Intelligent insole based on multi-layer double-sided microstructure flexible piezoresistive sensor and preparation method

Abstract

The invention relates to an intelligent insole based on a multi-layer double-sided microstructure flexible piezoresistive sensor and a preparation method, belongs to the technical field of flexible sensors, and solves the technical problems of insufficient portability, higher cost, insufficient dynamic detection, poor individual difference adaptability, more complex data analysis and the like of existing foot detection equipment. According to the solution, the intelligent insole based on the multi-layer double-sided microstructure flexible piezoresistive sensors comprises a pair of insole bodies with symmetrical structures, a plurality of flexible piezoresistive sensors and a monitoring circuit; the preparation method of the intelligent insole comprises the following steps: 1) designing the insole main body; (2) preparing a PDMS-graphene sensitive layer; (3) preparing an Ag-PDMS conductive film sensitive layer; 4) preparing a flexible piezoresistive sensor; and 5) preparing the intelligent insole. Compared with the prior art, the method has the advantages of low manufacturing cost, convenience, rapidness, improvement of individual difference adaptability, improvement of dynamic detection capability and the like.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensor technology, specifically relating to a smart insole based on a multilayer double-sided microstructure flexible piezoresistive sensor and its preparation method. Background Technology

[0002] With changing lifestyles and an aging society, health monitoring is receiving increasing attention, and foot monitoring is a particularly important part of health surveillance. Plantar pressure distribution reflects the interaction between the foot and the ground when the body is standing, walking, and exercising.

[0003] Currently, mainstream foot health testing technologies mainly include foot morphology measurement, foot imaging examination, and foot nerve function testing. Foot morphology measurement primarily uses 3D scanning or traditional measuring tools to obtain morphological parameters such as the length, width, height, and arch height of the foot. Abnormal foot morphology may be associated with various diseases, such as flat feet and high arches. Foot imaging examination mainly uses imaging techniques such as X-rays, CT scans, and MRI scans to obtain the structure of the foot's bones, joints, and soft tissues, used to diagnose diseases such as fractures, arthritis, and tumors. Foot nerve function testing mainly uses electrophysiological examinations, such as nerve conduction velocity measurement, to assess the functional status of the foot's nerves, which helps in the diagnosis of diseases such as diabetes and neuropathy.

[0004] Currently, these detection technologies generally suffer from several drawbacks: insufficient device portability (the devices are large and heavy, making them inconvenient for outdoor or primary healthcare settings); complex data analysis (the analysis and processing of collected foot data can be complex, requiring professional interpretation, and the results may be subjective); high cost (advanced foot detection technologies and equipment are typically expensive, limiting their widespread adoption); insufficient dynamic detection (current technologies may not be adequate for assessing foot function and changes during movement); and poor adaptability to individual differences (different people have significant differences in foot morphology and physiological characteristics, and some detection technologies may not be well adapted to individual differences). Summary of the Invention

[0005] In order to overcome the shortcomings of existing technologies and solve the technical problems of insufficient portability, high cost, insufficient dynamic detection, poor adaptability to individual differences, and complex data analysis of existing foot detection devices, this invention provides a smart insole based on a multi-layer double-sided microstructure flexible piezoresistive sensor and its preparation method.

[0006] The present invention is achieved through the following technical solutions.

[0007] This invention provides a smart insole based on a multilayer double-sided microstructure flexible piezoresistive sensor, comprising a pair of structurally symmetrical insole bodies, several flexible piezoresistive sensors, and a monitoring circuit.

[0008] The insole body has several through holes, and a flexible piezoresistive sensor is installed at each of the through holes.

[0009] The flexible piezoresistive sensor comprises, from top to bottom, a first PDMS encapsulation layer, a first interdigital electrode layer, a PDMS-graphene sensitive layer, an Ag-PDMS conductive film sensitive layer, a second interdigital electrode layer, and a second PDMS encapsulation layer; the PDMS-graphene sensitive layer is a PDMS-graphene composite film with a double-sided sandpaper microstructure, and the Ag-PDMS conductive film sensitive layer is an Ag-PDMS conductive film with a double-sided lotus leaf biomimetic microstructure.

