A flexible protective electronic skin with adjustable impact resistance and thermal insulation performance and a preparation method thereof

Abstract

The present application relates to a kind of flexible protective electronic skin with adjustable impact resistance and thermal insulation performance and its preparation method.The flexible protective electronic skin is the three-layer structure of the porous foam between two layers of conductive electrode, and its material is prepared by shear thickening material, shape memory material and conductive filler.The flexible protective electronic skin of the present application not only has excellent impact resistance and thermal insulation performance, but also can further regulate its force protection and heat protection effect by shape memory deformation.The flexible protective electronic skin of the present application has multi-mode sensing capability, not only generates sensing signal to contact and non-contact, but also can respond to impact and high temperature environment with high sensitivity.The flexible protective electronic skin of the present application has broad application prospect in the field of intelligent protection, wearable electronic device and robot.

Description

Technical Field

[0001] This invention belongs to the field of smart materials and flexible electronics technology, specifically relating to a flexible protective electronic skin with adjustable impact resistance and heat insulation properties and its preparation method. Background Technology

[0002] Flexible electronics have garnered increasing research attention due to their flexibility and comfort, and are widely used in health and fitness monitoring, wearable electronic devices, human-computer interaction products, and intelligent robots. Among these, capacitive pressure sensors have seen rapid development due to their simple structure, low power consumption, high sensitivity, fast response, stable signal, and unique non-contact proximity sensing capabilities. However, traditional flexible sensors cannot operate in harsh environments; they are easily damaged and malfunction when subjected to sudden mechanical impacts, hindering the development of intelligent electronic devices. Furthermore, with the growing demand for flexible electronics in more advanced and complex applications, developing practical flexible pressure sensors with multi-stimulus responses and protection against hazardous stimuli remains a significant challenge.

[0003] Shear-stiffening elastomers, with their rate-dependent "soft-to-hard transition" characteristics and excellent impact energy dissipation capabilities, are considered intelligent and flexible protective materials. Currently, various flexible wearable sensors based on shear-stiffening elastomers have been developed. However, extreme environments can cause not only force damage but also corresponding thermal damage. For example, firefighters may suffer injuries not only from impacts with debris from collapsed buildings but also from heat-related injuries such as increased blood pressure, skin burns, or collapse. Therefore, there is an urgent need to develop a flexible electronic skin with highly efficient force-thermal coupling protection performance and the ability to monitor environmental changes and physiological information in real time, thereby improving personal and equipment safety. Summary of the Invention

[0004] This invention addresses the shortcomings of traditional technologies by providing a flexible protective electronic skin with adjustable impact resistance and thermal insulation properties, along with its fabrication method. The method utilizes smart materials to prepare this flexible protective electronic skin with adjustable impact resistance and thermal insulation properties. This invention expands the functionality and intelligence of traditional electronic skin. Besides excellent impact resistance and thermal insulation, it can further adjust its force and thermal protection effects through shape memory deformation. Furthermore, the flexible protective electronic skin of this invention can achieve multi-mode sensing, generating stable sensing signals for contact strain and enabling non-contact near-field sensing, while also exhibiting high sensitivity in response to impact and high-temperature environments. Based on this, the flexible protective electronic skin has broad application prospects in fields such as smart protection, wearable electronic devices, and robotics.

[0005] The present invention adopts the following technical solution:

[0006] A flexible protective electronic skin with adjustable impact resistance and heat insulation properties, the flexible protective electronic skin is a three-layer structure consisting of two conductive electrode layers sandwiched with porous foam.

[0007] Furthermore, the conductive electrode and the porous foam are prepared by the following method:

[0008] a. Hydroxysilicone oil and boric acid are thoroughly mixed and reacted at 120°C to 200°C. Then, octanoic acid is added, and finally, the mixture is cooled to obtain a shear-hardening gel.

[0009] b. The shear-hardening gel obtained in step a is mixed with silicone rubber and benzoyl peroxide using an open mill to obtain a shear-hardening elastomer precursor.

[0010] c. Mix the shear-hardening elastomer precursor from step b with ethylene-vinyl acetate copolymer powder and crosslinking agent dicumyl peroxide in a certain proportion until homogeneous.

