CN116295970A - Multistage microstructure film for sensor and wearable flexible sensor - Google Patents

Multistage microstructure film for sensor and wearable flexible sensor Download PDF

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Publication number
CN116295970A
CN116295970A CN202310359593.XA CN202310359593A CN116295970A CN 116295970 A CN116295970 A CN 116295970A CN 202310359593 A CN202310359593 A CN 202310359593A CN 116295970 A CN116295970 A CN 116295970A
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film
microstructure
layer
sensor
pdms
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郭荣辉
王维杰
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Sichuan University
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Sichuan University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
    • B81B3/0021—Transducers for transforming electrical into mechanical energy or vice versa
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Computer Hardware Design (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

The invention discloses a multi-stage microstructure film for a sensor, wherein a plurality of array hemispherical bulges are regularly distributed on the surface of the multi-stage microstructure film, a plurality of conical bulges are randomly distributed in areas among the array hemispherical bulges and on the surfaces of the array hemispherical bulges, the array hemispherical bulges form a primary microstructure, and the conical bulges form a secondary microstructure. The invention uses the first-level microstructure of the regular array to lift the second-level microstructure of random distribution into the regular hemispherical convex array distribution with random distribution convex, and skillfully frames the random distribution and the regular distribution together instead of being mixed and disorderly, thereby improving the synergistic effect between the internal structures and realizing 243.24kPa in the linear range of 0-190kPa ‑1 Is of high sensitivity, improves the piezoresistanceSensor integrity.

Description

Multistage microstructure film for sensor and wearable flexible sensor
The invention relates to the technical field of sensors, in particular to a multi-stage microstructure film for a sensor and a wearable flexible sensor.
Background
The flexible pressure sensor is an electronic device capable of quantifying pressure information through physical contact, and can be used in the fields of human physiological monitoring, man-machine interaction, machine touch and the like. With the development of information technology, the demand for high-performance flexible pressure sensors for next-generation devices (such as electronic skin, internet of things devices and human-computer interfaces) is increasing. To meet these demands, flexible pressure sensors require high pressure sensitivity and a wide sensing range. Thus, flexible pressure sensors based on various sensing mechanisms such as piezoelectricity, capacitance, piezoresistance and triboelectricity are reported. Among these pressure sensors, piezoresistive pressure sensors are widely used due to their simple structure and signal processing.
In the continuous research and development improvement of the sensor, more and more researchers are beginning to research a method for constructing a special microstructure on the surface of a two-dimensional film to improve the comprehensive performance of the piezoresistive sensor. For example, shu et al first introduced a gaussian distribution structure on the contact surface of the piezoresistive sensor. The high sensitivity is about 13.8kPa because a new contact point is gradually created between the two electrodes as the pressure increases -1 And has good linearity over the entire sensing range of 0-14 kPa. Bae et al propose a hierarchical sensor that maintains 8.5kPa in a linear response range of 0-12kPa -1 Is a high sensitivity. Although these microstructure sensors prepared based on commercial and biological templates exhibit high sensitivity>10kPa -1 ) The linear response range of the sensor is generally narrow, however, and most can only maintain high sensitivity in the range of 20 kPa. Therefore, how to improve the comprehensive performance of the piezoresistive sensor, that is, the wide response and high sensitivity, and provide a low-cost and large-scale preparation method is a problem to be solved at present.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a multi-stage microstructure film for a sensor and a wearable flexible sensor. The obtained flexible sensor realizes 243.24kPa in linear range of 0-190kPa -1 Is a high sensitivity of (a).
The invention is realized by the following technical scheme:
a multi-stage microstructure film for a sensor is characterized in that a plurality of array hemispherical bulges are regularly distributed on the surface, a plurality of conical bulges are randomly distributed in areas among the array hemispherical bulges and on the surfaces of the array hemispherical bulges, the array hemispherical bulges form a primary microstructure, and the conical bulges form a secondary microstructure. Under SEM (magnification of 1000 times), the surface microstructure morphology of the multi-stage microstructure film is the litchi shell-like surface morphology. In the present invention, such an overall surface relief microstructure under SEM (magnification of 1000 times) may also be referred to as a regular litchi-like surface relief microstructure. According to the invention, the secondary microstructure with random distribution is lifted into the regular hemispherical convex array distribution with random distribution convex by the primary microstructure of the regular array, the random distribution and the regular distribution are skillfully framed together instead of being combined in disorder, the synergistic effect among internal structures is improved, the unification of high sensitivity and wide linear response range is realized, and the comprehensive performance of the piezoresistive sensor is improved.
