KR20240045375A - Polar fluid gated field effect devices - Google Patents

Abstract

Disclosed herein are nanoscale field effect transistors (NFETs), e.g., graphene-based field effect transistors (GFETs), that do not have a physical gate. Instead, they are gated by a polar fluid. Systems and methods using such transistors are also disclosed.

Description

Field effect devices with polar fluid gates {POLAR FLUID GATED FIELD EFFECT DEVICES}

Cross-reference to related applications

This application is based on U.S. Provisional Patent Application No. 62/356,729, filed on June 30, 2016, entitled “Detection of Ion Concentration in Fluids Using Nanoscale Materials Via Capacitive Response,” and Priority is granted to U.S. Provisional Patent Application No. 62/356,742, filed June 30 and entitled “Lactate-Oxidase-Functionalized Graphene Polymer Composite for Label-Free Detection of Lactate in Sweat and Other Body Fluids.” each of which is hereby incorporated by reference in its entirety.

field of invention

The invention disclosed herein relates generally to the design, fabrication and application of nanoscale field effect transistors (NFETs), and in particular graphene field effect transistors (GFETs), gated by polar fluids. The present invention also relates generally to chemical and biological sensing using field effect transistors, and more specifically to biochemical sensing using field effect transistors having biochemically sensitive channels comprising graphene.

A field-effect transistor (FET) is a transistor that uses electric fields to control the electrical behavior of a device. Typically, a FET has three terminals (eg, source, drain, and gate) and an active channel. For example, charge carriers (electrons or holes) flow from a source to a drain through an active channel formed by a semiconducting material.

Source (S) is where the carrier enters the channel. Drain (D) is where the carrier leaves the channel. The drain-to-source voltage is VDS and the source-to-drain current is IDS. The gate (G) adjusts the channel conductance by applying a gate voltage (VG) to control the current between the source and drain.

Nanoscale field-effect transistors (NFETs), such as graphene field-effect transistors (GFETs), are widely used in many applications such as bioprobes, implants, etc.

What is needed in this field is better design of FETs and new ways to use them.

In one aspect, a field effect transistor is disclosed herein. A field effect transistor has a drain electrode; drain electrode; source electrode; electrically insulating substrate; A layer of nanoscale material disposed on a substrate, wherein the layer of nanoscale material partially defines an electrically conductive and chemically sensitive channel, wherein the layer of nanoscale material and the channel extend between the drain electrode and the source electrode and between the drain electrode and the channel. Electrically connected to the source electrode - ; and a polar fluid induced gate terminal created by the polar fluid exposed to the nanoscale material layer. In some embodiments, the polar fluid includes the target analyte. In a further embodiment, the polarized fluid has a charge concentration sufficient to induce a polarized fluid gate voltage that optimizes the gate voltage to channel current characteristics of the field effect transistor in response to the target analyte.

In some embodiments, a constant current or constant voltage provided by a constant current source or constant voltage source is applied between the source electrode and the drain electrode.

In some embodiments, the nanoscale material includes graphene, CNTs, MoS2, boron nitride, metal dichalcogenides, phosphorene, nanoparticles, quantum dots, fullerene, 2D nanoscale material, 3D nanoscale material, OD nanoscale materials, 1D nanoscale materials, or any combination thereof.

In some embodiments, the polar fluid includes a solution with polar molecules, a gas with polar molecules, a target sensing analyte, or a combination thereof.

In some embodiments, polar fluids include sweat, breath, saliva, earwax, urine, semen, plasma, bio-fluids, chemical fluids, air samples, gas samples, or combinations thereof.

In some embodiments, the target analyte is electrolyte, glucose, lactic acid, IL6, cytokine, HER2, cortisol, ZAG, cholesterol, vitamin, protein, drug molecule. molecule, metabolite, peptide, amino acid, DNA, RNA, aptamer, enzyme, biomolecule, chemical molecule, synthetic molecule, or a combination thereof.

In some embodiments, the field effect transistor further includes a receptor layer deposited on the nanoscale material layer, where the receptor layer includes receptors targeting a target analyte.

In some embodiments, receptors include pyrene boronic acid (PBA), pyrene N-hydroxysuccinimide ester (pyrene-NHS), organic chemicals, aromatic molecules, cyclic molecules, enzymes, proteins, antibodies, viruses, Includes single-stranded DNA (ssDNA), aptamers, inorganic materials, synthetic molecules, and biological molecules.

In some embodiments, the field effect transistor further includes a back polymer layer beneath the nanoscale material layer to provide support for additional mechanical, electrical, chemical, biological functions, or combinations thereof.

In some embodiments, the back polymer layer includes carbon polymer, biopolymer, PMMA, PDMS, flexible glass, nanoscale material, silica gel, silicone, ink, printed polymer, or any combination thereof.

In one aspect, disclosed herein is a method for detecting a target analyte in a polar fluid. The method includes exposing a polar fluid sample to a field effect transistor, wherein the field effect transistor comprises: a drain electrode; a source electrode; an electrically insulating substrate; and a nanoscale material layer disposed on the substrate, wherein the nanoscale material layer is partially defines an electrically conductive and chemically sensitive channel, the nanoscale material layer and the channel extending between the drain electrode and the source electrode, electrically connected to the drain electrode and the source electrode, and exposed to the nanoscale material layer. A polar fluid induced gate terminal generated by a polar fluid, wherein the polar fluid includes a target analyte, and the polar fluid optimizes the gate voltage versus channel current characteristics of the field effect transistor to detect the analyte. has sufficient charge concentration to induce a gate voltage); measuring a first source-drain voltage at a first time point and measuring a second source-drain voltage at a second time point and subsequent time points; and determining the concentration of the target analyte in the polar fluid based on the first source-drain voltage and the second source-drain voltage.

In some embodiments, the nanoscale material is graphene, CNTs, MoS2, boron nitride, metal dichalcogenides, phosphorene, nanoparticles, quantum dots, fullerene, 2D nanoscale material, 3D nanoscale material, OD nanoscale materials, 1D nanoscale materials, or any combination thereof.

In some embodiments, the field effect transistor is functionalized with a receptor layer deposited on a nanoscale material layer, the receptor layer comprising receptors targeting a target analyte.

In some embodiments, receptors include pyrene boric acid (PBA), pyrene N-hydroxysuccinimide ester (pyrene-NHS), organic chemicals, aromatic molecules, cyclic molecules, enzymes, proteins, antibodies, viruses, single-stranded DNA ( ssDNA), aptamers, inorganic materials, synthetic molecules, and biological molecules.

In some embodiments, the target analyte is electrolytes, glucose, lactic acid, IL6, cytokines, HER2, cortisol, ZAG, cholesterol, vitamins, proteins, drug molecules, metabolites, peptides, amino acids, DNA, RNA, aptamers. , enzymes, biomolecules, chemical molecules, synthetic molecules, or combinations thereof.

In some embodiments, the polar fluid includes a solution with polar molecules, a gas with polar molecules, a target sensing analyte, or a combination thereof.

In some embodiments, the method further includes calculating a fractional change between the first source-drain voltage and the second source-drain voltage.

In some embodiments, the method further includes applying a constant current between the source and drain electrodes of the field effect transistor.

In some embodiments, the method further includes applying a constant voltage between the source electrode and the drain electrode of a field effect transistor.