[0011] d. Further mix the mixture obtained in step c with a certain mass fraction of conductive nanofiller;

[0012] e. Further mix the mixture obtained in step c with a certain mass fraction of sodium chloride particles;

[0013] f. Press the mixture obtained in step d into a mold and vulcanize and crosslink it under high temperature and high pressure;

[0014] g. Press the mixture obtained in step e into a mold and vulcanize and crosslink it under high temperature and high pressure;

[0015] h. Cool the product obtained in step f to room temperature to obtain a conductive electrode;

[0016] i. After cooling the product obtained in step g to room temperature, sonicate it, changing the water every two hours to ensure that the sodium chloride particles are completely dissolved and removed;

[0017] j. After drying the product obtained in step i in an oven for 24 hours, the product is removed to obtain porous foam.

[0018] In one embodiment of the present invention, the mass ratio of the shear-hardening elastomer precursor to the ethylene-vinyl acetate copolymer powder is 2:8 to 6:4. For example, the mass ratio of the shear-hardening elastomer precursor to the ethylene-vinyl acetate copolymer powder is 0.25, 0.35, 0.45, 0.55, 0.65, 0.75, 0.85, 0.95, 1, 1.25, 1.3, 1.4, or 1.5.

[0019] In one embodiment of the present invention, the crosslinking agent dicumyl peroxide has a mass fraction of 1% to 5% relative to the ethylene-vinyl acetate copolymer. For example, the mass fraction of the crosslinking agent dicumyl peroxide relative to the ethylene-vinyl acetate copolymer is 1%, 1.1%, 1.3%, 1.5%, 1.7%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 4.9%, or 5%.

[0020] In one embodiment of the present invention, the conductive nanofiller is one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, MXene, silver nanowires, etc.

[0021] In one embodiment of the invention, the mass fraction of the conductive nanofiller is 1% to 5% based on the total mass of the shear-hardening elastomer precursor, ethylene-vinyl acetate copolymer, and dicumyl peroxide (e.g., the mass fraction of the conductive nanofiller is 1.1%, 1.3%, 1.5%, 1.7%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 4.9%, or 5%).

[0022] In one embodiment of the invention, the mass fraction of the sodium chloride particles is 350% to 450% based on the total mass of the shear-hardening elastomer precursor, the ethylene-vinyl acetate copolymer, and dicumyl peroxide (e.g., the mass fraction of sodium chloride particles is 350%, 370%, 390%, 400%, 410%, 420%, 430%, 440%, or 450%).

[0023] In one embodiment of the invention, the high temperature of vulcanization and crosslinking is 120°C to 200°C, and the high pressure is 5 MPa to 40 MPa.

[0024] Furthermore, the flexible protective electronic skin is prepared by the following method:

[0025] a. Cut the aforementioned conductive electrode material into a predetermined shape;

[0026] b. Cut the porous foam into a shape with the same area as the conductive electrode in step a;

[0027] c. Place two layers of conductive electrodes on both sides of the porous foam, and heat-treat to make the conductive electrodes and porous foam adhere and heal;

[0028] d. Cool the product obtained in step c above to obtain flexible protective electronic skin.

[0029] In one embodiment of the present invention, the aforementioned suitable shape is one or more of a rectangle, a circle, a pentagon, etc.

[0030] In one embodiment of the present invention, the above-mentioned heating treatment method is one or more of hot air heating, electric heating, photothermal heating, etc.

[0031] The beneficial technical effects of this invention are that, compared to previously disclosed electronic skins, the flexible protective electronic skin of this invention possesses both excellent impact resistance and superior heat insulation performance. More uniquely, the flexible protective electronic skin of this invention exhibits a shape memory effect, allowing for intelligent adjustment of the force-thermal protection effect through shape memory deformation. Finally, the flexible protective electronic skin of this invention has multiple sensing modes, capable of recognizing both contact and non-contact stimuli, and responding to impact and high-temperature stimuli. The integrated functionality of the flexible protective electronic skin of this invention will promote the development of intelligent electronic products and military defense equipment. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of a flexible protective electronic skin (Example 1).

[0033] Figure 2 The maximum impact force was measured from different heights on a flexible protective electronic skin (Example 1), an ethylene-vinyl acetate copolymer cross-linked plate (Comparative Example 1), and a shear-hardening elastomer (Comparative Example 2).

[0034] Figure 3 The highest temperature at the center point of the upper surface of the flexible protective electronic skin (Example 1), the ethylene-vinyl acetate copolymer crosslinked plate (Comparative Example 1), and the shear-hardened elastomer (Comparative Example 2) were measured when heated by heating plates of different temperatures.

[0035] Figure 4 To regulate the impact protection effect of flexible protective electronic skin (Example 1) by changing the thickness through shape memory deformation.