The preparation method of the multi-stage microstructure film adopts a vacuum secondary template method to separately and sequentially prepare the PDMS film with a secondary microstructure and a primary microstructure, and specifically comprises the following steps:
s1, obtaining a PDMS film with a secondary microstructure through a secondary microstructure template, wherein the PDMS film can be attached to the secondary microstructure template when in implementation, and the PDMS film with the secondary microstructure is obtained through spin coating and curing in a vacuum environment;
s2, attaching the PDMS film with the secondary microstructure on the PMMA template with the primary microstructure of the porous array, opening vacuum, bending and sinking the PDMS film with the secondary microstructure under the action of pressure difference, spin-coating the surface of the sinking PDMS film, finally curing and stripping to obtain a finished film, and carrying out hydrophilic treatment on the finished film.
The preparation method of the hierarchical raised microstructure is different from the existing integral molding method in that a vacuum secondary template method is adopted, so that the controllable low-cost preparation of the hierarchical microstructure film is realized, and meanwhile, the separation design of a mesoscale primary microstructure and a microscale secondary microstructure is realized, the adjustment of the sizes, the shapes and the like of the primary microstructure and the secondary microstructure are mutually independent, more hierarchical microstructures can be combined and designed, and the modification of the microstructure is more convenient. The sensor structure and performance can be customized in a personalized way. Meanwhile, the regular primary microstructure design of the sensitive layer is beneficial to improving the uniformity of devices and consistency among batches, and is beneficial to realizing industrialization and marketization of products.
And S2, attaching a hollowed-out PDMS film on the back of the secondary microstructure template. During the experiment, the inventor found that the product formation was unstable during the preparation of the primary microstructure, and the situation was not improved by adjusting the factors in various aspects of the preparation process conditions. Finally, the inventor finds that the problem of contact tightness exists between the PMMA through hole template and the vacuum platform of the spin coater, so in order to eliminate the problem and further eliminate the influence on the formation of the primary microstructure, before the PDMS film with the secondary microstructure is attached to the PMMA template with the primary microstructure of the porous array, a layer of hollowed PDMS film is attached to the back surface of the template with the secondary microstructure, and the arrangement successfully solves the problem.
And S1, preparing a secondary microstructure template with negative conical protrusions on the surface by pouring the surface of the bionic material. And preparing a secondary microstructure template by adopting a casting and demolding method: pouring a proper amount of epoxy resin mixture on the surfaces of lotus leaves or other bionic materials such as petals and other blades; the template containing the epoxy mixture was degassed in vacuo for 30 minutes to remove any residual bubbles; after curing for 36 hours at room temperature, stripping lotus leaves or other bionic material surfaces such as petals and other blades from the epoxy resin to obtain a secondary microstructure template;
the method for carrying out hydrophobic treatment on the secondary microstructure template comprises the following specific steps: and a layer of uniform fluorine release agent is sprayed on the secondary microstructure mold, and the fluorine release agent adopts epoxy resin defluorination dry release agent RD-518, so that the film thickness is 0.1-1 mu m. Otherwise, a film having a thickness of less than 500 μm cannot be obtained. In the S2 spin coating process, the vacuum pressure is-0.06 to-0.1 Mpa; the rotating speed is 1000-1200r/min; the curing process uses 250W infrared light, the distance between the infrared lamp and the irradiated object is 20-25cm, and the curing time is 2-5min.
The height of the protrusions of the primary microstructure is 100-1000 mu m, and the height of the protrusions of the secondary microstructure is 1-100 mu m; the conductive material of the conductive layer is one of titanium carbide nano-sheets or carbon nano-tubes. The hierarchical raised microstructure of the invention consists of a regular hemispherical raised primary microstructure with mesoscale and a conical random secondary microstructure with microscale. Unlike large scale structures, which tend to result in low sensitivity and weak detection limits of the sensor at low pressures, micro scale structures tend to saturate the conductive path under pressure, resulting in limited sensing range.
A sensing layer for a sensor is a multi-level microstructured film as described above coated with a conductive layer.
A flexible sensor comprises a packaging layer, a middle layer and a bottom layer with electrodes from top to bottom, wherein the middle layer comprises a sensitive layer as described above.