[0010] The monitoring circuit is located below the insole body. The monitoring circuit includes a signal conditioning circuit and a data acquisition circuit. The input terminal of the signal conditioning circuit is electrically connected to the signal output terminal of the flexible piezoresistive sensor. The output terminal of the signal conditioning circuit is electrically connected to the input terminal of the data acquisition circuit. The output terminal of the data acquisition circuit is electrically connected to a computer.

[0011] Furthermore, the main body of the insole is made of memory foam.

[0012] Furthermore, the upper surface of the insole body matches the human body structure, the bottom surface of the insole body matches the internal bottom structure of the shoe, and the bottom surface of the insole body is an arc surface.

[0013] Furthermore, the through holes include toe through holes, two sole through holes, arch through holes, and heel through holes.

[0014] Furthermore, both the first PDMS encapsulation layer and the second PDMS encapsulation layer are made of PDMS thin film material.

[0015] Furthermore, both the first interdigital electrode layer and the second interdigital electrode layer are made of Cu interdigital electrode material.

[0016] Furthermore, a method for fabricating a smart insole based on a multilayer double-sided microstructure flexible piezoresistive sensor includes the following steps:

[0017] 1) Design the main body of the insole:

[0018] The shape and size of the insole body are designed using memory foam material based on common shoe sizes;

[0019] 2) Preparation of PDMS-graphene sensitive layer;

[0020] 3) Preparation of Ag-PDMS conductive film sensitive layer;

[0021] 4) Fabrication of flexible piezoresistive sensors:

[0022] A flexible piezoresistive sensor is obtained by stacking a PDMS-graphene sensitive layer and an Ag-PDMS conductive film sensitive layer together, placing a first interdigital electrode layer and a second interdigital electrode layer on top of the PDMS-graphene sensitive layer and below the Ag-PDMS conductive film sensitive layer, respectively. Both the first and second interdigital electrode layers are connected to wires. A first PDMS encapsulation layer and a second PDMS encapsulation layer are encapsulated from above the first interdigital electrode layer and below the second interdigital electrode layer, respectively.

[0023] 5) Fabrication of smart insoles:

[0024] Several flexible piezoresistive sensors are placed in the through holes of the insole body, and a monitoring circuit is set at the bottom of the insole body to finally assemble the smart insole.

[0025] Furthermore, the preparation method of the PDMS-graphene sensitive layer in step 2) is as follows:

[0026] PDMS potting compound and SK-184 curing agent were mixed at a mass ratio of PDMS potting compound: SK-184 curing agent = 10:1. After adding graphene and alcohol, the mixture was stirred for 20 minutes and then subjected to ultrasonic cleaning for 30 minutes to obtain a PDMS-graphene mixture.

[0027] The PDMS-graphene mixture was immersed in a saturated NaCl solution, stirred for 10 minutes and subjected to ultrasonic cleaning for 30 minutes to obtain a PDMS-graphene mixture containing Na ions and Cl ions.

[0028] A PDMS-graphene mixture containing Na and Cl ions was pressed onto the top and bottom surfaces of two 80CW sandpapers with the same force to form a 2mm thick mixture. The mixture was then cured in a 90℃ curing oven for 15 minutes to obtain a PDMS-graphene sensitive layer.

[0029] Furthermore, the preparation method of the Ag-PDMS conductive film sensitive layer in step 3) is as follows:

[0030] After washing and drying, the lotus leaf with the side containing the microstructure facing up is fixed in a silicone mold. The epoxy resin prepolymer and the first curing agent are mixed at a mass ratio of epoxy resin prepolymer: first curing agent = 3:1. After stirring for 10 minutes and vibrating in an ultrasonic cleaner for 10 minutes, the mixture is placed on the lotus leaf and cured at room temperature for 20 hours. After curing, the lotus leaf is peeled off to obtain two epoxy resin molds with opposite microstructures.

[0031] PDMS and the second curing agent were mixed at a mass ratio of PDMS: second curing agent = 10:1. After stirring for 20 minutes and vibrating in an ultrasonic cleaner for 30 minutes, the mixture was placed on an epoxy resin mold. Another epoxy resin mold was placed upside down on top of the epoxy resin mold and placed in an 80°C curing oven for 2 hours. After curing, the double-sided microstructure n-PDMS was obtained by peeling it off from the epoxy resin mold.

