Flexible electronic skin and preparation method and application thereof

Abstract

The invention belongs to the technical field of electromagnetic protection, and particularly relates to a flexible electronic skin and a preparation method and application thereof. The invention provides a flexible electronic skin. The flexible electronic skin comprises an adhesion layer, a flexible substrate layer, a conductive layer, a functional layer and a protective layer which are sequentially stacked, the material of the functional layer comprises carbide and ferrite; the surface of any side of the conductive layer comprises a plurality of protrusions arranged in an array. By constructing the multi-layer flexible composite structure and the intelligent attachment interface, efficient, light and repairable electromagnetic protection of a complex curved surface component is realized, and the electromagnetic compatibility and the system reliability are improved.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic protection technology, specifically relating to a flexible electronic skin, its preparation method, and its application. Background Technology

[0002] During operation in orbit, spacecraft face a complex space electromagnetic environment, including high-energy particles from the solar wind, geomagnetic disturbances, and radiation from inter-satellite communications. These electromagnetic disturbances induce currents and electromagnetic coupling effects on the spacecraft's structural surfaces and between the electronic compartments. Electromagnetic interference (EMI) can affect the stable operation of sensitive electronic equipment and may also cause data distortion, signal noise enhancement, or even device failure. Traditional electromagnetic shielding materials, such as metal foils and conductive coatings, suffer from difficulties in achieving complete adhesion and sealing on complex curved surfaces, susceptibility to fatigue, cracking, and peeling under thermal cycling and vacuum environments, and challenges in simultaneously achieving lightweight, high flexibility, and strong shielding effectiveness. Existing technologies exhibit poor flexibility in metal shielding, insufficient long-term stability of conductive polymer shielding films, and complex, unrepeatable, and easily delaminated processes in spraying / vacuum coating. These technologies cannot simultaneously meet the requirements of conformal adhesion and stress compatibility to complex curved surfaces of spacecraft, long-term reliability under extreme environments, and engineering feasibility such as low weight, low power consumption, and modular repairability. Summary of the Invention

[0003] The purpose of this invention is to provide a flexible electronic skin, its preparation method, and its application. The flexible electronic skin provided by this invention can achieve efficient, lightweight, and repairable electromagnetic protection for complex curved surface components.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a flexible electronic skin, comprising an adhesion layer, a flexible substrate layer, a conductive layer, a functional layer, and a protective layer stacked sequentially. The materials of the functional layer include carbides and ferrites; The surface of any one side of the conductive layer includes a plurality of protrusions arranged in an array.

[0005] Preferably, the material of the adhesion layer includes ionogel or shape memory polymer; The thickness of the adhesion layer is 15~20μm.

[0006] Preferably, the material of the flexible substrate layer includes at least one of polyimide, polydimethylsiloxane, fluorinated ethylene propylene copolymer, and polyethylene naphthalate; The thickness of the flexible substrate layer is 30~40μm.

[0007] Preferably, the material of the conductive layer includes at least one of silver nanowires, copper nanowires, carbon nanotubes, and graphene; The total thickness of the conductive layer is 20~25μm; The protrusions are square in shape; the average side length of a single protrusion is 35-40 μm; the average height of the protrusions is 10-15 μm; and the interval between adjacent protrusions is 10-20 μm.

[0008] Preferably, the carbide includes at least one of silicon carbide, boron carbide, and titanium carbide; The ferrite includes at least one of nickel-zinc ferrite, manganese-zinc ferrite, cobalt-zinc ferrite, and lithium-zinc ferrite. The mass ratio of the carbide to the ferrite is 1~9:1~9; The functional layer also includes a film-forming substance; the thickness of the functional layer is 30~35μm.

[0009] Preferably, the material of the protective layer includes silicon oxide or a fluoropolymer; The thickness of the protective layer is 5~10μm.

