A viscoelastic adjustable biomimetic flexible sensor with frequency selection function and a preparation method thereof

Abstract

The application discloses a kind of viscoelastic adjustable biomimetic flexible sensors with frequency selection function and preparation method thereof, it is related to flexible sensor technical field, viscoelastic adjustable biomimetic flexible sensor is sequentially from top to bottom by high elastic stable variable layer, vibration transmission layer and frequency identification layer three parts, high elastic stable variable layer is placed in the top and bottom of flexible sensor, and the contact surface with vibration transmission layer and frequency identification layer is the electrode layer prepared by spin coating process etc., can provide stable safe stress interface in vibration process and play the protection effect of dustproof, anti-interference signal.Vibration transmission layer includes high elasticity microspine conductive film and high elasticity micro-arch conductive film, and the two are connected in the direction of microstructure opposite direction, wherein microspine structure and micro-arch structure section axis coincide, in the process of stress, by the interface regulation of flexible microstructure, play the role of amplifying vibration effect and accurate force transmission.Frequency identification layer is tunable viscoelastic conductive sponge, made of polyester sponge and conductive suspension liquid, by adjusting the thickness of polyester sponge and the ratio and type of conductive particles in suspension liquid, change the response-relaxation time of conductive sponge to multi-frequency vibration, realize the identification and on-demand control of vibration frequency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible sensors, in particular to a viscoelastic adjustable bionic flexible sensor with frequency selection function and a preparation method thereof. BACKGROUND

[0002] The mixed load application frequency will cause the superposition of sensor signals and noise interference, affecting the system integration and detection accuracy of the sensor, therefore, it is urgent to improve the vibration frequency recognition function of the sensor. However, the design and manufacture of the current multi-layer flexible sensor mostly focus on improving the sensitivity, and the function research for vibration frequency recognition is still insufficient. In nature, arachnida, such as spiders and scorpions, has excellent vibration perception function. They have excellent recognition and selectivity ability for vibration frequency, can perceive weak signals through the crack structure and mucus on their body surface, and the viscoelastic keratin pad under the crack as a vibration frequency damper can cause specific phase change for different frequencies, thereby selectively filtering vibrations of different frequencies and identifying the key vibration information.

[0003] Based on this, the present application innovatively provides a viscoelastic adjustable bionic flexible sensor, which can effectively screen the vibration signals of non-target frequency by changing the adjustable parameters of the conductive sponge and analyzing the corresponding response-relaxation time, realize the function coupling and efficiency maximization of the super-sensitive perception and selective identification of the sensor, thereby inhibiting the noise and simplifying the signal processing, achieving the effect of improving the measurement accuracy and improving the system efficiency, and having important and broad application prospect. SUMMARY

[0004] In view of the above shortcomings of the prior art, the present application aims to provide a viscoelastic adjustable bionic flexible sensor with frequency selection function and a preparation method thereof, which can increase the signal-to-noise ratio of the multi-layer flexible sensor, effectively screen the vibration signals of non-target frequency, improve the anti-interference ability of the sensor, and optimize the accuracy and reliability of the data.

[0005] A viscoelastic adjustable bionic flexible sensor with frequency selection function, comprising a high-elastic stable variable layer, a vibration transmission layer and a frequency recognition layer.

[0006] The high-elastic stable variable layer is arranged at the top and bottom of the flexible sensor, the vibration transmission layer and the frequency recognition layer are arranged between the two high-elastic stable variable layers, the vibration transmission layer is located at the upper part, and the frequency recognition layer is located at the lower part.

[0007] The high-elastic stable layer is made of flexible material by high-temperature baking or chemical accumulation curing, and includes an external high-elastic stable layer and an internal high-elastic stable layer conductive layer, the internal high-elastic stable layer conductive layer is an electrode layer, and is prepared by one of electrochemical deposition, vapor deposition or spin coating method, and leads out a wire between the contact surface of the vibration transmission layer and the frequency identification layer;

[0008] The flexible material is one of polydimethylsiloxane (PDMS), polyurethane elastomer (TPU), silicone rubber (SR), polypropylene film (PP) and polyvinyl chloride (PVC).