[0032] The double-sided microstructured n-PDMS was washed and dried, and then Ag metal was deposited on the double-sided microstructured n-PDMS to prepare a flexible electrode, thus obtaining the Ag-PDMS conductive film sensitive layer.

[0033] The beneficial effects achieved by this invention are as follows: This invention uses a first PDMS encapsulation layer, a first interdigital electrode layer, a PDMS-graphene sensitive layer, an Ag-PDMS conductive film sensitive layer, a second interdigital electrode layer, and a second PDMS encapsulation layer, forming an innovative sandwich structure for a flexible piezoresistive sensor. The PDMS-graphene mixture is immersed in a saturated NaCl solution, which enhances the sensitivity of the PDMS-graphene sensitive layer, ultimately enabling the flexible piezoresistive sensor to maintain high sensitivity and linear response within the pressure range. The insole body is made of memory foam with elastic mechanical properties, improving wearing comfort. The insole body, several flexible piezoresistive sensors, and monitoring circuitry result in a simple structure and low manufacturing cost. The flexible piezoresistive sensors can also provide real-time monitoring data from multiple locations, improving dynamic detection capabilities and solving the problem of individual variation adaptability.

[0034] Compared with existing technologies, this invention has the advantages of low manufacturing cost, convenience and speed, improved adaptability to individual differences, and enhanced dynamic detection capabilities. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the flexible piezoresistive sensor structure of the present invention;

[0036] Figure 2 This is a schematic diagram of the PDMS-graphene sensitive layer structure of the present invention;

[0037] Figure 3 This is a schematic diagram of the Ag-PDMS conductive film sensitive layer structure of the present invention;

[0038] Figure 4 This is a schematic diagram showing the distribution of the flexible piezoresistive sensor of the present invention on the insole body.

[0039] In the figure: 1. Insole body; 2. Flexible piezoresistive sensor; 3. Through hole; 3-1. Toe through hole; 3-2. Sole through hole; 3-3. Arch through hole; 3-4. Heel through hole; 4. First PDMS encapsulation layer; 5. First interdigital electrode layer; 6. PDMS-graphene sensitive layer; 7. Ag-PDMS conductive film sensitive layer; 8. Second interdigital electrode layer; 9. Second PDMS encapsulation layer. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0041] like Figures 1 to 4 As shown, a smart insole based on a multi-layered double-sided microstructure flexible piezoresistive sensor includes a pair of structurally symmetrical insole bodies 1, several flexible piezoresistive sensors 2, and a monitoring circuit.

[0042] The left and right insole bodies 1 are designed symmetrically according to the structure of the human foot. Each insole body 1 is made of memory foam, which has elastic mechanical properties, enhancing comfort. The upper surface of each insole body 1 matches the human body structure, ensuring comfort. The bottom surface of each insole body 1 matches the internal structure of the shoe, and is a rounded surface for better fit within the shoe. Each insole body 1 has several through holes 3, including a toe hole 3-1, two ball-of-the-foot holes 3-2, an arch hole 3-3, and a heel hole 3-4. Flexible piezoresistive sensors 2 are installed at each through hole 3, allowing real-time measurement of pressure distribution at the toe, ball, arch, and heel.

[0043] The flexible piezoresistive sensor 2 includes, from top to bottom, a first PDMS encapsulation layer 4, a first interdigitated electrode layer 5, a PDMS-graphene sensitive layer 6, an Ag-PDMS conductive film sensitive layer 7, a second interdigitated electrode layer 8, and a second PDMS encapsulation layer 9. Both the first PDMS encapsulation layer 4 and the second PDMS encapsulation layer 9 are made of PDMS thin film. PDMS thin film has good light transmittance, strong biocompatibility, and is easily bonded to various materials at room temperature. It also has good elasticity and resilience, and high dielectric properties, resulting in good electrostatic adsorption and adhesion between the first PDMS encapsulation layer 4 and the second PDMS encapsulation layer 9, thus improving the encapsulation effect. Both the first interdigitated electrode layer 5 and the second interdigitated electrode layer 8 are made of Cu interdigitated electrode material and are customized using screen printing technology. The first interdigitated electrode layer 5 and the second interdigitated electrode layer 8 are used to increase the contact area with the PDMS-graphene sensitive layer 6 and the Ag-PDMS conductive film sensitive layer 7. The PDMS-graphene sensitive layer 6 is a PDMS-graphene composite film with a double-sided sandpaper microstructure, and the Ag-PDMS conductive film sensitive layer 7 is an Ag-PDMS conductive film with a double-sided lotus leaf biomimetic microstructure. The final flexible piezoresistive sensor 2 is a composite sensing unit with a multi-layered double-sided microstructure, using PDMS as a flexible substrate and graphene and silver target as active materials. Graphene exhibits the best conductivity at room temperature, high compatibility with the steady-state environment within the human body, and good thermal conductivity. Simultaneously, graphene has a high specific surface area, and its resistance is prone to phased changes. Furthermore, compared to single-layer microstructures, multi-layered double-sided microstructures play a crucial role in distributing pressure loads and improving the compressibility of the structure. The change in contact area and the increase in effective stress distribution between stacked layers enable the multi-layered double-sided microstructure to maintain its high sensitivity and linear response over a wide pressure range.