[0010] This invention also provides a method for preparing the flexible electronic skin described in the above technical solution, comprising the following steps: A conductive layer and a functional layer are sequentially fabricated on the surface of a flexible substrate to obtain an intermediate structure; After the adhesion layer and the intermediate structure are stacked and pressed, a protective layer is prepared on the surface of the functional layer to obtain the flexible electronic skin.

[0011] Preferably, the preparation of the conductive layer includes: coating a dispersion containing a conductive layer material onto the surface of the flexible substrate, drying it, and then performing laser etching to obtain the conductive layer; the laser etching power is 10~50W, and the scanning speed is 100~500mm / s; The preparation of the functional layer includes: spin-coating a dispersion containing the functional layer material onto the surface of a release film, removing the release film after curing, and attaching the obtained functional layer to the surface of the conductive layer; The pressing method is hot pressing, with a temperature of 80°C, a pressure of 0.5 MPa, and a time of 15 minutes.

[0012] Preferably, after preparing the protective layer, the adhesion layer is further subjected to low-temperature plasma activation treatment; The plasma power for the low-temperature plasma activation treatment is 100W, and the time is 5 minutes.

[0013] The present invention also provides the application of the flexible electronic skin described in the above technical solution or the flexible electronic skin prepared by the preparation method described in the above technical solution in electromagnetic shielding.

[0014] This invention provides a flexible electronic skin, comprising an adhesion layer, a flexible substrate layer, a conductive layer, a functional layer, and a protective layer stacked sequentially. The materials of the functional layer include carbides and ferrites; The surface of any one side of the conductive layer includes a plurality of protrusions arranged in an array.

[0015] This invention achieves efficient, lightweight, and repairable electromagnetic protection for complex curved surface components by constructing a multi-layered flexible conductive composite structure and an intelligent attachment interface, thereby improving electromagnetic compatibility and system reliability. The flexible electronic skin provided by this invention, tested according to ASTM D4935 standard, maintains a shielding effectiveness of over 95%, covers a frequency range of 0.1MHz to 10GHz, has a flexible attachment error of less than 0.1mm, and is adaptable to curved surfaces with a curvature radius of not less than 10mm. Compared to traditional metal shielding materials, it reduces weight by more than 30%, can operate stably under thermal cycling conditions of -150℃ to +150℃, supports multiple attachments and self-repair, and has a reliable lifespan exceeding 5000 cycles.

[0016] This invention utilizes a flexible electronic skin multilayer composite structure to achieve efficient shielding and energy absorption on complex curved surfaces. Combined with an electrostatically assisted attachment design, it enables long-term stable protection of critical spacecraft components in a broadband electromagnetic environment. The electronic skin provided by this invention has advantages such as high flexibility, light weight, re-attachability, and broadband efficient shielding, making it suitable for the protection of various electromagnetically sensitive components such as spacecraft cabins, radomes, and electronic equipment housings. Attached Figure Description

[0017] Figure 1 A schematic diagram illustrating a specific application of the flexible electronic skin provided by this invention; Figure 2 A schematic diagram of the structure of the flexible electronic skin provided by the present invention; Figure 3 This is a schematic diagram of the conductive layer structure; Figure 4 This is a schematic diagram illustrating the coupling principle of electromagnetic reflection and absorption. Figure 5 This is a schematic diagram of a shielding effectiveness testing device. Detailed Implementation

[0018] This invention provides a flexible electronic skin, comprising an adhesion layer, a flexible substrate layer, a conductive layer, a functional layer, and a protective layer stacked sequentially. The materials of the functional layer include carbides and ferrites; The surface of any one side of the conductive layer includes a plurality of protrusions arranged in an array.

[0019] In this invention, the material of the adhesion layer preferably includes ionogel or shape memory polymer.

[0020] In this invention, the raw materials for preparing the ionic gel preferably include an ionic liquid and a polyurethane prepolymer; the ionic liquid is preferably 1-butyl-3-methylimidazolium hexafluorophosphate or 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; the polyurethane prepolymer preferably includes an MDI-type polyurethane prepolymer or an MDI / TDI blend prepolymer; the mass percentage of NCO in the polyurethane prepolymer is preferably 10-11%.

