A flexible electrode and a method for preparing the same

Abstract

The present invention relates to the field of wearable flexible devices, and discloses a flexible electrode and a preparation method thereof. The flexible electrode provided by the present invention comprises a first flexible support structure, an electrode layer, and a second flexible support structure, wherein the electrode layer is disposed on the top of the first flexible support structure; the first flexible support structure comprises at least two first convex structures disposed at intervals, wherein the first convex structures are used to contact the skin, the first flexible support structure is conductive, and the second flexible support structure is disposed on the top of the electrode layer. Thus, the flexible electrode has the characteristics of good flexibility, high fixed fit with the skin, and simple structure.

Description

Technical Field

[0001] The present invention relates to the field of wearable flexible devices, and in particular to a flexible electrode and a preparation method thereof. Background Art

[0002] Flexible devices are flexible devices that can maintain stable properties when deformed. In recent years, with the demand for flexible, lightweight and portable electronic devices, flexible devices have been deeply studied and widely used in the fields of biomedicine, bionic skin, flexible wearable devices, etc. Because human skin is an important sensor of the human body, in addition to its ability to sense force, temperature and humidity, the muscle tissue underneath it is the key executor of human movement. It can transmit the physiological electrical signals generated by muscle movement through the skin. People can encode and decode the movement intention of the limbs based on this signal; thereby providing action instructions for externally controlled mechanical equipment.

[0003] In the biomedical field, the research on flexible devices mainly includes implantable devices and wearable medical devices. Implanted or wearable devices will directly contact the skin or soft tissue. In order to reduce the discomfort caused by the inconsistency of the mechanical properties of the device and the skin, the mechanical flexibility of this part of the material is very important. Traditional medical implants are based on hard inorganic semiconductor materials such as silicon (Young's modulus is about 100GPa), while the Young's modulus of biological tissues is mostly at the kPa level. Therefore, a flexible polymer film is selected as the substrate. While ensuring mechanical strength and flexibility, it reduces the thickness and weight of the device and gives the device biomimetic properties such as self-healing ability. Compared with silicon semiconductors, the mechanical properties of polymer materials and biological tissues are more matched, and the adverse reactions can be reduced when flexible devices come into contact with biological tissues.

[0004] For wearable flexible devices that are usually used to monitor physiological electrical signals, the adhesion between the device and the human skin and whether the device itself has stable electrical properties when undergoing large deformation are the key to determining whether it can collect ideal quality signals. Currently, common flexible electrodes generally have the following structure. One part uses polyimide, polydimethylsiloxane or polyethylene terephthalate as a flexible support substrate, and the conductor connection is made by designing the configuration of the inorganic rigid connection layer, such as Figure 1As shown, flexible skin electronics are made of wavy single-crystal silicon nanoribbons using polydimethylsiloxane (PDMS) as the main flexible substrate; the electrode connects scattered hard structure points through wavy lines, thereby improving its curved surface coating ability to achieve a small bending radius, and the electrode has good conformal adhesion performance; but when connecting rigid device units through wire configuration, or semiconductor material devices with a certain degree of deformability, their flexibility and adhesion are still greatly limited due to the limitations of the material itself, making it difficult to meet the arbitrary deformation of the device, and the processing technology is complicated, which is not suitable for large-scale and large-scale manufacturing. Summary of the invention

[0005] The present invention aims to solve the technical problems of the flexible electrode in the prior art, namely, poor flexibility and adhesion and complex molding and processing.

[0006] To solve the above technical problems, the present application discloses, on one hand, a flexible electrode, which includes a first flexible support structure, an electrode layer and a second flexible support structure;

[0007] The electrode layer is arranged on the top of the first flexible support structure; the first flexible support structure comprises at least two first convex structures arranged at intervals, the first convex structures are used to contact with the skin, and the first flexible support structure is conductive;

[0008] The second flexible supporting structure is arranged on the top of the electrode layer.