In some embodiments, polar fluids include sweat, breath, saliva, earwax, urine, semen, plasma, bio-fluids, chemical fluids, air samples, gas samples, or combinations thereof.

In some embodiments, the method further includes a back polymer layer beneath the nanoscale material layer to provide support for additional mechanical, electrical, chemical, biological functions, or combinations thereof.

In some embodiments, the back polymer layer includes carbon polymer, biopolymer, PMMA, PDMS, flexible glass, nanoscale material, silica gel, silicone, ink, printed polymer, or any combination thereof.

In one aspect, a field effect transistor; and

Disclosed herein is a system comprising a constant current source or constant voltage source electrically connected to a field effect transistor. A field effect transistor includes a drain electrode; source electrode; electrically insulating substrate; A layer of nanoscale material disposed on a substrate, wherein the layer of nanoscale material partially defines an electrically conductive and chemically sensitive channel, wherein the layer of nanoscale material and the channel extend between a drain electrode and a source electrode, and wherein the drain electrode and electrically connected to the source electrode - ; and a polar fluid induced gate terminal created by the polar fluid exposed to the nanoscale material layer. In some embodiments, the polar fluid includes the target analyte. In some embodiments, the polarized fluid has a charge concentration sufficient to induce a polarized fluid gate voltage that optimizes the gate voltage versus channel current characteristics of the field effect transistor in response to the target analyte.

In some embodiments, a constant current source maintains a constant current through a field effect transistor.

In some embodiments, a constant voltage source maintains a constant voltage across the field effect transistor.

In some embodiments, the voltage output or current output is communicated to the digital platform via wired or wireless transmission.

In some embodiments, the digital platform may be a smartphone, tablet computer, smart watch, in-vehicle entertainment system, laptop computer, desktop computer, computer terminal, television system, e-book reader, wearable device, or any other device that processes digital input. Includes tangible computing devices.

As known to those skilled in the art, any of the embodiments disclosed herein can be used alone or in combination with other embodiments, in connection with any aspect of the invention.

Those skilled in the art will understand that the drawings described below are for illustrative purposes only. The drawings are not intended to limit the scope of the teachings in any way.
1A shows a prior art embodiment representing a graphene field effect transistor (gFET).
Figure 1B shows a prior art embodiment showing the current between source and drain controlled by the gate voltage.
Figure 2A shows an exemplary embodiment demonstrating gateless graphene field effect (g-gFET).
Figure 2b shows an exemplary embodiment representing a g-gFET.
Figure 2C shows an exemplary embodiment representing a g-gFET.
Figure 2D shows an exemplary embodiment representing a g-gFET.
FIG. 3A shows an exemplary embodiment showing a polar fluid gate terminal (PFGT) in which polar fluid is stationary.
3B shows an exemplary embodiment showing a polarized fluid gate terminal with polarized fluid flowing in a first direction.
FIG. 3C shows an exemplary embodiment showing a polarized fluid gate terminal with polarized fluid flowing in a second direction.
FIG. 4A shows an example embodiment representing the base device shown in FIGS. 2A-2D with a dielectric and gate metal. Gate potential is measured between the gate metal and ground.
Figure 4B shows an example embodiment representing the base device shown in Figures 2A-2D with a metal electrode added within the PFGT. Gate potential is measured between a metal electrode and ground.
FIG. 4C shows an exemplary embodiment representing the base device shown in FIGS. 2A-2D reinforced with a gate metal and metal electrode and dielectric in the PFGT. Two gate potentials are measured as indicated.
Figure 5A shows an exemplary embodiment representing a GFET used in conjunction with a constant current source.
Figure 5b shows an exemplary embodiment representing a GFET used in conjunction with a constant voltage source.
Figure 6 shows an exemplary example showing selectivity measurement of NaCl reaction in DI water.
Figure 7 shows an exemplary example showing sensitivity measurements for NaCl reaction in DI water.
Figure 8 shows an exemplary embodiment showing the chloride response in sweat.
Figure 9 shows an exemplary example showing selectivity measurements of the glucose reaction in DI water.
Figure 10 shows an exemplary example showing the glucose response in NaCl versus glucose response in DI water.
Figure 11 shows an exemplary example showing selectivity measurement of glucose reaction in NaCl water.
Figure 12 shows an exemplary example showing the sensitivity measurement of D-glucose response in DI water.
Figure 13 shows an exemplary embodiment showing functionalization steps visualized through GFET fabrication.
Figure 14 shows an exemplary example showing D-glucose response in sweat.
Figure 15 shows an exemplary example showing D-glucose response in blood.
Figure 16 shows an exemplary embodiment showing the measurement correlation between blood glucose and sweat glucose.
Figure 17 shows an exemplary example showing selectivity measurements of the lactic acid reaction in DI water.
Figure 18 shows an exemplary example showing selectivity measurements of lactic acid reactions in various solutions.
Figure 19 shows an exemplary example showing the lactic acid reaction in NaCl versus the lactic acid reaction in DI water.
Figure 20 shows an exemplary embodiment showing the lactic acid functionalization steps visualized through GFET fabrication.
Figure 21 shows an exemplary embodiment representing a model for sensor correlation with sweat sodium concentration.
Figure 22 shows an exemplary embodiment representing a model for sensor correlation with sweat glucose concentration.
Figure 23 shows an exemplary embodiment showing a trans-conductance curve for a PFT.

Disclosed herein are nanoscale field effect transistors and methods of making and using the same.

Typical graphene field effect transistor

Graphene has remarkable mechanical resistance; This allows approximately the thickness of a single or double layer to be subjected to substantial mechanical stress without losing its main electrical properties. This mechanical strength makes graphene an ideal candidate to replace the current generation of transparent conducting oxides (TCOs), led by indium tin oxide (ITO). Unlike graphene, ITO is brittle and sensitive to mechanical stress; The low sheet resistance and high transparency are enough to offset the high material costs. Meanwhile, the fabrication of large-area and low-sheet-resistance graphene sheets is a relatively simple and scalable process using chemical vapor deposition (CVD), with a few atomic layers with transparency greater than 90% and less than 100 sheets after appropriate processing. Calculate resistance.

As shown in Figure 1A, graphene FETs are typically fabricated on a Si wafer covered with a SiO2 layer, with the graphene forming the transistor channel. The graphene transistor consists of three terminals: source and drain metal electrodes in contact with the graphene channel and a global back gate enabled by a doped Si substrate. These features promote the characteristic bipolar transport behavior of graphene in Grat-FETs, achieving both n-type and p-type transport when biased with an appropriate gate voltage at the substrate. Any applicable method can be applied to fabricate the GFET, including, for example, the information disclosed in International Patent Publication No. WO2015/164,552, which is hereby incorporated by reference in its entirety.

Figure 1b shows the current between source and drain controlled by the gate voltage. By changing the direction and magnitude of the gate voltage, the resulting current flow curve takes the source and drain "V" shape. At the leading edge of the V-shaped curve, small changes in gate voltage result in significant and detectable changes in the channel current (I _DS ), which tends to stabilize at the two ends of the V-shaped curve.

Gateless field-effect transistor

In one aspect, disclosed herein is a new type of field effect transistor (FET) that does not have a physical gate.