[0021] In this invention, the raw material for preparing the shape memory polymer is preferably a polycaprolactone-polyurethane block copolymer. The preparation methods of the ionogel and shape memory polymer are described in the following section on the preparation method of flexible electronic skin, and will not be discussed further here. In this invention, the thickness of the adhesion layer is preferably 15-20 μm, specifically 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.

[0022] In this invention, the adhesion layer can achieve reversible adhesion to interfaces of different shapes. The material can be selected as ion gel or shape memory polymer. Ion gel is suitable for parts that need to be repeatedly adhered, while shape memory polymer is suitable for areas with high requirements for high temperature stability. The layer can achieve molecular rearrangement under the drive of thermal or electric fields, ensuring that the electronic skin is tightly adhered to the surface of the part. It can also be re-adheded after being heated or electrically stimulated, realizing the self-repair and reuse of the skin.

[0023] In this invention, the material of the flexible substrate layer preferably includes at least one selected from polyimide (PI), polydimethylsiloxane (PDMS), fluorinated ethylene propylene copolymer (FEP), and polyethylene naphthalate (PEN). In this invention, the thickness of the flexible substrate layer is preferably 30-40 μm, specifically 30 μm, 32 μm, 34 μm, 35 μm, 36 μm, 38 μm, and 40 μm. In this invention, different flexible substrate layers can be selected based on different application scenarios to impart properties such as low-temperature resistance, radiation resistance, and high strength to the electronic skin.

[0024] In this invention, the material of the conductive layer preferably includes at least one selected from silver nanowires, copper nanowires, carbon nanotubes, and graphene. In this invention, the total thickness of the conductive layer is preferably 20-25 μm, specifically 21 μm, 22 μm, 23 μm, 24 μm, or 25 μm. In this invention, the shape of the protrusions is preferably square; the average side length of a single protrusion is preferably 35-40 μm; the average height of the protrusions is preferably 10-15 μm; and the spacing between adjacent protrusions is preferably 10-20 μm. By controlling the size, height, and spacing of the protrusions, conductive continuity and the flexibility of the conductive layer are ensured. A schematic diagram of the conductive layer structure in this invention is shown below. Figure 3 As shown.

[0025] In this invention, the conductive layer forms a continuous current loop to achieve electromagnetic reflection shielding. Different materials can be used in combination according to the shielding frequency band requirements of the component: Low frequency band (0.1MHz~1MHz): copper nanowires + carbon nanotubes are used. The excellent low-frequency conductivity of copper nanowires can enhance electromagnetic wave reflection, and carbon nanotubes improve structural flexibility; Mid frequency band (1MHz~100MHz): silver nanowires + graphene are used. Silver nanowires form a continuous conductive network, and the two-dimensional structure of graphene enhances electromagnetic wave attenuation; High frequency band (100MHz~10GHz): silver nanowires + carbon nanotubes are used. Silver nanowires reduce high-frequency impedance, and carbon nanotubes absorb the remaining electromagnetic waves through dielectric loss; Wide frequency band (0.1MHz~10GHz): silver nanowires + copper nanowires + graphene are used to balance the reflection and absorption performance of each frequency band.

[0026] In this invention, the material of the functional layer includes carbides and ferrites. Preferably, the carbide includes at least one of silicon carbide, boron carbide, and titanium carbide; the ferrite preferably includes at least one of nickel-zinc ferrite, manganese-zinc ferrite, cobalt-zinc ferrite, and lithium-zinc ferrite. The particle size of the carbide is preferably 40-60 nm, specifically 40 nm, 50 nm, or 60 nm; the particle size of the ferrite is preferably 75-85 nm, specifically 75 nm, 80 nm, or 85 nm. The mass ratio of carbide to ferrite is preferably 1-9:1-9, specifically 1:1.