[0009] The vibration transmission layer includes a high-elastic micro-spine conductive layer and a high-elastic micro-arch conductive layer, the high-elastic micro-spine conductive layer is uniformly provided with single-sided hemispherical microstructures, the high-elastic micro-arch conductive layer is uniformly provided with single-sided arch-shaped protruding microstructures, the single-sided hemispherical microstructures are connected to the single-sided arch-shaped protruding microstructures in opposition, the central axes of the single-sided hemispherical microstructures and the single-sided arch-shaped protruding microstructures coincide, and the spine-arch surface combined structure between the upper and lower microstructures can realize the effect enhancement effect of weak vibration and reduce the micro-vibration perception threshold.

[0010] The high-elastic micro-spine conductive layer and the high-elastic micro-arch conductive layer have a size of 20mm×20mm×1mm, and the hemispherical diameter and the arch-shaped protruding diameter are 100μm.

[0011] The frequency identification layer is a tunable viscoelastic conductive sponge, which is made of polyester sponge and conductive suspension liquid, wherein the geometric parameters of the polyester sponge and the ratio of the conductive solution are adjustable parameters, the polyester sponge has an open porous structure with high compressibility and high resilience, and can realize sufficient filling of conductive particles; the mechanical signal is converted into an electrical signal through the whole-fracture of the conductive particles on the surface of the conductive sponge and the contact-separation between the particles, and the frequency selectivity function is achieved by detecting the response-relaxation speed.

[0012] The internal high-elastic stable layer conductive layer, the high-elastic micro-spine conductive layer, the high-elastic micro-arch conductive layer and the tunable viscoelastic conductive sponge are connected by one of conductive silver paste, carbon black glue, high-temperature resistant red glue and liquid conductive polymer through one of high-temperature baking, ultraviolet irradiation and laser curing.

[0013] A preparation method of a viscoelastic tunable bionic flexible sensor with frequency selection function, comprising the following steps:

[0014] Step one, preparation of the vibration transmission layer

[0015] 1. High-elastic micro-spine conductive layer and high-elastic micro-arch layer mold preparation:

[0016] The high-elasticity micro-spine conductive layer and the high-elasticity micro-arch conductive layer have a size of 2 mm*20 mm*1 mm, and have single-face hemispherical and arch-shaped protruding structures on the surfaces, and the cross-section diameter of each structure is 100 microns, and the interval between every two structures is 100 microns;

[0017] The resin mold is manufactured by using a 3D printing method, the mold has a size of 30 mm*30 mm*3 mm, and has the reverse structure of the high-elasticity micro-spine conductive film and the high-elasticity micro-arch conductive film, and the surface of the mold is polished smooth by using fine sandpaper;

[0018] 2. Preparation of the conductive elastomer solution:

[0019] 1 g of carbon nanotubes MWCNT with a diameter of 8-15 nm and a length of 3-12 microns and 1 g of carbon black CB with a particle size of 40 nm are added to 20 g of a toluene solvent, and then 0.02 g of carboxymethyl cellulose CMC is added to uniformly disperse the conductive particles in the solvent;

[0020] The above solution is stirred at room temperature for 30 min by using a magnetic stirrer, 15 g of a polydimethylsiloxane PDMS reagent main agent and 8 g of methyl silicone oil are added, the methyl silicone oil serves to increase the flexibility of the composite material, the magnetic stirrer is set to 40 DEG C, and stirring is performed for 2 h;

[0021] After the mixed solution is taken out and cooled to room temperature, 1.5 g of a polydimethylsiloxane PDMS reagent curing agent is added, and the mixed solution is stirred at room temperature for 2 h by using a magnetic stirrer;

[0022] After the reagents are uniformly mixed, the mixed solution is placed in a vacuum air extractor, and air is extracted for 20 min to remove the air bubbles in the solution, so as to prepare the conductive elastomer solution;

[0023] 3. Preparation of the high-elasticity micro-spine conductive layer and the high-elasticity micro-arch layer

[0024] The above conductive solution is poured into the resin mold with the reverse structure of the high-elasticity micro-spine conductive layer and the high-elasticity micro-arch conductive layer, and after the solution surface is uniform and free of air bubbles for 20 min, the solution is sent into an 80 DEG C oven for baking for 3 h, and after being cooled to room temperature, the solution is demolded, so as to prepare the high-elasticity conductive film;

