Modulus gradient heterojunction-based triboelectric sensor for artificial larynx and preparation method

Abstract

The application discloses a frictional electric sensor for an artificial larynx based on a modulus gradient heterojunction and a preparation method thereof. The sensor comprises a high modulus first frictional layer composed of a PDMS / BST composite material and a low modulus second frictional layer composed of an Ecoflex / ZnO composite material to form a heterojunction laminated frictional pair, effectively widening the response range of the laryngeal muscle vibration (100-1000 Hz) and realizing consistent high-sensitivity collection of wideband signals. To solve the problem of easy peeling of the interface of the heterogeneous materials, a gradient modulus transition layer with a step change in composition is designed between the two frictional layers, and the interlayer chemical bonding and integrated molding are realized through an alternating spin coating and ultraviolet step curing process, which significantly improves the mechanical durability and signal stability of the sensor under long-term dynamic vibration. The application provides a high-fidelity and high-reliability voice signal collection solution for the artificial larynx.

Description

Technical Field

[0001] This invention belongs to the field of triboelectric nanogenerators, specifically relating to a triboelectric sensor for an artificial larynx based on a modulus gradient heterostructure. Background Technology

[0002] Patients who have undergone laryngectomy lose the ability to produce sound through vocal cord vibration. Artificial larynx technology aims to help patients regain the ability to "speak" by collecting vibrations from the remaining muscles in the larynx and converting them into controllable speech signals. Triboelectric nanogenerator (TENG) sensors have shown great potential in artificial larynx applications due to their high sensitivity, self-powered nature, and excellent flexibility.

[0003] However, existing TENG artificial laryngeal sensors mostly use a single friction layer material (such as pure PDMS or pure Ecoflex). Laryngeal muscle vibration is a complex signal containing multiple frequency components (typically 100Hz to 1000Hz) and amplitudes, such as voiceless consonants (high frequency, weak) and voiced consonants (low frequency, strong). Due to their inherent physical properties (such as modulus and dielectric constant), single materials struggle to maintain consistent sensitivity across the entire frequency band and amplitude range, leading to the loss of some key speech feature signals or excessively low signal-to-noise ratios, severely impacting the accuracy of subsequent speech recognition and synthesis.

[0004] Furthermore, if two materials with vastly different moduli (such as rigid PDMS and soft Ecoflex) are simply stacked to form a heterojunction, under long-term, dynamic mechanical vibration, the interface between the two materials will peel off and delaminate due to stress concentration, leading to sensor signal attenuation or even complete failure, and the reliability cannot meet the needs of daily use.

[0005] Therefore, there is an urgent need for a TENG sensor structure and fabrication method that can respond to throat vibrations over a wide frequency range and has long-term mechanical stability. Summary of the Invention

[0006] To address some of the technical problems existing in the prior art, the present invention aims to provide a TENG sensor that can uniformly respond to broadband vibrations of the throat and has excellent mechanical stability. Another objective of the present invention is to provide a method for fabricating the above-mentioned sensor, focusing on solving the technical problem of easy peeling between heterogeneous material layers due to modulus mismatch.

[0007] To achieve the above objectives, the present invention provides a triboelectric sensor for an artificial larynx based on a modulus gradient heterojunction, comprising a first electrode layer and a second electrode layer disposed opposite to each other, and a first friction layer and a second friction layer located between the first electrode layer and the second electrode layer. The first friction layer is adjacent to and electrically connected to the first electrode layer, and the second friction layer is adjacent to and electrically connected to the second electrode layer. The first friction layer is a high-modulus friction layer composed of polydimethylsiloxane and barium strontium titanate nanoparticles, and the second friction layer is a low-modulus friction layer composed of Ecoflex silicone rubber and zinc oxide nanowires. The first friction layer and the second friction layer constitute a heterostructured friction pair, and the Young's modulus of the first friction layer is greater than that of the second friction layer. A gradient modulus transition layer is disposed between the first friction layer and the second friction layer. The material composition of the gradient modulus transition layer changes in a stepwise manner along its thickness direction, with the material composition of the side in contact with the first friction layer being similar to the matrix material of the first friction layer, and the material composition of the side in contact with the second friction layer being similar to the matrix material of the second friction layer.