[0027] In this invention, the functional layer preferably further includes a film-forming substance; the film-forming substance preferably includes polyurethane or epoxy resin; the mass ratio of the total mass of the carbide and ferrite to the mass of the film-forming substance is preferably 10~20:5~10. In this invention, the film-forming substance is added to improve film-forming stability, and the addition does not affect the electromagnetic absorption performance.

[0028] In this invention, the functional layer absorbs and attenuates residual wave energy through magnetic and dielectric losses. In this invention, the conductive layer forms a continuous current loop, reflecting incoming electromagnetic waves into space; the functional layer, through magnetic-dielectric coupling, converts unreflected residual wave energy into heat dissipation; the two layers work together to achieve broadband electromagnetic interference suppression.

[0029] In this invention, the material of the protective layer preferably includes silicon oxide (SiO2). x The protective layer is preferably made of polytetrafluoroethylene (PTFE) or a fluoropolymer. In this invention, the thickness of the protective layer is preferably 5-10 μm, specifically 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. In this invention, the protective layer is resistant to aging and prevents the accumulation of charged dust.

[0030] A schematic diagram of the flexible electronic skin provided by this invention is shown below. Figure 2 As shown, from bottom to top, the layers are the substrate to be adhered, the adhesion layer, the flexible substrate layer, the conductive layer, the functional layer, and the protective layer.

[0031] This invention also provides a method for preparing the flexible electronic skin described in the above technical solution, comprising the following steps: A conductive layer and a functional layer are sequentially fabricated on the surface of a flexible substrate to obtain an intermediate structure; After the adhesion layer and the intermediate structure are stacked and pressed, a protective layer is prepared on the surface of the functional layer to obtain the flexible electronic skin.

[0032] The present invention prepares a conductive layer and a functional layer sequentially on the surface of a flexible substrate to obtain an intermediate structure.

[0033] In this invention, the flexible substrate layer is preferably a commercially available product or prepared by a casting process. The casting process described in this invention is not particularly limited and can be performed using a process well-known to those skilled in the art.

[0034] In this invention, the preparation of the conductive layer preferably includes: coating a dispersion containing a conductive layer material onto the surface of the flexible substrate, drying it, and then performing laser etching to obtain the conductive layer. In this invention, the mass concentration of the dispersion is preferably 5 mg / mL; the solvent of the dispersion is preferably at least one of ethanol, isopropanol, and water. In this invention, the laser etching power is preferably 10~50 W, specifically 10 W, 20 W, 30 W, 40 W, or 50 W; the scanning speed is preferably 100~500 mm / s, specifically 100 mm / s, 200 mm / s, 300 mm / s, 400 mm / s, or 500 mm / s.

[0035] In this invention, the preparation of the functional layer preferably includes: spin-coating a dispersion containing the functional layer material onto the surface of a release film, removing the release film after curing, and attaching the obtained functional layer to the surface of the conductive layer. In this invention, the solvent of the dispersion is preferably N-methylpyrrolidone or xylene; the solid content of the dispersion is preferably 10-20 wt%. In this invention, the spin-coating speed is preferably 2000-3000 rpm, and the time is preferably 30-60 s; the curing temperature is preferably 70-90℃, specifically 70℃, 80℃, or 90℃; the curing time is preferably 1-3 h, specifically 1 h, 2 h, or 3 h.

[0036] After obtaining the intermediate structure, the present invention stacks the adhesion layer and the intermediate structure and presses them together, and then prepares a protective layer on the surface of the functional layer to obtain the flexible electronic skin.