[0009] Optionally, the electrode layer includes N sub-electrodes arranged at intervals; N is a positive integer greater than or equal to 1;

[0010] The first flexible support structure includes N sub-support sets, and each sub-support set in the N sub-support sets includes at least two first convex structures;

[0011] The N sub-electrodes are connected to the N sub-support sets in a one-to-one correspondence.

[0012] Optionally, the first convex structure has a thickness of 10 to 50 microns;

[0013] The thickness of the first convex structure is 300-600 micrometers.

[0014] Optionally, the material of the electrode layer includes gold or platinum;

[0015] The material of the first flexible support structure includes a mixture of carbon nanotubes and polydimethylsiloxane.

[0016] Optionally, the second flexible support structure comprises a connected base layer and an adhesive structure;

[0017] The substrate layer is connected to the electrode layer;

[0018] The adhesive structure includes at least two second convex structures disposed at intervals.

[0019] Optionally, the width of the second convex structure is 100 micrometers to 1 millimeter;

[0020] The thickness of the second convex structure is 800 microns to 1200 microns;

[0021] The material of the second flexible support structure includes polydimethylsiloxane.

[0022] In another aspect, the present application also discloses a method for preparing a flexible electrode, which comprises the following steps:

[0023] providing a first substrate;

[0024] Forming at least two first grooves on the first substrate by an etching process;

[0025] Applying a predetermined solution in the at least two first grooves and curing the solution to obtain a first structure;

[0026] An electrode layer is prepared on the first structure, and the electrode layer is connected to the solidified preset solution; the solidified preset solution forms a first flexible supporting structure;

[0027] preparing a second flexible support structure on the electrode layer;

[0028] The first substrate is peeled off to obtain a flexible electrode.

[0029] Optionally, preparing a second flexible support structure on the electrode layer comprises:

[0030] providing a second substrate;

[0031] forming at least two second grooves on the second substrate by an etching process;

[0032] Spin coating a flexible material solution into the at least two second grooves to obtain a second structure;

[0033] placing the second structure on the electrode layer and curing;

[0034] The second substrate is peeled off.

[0035] Optionally, preparing an electrode layer on the first structure includes:

[0036] coating a photoresist on the first structure;

[0037] patterning the photoresist;

[0038] depositing an electrode layer on the first structure;

[0039] The photoresist is removed.

[0040] Optionally, the preset solution includes a mixture of carbon nanotubes and polydimethylsiloxane;

[0041] The flexible material solution includes a polydimethylsiloxane solution.

[0042] By adopting the above technical solution, the flexible electrode provided by the present application has the following beneficial effects:

[0043] The flexible electrode provided by the present application includes a first flexible support structure, an electrode layer and a second flexible support structure, wherein the electrode layer is arranged on the top of the first flexible support structure; the first flexible support structure includes at least two first convex structures arranged at intervals, wherein the first convex structures are used to contact the skin, the first flexible support structure is conductive, and the second flexible support structure is arranged on the top of the electrode layer. The above-mentioned flexible electrode with a sandwich structure has the advantages of good flexibility, simple structure and easy molding and processing, and because the convex structure is arranged on the electrode layer, the fixed fit between the electrode and the skin is improved, which is conducive to achieving high-quality signal acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0045] Figure 1 It is a schematic diagram of the structure of a flexible electrode in the prior art;

[0046] Figure 2 This is a schematic diagram of the structure of an optional flexible electrode of the present application;

[0047] Figure 3 A bottom view of an optional flexible electrode of the present application;

[0048] Figure 4 This is a schematic diagram of the structure of another optional flexible electrode of the present application;

[0049] Figure 5 A schematic diagram of a process for preparing an optional flexible electrode of the present application;

[0050] Figure 6 This is a schematic structural diagram of an optional first substrate of the present application;

[0051] Figure 7 This is a schematic diagram of an optional first structure of the present application;

[0052] Figure 8A schematic structural diagram of a first structure of an optional patterned photoresist of the present application;

[0053] Fig. 9 This is a schematic structural diagram of an optional first structure after depositing an electrode layer in the present application.

