, polymers, polymer brushes, ligands, organic compounds containing one or more functional groups, molecules covalently or non-covalently bonded to the carbon foam, or mixtures thereof.
133. The method of any of the preceding claims, wherein the connector is selected from: polymers, preferably (meth)acrylate polymers; organic compounds containing one or more functional groups; carbodiimides; diazo compounds; or mixtures thereof.
134. The method of any of the preceding claims, wherein the one or more functional groups are independently selected from: oxygen, nitrogen, sulfur, halide, hydroxyl, carbonyl, carboxyl, amine, amino, amide, hydrophilic polymer or mixtures thereof, optionally in combination with linear, branched or cyclic alkyl, alkenyl, alkynyl, aryl residue, acryloyl, acyl, acyloxy, alkoxy, alkeneoxy or mixtures thereof.
135. The method of any of the preceding claims, wherein the organic compound further comprises one or more cyclic moieties optionally containing one or more heteroatoms, and at least one of the cyclic moieties is directly or indirectly connected to at least one of the functional groups, or the connector is a derivative of an ester or salt of the organic compound, or a compound that releases the organic compound in a reaction with the carbon foam.
136. The method of any of the preceding claims, wherein the connector is selected from 1-pyrene butyric acid, N-hydroxysuccinimide (NHS), pyrene-1-carboxylic acid succinimide ester, 1-aminopyrene, N-(1-pyrene)maleimide, or a mixture thereof.
137. The method of any of the preceding claims, wherein the joint is bonded to the carbon foam via π-π interactions.
138. The method of any of the preceding claims, wherein the receptor is one of: an electrochemical receptor, a chemical receptor, a biological receptor, an optical receptor, a physical or mechanical receptor, preferably a biological receptor.
139. The method of any of the preceding claims, wherein the receptor is selected from crown ethers, catalysts, boric acid, concepts, ligands, aptamers, proteins, enzymes, antibodies, antigens, microorganisms, nucleic acids, fatty acids, fatty acid esters, molecularly imprinted polymers, metal-organic frameworks, polypeptides or oligopeptides capable of forming ligand binding, cells, organelles or other cellular components or mixtures thereof, preferably selected from proteins, nucleic acids, antibodies, enzymes or mixtures thereof.
140. The method of any of the preceding claims, wherein the receptor is selected from immunoglobulin A (IgA), glucose dehydrogenase, streptavidin, or a mixture thereof.
141. The method of any of the preceding claims, wherein the receptor is bonded to the connector in a physical, biological and/or chemical manner, preferably chemically, and more preferably covalently.
Supercapacitor Use Cases
142. The method of any of the preceding claims, wherein the carbon foam forms an electrode in an energy storage device, such as an electrochemical capacitor, a supercapacitor, a pseudocapacitor, or a capacitor.
143. The method of any of the preceding claims, wherein the carbon foam is treated with a metal oxide film or other pseudocapacitive material to provide pseudocapacitance.
144. The method of any of the preceding claims, wherein the carbon foam forms at least one electrode in the energy storage device, such as an electrochemical capacitor, supercapacitor, pseudocapacitor, or capacitor, and the hydrogel electrolyte encapsulates the electrode or each electrode in the active region to generate an enhanced operating voltage window.
145. The method of any of the preceding claims, wherein the carbon foam forms electrodes in the battery.
146. The method as claimed in any of the preceding claims, wherein the carbon foam forms an electrical conductor.
Manufacturing process details
147. The method as claimed in any of the preceding claims, comprising the step of screen printing electrical contacts onto or into the carbon precursor material prior to using the first laser beam.
148. The method as claimed in any of the preceding claims, comprising the step of screen printing electrical contacts onto or into the carbon precursor material after using the first laser beam and the second laser beam.
149. The method as claimed in any of the preceding claims, wherein the manufacturing method is a room temperature process.
150. The method as claimed in any of the preceding claims, wherein the manufacturing method is an environmental pressure process.