The thickness of the multi-stage microstructure film of the sensitive layer is 100-500 mu m; the packaging layer is a flexible transparent film, and is made of one of polyethylene terephthalate, polycarbonate and polyurethane; the thickness of the packaging layer is 25-50 mu m, and one side of the packaging layer is provided with glue; the bottom layer is a PI film with one side printed with interdigital electrodes.
The sensor further comprises a spacer layer, wherein the spacer layer is arranged below the sensitive layer and plays a supporting role on the sensitive layer, and the inner diameter of the spacer layer is equal to the outer diameter of the sensitive layer; the spacer layer thickness is equal to the sensitive layer thickness. The preparation method of the spacer layer comprises the following steps: PDMS prepolymer and curing agent are mixed according to the mass ratio of 10:1, uniformly mixing, vacuum defoaming for 30min, pouring the PDMS mixed solution into a spacer layer template, drying at 60 ℃ for 1h, and stripping to obtain the PDMS spacer layer. In practice it is necessary to design the spacer layer template in combination with the shape of the sensitive layer.
The implementation also relates to a packaged sensor, in particular to: cutting a sensitive layer PDMS film into 1cm multiplied by 1cm, enabling one side with a microstructure to be opposite to one side of the interdigital electrode, adopting a spacing layer to space the sensitive layer and the interdigital electrode layer, and finally fixing the sensitive layer and the spacing layer on the interdigital electrode layer by using a packaging layer film with a glue on one side.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention uses the primary microstructure of the regular array to lift the randomly distributed secondary microstructure into the regular hemispherical convex array with randomly distributed convex, and the random distribution and the regular distribution are skillfully framed togetherThe non-messy combination promotes the synergistic effect between the internal structures and realizes 243.24kPa in the linear range of 0-190kPa -1 The high sensitivity of the piezoresistive sensor improves the problems of low sensitivity and narrow sensing range, and greatly improves the comprehensive performance of the piezoresistive sensor.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention. In the drawings:
FIG. 1 is a schematic diagram of a flexible pressure sensor of the present invention;
FIG. 2 is a schematic diagram of a first-level PMMA circular via template of the present invention;
FIG. 3 is a schematic diagram of a vacuum secondary template process flow of the present invention;
FIG. 4 is an SEM image of a surface-graded-relief microstructured PDMS film of the present invention.
FIG. 5 is a graph of relative current versus pressure for a flexible pressure sensor provided in an embodiment of the present invention at a voltage of 1V;
FIG. 6 is a schematic diagram of response, recovery performance of a sensor constructed in accordance with an embodiment of the invention;
FIG. 7 is a schematic diagram of 10000 cycles stability at 6kPa for a sensor constructed in accordance with an embodiment of the present invention.
In the drawings, the reference numerals and corresponding part names:
1-packaging layer, 2-sensitive layer, 21-multi-stage microstructure film, 22-conductive layer, 3-spacer layer, 4-interdigital electrode layer, 41-interdigital electrode and 42-PI film.
Description of the embodiments
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
Examples
Unlike expensive photolithographic processes, the present invention uses a more cost-effective laser marking process to prepare circular via array primary microstructure templates on polymethyl methacrylate (PMMA) plates.
A circular array of through holes was machined in a 1mm thick PMMA plate using a CO2 laser marker. The number of marks, the speed of marking, the Q frequency and the power were set to 1 time, 1mm/s, 1.25kHz and 35%, respectively. The above-described setting was repeated 25 times at 10 second intervals. Circular array patterns were designed in Han's laser marking software. Different circular array pitches can regulate the performance of the sensor, and a design diagram of five different pitch templates is shown in fig. 2. The total area of the circular array remained uniform, approximately 9 x 9 mm 2 Different numbers of arrangements can be achieved by varying the spacing of the dots. The center distances of each dot in the horizontal and vertical directions are 1, 1.1, 1.3, 1.5 and 1.8 mm, respectively, and the corresponding numbers of round holes are 10×10, 9×9, 8×8, 7×7 and 6×6, respectively. Due to the expandability of the process, circular through hole array templates with different parameters can be prepared in large quantities at low cost.