[0025] The above conductive solution is poured into the resin mold with the high-elasticity micro-spine conductive layer, and after the solution surface is uniform and free of air bubbles for 20 min, the solution is sent into an 80 DEG C oven for baking for 3 h, and after being cooled to room temperature, the solution is demolded, so as to prepare the high-elasticity micro-spine conductive layer;

[0026] Step two, preparation of the high-elasticity stable variable layer:

[0027] The high-elasticity stable variable layer has a size of 24 mm*24 mm*0.5 mm, and the surface is free of microstructures;

[0028] The polydimethylsiloxane PDMS is mixed uniformly at a ratio of 10:1, placed in a vacuum air extractor, and air extracted for 20 min to remove the air bubbles in the solution, and then the solution is poured into a resin mold with a PDMS film structure, and then sent into a 100 DEG C oven for baking for 2h, and then demolded after cooling to room temperature;

[0029] The spin coater is set to a rotation speed of 2000r / min, and the conductive silver layer is uniformly coated on one side of the high-elasticity stable variable layer by spin coating for 60s, so as to prepare the high-elasticity stable variable layer and the conductive layer thereof;

[0030] Step three, preparation of the tunable viscoelastic conductive sponge:

[0031] The melamine sponge is cut to a size of 16mm*16mm*5mm, ultrasonically cleaned in anhydrous ethanol for 20 min, and then ultrasonically cleaned in pure water for 20 min after the anhydrous ethanol is squeezed clean with a cotton cloth, and then placed in a desiccator for room temperature drying;

[0032] 0.02g of carboxymethyl cellulose CMC is added to 20ml of pure water, stirred and dissolved for 20 min, 0.15g of carbon nanotubes MWCNT and 0.15g of carbon black CB are added, and the mixture is uniformly mixed by stirring at room temperature for 30 min using a magnetic stirrer, so as to prepare a conductive suspension;

[0033] The sponge is completely immersed in the conductive suspension, heated in a 120 DEG C water bath for 3h, and then taken out and placed in a 60 DEG C desiccator for baking for 3h until it is completely dried, so as to prepare the tunable viscoelastic conductive sponge;

[0034] Step four, packaging:

[0035] The structure of the flexible sensor is packaged in the order of the high-elasticity stable variable layer, the vibration transmission layer and the frequency identification layer, the conductive copper wire is connected at the center position of the conductive layer of the high-elasticity stable variable layer, and the conductive silver paste is used as the adhesive until the conductive silver paste is dry, so as to prepare the viscoelastic adjustable bionic flexible sensor with frequency selectivity.

[0036] The beneficial effects of the present application are:

[0037] The application provides a viscoelastic adjustable biomimetic flexible sensor with a frequency selection function and a preparation method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0038] Fig. 1 It is a structural schematic diagram of the application;

[0039] Fig. 2 It is an exploded view of the application;

[0040] Fig. 3 It is a front view of the application;

[0041] Fig. 4 It is a microstructure diagram of the high-elasticity microspine conductive layer and the high-elasticity micro-arch conductive layer of the application. DETAILED DESCRIPTION

[0042] Referring to Figs. 1 to 4 Fig. 1 shows a viscoelastic adjustable biomimetic flexible sensor with a frequency selection function, which comprises a high-elasticity stable variable layer, a vibration transmission layer and a frequency identification layer;

[0043] The high-elasticity stable variable layer is arranged at the top and bottom of the flexible sensor, the vibration transmission layer and the frequency identification layer are arranged between the two high-elasticity stable variable layers, the vibration transmission layer is arranged at the upper part, and the frequency identification layer is arranged at the lower part;

[0044] The high-elasticity stable variable layer is made of a flexible material through high-temperature baking or chemical accumulation solidification, and comprises an external high-elasticity stable variable layer 10 and an internal high-elasticity stable variable layer conductive layer 50.