[0054] Fig.10 This is a schematic diagram of an optional structure of a first substrate and a second substrate after bonding in the present application.

[0055] The following is a supplementary description of the attached drawings:

[0056] 1-first flexible support structure; 11-first convex structure; 2-electrode layer; 3-second flexible support structure; 31-second convex structure; 32-base layer; 33-adhesion structure; 4-first substrate; 41-first groove; 5-first structure; 6-photoresist; 7-second substrate. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0058] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may include one or more of the features explicitly or implicitly. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here.

[0059] For the purpose of the following detailed description, it should be understood that the present invention may adopt various alternative changes and step sequences, unless expressly specified to the contrary. In addition, except in any operating examples, or otherwise indicated, all numbers representing the amount of ingredients used in the specification and claims should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the attached claims are approximate values ​​that vary according to the desired performance to be obtained by the present invention. At least it is not intended to limit the application of the doctrine of equivalents to the scope of the claims, and each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques.

[0060] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0061] When a numerical range is disclosed herein, the above range is deemed to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges included therein. For example, a specified range from "1 to 10" should be deemed to include any and all sub-ranges between a minimum of 1 and a maximum of 10. Exemplary sub-ranges of ranges 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0062] In order to better reflect the beneficial effects of the technical solution of the present application, several technical solutions of flexible electrodes existing in the prior art are first discussed below.

[0063] In the first solution, polyimide, polydimethylsiloxane or polyethylene terephthalate are used as flexible support substrates, and the conductor connection is made by designing the configuration of the inorganic rigid connection layer, such as Figure 1 As shown, flexible skin electronics are made of wavy single-crystal silicon nanoribbons using PDMS as the main flexible substrate; the electrode connects scattered hard structure points through wavy lines, thereby improving its curved surface coating ability to achieve a small bending radius, and the electrode has good conformal adhesion performance.

[0064] The second option is to mix organic matter, polymers, and carbon nanomaterials to make conductive polymers, and use them as signal transmission conductor materials, taking advantage of the flexibility and stretchability of the polymer itself to achieve device adhesion.

[0065] The third option is to directly use stretchable organic conductors and semiconductor materials to prepare devices.

[0066] However, all of the above three solutions have the following disadvantages.

[0067] 1. The first type mentioned above uses wire configuration to connect rigid device units, or semiconductor material devices with a certain degree of deformability. Due to the limitations of the material itself, its flexibility and adhesion are still greatly limited, and it is difficult to meet the arbitrary deformation of the device. In addition, the processing technology is complicated and is not suitable for large-scale and wide-range manufacturing.

[0068] 2. The second type of electrode made of a mixed flexible conductive polymer substrate has better tensile properties, but the adhesion of these materials to metals is poor, resulting in a high impedance value of the electrode. Especially when the flexible substrate is deformed by force, it is difficult to ensure the stability of the electrical performance of the device when the flexible substrate is deformed, thereby reducing the amplitude of the collected physiological electrical signals;

[0069] 3. The third type of device mentioned above generally has the problem that when the limbs move, the electrode is difficult to fix and adhere to the skin contact surface.

[0070] In real life, due to the widespread popularity of flexible electronics and wearable devices in life, as well as the requirements for high-quality physiological electrical signals in clinical medicine and scientific research, it is a general trend to develop electrodes that integrate multiple advantages. The common flexible skin electrodes are undoubtedly the bottleneck of human-computer interaction detection and research. Developing a new type of flexible skin electrode for physiological electrical signal monitoring, which has the characteristics of "high-quality signal acquisition capability", "good adhesion", "low impedance" and "customization", is the key to breaking through the bottleneck.