[0037] In this invention, when the material of the adhesive layer is an ionic gel, the preparation method of the adhesive layer preferably includes: mixing an ionic liquid and a polyurethane prepolymer, coating the mixture onto the surface of a release film, and drying it to obtain the adhesive layer; the ionic liquid is preferably 1-butyl-3-methylimidazolium hexafluorophosphate or 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; the polyurethane prepolymer preferably includes an MDI-type polyurethane prepolymer or an MDI / TDI blend prepolymer; the mass percentage of NCO in the polyurethane prepolymer is preferably 10-11%; the mass concentration of the ionic liquid is preferably 10%; the mass ratio of the ionic liquid to the polyurethane prepolymer is preferably 1:3-5, specifically 1:3, 1:4, or 1:5; the drying temperature is preferably 60-70°C, and the drying time is preferably 1-2 hours.

[0038] In this invention, when the material of the adhesive layer is a shape memory polymer, the preparation method of the adhesive layer preferably includes: mixing polycaprolactone-polyurethane block copolymer, crosslinking agent and solvent, coating the resulting dispersion onto the surface of a release film, drying and removing the release film to obtain the adhesive layer; the crosslinking agent preferably includes trimethylolpropane (TMP) or hydrogenated MDI (H12MDI); the solvent preferably includes N,N-dimethylformamide (DMF) or tetrahydrofuran (THF); the mass ratio of the polycaprolactone-polyurethane block copolymer to the crosslinking agent is preferably 100:5~15; this invention does not have a special limitation on the amount of solvent used, as long as it can disperse the copolymer and crosslinking agent evenly; the drying temperature is preferably 70~80℃, and the drying time is preferably 1.5~2h; the shape memory effect is induced by adding a crosslinking agent.

[0039] In this invention, the pressing method is preferably hot pressing, the hot pressing temperature is preferably 80°C, the pressure is preferably 0.5 MPa, and the time is preferably 15 min.

[0040] In this invention, when the material of the protective layer is silicon oxide, the protective layer is preferably prepared by magnetron sputtering. In this invention, when the material of the protective layer is a fluoropolymer, the protective layer is preferably prepared by spraying or spin coating. This invention does not impose any particular limitation on the preparation process of the magnetron sputtering, spraying, or spin coating methods; any method well-known to those skilled in the art can be used.

[0041] In this invention, after preparing the protective layer, it is preferable to further perform a low-temperature plasma activation treatment on the adhesion layer; the plasma power of the low-temperature plasma activation treatment is preferably 100W, and the time is preferably 5min. In this invention, the adhesion layer can be activated by performing low-temperature plasma treatment to improve the reversible adhesion to the interface to be adhered.

[0042] The present invention also provides the application of the flexible electronic skin described in the above technical solution or the flexible electronic skin prepared by the preparation method described in the above technical solution in electromagnetic shielding.

[0043] In this invention, the preferred method of application includes: preheating the flexible electronic skin, then bringing the adhesive layer of the flexible electronic skin into contact with the interface to be adhered, and performing conformal attachment. In this invention, the preheating temperature is preferably 45°C.

[0044] In this invention, an electrostatic-assisted attachment module, a strain-sensing monitoring module, and a potential control module are preferably provided between the flexible electronic skin and the interface to be adhered. During the attachment process, a controllable electrostatic field is applied between the component and the skin to guide the skin to achieve precise directional attachment. The strain-sensing monitoring module is embedded within the skin to monitor the deformation and stress distribution after attachment in real time, achieving stress self-compensation by controlling the interface layer temperature or potential. Simultaneously, the strain-sensing monitoring module can dynamically adjust the reflectivity of the conductive mesh layer and the absorptivity of the functional absorption layer to adapt to multi-band electromagnetic protection requirements. A specific structural diagram is shown in Figure 1 (where the top layer is the flexible electronic skin, the bottom layer is the curved substrate, and the middle layer is the module).