2A-2D show various embodiments of a FET without a physical gate. 2A shows an exemplary graphene-based FET 210 comprising a substrate 1, source electrode 2, drain electrode 3, acceptor 4, graphene layer 5, and back polymer 6. do. As disclosed herein, the substrate may be polyamide, PET, PDMS, PMMA, other plastics, silicon dioxide, silicon, glass, aluminum oxide, sapphire, germanium, gallium arsenide, indium phosphide, alloys of silicon and germanium, fabrics, fibers, It may be silk, paper, cellulose-based material, insulator, metal, semiconductor, and may be rigid, flexible, or any combination thereof. In some embodiments, the substrate 1 may be a silicon carbide substrate, and the graphene layer 5 may be epitaxially grown directly on the silicon carbide substrate by sublimation of silicon from the silicon carbide substrate (FIG. 2B).

Source electrode 2 is an electrode region in a field effect transistor through which majority carriers flow into the inter-electrode conductive channel. Exemplary materials that can be used as the source electrode include, but are not limited to, silver, gold, carbon, graphite ink, conductive fabric, conductive fiber, metal, conductive material, conductive polymer, conductive gel, ion gel, conductive ink, non-metallic conductive material. It doesn't work.

The drain electrode 3 is an electrode on the side opposite to the source electrode 2. Exemplary materials that can be used as the source electrode include, but are not limited to, silver, gold, carbon, graphite ink, conductive fabric, conductive fiber, metal, conductive material, conductive polymer, conductive gel, ion gel, conductive ink, non-metallic conductive material. It doesn't work.

In some embodiments, the graphene layer 5 may have a uniform thickness, preferably a predetermined thickness of one or more graphene monolayers. Since thickness affects electrical properties, e.g. band gap, carrier concentration, etc., a uniform, preferably predetermined thickness provides control of the sensing properties and allows for the formation of reproducible devices with low variability between individual sensors. Make it possible.

In some embodiments, the graphene layer 5 may be an epitaxial layer, and the graphene layer substrate may be a substrate on which the graphene layer is epitaxially grown. By maintaining the graphene layer on the growth substrate, there is no need to typically handle nanoscale thin graphene layers and structures. Additionally, if the graphene layer can remain on the substrate, the risk of damaging the thin graphene layer during fabrication of the transistor is reduced.

In some embodiments, the graphene layer 5 may be surface treated with a receptor 4 for selectivity such that only selected types of analytes are detected by the graphene layer. Exemplary receptors (4) include pyrene boric acid (PBA), N-hydroxysuccinimide ester (Pyrene-NHS), organic chemicals, aromatic molecules, cyclic molecules, enzymes, proteins, antibodies, viruses, single-stranded DNA (ssDNA). ), aptamers, inorganic materials, synthetic molecules, and biological molecules, but are not limited thereto.

In some embodiments, graphene layer 5 and/or certain types of chemicals are prevented from reaching chemically sensitive channels. Surface treatment may include deposition of metal particles and/or polymers.

Back polymer 6 is used to provide mechanical support to the graphene. And, when doped, they can add new aspects to the sensing response. For example, the back polymer can be doped with biomolecules that can also bind to specific targets and contribute to changes in the resistance of the transistor channel.

Devices 220, 230, and 240 are variations of device 210. In device 220, back polymer layer 6 is omitted. In device 230, receptor layer 4 is omitted. In device 240, both back polymer layer 6 and receptor layer 4 are omitted.

As disclosed herein, the device or base device may be any of devices 210, 220, 230, and 240.

Polarized fluid gate terminal (PFGT)

Graphene is an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lattice with one atom forming each vertex. It is the basic structural element of graphite, charcoal, carbon nanotubes, and other allotropes, including fullerenes. This can be considered the ultimate case of infinitely large aromatic molecules, a family of flat polycyclic aromatic hydrocarbons. In some embodiments, graphene is a single layer of carbon atoms. Each carbon atom in graphene has 4 electrons. Through these three electrons, the carbon atom bonds to its three closest neighboring carbon atoms, forming a hexagonal lattice. For each atom, a fourth electron is delocalized in the entire graphene layer, allowing conduction of electronic current.

When a polar fluid is deposited on a graphene layer, graphene's special electronic properties will cause a reorganization of charges in the polar fluid and form a liquid-induced gate voltage that can regulate the current between the source and drain electrodes.

3A shows an exemplary embodiment representing a polarized fluid gate terminal in which the polarized fluid is stationary. As shown, polar or ionic charges are redistributed in the polar fluid to create a polar fluid gate terminal (PFGT) and an induced fluid gate voltage (V _FG ). This voltage can result in a shift in the x-axis (voltage) in the V-shaped current versus fluid gate voltage curve. As mentioned, at the leading edge of the V-shaped curve, small changes in gate voltage can result in significant and detectable changes in the channel current (I _DS ), which tends to stabilize at the two ends of the V-shaped curve. A shift to the tip of the V-shaped curve can lead to improved sensitivity: very small changes in voltage can be detected in response to changes in current. Likewise, very small changes in current can also be detected in response to voltage changes.

As mentioned above, a shift toward the tip of the V-shaped curve can lead to better sensitivity. This shift can be caused by a polarized fluid induced gate voltage. In some embodiments, the polar fluid induced gate voltage is related to the concentration of charged particles in the polar fluid. In some embodiments, the concentration may reflect the total amount of all negatively charged particles or all positively charged particles. The shift of the V-shaped curve can be correlated to a wide range of charged particle concentrations. In some embodiments, the shift is correlated to charged particle (e.g., NaCl) concentrations as low as 1 femto g/L. In some embodiments, the shift is correlated with charged particle (e.g., NaCl) concentrations as high as 300 g/L. The results suggest that the current sensing system is resilient and can tolerate a wide range of charge concentrations.

3B shows an exemplary embodiment showing a polarized fluid gate terminal with polarized fluid flowing in a first direction. The magnitude of the gate potential (V _FG ) will be directly proportional to the flow rate of the polar fluid. The sign or direction of V _FG will depend on the direction of flow of the polarized fluid, for example along and across the source drain terminal. For example, if the gate voltage is positive along the source-drain direction, it will be negative in the opposite direction, and vice versa. If a polar fluid flows across the source-drain voltage, if the gate voltage is positive along the Y direction, it will be negative along the -Y direction, and vice versa. If the direction of the polar fluid changes, the direction of the gate voltage will also change.

FIG. 3C shows an example embodiment showing a polarized fluid gate terminal with polarized fluid flowing in a second direction opposite to the first direction.

Gate voltage detection at polarized fluid gate terminal

4A-4C illustrate a setup in which the gate voltage is determined at the polarized fluid gate terminal (PFGT).

Figure 4a shows an exemplary embodiment representing a base device with a dielectric layer (7) and a gate metal (8). Here, the base device may be any device shown in FIGS. 2A to 2D, such as reference numerals 210, 220, 230, and 240. Gate potential is measured between the gate metal and the electric potential. A dielectric layer 7 is added beneath the substrate of the base device (e.g., substrate 1 shown in FIGS. 2A-2D). Gate metal (8) is added beneath the dielectric layer (7). Gate metal 8 is added only to measure the induced gate voltage; no voltage will be applied through gate metal 8. In some embodiments, Vg1 may vary in a non-linear manner depending on PFGT device characteristics and channel type. For example, if the channel is graphene (ambipolar), Vg1 may follow the transconductance response typical for graphene devices.