[0071] Based on this, the present application proposes a flexible electrode, see Figure 2 , Figure 2 This is a schematic diagram of the structure of an optional flexible electrode of the present application. The flexible electrode includes a first flexible support structure 1, an electrode layer 2 and a second flexible support structure 3. The electrode layer 2 is provided on the top of the first flexible support structure 1; the first flexible support structure 1 includes at least two first convex structures 11 arranged at intervals, the first convex structures 11 are used to contact the skin, the first flexible support structure 1 is conductive, and the second flexible support structure 3 is provided on the top of the electrode layer 2. This structure not only has good flexibility and low impedance, but also can further improve the fit between the electrode layer 2 and the skin by providing the first convex structure 11 on the electrode layer 2, thereby ensuring the ability to collect high-quality signals.

[0072] In a possible embodiment, see Figure 3 , Figure 3 This is a bottom view of an optional flexible electrode of the present application. The electrode layer 2 includes N sub-electrodes arranged at intervals; N is a positive integer greater than or equal to 1, the first flexible support structure 1 includes N sub-support sets, each of the N sub-support sets includes at least two first convex structures 11, and the N sub-electrodes are connected to the N sub-support sets in a one-to-one correspondence.

[0073] In a feasible embodiment, the width of the first convex structure 11 is 10-50 micrometers, and the thickness of the first convex structure 11 is 300-600 micrometers.

[0074] Optionally, the cross-section of the first convex structure 11 and the second convex structure 31 may be in a rectangular, circular, or other shape. To improve user experience, the end of the first convex structure 11 and the end of the second convex structure 31 are both arc surfaces.

[0075] In a feasible embodiment, the material of the electrode layer 2 includes gold or platinum. If the electrode layer 2 is prepared by sputtering or evaporation, in order to improve the adhesion between the conductive layer and the flexible support structure, the electrode layer 2 includes a stacked first adhesion layer, a conductive layer and a second adhesion layer; the materials of the first adhesion layer and the second adhesion layer include chromium or titanium; the material of the conductive layer includes gold or platinum; in another optional embodiment, the electrode layer 2 can also only include a stacked first adhesion layer and a conductive layer, and the first adhesion layer is connected to the first flexible support structure 1.

[0076] Optionally, the material of the first flexible support structure 1 includes a mixture of carbon nanotubes and polydimethylsiloxane. Due to the advantage of stable conductivity of inorganic metals, the impedance of the electrode is effectively reduced, the flexibility of the electrode structure is ensured, and the fit with the skin is improved.

[0077] In a possible embodiment, see Figure 4 , Figure 4 This is a schematic diagram of the structure of another optional flexible electrode of the present application. The second flexible support structure 3 includes a connected base layer 32 and an adhesive structure 33, the base layer 32 is connected to the electrode layer 2, and the adhesive structure 33 includes at least two second convex structures 31 arranged at intervals. The flexible electrode of this structure can be used for (in vivo) subcutaneous signal detection to ensure the fixation of both sides of the flexible electrode and improve the accuracy and stability of signal detection.

[0078] In a feasible embodiment, the width of the second convex structure 31 is 100 micrometers to 1 millimeter, and the thickness of the second convex structure 31 is 800 micrometers to 1200 micrometers.

[0079] It should be noted that the first convex structures 11 and the second convex structures 31 can be equidistant from each other to facilitate molding and processing. Of course, as needed, they can also be arranged into structures of varying densities to reflect differentiated customization of the adhesion area, as long as the flexible electrode can be tightly attached to the preset position of the skin. Optionally, the distance between the centers of adjacent first convex structures 11 can be twice the width of the first convex structure 11. Similarly, the distance between the centers of adjacent second convex structures 31 can be twice the width of the second convex structure 31.

[0080] Optionally, the material of the second flexible supporting structure 3 includes polydimethylsiloxane.

[0081] See also Figure 5 , Figure 5 The present application also discloses a method for preparing a flexible electrode, which comprises the following steps:

[0082] S501: providing a first substrate 4.