[0036] Figure 5 To regulate the impact protection effect of flexible protective electronic skin (Example 1) by changing the deformation area through shape memory.

[0037] Figure 6 To regulate the heat insulation and protection effect of flexible protective electronic skin (Example 1) by changing the thickness through shape memory deformation.

[0038] Figure 7 To regulate the heat insulation and protection effect of flexible protective electronic skin (Example 1) by changing the deformation area through shape memory.

[0039] Figure 8 Sensing response of flexible protective electronic skin (Example 1) to contact strain.

[0040] Figure 9 The non-contact sensing response of the flexible protective electronic skin (Example 1).

[0041] Figure 10 Sensing response of flexible protective electronic skin (Example 1) to impact excitation.

[0042] Figure 11 Sensing response of flexible protective electronic skin (Example 1) to high-temperature loading. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0044] The performance parameters of the samples prepared in the following examples were tested according to the following test methods:

[0045] A. The specific method for measuring the impact resistance of flexible protective electronic skin is as follows:

[0046] The impact resistance of flexible protective electronic skin was studied using a drop hammer test apparatus. A 0.54 kg hammer was dropped freely from different heights onto the flexible protective electronic skin, and the residual impact force was recorded using a force sensor.

[0047] B. The specific method for measuring the thermal insulation performance of flexible protective electronic skin is as follows:

[0048] The flexible protective electronic skin was placed on the heating plate after the base plate temperature was set to 50 degrees Celsius, 100 degrees Celsius, and 150 degrees Celsius. An infrared camera was used to record the surface temperature of the flexible protective electronic skin during the heating process.

[0049] C. The specific method for measuring the sensor performance of flexible protective electronic skin is as follows:

[0050] The electrodes at both ends of the flexible protective electronic skin are connected to an LCR digital bridge to record the capacitance values ​​during contact, non-contact, impact, and high-temperature processes.

[0051] D. The specific method for performing compression programming is as follows:

[0052] The flexible protective electronic skin is first heated to 80 degrees Celsius using a hot air blower, then compressed with different strains, while keeping the strain constant and cooling to room temperature. The load is then removed to obtain the programmed flexible protective electronic skin.

[0053] The following embodiments of the present invention use the following raw materials: silicone rubber (methyl vinyl silicone rubber, model VMQ 110-2, molecular weight 480,000, vinyl content 0.17wt%).

[0054] Ethylene-vinyl acetate copolymer (DuPont, USA, Model 250, vinyl acetate content 28wt%)

[0055] Carbon nanotubes (99% ultrapure multi-walled carbon nanotubes, with an outer diameter of 8 to 15 nanometers and a length of 10 to 50 micrometers)

[0056] Hydroxyl silicone oil (poly(dimethylsiloxane) hydroxyl-terminated, weight-average molecular weight 4000)

[0057] Examples of methods for preparing flexible protective electronic skin:

[0058] Comparative Example 1:

[0059] Add 3% (by weight of the ethylene-vinyl acetate copolymer powder) of dicumyl peroxide to the ethylene-vinyl acetate copolymer powder and mix thoroughly. Then, place the mixed powder in a mold and vulcanize at 170°C and 20 MPa for 30 minutes. After cooling, a pure ethylene-vinyl acetate copolymer cross-linked board is obtained.

[0060] Comparative Example 2:

[0061] Hydroxysilicone oil and boric acid were thoroughly mixed at a mass ratio of 36:1 and reacted at 180°C for 1.5 hours. Then, 1 ml of n-octanoic acid was added and the reaction was continued for another 0.5 hours. Finally, the mixture was cooled to obtain a shear-hardening gel. The obtained shear-hardening gel was mixed with silicone rubber and benzoyl peroxide at a mass ratio of 7:3:0.4 using an open mill to obtain a shear-hardening elastomer precursor. The shear-hardening elastomer precursor was then placed in a mold and vulcanized at a high temperature of 100°C and a high pressure of 20 MPa for 30 minutes. After cooling, the shear-hardening elastomer was obtained.