[0045] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0046] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0047] Example 1 An ionic liquid with a concentration of 10 wt% (specifically 1-butyl-3-methylimidazolium hexafluorophosphate) and a polyurethane prepolymer (specifically MDI-type polyurethane prepolymer with an NCO mass fraction of 10%) were mixed at a mass ratio of 1:4. The mixture was then coated onto the surface of a release film using a blade coating method and cured in an oven at 60°C for 1 hour. After removing the release film, an adhesion layer with a thickness of 18 μm was obtained. A PI substrate layer with a thickness of 35 μm was prepared by casting. A silver nanowire dispersion (concentration 5 mg / mL, solvent is ethanol / water mixed solvent, volume ratio 3:1) was uniformly coated on the surface of the substrate. After drying, a grid structure was formed on one side of the surface by laser etching (laser power 20 W, scanning speed 300 mm / s, grid gap 15 μm, average side length of a single protrusion 37 μm, average height of a protrusion 12 μm) to obtain a conductive layer with a total thickness of 22 μm. Silicon carbide powder (50 nm particle size) and nickel-zinc ferrite powder (80 nm particle size) were mixed with polyurethane and N-methylpyrrolidone in a mass ratio of 1:1 (wherein the mass ratio of powder to film-forming substance was 15:7, and the solid content of the spin coating solution was 15 wt%). The mixture was then coated onto the surface of a release film using a spin coating method at a spin coating speed of 2500 rpm and a spin coating time of 40 s. After curing at 80 °C for 2 h, the release film was removed to obtain a functional layer with a thickness of 32 μm. The functional layer was then attached to the surface of the conductive layer to obtain the intermediate structure. The adhesion layer and the intermediate structure were bonded together by hot pressing at a temperature of 80°C, a pressure of 0.5 MPa, and a time of 15 min. Subsequently, an 8 μm thick SiO₂ layer was deposited on the surface of the functional layer using magnetron sputtering. x Protective layer; The adhesion layer was activated by low-temperature plasma with a plasma power of 100W and a treatment time of 5 minutes to obtain a flexible electronic skin.

[0048] Example 2 Polycaprolactone-polyurethane block copolymer, crosslinking agent and solvent were mixed, wherein the crosslinking agent was trimethylolpropane (TMP) and the solvent was N,N-dimethylformamide (DMF), and the mass ratio of polycaprolactone-polyurethane block copolymer to crosslinking agent was 100:10; the resulting dispersion was coated onto the surface of a release film by a blade coating method, cured in an oven at 70°C for 1.5 h, and after removing the release film, an adhesion layer with a thickness of 16 μm was obtained; A PDMS substrate layer with a thickness of 32 μm was prepared by casting. A copper nanowire + carbon nanotube dispersion (copper nanowire and carbon nanotube mass ratio 3:1, total concentration 5mg / mL, solvent is isopropanol / water mixed solvent, volume ratio 2:1) was coated on the surface of the substrate. After drying, a grid structure was formed on one side of the surface by laser etching (laser power 30W, scanning speed 400mm / s, grid gap 12μm, average side length of a single protrusion 37μm, average height of a protrusion 12μm) to obtain a conductive layer with a thickness of 23μm. Titanium carbide powder (45 nm particle size) and manganese zinc ferrite powder (75 nm particle size) were mixed with epoxy resin and N-methylpyrrolidone at a mass ratio of 1:2 (wherein the mass ratio of powder to film-forming substance was 2:1, and the solid content of the spin coating solution was 18 wt%). The mixture was then coated onto the surface of a release film using a spin coating method at a spin coating speed of 2400 rpm and a spin coating time of 45 s. The mixture was cured at 85 °C for 1.5 h. After removing the release film, a functional layer with a thickness of 33 μm was obtained. The functional layer was then attached to the surface of the conductive layer to obtain the intermediate structure. The adhesive layer and the intermediate structure were bonded together by hot pressing at a temperature of 80°C, a pressure of 0.5 MPa, and a time of 15 min. Subsequently, a 7 μm thick protective layer of fluoropolymer (specifically polytetrafluoroethylene) was coated on the surface of the functional layer by spraying. The adhesion layer was activated by low-temperature plasma with a plasma power of 100W and a treatment time of 5 minutes to obtain a flexible electronic skin.