Figure 4B shows an example embodiment representing the base device shown in Figures 2A-2D with a metal electrode added within the PFGT. Gate potential is measured between a metal electrode and ground. Vg2 is the top gate voltage formed by the double layer capacitance between the added metal electrode and the active channel. Vg2 can vary in a non-linear manner depending on PFGT device characteristics and channel type. For example, if the channel is graphene (bipolar), Vg2 will follow the transconductance response typical for graphene devices (see, for example, Figure 23).

FIG. 4C shows an exemplary embodiment representing the base device shown in FIGS. 2A-2D reinforced with a gate metal and metal electrode and dielectric in the PFGT. As indicated, two gate potentials are measured. The two gate potentials (Vg1 and Vg2) are electrical output regulated using the source-drain current/voltage and the induced PFG. Simultaneous measurement of Vg1 and Vg2 creates a triple-gate structure that can be used to develop next-generation microprocessors, logic gates, computational circuits, radio frequency (RF) devices, sensors, and more.

FIG. 4C shows an exemplary embodiment representing the base device shown in FIGS. 2A-2D reinforced with a gate metal and metal electrode and dielectric in the PFGT. Two gate voltages (e.g., Vg1 and Vg2) are supplied to the PFGT to adjust the overall electrical characteristics of the PFGT device for the desired application. Simultaneous regulation by Vg1 and Vg2 creates a triple gate structure that can be used to shift device operation to the desired electrical performance in a more controlled manner using minimal energy. These devices can be used to develop next-generation microprocessors, logic gates, computational circuits, radio frequency (RF) devices, sensors, and more.

FIG. 5A shows an exemplary embodiment representing a circuit used for sensor readout via a polarized fluid graphene field effect transistor (PFGFET). In Figure 5a, a constant current ( _IC ) is supplied to the PFGFET. The output voltage (V _OUT ) is read across the PFGFET using a divider and current limiting resistor (R). The voltage output is then corrected for the concentration of the analyte being sensed.

Figure 5b shows an example embodiment illustrating another circuit used for sensor readout through a PFGFET. Here, a constant voltage (Vs) is supplied to the PFGFET. Current or charge (Ι _OUT ) is read from the PFGFET using a current limiting resistor (R). The current output is then adjusted to the concentration of analyte being sensed.

Although the invention has been described in detail, it will be apparent that modifications, variations and equivalent embodiments are possible without departing from the scope of the invention as defined in the appended claims. Additionally, it should be understood that all examples of the invention are provided by way of non-limiting example.

examples

The non-limiting examples described below are provided to further illustrate embodiments of the invention disclosed herein. It should be understood by those skilled in the art that the techniques disclosed in the examples that follow represent approaches that have been found to function well in the practice of the invention, and therefore may be considered as constituting examples of modes for its practice. However, those skilled in the art should understand that, in light of the present invention, many changes may be made in the specific embodiments disclosed and still obtain similar or comparable results without departing from the spirit and scope of the present invention.

Example 1

Experimental conditions for nanoscale field-effect transistors

The device was fabricated with graphene as the carrier channel of a two-terminal NFET without a physical gate terminal.

The polymer is placed on graphene, which typically has a thickness of less than 0.5 mm, which is then separated from the catalyst substrate on which the graphene was grown. A flexible polymer platform for the sensing system was used to stage a graphene polymer composite and two metal electrical contacts. Graphene polymer composites were incorporated into a flexible polymer platform. A solution of the desired linker molecule is deposited on the graphene polymer composite and cultured. Excess linker molecule solution was removed from the graphene polymer composite; Two metal electrical contacts were deposited on both edges of the graphene polymer composite.

Afterwards, the graphene polymer complex was placed on a polymer substrate such as Teflon, polyimide, etc., and then heated at 80-150 °C for 1-10 minutes to remove any impurities.

After that, the GFET sensor is ready to use. In some cases, receptors for specific analytes were deposited in the graphene layer.

In a sensor system for detecting an analyte through sweat, the sensor:

o Flexible polymer platform consisting of (kapton);

o Graphene polymer composite bonded to a flexible polymer platform;

o a source electrode and a drain electrode positioned in the sensor configuration on opposing edges of a layer of graphene polymer composite also bonded to a flexible polymer platform;

o Each source and drain electrode composed of a conductive metal;

o A layer of graphene polymer composite functionalized with linker molecules for biosensing of the desired analyte between two electrodes; and

o Sensor system held in close proximity to the source of clean sweat to be analyzed.

The method for determining analyte concentration through sweat includes the following steps:

o Applying a constant bias voltage to the functionalized graphene polymer composite sensor having a conductive channel;

o measuring a first source-drain voltage across the sensor;

o exposing the conduction channel to clean sweat by bringing the conduction channel very close to the source of sweat;

o The analyte binds to the linker molecule by releasing electrons into the channel through the linker, which results in a change in potential at both ends of the channel;

o measuring a second source-drain voltage across the sensor;

o Determining the concentration of the analyte based on the fractional change between the first source-drain voltage and the second source-drain voltage.

During analysis, a fixed current or voltage is passed through the sensor. The electrical response of the GFET sensor was recorded for the analyte in polar solution, using the analyte in deionized (DI) water as a negative control. The DI water response in the functionalized GFET was also measured. Analytes included NaCl, D-glucose, and lactic acid.

Example 2

Analysis of NaCl samples

In these examples, a fixed current or voltage was passed through the GFET. The electrical response of the GFET sensor was recorded against the NaCl concentration in DI water or the DI water response in the functionalized GFET.

Selectivity : The response of various NaCl concentrations in DI water was measured on the GFET to study the sensitivity of the sensor to NaCl. Solutions of various NaCl concentrations ranging from 0 to 1 g/L were prepared in DI water. The test begins by introducing 2 μl of the lowest concentration into the GFET, followed by a higher concentration 3 minutes later, and so on; For example, in the example shown in Figure 6, it goes from 0.05 g/L to 0.1 g/L. This continued until all concentrations were introduced onto the GFET.

Figure 6 shows that the GFET does not show a significant response to just DI water, but shows a linear response to increasing NaCl concentration in DI water. Increasing concentration varied the voltage across the channel, resulting in high selectivity for NaCl in DI water as a control.

Sensitivity : The response of different NaCl concentrations in DI water was also measured on the GFET to study the range of sensitivity of the sensor towards NaCl. Solutions with exponentially increasing NaCl concentrations ranging from 0.1 mg/dl to 10 mg/dl in DI water were prepared. The test began by introducing 2ul of the lowest concentration onto the GFET, then applying the next higher concentration 3 minutes later, and so on. Here, the concentration increased logarithmically, for example, from 0.1 ng/dl to 1 ng/dl, then to 10 ng/dl, then to 0.1 ug/dl, etc. This continued until all concentrations were introduced onto the GFET.

Figure 7 shows that the GFET only showed no significant response to DI water, showing an exponential response starting from the lowest to the highest concentration of NaCl in DI water. Increasing concentrations varied the voltage across the channel, resulting in high sensitivity of approximately 250 femtograms/liter for NaCl in DI water as a control.

Chloride response in sweat : Measurements of chloride concentration in human sweat were performed on human subjects. The test required subjects to perform physical activities such as running and occasionally drinking water for hydration.

GFETs were worn on the forearms and lower back (eccrine glands) by human subjects. Electrical responses due to chloride concentration in sweat were transmitted and recorded continuously (every 500 milliseconds) while subjects performed intense physical activity (such as running). As shown in Figure 8, changes in sweat chloride concentration are observed and indicated by partial changes in voltage.