[0045] The flexible material is one of polydimethylsiloxane (PDMS), polyurethane elastomer (TPU), silicone rubber (SR), polypropylene film (PP) and polyvinyl chloride (PVC);

[0046] Specifically, the high-elasticity stable variable layer provides a stable and safe stress interface during vibration generation, and protects the vibration transmission layer and the frequency identification layer inside the viscoelastic adjustable biomimetic flexible sensor;

[0047] The vibration transmission layer includes a high-elasticity micro-spine conductive layer 20 and a high-elasticity micro-arch conductive layer 30, the high-elasticity micro-spine conductive layer 20 is uniformly provided with a single-sided hemispherical microstructure, the high-elasticity micro-arch conductive layer 30 is uniformly provided with a single-sided arch-shaped protruding microstructure, the single-sided hemispherical microstructure is connected to the single-sided arch-shaped protruding microstructure in opposition, the single-sided hemispherical microstructure and the single-sided arch-shaped protruding microstructure have coinciding central axes, the spine-camber combined structure between the upper and lower microstructures can realize the effect enhancement effect of weak vibration, and the micro-vibration perception threshold is reduced.

[0048] Specifically, the high-elasticity micro-spine conductive layer 20 and the high-elasticity micro-arch conductive layer 30 are made of one of polyaniline, polythiophene, polyphenylacetylene and polymer composite colloidal curable conductive material, and are solidified in a corresponding mold; the microstructures in the vibration transmission layer are opposite to each other at positions with coinciding central axes, and the interface regulation of the microstructures plays a role of amplifying vibration effect and accurately transmitting force.

[0049] The high-elasticity micro-spine conductive layer 20 and the high-elasticity micro-arch conductive layer 30 have a size of 20mm*20mm*1mm, and the diameters of the hemispherical and arch-shaped protruding structures are 100μm.

[0050] The frequency identification layer is a tunable viscoelastic conductive sponge 40, which is made of a polyester sponge and a conductive suspension liquid, wherein the geometric parameters of the polyester sponge and the ratio of the conductive solution are adjustable parameters, the polyester sponge has an open porous structure with high compressibility and high resilience, and can realize sufficient filling of conductive particles; the mechanical signal is converted into an electrical signal through the overall-fracture of the conductive particles on the surface of the conductive sponge and the contact-separation between the particles, and the frequency selectivity function is achieved by detecting the response-relaxation speed.

[0051] Specifically, the tunable viscoelastic conductive sponge 40 is made of one or more of silver nanoparticles Ag, carbon nanotubes MWCNT, carbon black CB and graphene GN conductive particles, and one of carboxymethyl cellulose CMC, cetyltrimethylammonium bromide CTAB and polyacrylamide PAM dispersant is mixed, and the conductive suspension liquid is prepared after uniform stirring in a solvent; one of polyvinyl alcohol sponge PVA, polyurethane sponge PU and melamine sponge is fully immersed in the conductive suspension liquid, and is fully dried by high-temperature baking, natural air drying and other methods.

[0052] The internal high-elasticity stable variable layer conductive layer 50, the high-elasticity micro-spine conductive layer 20, the high-elasticity micro-arch conductive layer 30 and the tunable viscoelastic conductive sponge 40 are connected by one of conductive silver paste, carbon black glue, high-temperature-resistant red glue and liquid conductive polymer tin paste, and are connected by one of high-temperature baking, ultraviolet irradiation and laser curing.

[0053] A method for preparing a viscoelastic adjustable biomimetic flexible sensor with frequency selection function, comprising the following steps:

[0054] Step one, preparation of vibration transmission layer

[0055] 1. Preparation of high-elasticity microspine conductive layer and high-elasticity micro-arch conductive layer mold:

[0056] The size of the high-elasticity microspine conductive layer and the high-elasticity micro-arch conductive layer is designed to be 2mm x 20mm x 1mm, and there are single-sided hemispherical and arched protruding structures on the surface, with a cross-sectional diameter of 100μm, and an interval of 100μm between every two structures;

[0057] A resin mold is manufactured using a 3D printing method, and the mold size is 30mm x 30mm x 3mm, which has the reverse structure of the high-elasticity microspine conductive film and the high-elasticity micro-arch conductive film, and the surface of the mold is polished smooth with fine sandpaper;