Cutting fresh folium Nelumbinis into pieces of about 2×4cm 2 Is rinsed 5 times with deionized water. The cleaned blade is blow-dried with nitrogen. The cut lotus leaf or other bionic materials such as petals and leaves are stuck on the bottom surface of the double-sided tape with the area of 4 multiplied by 6cm 2 Is arranged in the silica gel mold; mixing the epoxy resin prepolymer and the curing agent under mechanical stirring, wherein the weight ratio of the epoxy resin prepolymer to the curing agent is 3:1; then pouring the proper amount of epoxy resin mixture on lotus leaves; the template containing the epoxy mixture was degassed in vacuo for 30 minutes to remove any residual bubbles; after curing for 36 hours at room temperature, stripping lotus leaves or other bionic materials such as petals and leaves from the epoxy resin to obtain a secondary microstructure template; and carrying out hydrophobic treatment on the secondary microstructure template.
The preparation method of the PDMS film with the secondary microstructure comprises the following steps: the spin coating procedure is: the rotating speed is 500r/min, and the time is 30s; then the rotating speed is 1000r/min, and the time is 1min. Firstly, dripping PDMS spin coating liquid on a secondary microstructure template, and executing a primary spin coating program; and adding PDMS spin coating liquid on the surface of the spin-coated film again, and executing the spin coating procedure again. The 250W infrared lamp irradiation was applied throughout the process.
A primary hemispherical regular array is formed on a PDMS film having a secondary conical microstructure. First, a secondary conical microstructure PDMS (L-PDMS) was prepared based on the secondary microstructure epoxy mold prepared in the previous step. The L-PDMS film having a predetermined thickness was gently attached to the primary microstructure PMMA circular through-hole template prepared in step S1. The vacuum was turned on by placing the L-PDMS film and PMMA template on the spin coater, and the pressure differential across the L-PDMS film resulted in a bending depression of the film. Uniformly mixing the PDMS prepolymer and the curing agent in a mass ratio of 10:1, and defoaming in a vacuum environment to obtain the PDMS spin coating liquid. And (3) coating the PDMS spin coating liquid on the recessed L-PDMS film, wherein the rotating speed is 1000r/min, simultaneously using 250W infrared light to cure the PDMS spin coating liquid in situ, fixing the distance between the infrared lamp and the L-PDMS film to be 20cm, and setting the curing time to be 2-5min. Finally, peeling off the PDMS film on the PMMA template to obtain the PDMS film with the graded convex surface microstructure, wherein the SEM appearance of the film is shown as shown in figure 4, the appearance of the film is the graded convex surface microstructure PDMS film which looks particularly like the appearance of the litchi shells, and finally, hydrophilic treatment is carried out on the surface of the PDMS film microstructure.
In order to solve the problem of contact tightness between the PMMA through hole template and the vacuum platform of the spin coater, a hollowed PDMS film can be designed to be attached to one side of the PMMA through hole template, which is contacted with the vacuum platform of the spin coater, otherwise, air leakage is easy to cause, and the primary microstructure formation is affected. The thickness of the auxiliary PDMS film is 100-500 μm.
In addition, as is clear from fig. 4, the surface of the multi-stage microstructure film of the present invention is regularly distributed with a plurality of array hemispherical protrusions, and a plurality of conical protrusions are randomly distributed in the areas between the plurality of array hemispherical protrusions and on the surfaces of the plurality of array hemispherical protrusions, wherein the plurality of array hemispherical protrusions form a primary microstructure, and the plurality of conical protrusions form a secondary microstructure. Under SEM, the surface convex shape of the multi-level microstructure film is a litchi shell-like surface shape, namely the regular litchi dendritic surface microstructure.
Ti 3 C 2 Preparation of Tx-MXene nanoplatelets.
Dissolving lithium fluoride at room temperatureThe solution was dissolved in HCl (9M) in a polytetrafluoroethylene beaker to prepare an etching solution. Subsequently, ti is added 3 AlC 2 Powder is added to the etching solution. The mixture was stirred at 38 ℃ to remove aluminum 36 h and the acidic multi-layered Ti obtained was washed in deionized water 3 C 2 Tx dispersion up to pH>6. Then, the multi-layer Ti was treated by ultrasonic (100 w) 3 C 2 Tx dispersion 60min preparation of layered Ti 3 C 2 Tx. Finally, after centrifugation at 3500 rpm for 30 minutes, a small amount of Ti was obtained 3 C 2 Tx nanoplatelets.
Coated with a conductive layer Ti 3 C 2 Preparation of Tx stepped raised microstructure PDMS film
To spray a layer of Ti 3 C 2 Tx was used as the conductive layer, the microstructured PDMS substrate was placed on a heated plate at 180℃C, and a spray gun was placed on top of the PDMS substrate at a distance of about 10 cm. To avoid large droplets and to homogenize the conductive layer, we spray the layer with a 10% duty cycle (10 seconds per cycle: 1 second for spraying, 9 seconds for solvent evaporation). By controlling the number of spraying, we can control the conductivity of the coating.