[0083] Optionally, the first substrate 4 is one or a combination of silicon, silicon oxide, sapphire, diamond, aluminum nitride, gallium nitride or silicon carbide.

[0084] S502 : forming at least two first grooves 41 on the first substrate 4 by using an etching process.

[0085] Optionally, a plurality of first grooves 41 may be etched on the surface of the first substrate 4 by deep reactive ion etching, such as Figure 6 As shown, Figure 6 This is a schematic structural diagram of an optional first substrate of the present application.

[0086] S503: Coating the predetermined solution in the at least two first grooves 41 and curing the solution to obtain the first structure 5, see Figure 7 , Figure 7 This is a schematic structural diagram of an optional first structure of the present application.

[0087] In a feasible embodiment, the predetermined solution includes a mixture of carbon nanotubes and polydimethylsiloxane.

[0088] Optionally, the mass fraction of the carbon nanotubes in the preset solution is 2.5-6 wt%, for example, 2.5 wt%, 3 wt%, 4 wt%, 4.5 wt% or 6 wt%.

[0089] Optionally, the curing conditions in step S403 are: curing temperature of 60 to 120 degrees Celsius and time of 30 minutes to 3 hours.

[0090] Optionally, after step S403, the first structure 5 may be subjected to plasma treatment to improve the adhesion between the structure and the subsequent electrode layer 2. Of course, other hydrophilic treatment methods may also be used. Optionally, during the plasma treatment, a plasma power of 500 to 800 watts, a time of 3 to 7 minutes, and a flow rate of 150 to 300 ml / min may be used.

[0091] Optionally, the preset solution may be coated in the first groove 41 of the first substrate 4 by spin coating. In order to ensure the stability of the electrode structure prepared subsequently, the surface of the preset solution after spin coating should be flat.

[0092] S504: preparing an electrode layer 2 on the first structure 5, wherein the electrode layer 2 is connected to the solidified preset solution; and the solidified preset solution forms a first flexible support structure 1.

[0093] In a possible embodiment, see Figure 8 and Fig. 9 , Figure 8 This is a schematic structural diagram of a first structure of an optional patterned photoresist of the present application. Fig. 9 Schematic diagram of the structure of the first structure after the electrode layer is deposited in the present application. The process of preparing the electrode layer 2 in step S404 may be: coating the photoresist 6 on the first structure 5, patterning the photoresist 6 (such as Figure 8 As shown), depositing an electrode layer 2 on the first structure 5, removing the photoresist 6 (as shown Fig. 9 shown).

[0094] Optionally, the thickness of the photoresist 6 is 2-5 microns, the rotation speed of the photoresist 6 during spin coating is 500-800 rpm, and the spin coating time is 25-40 seconds.

[0095] S505 : preparing a second flexible support structure 3 on the electrode layer 2 .

[0096] In a possible embodiment, see Fig.10 This is a schematic diagram of an optional structure after the first substrate and the second substrate are bonded together in the present application. Step S405 can be specifically described as: providing a second substrate 7; forming at least two second grooves on the second substrate 7 by an etching process; spin coating a flexible material solution in the at least two second grooves to obtain a second structure; placing the second structure on the electrode layer 2 and curing it; and peeling off the second substrate 7.

[0097] The flexible material solution includes a polydimethylsiloxane solution.

[0098] Optionally, the second substrate 7 is one or a combination of silicon, silicon oxide, sapphire, diamond, aluminum nitride, gallium nitride or silicon carbide.

[0099] S506: peeling off the first substrate 4 to obtain a flexible electrode.