[0044] The monitoring circuit is located below the insole body 1. It collects and monitors real-time plantar pressure information. The monitoring circuit includes a signal conditioning circuit and a data acquisition circuit. The input terminal of the signal conditioning circuit is electrically connected to the signal output terminal of the flexible piezoresistive sensor 2. The output terminal of the signal conditioning circuit is electrically connected to the input terminal of the data acquisition circuit. The output terminal of the data acquisition circuit is electrically connected to a computer, and the data is ultimately analyzed by software.

[0045] A method for fabricating a smart insole based on a multilayer double-sided microstructure flexible piezoresistive sensor includes the following steps:

[0046] 1) Design of the main body of the insole:

[0047] The shape and size of the insole body 1 are designed based on memory foam material selected according to common shoe sizes, and the memory foam material enhances the comfort of the insole body 1.

[0048] 2) Preparation of PDMS-graphene sensitive layer 6:

[0049] PDMS potting compound and SK-184 curing agent were mixed at a mass ratio of PDMS potting compound: SK-184 curing agent = 10:1. After adding graphene and alcohol, the mixture was manually stirred for 20 minutes and then subjected to ultrasonic cleaning machine vibration for 30 minutes to ensure that the graphene and PDMS were uniformly mixed to obtain a PDMS-graphene mixture.

[0050] The PDMS-graphene mixture was immersed in a saturated NaCl solution, and the macromolecules were manually stirred for 10 minutes and the small molecules were oscillated and mixed using an ultrasonic cleaner for 30 minutes to obtain a PDMS-graphene mixture containing Na ions and Cl ions.

[0051] A PDMS-graphene mixture containing Na and Cl ions was pressed onto the top and bottom surfaces of two 80CW sandpapers with the same force to form a 2mm thick mixture. This mixture was then cured in a 90℃ curing oven for 15 minutes to obtain the PDMS-graphene sensitive layer 6. Na and Cl ions from the saturated NaCl solution adhere to the surface of the PDMS-graphene sensitive layer 6 or penetrate into its interior, providing more carriers for charge movement and making it easier for current to pass through, ultimately resulting in improved conductivity. The PDMS-graphene sensitive layer 6 has a surface microstructure, and immersion in the saturated NaCl solution enhances its sensitivity, ultimately enabling the flexible piezoresistive sensor 2 to maintain high sensitivity and linear response within the pressure range.

[0052] 3) Preparation of Ag-PDMS conductive film sensitive layer 7:

[0053] After washing the lotus leaf three times with deionized water and air-drying it naturally, the side with the microstructure facing up was fixed in a silicone mold. The epoxy resin prepolymer and the first curing agent were mixed at a mass ratio of epoxy resin prepolymer: first curing agent = 3:1. After stirring for 10 minutes and vibrating in an ultrasonic cleaner for 10 minutes, the mixture was placed on the lotus leaf and cured at room temperature for 20 hours. After curing, the lotus leaf was peeled off to obtain two epoxy resin molds with opposite microstructures, so that the final Ag-PDMS conductive film sensitive layer 7 has a lotus leaf biomimetic microstructure.

[0054] PDMS and the second curing agent were mixed at a mass ratio of PDMS: second curing agent = 10:1. After stirring for 20 minutes and vibrating in an ultrasonic cleaner for 30 minutes, the mixture was placed on an epoxy resin mold. Another epoxy resin mold was placed upside down on top of the epoxy resin mold and placed in an 80°C curing oven for 2 hours. After curing, the double-sided microstructure n-PDMS was obtained by peeling it off from the epoxy resin mold.