Figure 8 shows real-time concentration of sweat osmolarity of two human subjects using PFGFETs attached to the skin. Osmolality in sweat is directly correlated with an individual's physical function. Subject 1 was a sprinter and Subject 2 was a jogger. The sprinter (Subject 1) ran the same distance at a faster pace (Run 1) compared to the jogger (Subject 2 and Run 2). The more intense the subject's physical activity, the higher the measured body osmolarity was observed. Peaks in body osmolality were observed during periods of most intense physical activity. It has also been observed that body osmolality decreases during periods of intense physical activity. This occurred when subjects consumed too much water without adequate salt supplementation. In this data, when the slope of the curve is 0, it indicates hyponatremia. During this period, the body tries to retain as much salt as possible (to maintain ionic balance), so overall body osmolarity changes very slowly.

The following novel results and/or characteristics were observed.

High selectivity : PFGT-modulated GFET (NFET) showed highly selective response (>97%) to NaCl concentration in different control fluids.

High sensitivity : GFETs functionalized with PBA showed high sensitivity to NaCl with a limit of detection (LOD) of 250 femtograms/liter. GFET sensors have a high signal-to-noise ratio, are highly selective, and have higher coupling between surfaces and molecules due to their high surface area for binding. All of these factors play a significant differentiating role in making GFETs very sensitive.

Gate regulation due to polar molecules : In polar fluids (water, salt, etc.), it has been observed that polar molecules (ions, etc.) form a polar fluid gate terminal (PFGT) on the NFET. Polar molecules near the graphene surface induced a dielectric effect that created channels for charge transfer. The gating strength of PFGT depended on both the charge and concentration of polar molecules in the fluid. This third polar fluid gate terminal (PFGT) modulated the electrical response from the NaCl concentration in the polar fluid.

Continuous monitoring : The ion concentration in the fluid was continuously measured due to modulation of the NFET channel current from the induced polarity fluid gate terminal. Once the ionic solution was removed from the surface of the NFET, the electrical response of the polar fluid gated NFET returned to its baseline or initial value.

Induced movement of polar fluids on the NFET surface : Due to the increased hydrophobicity between the NFET surface and the polar fluid, we observed that polar fluids (such as NaCl in DI water) immediately try to repel or escape from the NFET surface. The higher the concentration of polar molecules (e.g. NaCl) in the fluid, the higher the strength of the PFGT and thus the greater the repulsion effect. This repulsion effect, combined with the modulation of the electrical response due to PFGT by NaCl molecules on the NFET, enables a highly sensitive, selective, and continuously monitored electrolyte system.

Real-time continuous chloride monitoring of human sweat : As an example, GFETs were worn on the forearm and lower back (eccrine sweat glands) by human subjects. Sweat is diluted, ultra-filtered blood. While a subject is performing a) intense physical activity (exercise) b) non-intense physical activity (such as sitting at an office desk and eating), electrical responses due to chloride concentration in sweat occur continuously (every 500 milliseconds). Sent and recorded. It was observed that background ion concentrations in sweat (mainly NaCl) formed PFGTs on the two-terminal GFET device. Changes in the gating strength of induced PFGT on GFET due to CI- ions enabled continuous non-invasive monitoring of CI ion molecules in human sweat. Sweat has been observed to be a very good polar fluid for continuous measurement of chloride concentration, as it is highly diluted and ultrafiltered.

Example 3

Analysis of D-glucose samples

In these examples, a fixed current or voltage is passed through the GFET.

The electrical response of the GFET/PBA sensor was recorded for:

o D-glucose concentration in DI water

o D-glucose concentration in artificial sweat (DI + NaCl + lactic acid)

o D-glucose concentration in DI water on non-functionalized GFET

o Lactose concentration in DI water on the functionalized device (Control 1)

o Artificial sweat concentration of the functionalized device (Control 2)

o DI water response on functionalized GFETs

o Human sweat glucose measurement: Real-time continuous monitoring of glucose concentration in human sweat was performed using wearable GFET/PBA sensors. Real-time continuous sweat glucose responses were correlated with blood glucose measurements using a commercially available blood glucose meter.

Functionalization : As an example, a graphene FET was functionalized with a linker molecule (lock) that specifically binds to glucose molecules in the fluid. As an example, GFETs were functionalized with Pyrene Boronic Acid (PBA). Pyrene boric acid binds to the graphene surface using pi-pi bonds. PBA forms a reversible boron-anion complex with D-glucose. The manufacturing steps are as follows:

o The polymer was placed on graphene, typically less than 0.5 mm thick, which was then separated from the grown catalyst substrate.

o After that, the graphene polymer complex is placed on a polymer substrate such as Teflon, polyimide, etc. and heated at 80-150℃ for 1-10 minutes to remove any impurities.

o Afterwards, the graphene polymer was introduced into the PBA solution for 5–20 min for functionalization at room temperature.

o After the functionalization step, the sensor is ready for use.

The response of various D-glucose concentrations in DI water was measured on a GFET to study the sensitivity of the functionalized sensor to D-glucose.

Solutions with varying concentrations of D-glucose ranging from 0.1 to 100 mg/dL in DI water were prepared, as well as various concentrations of lactose in DI water. The test began by introducing 5ul of the lowest concentration into the GFET, then proceeding to the next higher concentration after 3 minutes, and so on. This was continued until all concentrations were introduced into the GFET.

Figure 9 shows that GFET only showed no significant response to DI water or lactose solution, and showed an exponential response to increasing D-glucose concentration in DI water. Increasing concentration changed the voltage across the channel, thereby showing high selectivity for D-glucose with DI water as control.

Glucose response in NaCl versus glucose response in DI water : The response of various D-glucose concentrations in DI water and NaCl solutions was measured on a GFET to determine the sensitivity of the functionalized sensor to D-glucose in DI water versus D-glucose in NaCl. studied and understood the effects of NaCl.

Solutions were prepared with various concentrations of D-glucose ranging from 0.1 to 100 mg/dL in DI water and NaCl, respectively. The test began by introducing 5 ul of the lowest concentration onto the GFET, then proceeding 3 minutes later to the next higher concentration, and so on. Here, the concentration increased logarithmically. This was continued until all concentrations were introduced into the GFET.

Figure 10 shows that the D-glucose response in NaCl was more amplified than the D-glucose response in DI water. Polar solutions providing PFGT on GFETs increased sensitivity and provided reversibility by amplifying the electrical response through the channel.

Determination of selectivity of glucose response in NaCl solution : The response of various D-glucose concentrations in NaCl was measured on GFET to study the sensitivity of the functionalized sensor to D-glucose.

Solutions with various concentrations of D-glucose ranging from 0.1 to 100 mg/dL were prepared in NaCl solution, as well as various concentrations of NaCl in DI water. The test began by introducing 5 ul of the lowest concentration onto the GFET, then proceeding 3 minutes later to the next higher concentration, and so on. Here, the concentration increased logarithmically. This continued until all concentrations were introduced onto the GFET.

Figure 11 shows that the GFET shows no significant response to NaCl solutions alone, but a linear response to solutions of increasing D-glucose concentration at a fixed NaCl concentration compared to solutions of increasing NaCl concentration. Increasing concentration changed the voltage across the channel, resulting in high selectivity for D-glucose. GFET (NFET) functionalized with PBA showed a highly selective response (>95%) to glucose concentration.