[0100] In summary, the flexible electrode provided by the present application first uses polydimethylsiloxane material as a flexible substrate. The polydimethylsiloxane material can be made into a film with high tensile elasticity as required, and its contact interface is more viscous, thereby increasing the tensile deformation ability and interface adhesion of the electrode, and enabling the electrode to maintain a relative displacement of zero with the biological interface at an interface with poor adhesion, thereby realizing fixed-point collection of physiological signals over a long period of time;

[0101] Secondly, columnar three-dimensional microstructures (i.e., the first convex structure 11 and the second convex structure 31) are used on the upper and lower surfaces of the electrode, and are made of polydimethylsiloxane material, which has the ability to deform to a certain extent according to the roughness of the contact surface, and can increase the contact area between the electrode contact, the electrode itself, and the human body and skin tissue interface, thereby increasing adhesion and reducing the contact impedance of the electrode;

[0102] Furthermore, a mixture of carbon nanotubes and polydimethylsiloxane is selected as the microstructure material of the exposed side of the contact. The mixed material of carbon nanotubes and polydimethylsiloxane has good conductivity. Cr / Au metal is used as the intermediate conductor metal of the electrode and the mixed material of carbon nanotubes and polydimethylsiloxane is hydrophilically treated at the interface between the metal and the organic polymer, thereby increasing the adhesion of the metal and utilizing the advantage of the stable conductivity of inorganic metals, effectively reducing the impedance of the electrode.

[0103] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A flexible electrode, characterized in that: comprising a first flexible support structure, an electrode layer and a second flexible support structure; The electrode layer is arranged on the top of the first flexible support structure; the first flexible support structure comprises at least two first convex structures arranged at intervals, the first convex structures are used to contact with the skin, and the first flexible support structure is conductive; The second flexible supporting structure is provided on the top of the electrode layer.

2. The flexible electrode according to claim 1, characterized in that: The electrode layer includes N sub-electrodes arranged at intervals; N is a positive integer greater than or equal to 1; The first flexible support structure includes N sub-support sets, and each sub-support set in the N sub-support sets includes at least two of the first convex structures; The N sub-electrodes are connected to the N sub-support sets in a one-to-one correspondence.

3. The flexible electrode according to claim 1, characterized in that: The width of the first convex structure is 10 to 50 microns; The thickness of the first convex structure is 300-600 micrometers.

4. The flexible electrode according to claim 1, characterized in that: The material of the electrode layer includes gold or platinum; The material of the first flexible support structure includes a mixture of carbon nanotubes and polydimethylsiloxane.

5. The flexible electrode according to claim 1, characterized in that: The second flexible support structure includes a connected base layer and an adhesive structure; The substrate layer is connected to the electrode layer; The adhesive structure includes at least two second convex structures disposed at intervals.

6. The flexible electrode according to claim 5, characterized in that: The width of the second convex structure is 100 micrometers to 1 millimeter; The thickness of the second convex structure is 800 microns to 1200 microns; The material of the second flexible supporting structure includes polydimethylsiloxane.

7. A method for preparing a flexible electrode, characterized in that: The following steps are involved: providing a first substrate; Forming at least two first grooves on the first substrate by an etching process; Applying a predetermined solution in the at least two first grooves and curing the solution to obtain a first structure; preparing an electrode layer on the first structure, wherein the electrode layer is connected to the solidified preset solution; The solidified preset solution forms a first flexible supporting structure; preparing a second flexible support structure on the electrode layer; The first substrate is peeled off to obtain a flexible electrode.

8. The preparation method according to claim 7, characterized in that: The step of preparing a second flexible support structure on the electrode layer comprises: providing a second substrate; forming at least two second grooves on the second substrate by an etching process; Spin-coating a flexible material solution into the at least two second grooves to obtain a second structure; placing the second structure on the electrode layer and curing it; The second substrate is peeled off.

9. The preparation method according to claim 7, characterized in that: The step of preparing an electrode layer on the first structure comprises: coating a photoresist on the first structure; patterning the photoresist; depositing an electrode layer on the first structure; The photoresist is removed.

10. The preparation method according to claim 8, characterized in that: The preset solution includes a mixture of carbon nanotubes and polydimethylsiloxane; The flexible material solution includes a polydimethylsiloxane solution.

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