[0062] Example 1:

[0063] Hydroxysilicone oil and boric acid were thoroughly mixed at a mass ratio of 36:1 and reacted in an oven at 180°C for 1.5 hours. Then, 1 mL of n-octanoic acid was added, and the reaction continued for another 0.5 hours. Finally, the mixture was cooled to obtain a shear-hardening gel. The obtained shear-hardening gel was then mixed with silicone rubber and benzoyl peroxide at a mass ratio of 7:3:0.4 using a two-roll mill to obtain a shear-hardening elastomer precursor. 31.2 g of the shear-hardening elastomer precursor was then thoroughly mixed with 31.2 g of ethylene-vinyl acetate copolymer powder and 0.96 g of dicumyl peroxide to obtain a mixed colloid. Based on the total mass of the mixed colloid, 3% by mass of multi-walled carbon nanotubes were added, and the mixture was pressed into a 1 mm thick mold and vulcanized at 170°C and 20 MPa for 30 minutes. After cooling, a conductive electrode was obtained. Based on the total mass of the mixed colloid, four times the mass of sodium chloride particles were added to the mixed colloid, and then pressed into a 1 cm thick mold and vulcanized at 170°C and 20 MPa for 30 minutes. After cooling, it was ultrasonically treated, with the water changed every two hours to completely remove the sodium chloride particles. It was then further dried in an oven for 24 hours to obtain a porous foam. A piece of porous foam was sandwiched between two conductive electrodes and placed in an 80°C oven for 12 hours to adhere and heal. After cooling, a flexible protective electronic skin was obtained.

[0064] Example 2:

[0065] The only difference from Example 1 is that the following mass ratio of raw materials is used:

[0066] Shear-hardening elastomer precursor prepared in Example 1: Ethylene-vinyl acetate copolymer powder = 6:4

[0067] The rest is the same as in Example 1.

[0068] Example 3:

[0069] The only difference from Example 1 is that the following mass ratio of raw materials is used:

[0070] Shear-hardening elastomer precursor prepared in Example 1: Ethylene-vinyl acetate copolymer powder = 7:3

[0071] The rest is the same as in Example 1.

[0072] Example 4:

[0073] The only difference from Example 1 is that the mass fraction of multi-walled carbon nanotubes added is 4% based on the total mass of the mixed colloid.

[0074] The rest is the same as in Example 1.

[0075] Example 5:

[0076] The only difference from Example 1 is that the mass fraction of multi-walled carbon nanotubes added is 5% based on the total mass of the mixed colloid.

[0077] The rest is the same as in Example 1.

[0078] Example 6:

[0079] The only difference from Example 1 is that the multi-walled carbon nanotubes are replaced with graphene with sheet diameters of 10 to 50 micrometers.

[0080] The rest is the same as in Example 1.

[0081] Example 7:

[0082] The only difference from Example 1 is that the multi-walled carbon nanotubes are replaced with silver nanowires with a diameter of 30 to 60 nanometers and a length of 10 to 20 micrometers.

[0083] The rest is the same as in Example 1.

[0084] Example 8:

[0085] The only difference from Example 1 is that the vulcanization pressure is 10 MPa.

[0086] The rest is the same as in Example 1.

[0087] Example 9:

[0088] The only difference from Example 1 is that the vulcanization pressure is 15 MPa.

[0089] The rest is the same as in Example 1.

[0090] Example 10:

[0091] The only difference from Example 1 is that a porous foam is sandwiched between two conductive electrodes and heated with a 100-degree Celsius hot air blower for 3 minutes to adhere and heal. After cooling, a flexible protective electronic skin is obtained.

[0092] The rest is the same as in Example 1.

[0093] Figure 1 This is a schematic diagram of the flexible protective electronic skin. The flexible protective electronic skin consists of two layers of conductive electrodes sandwiched in a porous foam. The conductive electrodes are 0.9 mm thick, and the porous foam is 9.2 mm thick. (Prepared from Example 1)

[0094] Figure 2The maximum residual impact force of the flexible protective electronic skin was measured from different heights. The residual impact force was highest when no protective material was present. At an impact height of 500 mm, the flexible protective electronic skin (Example 1) reduced the maximum residual impact force from 4.94 kN to 0.56 kN, which is 0.09 kN lower than the maximum residual impact force of the ethylene-vinyl acetate copolymer (Comparative Example 1). Furthermore, at impact heights of 400 mm, 300 mm, and 200 mm, the maximum residual impact forces of the flexible protective electronic skin (Example 1) were 0.50 kN, 0.35 kN, and 0.17 kN, respectively, which are lower than the maximum residual impact forces of the ethylene-vinyl acetate copolymer (Comparative Example 1) (0.56 kN, 0.44 kN, and 0.28 kN), and smaller than the 4.38 kN, 3.41 kN, and 2.79 kN without protection. Therefore, the flexible protective electronic skin exhibits excellent impact protection at all heights, thanks to the impact energy dissipation effect of the shear-stiffening elastomer material. Because when the impact height is between 500 mm and 200 mm, the maximum residual impact force of the shear-hardened elastomer material (Comparative Example 2) is between 0.40 kN and 0.10 kN.