Figure 11 provides an idea that while the functionalized glucose sensor is not insensitive to NaCl (the orange curve is fairly flat), the glucose curve increases with increasing concentrations of glucose present in the NaCl solution.

Sensitivity measurement of D-glucose response in DI water : The response of various D-glucose concentrations in DI was measured on GFET to study the sensitivity range of the functionalized sensor to D-glucose.

Solutions were prepared with exponentially increasing glucose concentrations ranging from 250 femtograms/L to 100 mg/L in DI water. The test began with three introductions of 5 ul of DI water every 3 minutes, followed by the lowest concentration of 5 ul, followed by the next higher concentration 3 minutes later on the GFET, and so on. Here, the concentration increased logarithmically; For example, from 0.25 pg/l, then 2.5 pg/l, etc. This continued until all concentrations were introduced onto the GFET.

Figure 12 shows that the GFET did not show a significant response to the DI number only, but showed a linear response starting from the lowest concentration to the highest concentration with increasing concentration of the current across the channel varied, resulting in a response of about 250 femto for D-glucose. It showed a high sensitivity of grams/liter (i.e., 1.38e ^-12 mmol/l).

Functionalization Steps : Shown in Figure 13 is the current response for the graphene sensor before functionalization, after functionalization and after glucose was introduced onto the sensor. This helps us understand each stage of the GFET manufacturing process and how the GFET's current response changes after each stage. For example, in Figure 13, the current response increases after functionalization (orange) compared to before functionalization (blue), and this is because the linker molecules are bound by pi-pi bonds and the overall charge on the surface of graphene increases. It is shown that this occurs. The linker molecule attracts the glucose molecule and uses this charge cloud to bind to the glucose molecule, reducing the current on the GFET compared to the previous state.

D-Glucose Response in Sweat and Blood : Measurements of glucose concentration in human sweat were performed on human subjects. The test required the subject to perform a physical activity, such as running, and every few minutes a blood sample was taken to measure blood glucose using a blood glucose meter. GFETs are worn by human subjects on the forearms and lower back (eccrine sweat glands). Electrical responses due to sweat D-glucose concentration were transmitted and recorded continuously (every 500 milliseconds) while the subject was performing intense physical activity (such as running).

In this particular case, the physical activity was eating food. When the subject sits down, his glucose will begin to rise as seen in both sweat and blood glucose. Once a person has finished eating, glucose levels will begin to drop and stabilize.

In the case of running, as you start running, your body uses glucose and breaks it down to get energy for running. Therefore, you will see a decrease in glucose. However, after a certain point, the body's insulin will kick in and overall glucose levels will begin to rise again.

Figure 14 shows changes in sweat D-glucose concentration as indicated by partial changes in voltage.

The blood glucose data in Figure 15 was also plotted against time for the entire duration of exercise. Sweat glucose measurements were correlated with blood glucose measurements. Here, sweat glucose values versus corresponding blood glucose values were plotted against blood (blood vs. sweat) to obtain the correlation R ² , which gave an idea of how well sweat glucose and blood glucose matched.

Figure 16 further shows the measurement correlation between blood glucose and sweat glucose. Here, three different sensors were used on the same person at the same time. More than 150 sweat glucose curves were collected from 10 human subjects for correlation, along with their blood glucose, over the entire period of the study. Subjects either performed physical activity (exercise, running, etc.) or did not perform physical activity (sitting at a desk, etc.). The correlation calculated for these 150 curves was R ² = 84% between sweat and blood, as also shown in Figure 16.

The following novel results and/or characteristics were observed.

High selectivity : PBA-functionalized GFETs (FETs) showed highly selective responses (>95%) to glucose concentrations in different control fluids.

High sensitivity : GFET functionalized with PBA showed high sensitivity to D-glucose with a limit of detection (LOD) of 250 femtograms/liter, i.e., 1.38e ^-12 mmol/l. Conventional glucose measurements have an LOD between 0.3-1.1 mmol/l. GFETs functionalized with PBA are approximately 10 to 10 times more sensitive than existing standard glucose measurement devices. GFET sensors have a high signal-to-noise ratio, are highly selective, and there is higher binding between the surface and the receptor molecule due to the high surface area for binding. All these factors play a big differentiating role in making GFETs very sensitive.

Gate control due to polar molecules : In polar fluids (such as water, salt, etc.), polar molecules (such as ions) have been observed to form a polar fluid gate terminal (PFGT) on the NFET. Polar molecules near the graphene surface induced a dielectric effect that created channels for charge transfer. The gating strength of PFGT depended on both the charge and concentration of polar molecules in the fluid. This third polarized fluid gate terminal (PFGT) modulated the electrical response from the glucose concentration in the polarized fluid.

Continuous glucose monitoring : The reversibility of PBA-glucose binding on the graphene surface was greatly enhanced by charge control due to the polar fluid gate terminal on the NFET formed with polar fluid. The higher the concentration of polar molecules (such as ions) in the polar fluid, the greater the reversibility of the PBA-D-glucose bond was observed. When the concentration of glucose bound to the sensor is higher than the glucose concentration in sweat, due to its Gibbs free energy, unbound glucose molecules from PBA and reversibility are observed, as shown in Figure 14 when the concentration of glucose briefly drops. This is clearly visible in the recorded electrical response. This allowed reusable, real-time continuous monitoring of D-glucose molecules in polar fluids.

Reusability of glucose sensors due to movement of polar fluids over the sensor surface : It has been observed that movement of polar fluids (such as glucose in salt) over NFETs enhances the removal of bound glucose molecules from linker molecules. For example, when the glucose solution was removed from the graphene surface within the GFET, the electrical response of the GFET returned to its default value.

Induced movement of polar fluids on the NFET surface : It has been observed that polar fluids (such as glucose in salt) immediately repel or try to escape from the NFET surface due to the increased hydrophobicity between the NFET surface and the polar fluid. The higher the concentration of polar molecules in the fluid, the higher the strength of the PFGT and the greater the repulsion effect. This repulsive effect combined with the removal of bound glucose molecules (described above in section e) and the modulation of the electrical response due to PFGT on the NFET allowed highly sensitive, selective and continuous monitoring of the glucose system.

Real-time continuous glucose monitoring in human sweat : GFETs functionalized with PBA were worn on the forearm and lower back (eccrine sweat glands) by human subjects. Sweat is diluted, ultrafiltered blood. While subjects are performing a) intense physical activity (exercise) and b) non-intense physical activity (such as eating while sitting at an office desk), an electrical response due to the concentration of glucose in sweat occurs continuously (500 milliseconds). each) was transmitted and recorded. The sweat glucose response was correlated with blood glucose readings taken every few minutes using blood glucose measurements over the length of the activity (typically 20 minutes to over 6 hours). It was observed that background ion concentrations in sweat (mainly NaCl) formed PFGTs on two terminal GFET/PBA devices. The enhanced reversibility between PBA and D-glucose binding due to PFGT on GFET enabled continuous, noninvasive monitoring of glucose molecules in human sweat. A correlation of 84% (R ² ) was calculated between blood glucose and sweat glucose measurements. Correlations were calculated for over 150 sweat glucose responses collected from 10 human subjects under various physical activity conditions. It has been observed that sweat is a very good polar fluid for continuous measurement of glucose because it is highly diluted and ultrafiltered.