Designing a supporting layer mold, processing an ABS mold by adopting a 3D printing process according to a design scheme, uniformly mixing a PDMS prepolymer and a curing agent according to a mass ratio of 10:1, defoaming for 30-35 min in a vacuum environment, pouring a PDMS mixed solution into the ABS mold, drying in a 60 ℃ oven for 1h, and demolding after curing to obtain the PDMS supporting layer.
Adding terpineol into the conductive silver paste for dilution, wherein the mass ratio of the terpineol to the conductive silver paste is 0.025-0.05:1; printing the diluted conductive silver paste on a PI film by adopting a 300-mesh screen printing plate, and then drying the PI film in an oven at 80 ℃ for 5-10 min. And connecting the two copper wires at two ends of the interdigital electrode by adopting a double-sided conductive copper tape.
The sensor consists of four layers, namely a top packaging PU film and a microstructure Ti from top to bottom 3 C 2 Tx/PDMS film, PDMS spacer layer and PI interdigital electrode; ti to be microstructured 3 C 2 Tx/PDMS film was cut into 1cm X1 cm pieces as sensitiveThe sensitive layer film is embedded into the prepared PDMS spacer layer; finally, the side of the sensitive layer with the microstructure is placed opposite to the interdigital electrode, and a medical waterproof PU adhesive tape with the thickness of 10 mu m is adopted to fix the top to form a package. The process is shown in figure 3.
In an implementation, a flexible pressure sensor as shown in fig. 1: the packaging layer 1, the sensitive layer 2, the spacing layer 3 and the interdigital electrode layer 4 are arranged from top to bottom; the packaging layer 1 is a flexible transparent film, the sensitive layer 2 is a PDMS film 21 with a graded convex microstructure on one side, and a layer of conductive material 22 is sprayed on the surface of the PDMS film 21 with the graded convex microstructure; the spacing layer is a rectangular hollowed-out PDMS film 3 and is used for supporting the sensitive layer 2; the interdigital electrode layer 4 is a PI film 42 with one side printed with an interdigital electrode 41.
The primary structure scale of the hemispherical bulge is mesoscale (100-1000 μm), and the secondary structure scale of the conical bulge is microscale (1-100 μm); the interval can be adjusted when the hemispherical bulges in regular arrangement are in primary structure through the design of the template.
The flexible transparent film of the packaging layer is one of polyethylene terephthalate (PET), polycarbonate (PC) and Polyurethane (PU); the thickness of the packaging layer film is 25-50 mu m, and one side of the packaging layer film is provided with glue.
The thickness of the PDMS film of the sensitive layer is 100-500 mu m.
The conductive material sprayed on the sensitive layer is one of titanium carbide nano-sheets (MXene-Ti 3C2 Tx) or carbon nano-tubes (CNTs).
The interdigital electrode is a silver interdigital electrode. The finger width of the interdigital electrode is 0.25 mm-0.5 mm, and the finger pitch is 0.25 mm-0.5 mm.
Examples
The performance of the sensor was measured using a Keithley2450 digital source meter and a motion control platform with a digital display push-pull meter.
At a voltage of 1V, the gradually increasing pressure is vertically loaded by the motion control stage, while the real-time current is recorded, the change in the relative current increases with the increase in the load pressure, and as shown in fig. 5, two linear regions of the change rate of the current with the change in the applied pressure can be observed. For the purpose ofIn comparison with the performance of the sensor prepared in the examples of the present invention, a flexible pressure sensor (L-PDMS) containing only a second-order microstructured PDMS film and a flexible pressure sensor (H-PDMS) containing only a first-order microstructured PDMS film were prepared using the methods described in the examples. From FIG. 5, it is observed that for the flexible pressure sensor (M-PDMS) obtained in the examples of the present invention, the sensitivity of the device reached 243.24kPa when the applied pressure was less than 190kPa -1 . Within the pressure range of 190kPa to 225kPa, the sensitivity of the device is 187.5kPa -1 . In contrast, the sensitivity of the sensor L-PDMS and the sensor H-PDMS in the low pressure and high pressure ranges is lower than that of the sensor M-PDMS, and the maximum sensing range of the M-PDMS can reach 225kPa. The structure design of the sensor M-PDMS adopts a mesoscale and microscale cooperative hierarchical microstructure, and the hierarchical structure enables the conductive path of the sensor to be continuously compensated in the compression process, so that the sensing range is higher than that of an L-PDMS sensor and an H-PDMS sensor with only one-level microstructure, and the unification of the sensitivity and the sensing range is enough to meet the pressure measurement of all parts of a human body and various motion modes.