[0055] The double-sided microstructure n-PDMS was washed with alcohol in an ultrasonic cleaner to remove fine impurities, and then dried at room temperature. The Ag-PDMS conductive film sensitive layer 7 was obtained by preparing a flexible electrode on the double-sided microstructure n-PDMS using a magnetron sputtering coating machine.

[0056] 4) Fabrication of a flexible piezoresistive sensor 2:

[0057] A PDMS-graphene sensitive layer 6 and an Ag-PDMS conductive film sensitive layer 7 are stacked together. A first interdigital electrode layer 5 and a second interdigital electrode layer 8 are placed on top of the PDMS-graphene sensitive layer 6 and below the Ag-PDMS conductive film sensitive layer 7, respectively, to increase the contact area between the first and second interdigital electrode layers 5 and the top of the PDMS-graphene sensitive layer 6 and the Ag-PDMS conductive film sensitive layer 7, respectively. Both the first and second interdigital electrode layers 5 and 8 are connected to wires. A first PDMS encapsulation layer 4 and a second PDMS encapsulation layer 9 are encapsulated from above the first interdigital electrode layer 5 and below the second interdigital electrode layer 8, respectively, to obtain a "sandwich" type flexible piezoresistive sensor 2. The first PDMS encapsulation layer 4 and the second PDMS encapsulation layer 9 also serve to protect the internal structure.

[0058] 5) Fabrication of smart insoles:

[0059] Several flexible piezoresistive sensors 2 are placed in the through holes 3 of the insole body 1, and a monitoring circuit is set at the bottom of the insole body 1. Finally, the smart insole is assembled.

[0060] The insole body 1, several flexible piezoresistive sensors 2, and monitoring circuit are selected. The structure is simple and the manufacturing cost is low. The flexible piezoresistive sensors 2 can also provide real-time monitoring data from multiple locations, improving dynamic detection capabilities and solving the problem of individual difference adaptability.

[0061] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, modifications can still be made to the embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An intelligent insole based on a multilayer double-sided microstructured flexible piezoresistive sensor, characterized in that: It comprises a pair of structurally symmetrical insole bodies (1), a plurality of flexible piezoresistive sensors (2) and a monitoring circuit; A plurality of through holes (3) are arranged on the insole body (1), and the flexible piezoresistive sensors (2) are arranged on the through holes (3); The flexible piezoresistive sensor (2) comprises, from top to bottom, a first PDMS packaging layer (4), a first interdigital electrode layer (5), a PDMS-graphene sensitive layer (6), an Ag-PDMS conductive film sensitive layer (7), a second interdigital electrode layer (8) and a second PDMS packaging layer (9); the PDMS-graphene sensitive layer (6) is a double-sided sandpaper microstructure PDMS-graphene composite film, and the Ag-PDMS conductive film sensitive layer (7) is a double-sided lotus leaf bionic microstructure Ag-PDMS conductive film; The monitoring circuit is arranged below the insole body (1), and the monitoring circuit comprises a signal conditioning circuit and a data acquisition circuit, the input end of the signal conditioning circuit is electrically connected with the signal output end of the flexible piezoresistive sensor (2), the output end of the signal conditioning circuit is electrically connected with the input end of the data acquisition circuit, and the output end of the data acquisition circuit is electrically connected with a computer.

2. The smart insole based on multi-layer double-sided microstructure flexible piezoresistive sensor according to claim 1, characterized in that: The insole body (1) is made of memory cotton. 3.The smart insole based on the multilayer double-sided microstructure flexible piezoresistive sensor of claim 1, characterized in that: The upper surface of the insole body (1) is matched with the human body structure, the bottom surface of the insole body (1) is matched with the internal bottom surface structure of the shoe, and the bottom surface of the insole body (1) is a circular arc surface.

4. The smart insole based on multilayer double-sided microstructure flexible piezoresistive sensor according to claim 1, characterized in that: The through hole (3) comprises a toe through hole (3-1), two metatarsal through holes (3-2), an arch through hole (3-3) and a heel through hole (3-4).