Example 4

Analysis of miscarriage samples

In these examples, a fixed current or voltage is passed through the GFET.

Functionalization : The graphene FET was functionalized with a linker molecule (Locke) that specifically binds to lactic acid molecules in the fluid. For example, GFETs were functionalized with lactate oxidase (LOx) on the graphene surface using intermediate pyrene-NHS link chemistry.

o A polymer is placed on graphene, typically less than 0.5 mm thick, which is then separated from the grown catalyst substrate.

o Afterwards, the graphene polymer complex is placed on a polymer substrate such as Teflon, polyimide, etc. and heated at 80-150°C for 1-10 minutes to remove any impurities.

o Afterwards, the graphene polymer is introduced into the pyrene-NHS solution for 5-20 min for functionalization at room temperature.

o Afterwards, the graphene polymer is introduced into the LOx solution for binding for 5-20 minutes at room temperature.

o After the functionalization step, the sensor is ready for use.

The electrical response of the GFET/LOx sensor was recorded for:

o Lactic acid concentration in DI water

o Lactic acid concentration in artificial sweat (DI + NaCl + glucose)

o Lactic acid concentration of NaCl on non-functionalized GFET

o Lactic acid concentration of NaCl on functionalized GFET

o Artificial sweat concentration of the functionalized device (Control 2)

o DI water response on functionalized GFETs

Selectivity measurement of lactic acid response in DI water : The response of various lactic acid concentrations in DI was measured on a GFET to study the sensitivity of the functionalized sensor toward lactic acid. Solutions with various concentrations of lactic acid ranging from 0-25mM in DI water were prepared. The test began by introducing 2ul of the lowest concentration onto the GFET, then proceeding 3 minutes later to the next highest concentration, and so on. This continued until all concentrations were introduced onto the GFET.

Figure 17 shows that the GFET does not simply produce a significant response to DI water, but exhibits a polynomial response to increasing lactic acid concentrations in DI water, with increasing concentrations changing the voltage across the channel, thereby using DI water as a control. This indicates that it shows high selectivity for lactic acid in DI water.

Determination of selectivity of lactic acid response in different solutions : The response of various lactic acid concentrations in different solutions was measured on the GFET to study the sensitivity and response of the functionalized sensor to lactic acid over the non-functionalized sensor. Solutions with various concentrations of lactic acid ranging from 0-25mM were prepared in NaCl and NaCl-glucose. The test began by introducing 2ul of the lowest concentration onto the GFET, then proceeding 3 minutes later to the next highest concentration, and so on. This was continued separately for each solution until all concentrations were introduced onto the GFET.

Figure 18 shows that GFET showed no significant response to only NaCl or NaCl-glucose controls, but showed a polynomial response to increasing lactic acid concentrations in NaCl and NaCl-glucose solutions. Increasing concentration changed the voltage across the channel, resulting in high selectivity for lactic acid. There was no significant response to the non-functionalized sensor in lactic acid NaCl solution, further highlighting the selectivity and sensitivity of the sensor to lactic acid.

Lactic acid response in NaCl versus lactic acid response in DI water : The response of various lactic acid concentrations in DI water and NaCl solutions was measured on a GFET to study the sensitivity of the functionalized sensor to lactic acid in DI water versus lactic acid in NaCl and the effect of NaCl solution. I understand. Solutions with various concentrations of lactic acid ranging from 0.1 to 100 mg/dL were prepared in DI water and NaCl, respectively. The test began by introducing 2ul of the lowest concentration onto the GFET, then applying the next higher concentration 3 minutes later, and so on. This continued until all concentrations were introduced onto the GFET.

Figure 19 shows that the lactic acid reaction in NaCl is less amplified than the lactic acid reaction in DI water.

Lactic acid functionalization steps visualized through GFET fabrication : the current response for the graphene sensor before and after functionalization and after the introduction of lactic acid into the sensor is shown in Figure 20. This helps us understand each stage of the GFET manufacturing process and how the GFET's current response changes after each stage. For example, Figure 20 shows a decrease in current response after functionalization (orange) compared to before functionalization (blue). The linker molecule attracts and binds to the lactic acid molecule, reducing the current on the GFET compared to the previous state.

The following novel results and/or characteristics were observed.

High selectivity : LOx-functionalized GFETs (FETs) showed highly selective responses (>94%) to lactic acid concentrations in different control fluids.

High sensitivity : GFET functionalized with pyrene NHS showed high sensitivity to lactic acid with a limit of detection (LOD) of 250 femtograms/liter, i.e. 2.78e ^-12 mmol/l. Conventional lactic acid measurements have LODs between 0.001 and 10 mmol/l. GFETs functionalized with pyrene NHS are approximately 108 times more sensitive than existing standard lactic acid measurement devices. GFET sensors have a high signal-to-noise ratio, are highly selective, and due to their high surface area for binding, there is higher binding between the surface and the receptor molecule. All these factors play a big differentiating role in making GFETs very sensitive.

Gate regulation due to polar molecules : In polar fluids (such as water, salt, etc.), it has been observed that polar molecules (such as ions) form polar fluid gate terminals (PFGTs) on the NFET. Polar molecules near the graphene surface induced a dielectric effect that created channels for charge transfer. The gating strength of PFGT depended on both the charge and concentration of polar molecules in the fluid. This third polarized fluid gate terminal (PFGT) modulated the electrical response from the lactic acid concentration in the polarized fluid.

Induced movement of polar fluids on the NFET surface : Polar fluids (such as lactic acid in artificial sweat) have been observed to immediately repel or try to escape from the NFET surface due to the increased hydrophobicity between the NFET surface and the polar fluid. The higher the concentration of polar molecules in the fluid, the higher the strength of the PFGT and the greater the repulsion effect. This repulsion effect combined with the modulation of the electrical response due to PFGT on the NFET enabled highly sensitive, selective and continuous monitoring of the lactic acid system.

Example 5

Additional analysis

Sweat Salt Concentration Correlation : Figure 21 shows the sweat sensor response to the corresponding sweat sodium concentration.

Increasing concentrations of NaCl (0.1 mg/dl to 100 mg/dl) were added onto the graphene sensor every 3 minutes. The test began by dropping 2 ul of the lowest concentration (e.g., 0.1 mg/dl), followed by the next higher concentration (e.g., 0.2 mg/dl) at 3-minute intervals. The corresponding partial change in voltage was measured. This was repeated for 10 different sensors and a maximum error of 15% was observed. This serves as a model for the correlation between sweat sodium and corresponding voltage changes.

Sweat Glucose Concentration Correlation : Figure 22 shows the sweat sensor response to the corresponding sweat glucose concentration.

Increasing concentrations of glucose (0.1 mg/dl to 100 mg/dl) were added onto the graphene sensor every 3 minutes. The test began with a 5 ul drop of the lowest concentration (e.g. 0.1 mg/dl) followed by a 3 minute interval to the next higher concentration (e.g. 0.2 mg/dl), and so on. The partial change in voltage was measured. This was repeated for 10 different sensors and a maximum error of 5% was observed. This serves as a model for the correlation between sweat glucose and corresponding voltage changes.

Trans-conductance curve : Figure 23 shows the trans-conductance curve for the PFGT device.