[0095] Figure 3 The highest temperature at the center point of the upper surface of the flexible protective electronic skin was measured when heated with heating plates at different temperatures. Using heating plates at 50°C, 100°C, and 150°C to heat the flexible protective electronic skin and its comparative examples, it was found that the flexible protective electronic skin had the lowest maximum temperature after temperature stabilization. When the heating plate temperature was 150°C, the highest temperature of the flexible protective electronic skin (Example 1) was only 88.8°C, while the highest temperatures of the ethylene-vinyl acetate copolymer (Comparative Example 1) and the shear-stiffening elastomer (Comparative Example 2) reached as high as 111.2°C and 109.2°C, respectively.

[0096] Figure 4 To control the impact protection effect of flexible protective electronic skin by varying its thickness through shape memory deformation, the flexible protective electronic skin (Example 1) was first shape-programmed with different compressive strains, and its protective performance under drop hammer impact at the same height was tested. The maximum residual impact force increased with increasing compressive programming strain. For example, when the compressive programming strain was 0%, the maximum residual impact force was 0.31 kN. However, when the compressive programming strain increased to 20%, 40%, and 60%, the maximum residual impact force increased to 0.37 kN, 0.42 kN, and 0.62 kN, respectively, indicating different impact protection effects.

[0097] Figure 5To control the impact protection effect of flexible protective electronic skin by changing the deformation area through shape memory, the flexible electronic skin, after being folded and programmed with shape memory, can self-deform upon heating, increasing the force protection area from 20.3 square centimeters to 47.5 square centimeters. Figure 4 and Figure 5 The results fully demonstrate that flexible protective electronic skin can utilize shape memory deformation to regulate its impact resistance.

[0098] Figure 6 To control the thermal insulation effect of flexible protective electronic skin through shape memory deformation thickness variation, the flexible protective electronic skin (Example 1) was first shape-programmed with different compressive strains, and the upper surface temperature curves were tested when heated by a 100°C heating plate. The heating rate increased with increasing compressive programming strain. For example, after heating for 300 seconds, the upper surface temperature was 50.1°C with a compressive programming strain of 0%, while the upper surface temperatures of the flexible protective electronic skin (Example 1) were 52.7°C and 54.2°C with compressive programming strains of 20% and 40%, respectively, indicating different heating rates.

[0099] Figure 7 To regulate the heat insulation effect of flexible protective electronic skin by changing the deformation area through shape memory, an array of flexible protective electronic skin (Example 1) programmed with shape memory extrusion can self-deploy after heating, increasing the heat protection area from 19.5 square centimeters to 46.9 square centimeters. Figure 6 and Figure 7 The results fully demonstrate that flexible protective electronic skin can utilize shape memory deformation to regulate thermal insulation performance.

[0100] Figure 8 This describes the sensing response of the flexible protective electronic skin to contact strain. Increased contact strain leads to a decrease in the distance between the two electrode layers, resulting in an increase in the capacitance of the flexible protective electronic skin (Example 1). When the contact strain increases from 10% to 60%, the change in capacitance (ΔC / C0) significantly increases from 0.03 to 1.93, indicating a positive capacitance change and a wide detection range.

[0101] Figure 9 This study describes the non-contact sensing response of a flexible protective electronic skin. When an aluminum plate is brought close to the flexible protective electronic skin, the capacitance of the skin (Example 1) decreases as the target approaches, resulting in a negative change in capacitance. Furthermore, the smaller the non-contact distance, the larger the absolute value of the capacitance change. For example, when the non-contact distance decreases from 25 mm to 5 mm, the change in capacitance (ΔC / C0) changes from -1.22% to -5.35%.

[0102] Figure 10This describes the sensing response of a flexible protective electronic skin to impact excitation. The capacitance change of the flexible protective electronic skin (Example 1) completely records an impact process. For example, when the impacting hammer head contacts the flexible protective electronic skin, the capacitance increases rapidly, causing the capacitance change to reach a peak of 0.47. Subsequently, the hammer head rebounds and eventually comes to rest on the flexible protective electronic skin, resulting in a rebound and a stable capacitance signal plateau, at which point the capacitance change remains at approximately 0.27. When the hammer head is removed, the capacitance returns to its initial value, and the capacitance change returns to 0.