To study the response time of the sensor, the sensor was pressed with a finger. As shown in fig. 6, the sensor current rapidly rises within a response time of 32ms, corresponding to the response time of human skin (30-50 ms), and then after a steady value is maintained to release pressure, the sensor current rapidly drops within 53ms with rapid recovery of the sensor, and then decays to an initial value.
To test the stability of the prepared multilayer flexible pressure sensor 10000 load and unload cycles were performed at a pressure of 6 kPa. The experimental results are shown in fig. 7, with the enlarged inset showing the signal of the two phases of the repeated test, no significant degradation of the waveform, indicating no fatigue during 10000 loading and unloading cycles, indicating good stability and reliability of the prepared sensor.
In the present invention, none of the prior art is described in detail.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (10)

1. The multi-stage microstructure film for the sensor is characterized in that a plurality of array hemispherical bulges are regularly distributed on the surface of the film, a plurality of conical bulges are randomly distributed in areas among the array hemispherical bulges and on the surfaces of the array hemispherical bulges, the array hemispherical bulges form a primary microstructure, and the conical bulges form a secondary microstructure.
2. The multi-level microstructured film of claim 1, wherein the primary microstructures have a protrusion height of 100 μm to 1000 μm, the secondary microstructures have a protrusion height of 1 μm to 100 μm, and the multi-level microstructured film has a thickness of 100 μm to 500 μm.
3. The multi-stage microstructured film of claim 1, wherein the surface topography of the multi-stage microstructured film is a simulated litchi rind surface topography under SEM.
4. The multi-stage microstructured film of claim 1, wherein the multi-stage microstructured film is prepared by vacuum secondary templating to separately and sequentially prepare PDMS films having a secondary microstructure and a primary microstructure, the preparation method specifically comprising:
s1, obtaining a PDMS film with a secondary microstructure through a secondary microstructure template; s2, attaching the PDMS film with the secondary microstructure on the PMMA template with the primary microstructure of the porous array, opening vacuum, bending and sinking the PDMS film with the secondary microstructure under the action of pressure difference, spin-coating the surface of the sinking PDMS film, and finally solidifying and stripping to obtain the finished film.
5. The multi-stage microstructured film of claim 4, wherein in step S2, a hollowed-out PDMS film is attached to the back of the secondary microstructured template.
6. The multi-stage microstructured film of claim 4, wherein the preparation of the secondary microstructured template: the secondary microstructure template with the surface provided with the negative conical protrusions is obtained by casting the surface of the bionic material.
7. A sensing layer for a sensor, characterized in that it is a multi-stage microstructured film according to any of claims 1-6 coated with a conductive layer.
8. A wearable flexible sensor comprising, in order from top to bottom, a packaging layer, an intermediate layer, and an electrode-bearing bottom layer, wherein the intermediate layer comprises the sensitive layer of claim 7.
9. The flexible sensor of claim 8, wherein the multi-level microstructured film packaging layer is a flexible transparent film made of one of polyethylene terephthalate, polycarbonate, and polyurethane; the thickness of the packaging layer is 25-50 mu m, and one side of the packaging layer is provided with glue; the bottom layer is a PI film with one side printed with interdigital electrodes; the conductive material of the conductive layer is one of titanium carbide nano-sheets or carbon nano-tubes.
10. The flexible sensor of claim 8, further comprising a spacer layer disposed below the sensitive layer for supporting the sensitive layer, the spacer layer having an inner diameter equal to an outer diameter of the sensitive layer; the spacer layer thickness is equal to the sensitive layer thickness.
CN202310359593.XA 2023-04-06 2023-04-06 Multistage microstructure film for sensor and wearable flexible sensor Pending CN116295970A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118243262A (en) * 2024-04-11 2024-06-25 浙江大学 Manufacturing method of curved surface microstructure flexible pressure sensor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118243262A (en) * 2024-04-11 2024-06-25 浙江大学 Manufacturing method of curved surface microstructure flexible pressure sensor

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