151. The method as claimed in any of the preceding claims, wherein the manufacturing method can be performed on a plastic substrate.
152. The method of any of the preceding claims, wherein the manufacturing method enables the generation of 3D carbon foam on a flexible substrate.
153. The method of any of the preceding claims, wherein the manufacturing method produces carbon foam material only in the region below the encapsulation surface of the carbon precursor material, and not on any surface of the carbon precursor material.
154. The method as claimed in any of the preceding claims, wherein the manufacturing method uses a combination of industry-standard, low-cost, and scalable (i) screen printing technology and (ii) computer-controlled laser scanning technology.
155. The method of any of the preceding claims, wherein the manufacturing method uses high-speed, high-volume roll-to-roll or roll-to-sheet production.
156. The method as claimed in any of the preceding claims, wherein step (a) as claimed in claim 1 is performed in a manufacturing facility, and step (b) as claimed in claim 1 is performed in a different facility.
157. The method of any of the preceding claims, comprising the steps of: (a) screen printing electrical contacts onto or in a carbon precursor material; (b) irradiating an encapsulation region or subsurface region of the carbon precursor material below a surface using a laser beam operating in a first band to generate carbon foam in the encapsulation region or subsurface region, wherein steps (a) and (b) may be performed in the order of (a) then (b) or (b) then (a); and then (c) removing or ablating material located between the carbon foam and the surface of the carbon precursor material using a laser beam operating in a second band to expose at least some of the carbon foam connected to the electrical contacts.
application
158. The method of any one of the preceding claims for manufacturing a biosensor comprising a sensing electrode, said sensing electrode comprising at least in part a carbon foam manufactured by the method of any one of the preceding manufacturing methods.
159. The method of any of the preceding claims for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode, each of the sensor electrodes comprising at least partially carbon foam made by the method of any of the preceding manufacturing methods, and the method comprising screen printing electrical connection traces over each electrode and screen printing a dielectric material to at least partially cover the electrodes and the connection traces.
160. The method of any one of the preceding claims for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each of the sensor electrodes comprising at least partially carbon foam produced by the method of any one of the preceding manufacturing methods, and the method comprising an additional step of adding functionalizing groups to the working electrode in a different manufacturing facility.
161. The method of any one of the preceding claims for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode in a manufacturing facility, each of the sensor electrodes comprising at least partially carbon foam produced by the method of any one of the preceding manufacturing methods, and the method comprising an additional step of adding functionalized groups to the working electrode in the manufacturing facility.
162. A method as claimed in any of the preceding claims for manufacturing a biosensor comprising sensor electrodes such as a working electrode and a counter electrode, each of the sensor electrodes comprising at least partially carbon produced by the method as claimed in any of the preceding manufacturing method claims, and the method comprising the steps of: (a) screen printing a carbon layer on the substrate; (b) screen printing an electrical connection trace and a reference electrode; (c) screen printing a dielectric layer over the carbon and the electrical connection trace and the reference electrode; and then (d) producing a carbon foam sensor electrode using the method as claimed in any of the preceding manufacturing method claims.
163. The method of any one of the preceding claims for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material produced by the method of any one of the preceding manufacturing methods.
164. The method of any one of the preceding claims for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material produced by the method of any one of the preceding manufacturing methods;
The method includes the steps of screen printing electrical connection traces over at least a portion of each electrode and screen printing a dielectric layer to at least partially cover the electrodes and connection traces.
165. The method of any one of the preceding claims for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least partially a carbon foam material produced by the method of any one of the preceding manufacturing methods and arranged in an interdigitated pattern;
The method includes the step of screen printing electrical connection traces over at least a portion of each electrode, wherein a single electrical connection trace is connected to a lower layer finger extending vertically from both sides of the electrical connection trace.
166. The method as described in any of the preceding claims, used for manufacturing energy storage devices such as supercapacitors or pseudocapacitors;
The method includes the following steps: (a) screen printing an electrical connector onto a substrate; (b) screen printing a carbon layer over the current collector; (c) screen printing a dielectric over at least some of the carbon layer; and then (d) producing a carbon foam energy storage electrode at least partially by the method described in any one of the preceding manufacturing method claims.