[0049] Example 3 An ionic liquid with a concentration of 10 wt% (specifically 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt) and a polyurethane prepolymer (specifically an MDI / TDI blend prepolymer with an NCO mass fraction of 11%) were mixed at a mass ratio of 1:5. The mixture was then coated onto the surface of a release film using a blade coating method and cured in an oven at 65°C for 1.2 h. The release film was then removed to obtain an adhesive layer with a thickness of 19 μm. A 38 μm thick PEN substrate layer was prepared using a casting method. A graphene + silver nanowire dispersion (graphene and silver nanowire mass ratio 1:5, total concentration 5 mg / mL, solvent: ethanol) was coated on the substrate surface. After drying, a grid structure was formed by laser etching (laser power 15 W, scanning speed 200 mm / s, grid gap 10 μm, average side length of a single protrusion 37 μm, average height of a protrusion 12 μm) to obtain a conductive layer with a thickness of 21 μm. Tungsten carbide powder (55 nm particle size) and cobalt-zinc ferrite powder (85 nm particle size) were mixed with epoxy resin and N-methylpyrrolidone at a mass ratio of 2:1 (wherein the mass ratio of powder to film-forming substance was 16:8, and the solid content of spin coating liquid was 16 wt%). The mixture was then coated onto the surface of a release film using a spin coating method at a spin coating speed of 2600 rpm and a spin coating time of 38 s. The mixture was cured at 75 °C for 2.5 h. After removing the release film, a functional layer with a thickness of 34 μm was obtained. The functional layer was then attached to the surface of the conductive layer to obtain the intermediate structure. The adhesion layer and the intermediate structure were bonded together by hot pressing at a temperature of 80°C, a pressure of 0.5 MPa, and a time of 15 min. Subsequently, a 9 μm thick SiO₂ layer was deposited on the surface of the functional layer using magnetron sputtering. x Protective layer; The adhesion layer was activated by low-temperature plasma with a plasma power of 100W and a treatment time of 5 minutes to obtain a flexible electronic skin.

[0050] Performance testing (1) The electromagnetic shielding performance of the flexible electronic skins obtained in Examples 1-3 was tested; The testing process is as follows: After preheating the flexible electronic skin at 45°C, the adhesive layer of the flexible electronic skin is brought into contact with the interface to be adhered, and conformal attachment is performed. The shielding effectiveness was tested using the standard ASTM D4935 method. The test conditions were: cyclic testing under thermal vacuum conditions with a vacuum level of 10. -5 Pa, frequency range 0.1MHz~10GHz, temperature range -150℃~150℃; Figure 5 This is a schematic diagram of a shielding effectiveness testing device, which consists of core testing equipment and auxiliary monitoring components: The central component is a thermal vacuum environment simulation chamber (used to simulate space vacuum conditions), inside which is a curved testing fixture on which the flexible electronic skin sample to be tested is fixed; a vector network analyzer (used to emit electromagnetic waves in the 0.1MHz~10GHz frequency band and receive signals after penetrating the sample to calculate shielding effectiveness) is connected to the outside of the simulation chamber; a laser rangefinder is placed beside the chamber (used to monitor the adhesion status of the sample and the fixture in real time). All components are connected to a control terminal via signal lines, forming a complete shielding performance testing system. Test results show that the shielding effectiveness retention rate is 96.2% for Example 1, 95.8% for Example 2, and 97.1% for Example 3. The electromagnetic shielding effectiveness retention rate of the flexible electronic skins obtained in the above examples is over 95%.

[0051] (2) Flexibility and adhesion performance test: Test method: The attachment was applied to curved parts with curvature radii of 10mm, 15mm, and 20mm, and the attachment error was measured using a laser rangefinder; the structural integrity was observed after 5000 bends (bending angle ±90°, bending rate 1 time / s). Test results: The attachment error of the flexible electronic skin in Example 1 was 0.08 mm, in Example 2 it was 0.07 mm, and in Example 3 it was 0.09 mm; after bending, there was no cracking or delamination, and the shielding effectiveness decreased by ≤3%.