NaCl solutions with increasing concentrations ranging from 0.1 ng/dl to 1 mg/dl are dripped onto the sensor every 3 minutes. The test began by dropping 2 ul of the lowest concentration (e.g., 0.1 ng/dl) and then proceeding to the next higher concentration (1 ng/dl) at 3-minute intervals.

As the polar fluid is introduced, a debye layer is formed on the graphene sensor and a gating effect is observed, with both the debye length and the gating effect being a function of the concentration of polar molecules. For the initial concentration of NaCl solution, DI is more dominant, which results in more holes and a drop in voltage. However, after dropping a few drops, as the NaCl concentration in the solution increases, it becomes more dominant and more electrons are generated near the device layer, thereby resulting in an increase in voltage.

This shows the trans-conductance characteristics of a graphene sensor gated with a polar fluid.

The various methods and techniques described above provide numerous ways to carry out the invention. Of course, it should be understood that not every described object or advantage will necessarily be achieved in accordance with any particular embodiment described herein. Thus, for example, a person skilled in the art will be able to achieve or optimize one advantage or group of advantages taught herein without necessarily achieving another object or advantage that may be taught or suggested herein. It will be appreciated that the method may be performed. Various advantageous and disadvantageous alternatives are mentioned herein. Some preferred embodiments specifically include one, other or several advantageous features, while others specifically exclude one, other or several disadvantageous features, while still others include one, other or several advantageous features and thus present It must be understood that it specifically alleviates disadvantageous characteristics.

Additionally, those skilled in the art will understand the applicability of various features from different embodiments. Likewise, the various elements, features and steps described above, as well as other known equivalents for each of these elements, features or steps, can be mixed and matched by those skilled in the art to carry out methods according to the principles described herein. It can be. Some of the various elements, features and steps will be specifically included and others will be specifically excluded in various embodiments.

Although the present invention has been disclosed with respect to specific embodiments and examples, it is understood in the art that the embodiments of the invention extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and modifications and equivalents thereof. It will be understood by those skilled in the art.

Many modifications and alternative elements are disclosed in embodiments of the invention. Further variations and alternative elements will be apparent to those skilled in the art.

In some embodiments, numbers expressing quantities, properties of elements, such as molecular weight, reaction conditions, etc., used to describe and claim specific embodiments of the invention are understood to be modified in some cases by the term "about". It has to be. Accordingly, in some embodiments, the numerical parameters set forth in the written description and appended claims are approximations that may vary depending on the desired properties sought to be achieved by a particular embodiment. In some embodiments, numeric parameters should be interpreted in light of the number of reported significant digits and applying ordinary rounding techniques. Although the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in specific examples are reported as accurately as possible. The values presented in some embodiments of the invention may include certain errors that necessarily arise from the standard deviation found in the respective test measurements.

In some embodiments, the terms “a” and “an” and “the” are used in the context of describing specific embodiments of the invention (especially in the specific context of the claims below). and similar references may be construed to include both singular and plural forms. The description of ranges of values herein is merely intended to serve as a shorthand way of referring individually to each individual value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples or exemplary language (e.g., “such as”) provided in connection with specific embodiments herein is intended only to better illustrate the invention and to the invention as otherwise claimed. Do not limit the scope. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

No group of alternative elements or embodiments of the invention disclosed herein should be construed as limiting. Each group member may be referred to or claimed individually or in any combination with other members of the group or other elements present herein. For reasons of convenience and/or patentability, one or more members of a group may be included in or removed from the group. If any such inclusion or deletion occurs, the specification is herein deemed to include the group as modified, carrying out the recited description of all Markush groups used in the appended claims.

Preferred embodiments of the invention are described herein. Modifications to these preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. It is contemplated that those skilled in the art may employ such modifications as appropriate, and that the invention may be practiced otherwise than as specifically described herein. Accordingly, many embodiments of the present invention include all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Additionally, numerous references are made to patents and printed publications throughout this specification. Each of the references and printed publications cited above is individually incorporated herein by reference in its entirety.

In conclusion, the embodiments of the invention disclosed herein should be understood as illustrative of the principles of the invention. Other modifications that may be employed may be within the scope of the present invention. Accordingly, by way of example and not limitation, alternative configurations of the invention may be utilized in accordance with the teachings herein. Accordingly, embodiments of the invention are not limited to exactly as shown and described.

Claims (12)

In the field effect transistor,
drain electrode;
source electrode;
a layer of nanoscale material partially defining an electrically conductive and chemically sensitive channel, wherein the layer of nanoscale material and the channel extend between the drain electrode and the source electrode and are electrically connected to the drain electrode and the source electrode. became -; and
A polar fluid induced gate terminal generated by a polar fluid exposed to the layer of nanoscale material, wherein the polar fluid comprises a target analyte, and wherein a gate voltage is induced by the polar fluid and varies with the concentration of the target analyte. Related ―
A field effect transistor containing a. According to paragraph 1,
A field effect transistor wherein a constant current or constant voltage is applied between the source electrode and the drain electrode, and the constant current or constant voltage is provided by a constant current source or a constant voltage source. According to paragraph 1,
The field effect transistor further comprises an electrically insulating substrate, and the nanoscale material layer is disposed on the electrically insulating substrate. According to paragraph 1,
A field effect transistor, wherein the polar fluid includes a solution containing polar molecules, a gas containing polar molecules, a target sensing analyte, or a combination thereof. According to paragraph 1,
A field effect transistor, wherein the polar fluid includes sweat, breath, saliva, earwax, urine, semen, plasma, bio-fluid, chemical fluid, air sample, gas sample, or a combination thereof. According to paragraph 1,
The target analytes include electrolytes, glucose, lactic acid, IL6, cytokines, HER2, cortisol, ZAG, cholesterol, vitamins, proteins, drug molecules, and metabolites. A field effect transistor comprising a metabolite, peptide, amino acid, DNA, RNA, aptamer, enzyme, biomolecule, chemical molecule, synthetic molecule, or a combination thereof. According to paragraph 1,
A field effect transistor, further comprising a receptor layer deposited on the nanoscale material layer, the receptor layer comprising receptors configured to target the target analyte. In clause 7,
The receptors include pyrene boronic acid (PBA), pyrene N-hydroxysuccinimide ester (pyrene-NHS), organic chemicals, aromatic molecules, cyclic molecules, enzymes, proteins, antibodies, viruses, and single-stranded DNA ( A field effect transistor comprising ssDNA), aptamers, inorganic materials, synthetic molecules, or biological molecules. According to paragraph 1,
A field effect transistor further comprising a back polymer layer beneath the layer of nanoscale material, configured to provide support for additional mechanical, electrical, chemical, biological, or combinations thereof. According to clause 9,
The field effect transistor of claim 1 , wherein the back polymer layer includes carbon polymer, biopolymer, PMMA, PDMS, flexible glass, nanoscale material, silica gel, silicon, ink, printed polymer, or any combination thereof. In a method for detecting a target analyte in a polar fluid,
exposing a sample of the polar fluid to the field effect transistor of any one of claims 1 to 10;
measuring a first source-drain voltage at a first time point and a second source-drain voltage at a second subsequent time point; and
determining the concentration of the target analyte in the polar fluid based on the first source-drain voltage and the second source-drain voltage.
A method for detecting a target analyte in a polar fluid comprising a. In the system,
field effect transistor; and a constant current source or constant voltage source electrically connected to the field effect transistor,
A system wherein the field effect transistor includes the field effect transistor of any one of claims 1 to 10.