167. The method of any one of the preceding claims for manufacturing an energy storage device such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material produced by the method of any one of the preceding manufacturing methods;
The method includes the step of applying a pseudocapacitive material, such as a metal oxide, to the energy storage electrode via an electrochemical deposition process.
168. The method of any one of the preceding claims for manufacturing an energy storage device, such as a supercapacitor or a pseudocapacitor, wherein the energy storage electrode comprises at least in part a carbon foam material produced by the method of any one of the preceding manufacturing methods;
The method includes the step of applying an ion gel in a low-humidity but non-inert environment, wherein the levels of O2 and H2O in the environment are measured and controlled to optimize the capacitance of the energy storage device.
169. The method of any one of the preceding claims for manufacturing an electrical conductor, wherein the electrical conductor comprises at least in part carbon foam manufactured by the method of any one of the preceding manufacturing methods.
170. The method of any one of the preceding claims for manufacturing an apparatus comprising both a sensor and an energy storage device, such as a supercapacitor, wherein both the sensor and the energy storage device comprise at least in part a carbon foam material produced by the method of any one of the preceding claims.
171. The method of any one of the preceding claims for manufacturing an integrated device comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material manufactured by the method of any one of the preceding claims.
172. The method of any one of the preceding claims for manufacturing an integrated device comprising an antenna and a supercapacitor, wherein the supercapacitor provides power to the antenna and comprises at least in part a carbon foam material manufactured by the method of any one of the preceding claims.
173. The method as described in any of the preceding claims, used for manufacturing an apparatus comprising one or more electrodes, each electrode comprising a carbon foam material;
The method described therein includes a series of operations required to produce a carbon foam material by means of a continuous roll of carbon precursor film, which is at least partially produced by means of any one of the preceding manufacturing method claims.
Device
174. An apparatus comprising a carbon foam material, at least in part, produced by the method described in any one of the preceding manufacturing methods.
175. The apparatus of any one of the preceding claims, comprising an energy harvester system and a supercapacitor, wherein the supercapacitor provides power to an antenna and comprises at least in part a carbon foam material manufactured by the method of any one of the preceding claims.
176. The device as claimed in any of the preceding claims, which is an energy storage device, such as a supercapacitor, comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the collector layer; and
(v) An energy storage electrode comprising at least part of a carbon foam material made from the carbon precursor film by the method described in any one of the preceding manufacturing method claims, wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer.
177. The device according to any one of the preceding claims, wherein the device is a smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by the method according to any one of the preceding claims of the manufacturing method;
The smart tag includes electronic devices powered by a battery, such as sensor electronics, and a data transmitter powered by the supercapacitor.
178. The device according to any one of the preceding claims, which is a smart tag comprising a battery and a supercapacitor, the battery providing long-term power and the supercapacitor providing short-term power at a level higher than that of the battery, wherein the supercapacitor comprises at least in part a carbon foam material made by the method according to any one of the preceding claims of the manufacturing method;
The smart tag includes electronic devices powered by the battery, such as sensor electronics, and a data transmitter powered by the supercapacitor, wherein the supercapacitor provides sufficient power to enable the data transmitter to establish a data connection with a base station or hub and to transmit a data payload once the data connection is established.
179. The device as claimed in any of the preceding claims, which is an energy storage device, such as a supercapacitor, includes a sub-assembly comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed current collector layer, which is above the screen-printed conductive paste or ink layer;
(iv) A screen-printed dielectric layer above the current collector layer;
(v) An energy storage electrode comprising at least part of a carbon foam material made from the carbon precursor film by the method as described in any one of the preceding manufacturing method claims, and wherein a conductive path is formed from the carbon foam material to the current collector layer via the conductive paste or ink layer;
Furthermore, multiple sub-components are stacked together, and adjacent energy storage electrodes are separated by an ion gel electrolyte.