5. The smart insole based on multilayer double-sided microstructured flexible piezoresistive sensors according to claim 1, characterized in that: The first PDMS packaging layer (4) and the second PDMS packaging layer (9) are both PDMS film materials.

6. The smart insole based on multilayer double-sided microstructured flexible piezoresistive sensors according to claim 1, characterized in that: The first interdigital electrode layer (5) and the second interdigital electrode layer (8) are both Cu interdigital electrode materials.

7. A method of manufacturing a smart insole based on a multilayer double-sided microstructured flexible piezoresistive sensor according to claim 1, characterized in that: It comprises the following steps: 1) Design the insole body (1): According to the common shoe size, the shape and size of the insole body (1) are designed by selecting the memory cotton material; 2) Prepare the PDMS-graphene sensitive layer (6); 3) Prepare the Ag-PDMS conductive film sensitive layer (7); 4) Prepare the flexible piezoresistive sensor (2): Stack the PDMS-graphene sensitive layer (6) and the Ag-PDMS conductive film sensitive layer (7) together, place the first interdigital electrode layer (5) and the second interdigital electrode layer (8) on the upper surface of the PDMS-graphene sensitive layer (6) and the lower surface of the Ag-PDMS conductive film sensitive layer (7) respectively, and connect the first interdigital electrode layer (5) and the second interdigital electrode layer (8) with wires, and then encapsulate the first PDMS packaging layer (4) and the second PDMS packaging layer (9) from above the first interdigital electrode layer (5) and below the second interdigital electrode layer (8) respectively to obtain the flexible piezoresistive sensor (2); 5) Prepare the intelligent insole: Arrange a plurality of flexible piezoresistive sensors (2) in the through holes (3) of the insole body (1), arrange the monitoring circuit below the insole body (1), and finally assemble the intelligent insole.

8. The preparation method of the smart insole based on the multilayer double-sided microstructure flexible piezoresistive sensor according to claim 7, characterized in that: The preparation method of the PDMS-graphene sensitive layer (6) in step 2) is: The PDMS potting adhesive and the SK-184 curing agent are mixed according to a mass ratio of PDMS potting adhesive:SK-184 curing agent=10:1, and after the graphene and alcohol are continuously added, stirring is performed for 20 min and ultrasonic cleaner oscillation is performed for 30 min to obtain a PDMS-graphene mixture; The PDMS-graphene mixture is soaked in a saturated NaCl solution, stirring is performed for 10 min and ultrasonic cleaner oscillation is performed for 30 min to obtain a PDMS-graphene mixture containing Na ions and Cl ions; The PDMS-graphene mixture containing Na ions and Cl ions is pressed on the upper and lower surfaces by two 80CW sandpapers at the same force to form a mixture with a thickness of 2 mm, and then placed in a curing oven at 90°C for curing for 15 min to obtain a PDMS-graphene sensitive layer (6).

9. The preparation method of the smart insole based on the multilayer double-sided microstructure flexible piezoresistive sensor according to claim 7, characterized in that: The preparation method of the Ag-PDMS conductive film sensitive layer (7) in step 3) is as follows: The lotus leaf sheet after washing and air drying is fixed with the side having microstructures facing upward in a silica gel mold, epoxy resin prepolymer and a first curing agent are mixed according to a mass ratio of epoxy resin prepolymer: first curing agent=3:1, stirring is performed for 10 min and ultrasonic cleaner oscillation is performed for 10 min, and then placed on the lotus leaf sheet for curing at room temperature for 20 h, after the curing is completed, the lotus leaf is peeled off to obtain two epoxy resin molds with reverse microstructures; PDMS and a second curing agent are mixed according to a mass ratio of PDMS: second curing agent=10:1, stirring is performed for 20 min and ultrasonic cleaner oscillation is performed for 30 min, and then placed on one epoxy resin mold, the upper surface of the epoxy resin mold is reversely placed on another epoxy resin mold, and placed in an 80°C curing oven for curing for 2 h, after the curing is completed, the double-sided microstructure n-PDMS is peeled off from the epoxy resin mold. The double-sided microstructure n-PDMS is washed and air dried, a flexible electrode is prepared by magnetron sputtering on the double-sided microstructure n-PDMS to obtain an Ag-PDMS conductive film sensitive layer (7).

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