[0058] 2. Preparation of conductive elastomer solution:

[0059] 1g of carbon nanotube MWCNT with a diameter of 8-15nm and a length of 3-12μm, and 1g of carbon black CB with a particle size of 40nm are added to 20g of toluene solvent, and then 0.02g of carboxymethyl cellulose CMC is added to uniformly disperse the conductive particles in the solvent;

[0060] The above solution is stirred at room temperature for 30min using a magnetic stirrer, 15g of polydimethylsiloxane PDMS reagent main agent and 8g of methyl silicone oil are added, the methyl silicone oil serves to increase the flexibility of the composite material, the magnetic stirrer is set to 40℃, and stirring is performed for 2h;

[0061] The mixed solution is taken out and cooled to room temperature, 1.5g of polydimethylsiloxane PDMS reagent curing agent is added, and the magnetic stirrer is used to stir at room temperature for 2h;

[0062] After the reagents are uniformly mixed, the mixed solution is placed in a vacuum air extractor, and air is extracted for 20min to remove internal bubbles of the solution, thereby preparing a conductive elastomer solution;

[0063] 3. Preparation of high-elasticity microspine conductive layer and high-elasticity micro-arch layer

[0064] The above conductive solution is poured into the resin mold with the reverse structure of the high-elasticity microspine conductive layer and the high-elasticity micro-arch conductive layer, and after the solution surface is uniform and bubble-free for 20min, it is sent into an 80℃ oven for baking for 3h, and then demolded after cooling to room temperature, thereby preparing a high-elasticity conductive film;

[0065] The conductive solution is poured into a resin mold with the shape characteristics of the high-elasticity micro-spine conductive layer, and after the solution surface is uniform and free of bubbles after standing for 20 min, it is sent into an 80°C oven for baking for 3 h, and after cooling to room temperature, it is demolded to form the high-elasticity micro-spine conductive layer;

[0066] Step two, preparation of the high-elasticity stable variable layer:

[0067] The high-elasticity stable variable layer has a size of 24 mm x 24 mm x 0.5 mm and no microstructure on the surface;

[0068] The polydimethylsiloxane PDMS is mixed uniformly at a ratio of 10:1, placed into a vacuum air extractor, and air extracted for 20 min to remove the internal bubbles of the solution. The solution is poured into a resin mold with a PDMS film structure, sent into a 100°C oven for baking for 2 h, and after cooling to room temperature, it is demolded;

[0069] The spin coater is set to a rotation speed of 2000 r / min and a spin coating time of 60 s to uniformly coat the conductive silver layer on one side of the high-elasticity stable variable layer to form the high-elasticity stable variable layer and the conductive layer thereof;

[0070] Step three, preparation of the tunable viscoelastic conductive sponge:

[0071] The melamine sponge is cut to a size of 16 mm x 16 mm x 5 mm, ultrasonically cleaned in anhydrous ethanol for 20 min, and then ultrasonically cleaned in pure water for 20 min after the anhydrous ethanol is squeezed clean with a cotton cloth. It is placed in a desiccator and dried at room temperature;

[0072] 0.02 g of carboxymethyl cellulose CMC is added to 20 ml of pure water, stirred and dissolved for 20 min, and then 0.15 g of carbon nanotubes MWCNT and 0.15 g of carbon black CB are added. The mixture is uniformly mixed at room temperature for 30 min using a magnetic stirrer to form a conductive suspension;

[0073] The sponge is completely immersed in the conductive suspension, heated in a 120°C water bath for 3 h, and then taken out and placed in a 60°C desiccator for baking for 3 h until it is completely dry to form the tunable viscoelastic conductive sponge;

[0074] Step four, packaging:

[0075] The structure of the flexible sensor is packaged in the order of the high-elasticity stable variable layer, the vibration transmission layer, and the frequency identification layer. The conductive copper wire is connected at the center of the conductive layer of the high-elasticity stable variable layer, and the conductive silver paste is used as the adhesive until the conductive silver paste is dry to form the viscoelastic adjustable biomimetic flexible sensor with frequency selectivity.