180. The device according to any one of the preceding claims, which is a microfluidic diagnostic device including a sample well positioned on the upper surface of the device, wherein the reference electrode, working electrode and counter electrode are at least partially formed from a carbon precursor film by the method according to any one of the preceding claims of manufacturing method and are in a layer below the sample well, and the reference electrode connector, working electrode connector and counter electrode connector are in a layer below the reference electrode, working electrode and counter electrode.
181. The apparatus as claimed in any of the preceding claims, which is a lab-on-a-chip device, includes a sub-component comprising:
(i) Carbon precursor membrane;
(ii) Screen printing a conductive paste or ink layer on the surface of the carbon precursor film;
(iii) A screen-printed conductive layer, which is above the screen-printed conductive paste or ink layer;
(iv) Screen-printed reference electrode;
(v) A screen-printed dielectric layer above the current collector layer;
(vi) A sensor electrode comprising at least in part a carbon foam material made from the carbon precursor film by the method described in any one of the preceding manufacturing method claims, wherein a conductive path is formed from the carbon foam material to the conductive layer via the conductive paste or ink layer.
182. The apparatus as claimed in any of the preceding claims, wherein the apparatus comprises a laser-induced carbon foam material, the laser-induced carbon foam material being manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material between the carbon foam and the surface of the carbon precursor material to expose at least some of the carbon foam.
183. The apparatus as claimed in any one of the preceding claims, wherein the apparatus comprises a laser-induced carbon foam material, said laser-induced carbon foam material being manufactured by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material between the carbon foam and the surface of the carbon precursor material to expose at least some of the carbon foam; wherein the device is or includes one of the following: a Hall effect sensor; a tactile sensor for, for example, robotics; an infectious disease sensor; a biosensor; a continuously monitoring chemical sensor; a glucose monitoring sensor; a lactic acid sensor; a gas detection sensor; a self-charging hybrid energy generation device; a green gas conversion device; a fuel cell, such as a hydrogen fuel cell; a filter, including a permeable filter; a heating device.
Carbon foam
184. A laser-induced carbon foam, which is produced by:
(a) Irradiating an encapsulation region or subsurface region of a carbon precursor material below the surface of the material with a laser beam operating in a first wavelength band to generate carbon foam in the subsurface region, and then
(b) Using a laser beam operating in the second band to remove or ablate the material between the carbon foam and the surface of the carbon precursor material to expose at least some of the carbon foam.
185. A laser-induced carbon foam, which is manufactured using the method described in any one of the preceding manufacturing methods.
186. A laser-induced carbon foam, manufactured using the method described in any one of the preceding manufacturing methods, wherein the carbon foam comprises one or more carbon nanostructures, such as carbon nano-onions, carbon nano-horns, carbon nanotubes, carbon nanodots, nanodiamonds and fullerenes, or any combination thereof.
Applications Claiming Priority (18)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2118948.5 | 2021-12-23 | ||
| GB2202372.5 | 2022-02-22 | ||
| GB2202362.6 | 2022-02-22 | ||
| GB2202357.6 | 2022-02-22 | ||
| GB2202360.0 | 2022-02-22 | ||
| GB2202369.1 | 2022-02-22 | ||
| GB2202382.4 | 2022-02-22 | ||
| GB2202387.3 | 2022-02-22 | ||
| GB2202375.8 | 2022-02-22 | ||
| GB2202356.8 | 2022-02-22 | ||
| GB2202364.2 | 2022-02-22 | ||
| GB2202380.8 | 2022-02-22 | ||
| GB2202353.5 | 2022-02-22 | ||
| GB2202384.0 | 2022-02-22 | ||
| GB2202388.1 | 2022-02-22 | ||
| GB2202366.7 | 2022-02-22 | ||
| GB2202389.9 | 2022-02-22 | ||
| GB2202376.6 | 2022-02-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| HK40112902A true HK40112902A (en) | 2025-01-28 |
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