[0103] Figure 11 This describes the sensing response of a flexible protective electronic skin to high-temperature loading. The capacitance of the compressed-programmed flexible protective electronic skin (Example 1) significantly decreases during a 100°C temperature rise, causing the capacitance change to decrease from 1.00 to 0.81 as the temperature increases.

[0104] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A flexible protective e-skin with adjustable impact resistance and thermal insulation properties, characterized in that, The flexible protective electronic skin is a three-layer structure composed of a porous foam sandwiched between two conductive electrodes; The conductive electrode is a product obtained by heat treatment and high pressure of a mixture of a shear-hardening elastomer precursor, ethylene-vinyl acetate copolymer, dicumyl peroxide and conductive nanofiller; The mass ratio of the shear-hardening elastomer precursor and the ethylene-vinyl acetate copolymer is 0.25 to 1.4; the mass fraction of dicumyl peroxide relative to the ethylene-vinyl acetate copolymer is 1.1% to 4.9%; The conductive nanofiller is one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, MXene and silver nanowires; the mass fraction of the conductive nanofiller is 1.1% to 4.9% based on the total mass of the shear-hardening elastomer precursor, ethylene-vinyl acetate copolymer and dicumyl peroxide; The heat treatment is 120 degrees Celsius to 200 degrees Celsius; the high pressure is 5 megapascals to 40 megapascals; The shear-hardening elastomer precursor is a product obtained by uniformly mixing a shear-hardening gel, silicone rubber and benzoyl peroxide using an open mill; The shear-hardening gel is a product obtained by fully mixing hydroxy silicone oil and boric acid, and then adding n-octanoic acid after reaction at 120 degrees Celsius to 200 degrees Celsius and cooling; The conductive electrode is prepared by a method comprising the following steps: a. Mixing and reacting hydroxy silicone oil and boric acid, then adding n-octanoic acid, and finally cooling to obtain a shear-hardening gel; b. Uniformly mixing the shear-hardening gel obtained in step a with silicone rubber and benzoyl peroxide using an open mill to obtain a shear-hardening elastomer precursor; c. Uniformly mixing the shear-hardening elastomer precursor in step b with ethylene-vinyl acetate copolymer, dicumyl peroxide and conductive nanofiller; d. Pressing the mixture obtained in step c into a mold and vulcanizing and crosslinking at a temperature of 120 degrees Celsius to 200 degrees Celsius and a pressure of 5 megapascals to 40 megapascals; e. Cooling the product obtained in step d to room temperature to obtain the conductive electrode; The porous foam is a product obtained by 120 degrees Celsius to 200 degrees Celsius; 5 megapascals to 40 megapascals treatment of a mixture of a shear-hardening elastomer precursor, ethylene-vinyl acetate copolymer, dicumyl peroxide and sodium chloride particles, and further ultrasonic dissolution to remove sodium chloride particles and drying; The mass fraction of the sodium chloride particles is 350% to 450% based on the total mass of the shear-hardening elastomer precursor, ethylene-vinyl acetate copolymer and dicumyl peroxide; The porous foam is prepared by a method comprising the following steps: a. Mixing and reacting hydroxy silicone oil and boric acid at 120 degrees Celsius to 200 degrees Celsius, then adding n-octanoic acid, and finally cooling to obtain a shear-hardening gel; b. Uniformly mixing the shear-hardening gel obtained in step a with silicone rubber and benzoyl peroxide using an open mill to obtain a shear-hardening elastomer precursor; c. Uniformly mixing the shear-hardening elastomer precursor in step b with ethylene-vinyl acetate copolymer, dicumyl peroxide and sodium chloride particles; d. The mixture obtained in step c is pressed into a mold and vulcanized and crosslinked at a temperature of 120 to 200 degrees Celsius and a pressure of 5 to 40 megapascals; e. After the product obtained in step d is cooled to room temperature, it is ultrasonically treated, and the water is changed every two hours to ensure that the sodium chloride particles are completely dissolved and removed; f. The product obtained in step e is dried in an oven, and the porous foam is obtained.

2. A method for preparing the flexible protective electronic skin as claimed in claim 1, the method comprising the following steps: a. Take a conductive electrode; b. Cut the porous foam into the same shape as the area of the conductive electrode in step a; c. Place two layers of conductive electrodes on both sides of the porous foam, and heat treat to make the conductive electrode and the porous foam adhere and heal; d. Cool the product obtained in step c above to obtain the flexible protective electronic skin.

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