[0076] In summary, the viscoelastic adjustable biomimetic flexible sensor with frequency selectivity function and the preparation method thereof, the viscoelastic adjustable biomimetic flexible sensor from top to bottom is high-elastic stable variable layer, vibration transmission layer and frequency identification layer, the high-elastic stable variable layer is in contact with the upper and lower surface electrode layers of the vibration transmission layer and the frequency identification layer, and plays a stable and safe force transmission role, the vibration transmission layer includes high-elasticity micro-spine protrusion conductive layer and high-elasticity micro-arch conductive layer, and through the deformation of the double micro-structures, the super-sensitivity and pressure efficient transmission are realized, the frequency identification layer is a tunable viscoelastic conductive sponge, and due to the high compressibility and high elasticity of the conductive sponge, the action interval of high-frequency vibration is short, the rebound of the conductive sponge is interrupted, and the action of low-frequency vibration is opposite, the adjustable parameters of the conductive sponge can be changed, and the corresponding response-relaxation time is analyzed, the vibration signals of non-target frequency are effectively screened, and the function coupling of super-sensitive perception and selective identification of the sensor and the efficiency maximization are realized.

[0077] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A method for preparing a frequency-selective viscoelastic adjustable biomimetic flexible sensor, characterized in that the prepared frequency-selective viscoelastic adjustable biomimetic flexible sensor comprises a high-elastic stable layer, a vibration transmission layer and a frequency identification layer. The high-elastic stable layer is placed on the top and bottom of the flexible sensor, the vibration transmission layer and the frequency identification layer are arranged between the two high-elastic stable layers, the vibration transmission layer is located on the upper part, and the frequency identification layer is located on the lower part. The high-elastic stable layer is made of a flexible material by high-temperature baking or chemical accumulation curing, and comprises an external high-elastic stable layer (10) and an internal high-elastic stable layer conductive layer (50), the internal high-elastic stable layer conductive layer (50) is an electrode layer, and is prepared by one of electrochemical deposition, vapor deposition or spin coating method, and leads out wires from the contact surfaces of the vibration transmission layer and the frequency identification layer. The flexible material is one of polydimethylsiloxane (PDMS), polyurethane elastomer (TPU), silicone rubber (SR), polypropylene film (PP) and polyvinyl chloride (PVC). The vibration transmission layer comprises a high-elasticity micro-spine conductive layer (20) and a high-elasticity micro-arch conductive layer (30), the high-elasticity micro-spine conductive layer (20) is uniformly provided with a single-sided hemispherical microstructure, the high-elasticity micro-arch conductive layer (30) is uniformly provided with a single-sided arch-shaped protruding microstructure, the single-sided hemispherical microstructure is connected to the single-sided arch-shaped protruding microstructure in opposition, the central axes of the cross sections of the single-sided hemispherical microstructure and the single-sided arch-shaped protruding microstructure coincide, and the spine-camber combined structure between the upper and lower microstructures can realize the effect enhancement effect of weak vibration and reduce the micro-vibration perception threshold. The high-elasticity micro-spine conductive layer (20) and the high-elasticity micro-arch conductive layer (30) have a size of 20mm×20mm×1mm, and the diameters of the hemispherical and arch-shaped protruding are 100μm. The frequency identification layer is a tunable viscoelastic conductive sponge (40) made of polyester sponge and conductive suspension liquid, wherein the geometric parameters of the polyester sponge and the ratio of the conductive solution are adjustable parameters, the polyester sponge has an open porous structure with high compressibility and high resilience, and can realize full filling of conductive particles; the mechanical signal is converted into an electrical signal through the whole-fracture of the conductive particles on the surface of the conductive sponge and the contact-separation between the particles, and the frequency selectivity function is achieved by detecting the response-relaxation speed. The internal high-elastic stable layer conductive layer (50), the high-elasticity micro-spine conductive layer (20), the high-elasticity micro-arch conductive layer (30) and the tunable viscoelastic conductive sponge (40) are connected by one of conductive silver paste, carbon black glue, high-temperature resistant red glue, tin paste and liquid conductive polymer, and are connected by one of high-temperature baking, ultraviolet irradiation and laser curing processing means. The method comprises the following steps: Step one, preparation of the vibration transfer layer:

1. High elasticity micro-spine conductive layer and high elasticity micro-arch conductive layer mold preparation: Design high elasticity micro-spine conductive layer, high elasticity micro-arch conductive layer size is 2mm×20mm×1mm, with single-sided hemispherical and arch-shaped convex structure, cross-section diameter 100μm, every two structures interval 100μm; Use 3D printing method to manufacture resin mold, mold size is 30mm×30mm×3mm, with the above high elasticity micro-spine conductive layer, high elasticity micro-arch conductive layer reverse structure, use fine sandpaper to polish the surface of the mold smooth; 2. Preparation of conductive elastomer solution: 1g of carbon nanotube MWCNT with diameter of 8-15 nm and length of 3-12 μm, 1g of carbon black CB with particle size of 40 nm are added to 20g of toluene solvent, and then 0.02g of carboxymethyl cellulose CMC is added to uniformly disperse the conductive particles in the solvent; Use magnetic stirrer to stir the above solution at room temperature for 30 min, add 15g of polydimethylsiloxane PDMS reagent main agent and 8g of methyl silicone oil, which increases the flexibility of the composite, set the magnetic stirrer to 40℃, and stir for 2h; Take out the mixed solution and cool it to room temperature, then add 1.5g of polydimethylsiloxane PDMS reagent curing agent, and use a magnetic stirrer to stir at room temperature for 2h; After the reagents are uniformly mixed, the mixed solution is placed in a vacuum pump to remove internal bubbles for 20 min to prepare a conductive elastomer solution; 3. Preparation of high elasticity micro-spine conductive layer and high elasticity micro-arch layer: Pour the above conductive elastomer solution into the resin mold with high elasticity micro-spine conductive layer and high elasticity micro-arch conductive layer reverse structure, and after 20 min of standing until the solution surface is uniform and bubble-free, send it to an 80℃ oven for 3h, and then demold after cooling to room temperature to prepare a high elasticity conductive film; Pour the above conductive elastomer solution into the resin mold with high elasticity micro-spine conductive layer features, and after 20 min of standing until the solution surface is uniform and bubble-free, send it to an 80℃ oven for 3h, and then demold after cooling to room temperature to prepare a high elasticity micro-spine conductive layer; Step two, preparation of high elasticity stable variable layer: The high elasticity stable variable layer has a size of 24mm×24mm×0.5mm and no microstructure on the surface; Mix polydimethylsiloxane PDMS at a ratio of 10:1, place it in a vacuum pump, and remove internal bubbles for 20 min, then pour the solution into a resin mold with PDMS film structure, send it to a 100℃ oven for 2h, and then demold after cooling to room temperature; Set the spin coater rotation speed to 2000r / min and the spin coating time to 60s, uniformly coat the conductive silver layer on one side of the high elasticity stable variable layer to prepare the high elasticity stable variable layer and its conductive layer; Step three, preparation of tunable viscoelastic conductive sponge: Cut the melamine sponge to a size of 16mm×16mm×5mm, soak it in anhydrous ethanol for ultrasonic cleaning for 20 min, squeeze the anhydrous ethanol with a cotton cloth, then soak it in pure water for ultrasonic cleaning for 20 min, and place it in a desiccator for room temperature drying; 0.02 g carboxymethyl cellulose CMC was added to 20 ml pure water, stirred and dissolved for 20 min, 0.15 g carbon nanotubes MWCNT and 0.15 g carbon black CB were added, and stirred at room temperature for 30 min to make a conductive suspension using a magnetic stirrer; The sponge was completely immersed in the conductive suspension, heated in a 120℃ water bath for 3h, and after taking out the conductive sponge, it was placed in a 60℃ dryer for 3h to dry completely, to make a tunable viscoelastic conductive sponge; Step four, packaging: The structure of the above flexible sensor was packaged in the order of high-elastic stable variable layer, vibration transmission layer and frequency identification layer, and the conductive copper wire was connected at the center of the conductive layer of the high-elastic stable variable layer, with conductive silver paste as the adhesive, until the conductive silver paste was dry, to make a viscoelastic adjustable bionic flexible sensor with frequency selectivity function.

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