[0052] Figure 4 This is a schematic diagram of the electromagnetic reflection and absorption coupling principle. The arrow on the left in the diagram represents the incident electromagnetic wave. In the first stage, the electromagnetic wave enters the functional layer, and the carbide and ferrite convert the electromagnetic energy into heat energy through magnetic loss. In the second stage, in this layer, the conductive network uses "electromagnetic induction" to form a reverse current, which cancels out most of the remaining electromagnetic wave, and finally achieves electromagnetic wave attenuation.

[0053] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A flexible electronic skin, characterized in that, It includes an adhesive layer, a flexible substrate layer, a conductive layer, a functional layer, and a protective layer that are stacked sequentially. The materials of the functional layer include carbides and ferrites; The surface of any one side of the conductive layer includes a plurality of protrusions arranged in an array.

2. The flexible electronic skin according to claim 1, characterized in that, The material of the adhesion layer includes ionogel or shape memory polymer; The thickness of the adhesion layer is 15~20μm.

3. The flexible electronic skin according to claim 1, characterized in that, The flexible substrate layer is made of at least one of polyimide, polydimethylsiloxane, fluorinated ethylene propylene copolymer and polyethylene naphthalate. The thickness of the flexible substrate layer is 30~40μm.

4. The flexible electronic skin according to claim 1, characterized in that, The conductive layer is made of at least one of silver nanowires, copper nanowires, carbon nanotubes, and graphene. The total thickness of the conductive layer is 20~25μm; The protrusions are square in shape; the average side length of a single protrusion is 35-40 μm; the average height of the protrusions is 10-15 μm; and the interval between adjacent protrusions is 10-20 μm.

5. The flexible electronic skin according to claim 1, characterized in that, The carbide includes at least one of silicon carbide, boron carbide and titanium carbide; The ferrite includes at least one of nickel-zinc ferrite, manganese-zinc ferrite, cobalt-zinc ferrite, and lithium-zinc ferrite. The mass ratio of the carbide to the ferrite is 1~9:1~9; The functional layer also includes a film-forming substance; the thickness of the functional layer is 30~35μm.

6. The flexible electronic skin according to claim 1, characterized in that, The material of the protective layer includes silicon oxide or fluoropolymer; The thickness of the protective layer is 5~10μm.

7. The method for preparing the flexible electronic skin according to any one of claims 1 to 6, characterized in that, Includes the following steps: A conductive layer and a functional layer are sequentially fabricated on the surface of a flexible substrate to obtain an intermediate structure; After the adhesion layer and the intermediate structure are stacked and pressed, a protective layer is prepared on the surface of the functional layer to obtain the flexible electronic skin.

8. The preparation method according to claim 7, characterized in that, The preparation of the conductive layer includes: coating a dispersion containing a conductive layer material onto the surface of the flexible substrate, drying it, and then performing laser etching to obtain the conductive layer; the laser etching power is 10~50W, and the scanning speed is 100~500mm / s; The preparation of the functional layer includes: spin-coating a dispersion containing the functional layer material onto the surface of a release film, removing the release film after curing, and attaching the obtained functional layer to the surface of the conductive layer; The pressing method is hot pressing, with a temperature of 80°C, a pressure of 0.5 MPa, and a time of 15 minutes.

9. The preparation method according to claim 7, characterized in that, After preparing the protective layer, the process further includes performing a low-temperature plasma activation treatment on the adhesion layer; The plasma power for the low-temperature plasma activation treatment is 100W, and the time is 5 minutes.

10. The application of the flexible electronic skin according to any one of claims 1 to 6 or the flexible electronic skin prepared by the preparation method according to any one of claims 7 to 9 in electromagnetic shielding.

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