[0008] In one specific embodiment, the mass fraction of the barium strontium titanate nanoparticles in the first friction layer is 10% to 20%; and the mass fraction of the zinc oxide nanowires in the second friction layer is 5% to 15%.

[0009] In one specific embodiment, the gradient modulus transition layer bonds the first friction layer and the second friction layer together to form a gapless, integrated heterogeneous stacked structure; the first friction layer, the gradient modulus transition layer and the second friction layer together respond to external vibrations and realize triboelectric power generation through the periodic deformation inside the heterogeneous stacked structure.

[0010] In one specific embodiment, the gradient modulus transition layer comprises at least two sublayers composed of a mixture of polydimethylsiloxane and Ecoflex, wherein the mass proportion of polydimethylsiloxane in the mixture decreases layer by layer from the first friction layer to the second friction layer, and the mass proportion of Ecoflex increases layer by layer.

[0011] In one specific embodiment, the gradient modulus transition layer comprises three sublayers: a first sublayer in which the mass ratio of polydimethylsiloxane to Ecoflex is (6:4) to (8:2); a second sublayer in which the mass ratio is (4:6) to (6:4); and a third sublayer in which the mass ratio is (2:8) to (4:6).

[0012] In one specific embodiment, the first electrode layer and the second electrode layer are prepared on a flexible substrate of polyethylene terephthalate or polyimide.

[0013] In one specific embodiment, the sensor is entirely encapsulated in a biocompatible flexible encapsulation material, and its shape is configured to conform to the anatomical structure of the human throat.

[0014] A second aspect of the present invention provides a method for preparing the sensor provided in the first aspect of the present invention, wherein the gradient modulus transition layer is prepared by an alternating spin coating and ultraviolet step curing process, comprising the following steps:

[0015] On the surface of the completed first friction layer, a first layer of mixed slurry is spin-coated. The slurry contains polydimethylsiloxane prepolymer, Ecoflex component A and component B, with polydimethylsiloxane prepolymer having the highest proportion.

[0016] The first layer of mixed slurry is pre-cured by ultraviolet light to form the first gradient sublayer;

[0017] On the surface of the first gradient sublayer, a second layer of mixed slurry is spin-coated, wherein the proportion of polydimethylsiloxane prepolymer in the slurry is reduced and the proportion of Ecoflex component is increased.

[0018] The second layer of mixed slurry is pre-cured by a second round of ultraviolet light to form a second gradient sublayer.

[0019] All coatings and the second friction layer are subjected to final thermosetting to achieve interlayer chemical cross-linking and integrated molding.

[0020] In one specific embodiment, the wavelength of the light source for ultraviolet light pre-curing is 365nm, and the energy density is 200-500mJ / cm²; the final thermal curing temperature is 70-85℃, and the time is 1-2 hours.

[0021] In one specific embodiment, the total thickness of the gradient modulus transition layer is controlled between 20 μm and 50 μm; and the viscosity of both the first layer mixing slurry and the second layer mixing slurry is adjusted to the range of 500 cP to 2000 cP to ensure the uniformity of spin-coating and the interface fusion quality between sublayers.

[0022] Beneficial effects

[0023] 1) This invention employs a heterogeneous stacked structure composed of a PDMS / BST high-modulus friction layer and an Ecoflex / ZnO low-modulus friction layer. This structure utilizes the different mechanical and electrical properties of the two materials to synergistically respond to a wide-bandwidth (100-1000Hz) vibration signal in the throat, ranging from strong low-frequency to weak high-frequency. To further improve device reliability, a gradient modulus transition layer is introduced between the two friction layers. This transition layer is composed of a mixture of PDMS and Ecoflex in a proportionally stepped manner, achieving a smooth stress transition and effectively suppressing interface delamination.

[0024] 2) The gradient modulus transition layer of this invention is prepared using an innovative "alternating spin coating and UV step curing" process. This process involves spin coating different proportions of mixed slurry layer by layer and pre-curing each layer with UV light. By controlling key parameters such as the total thickness of the transition layer and the viscosity of the slurry, the film quality and interface fusion effect are ensured. Finally, a one-step thermal curing process is used to achieve strong chemical bonding between all layers, ensuring the integration and long-term stability of the structure.

[0025] 3) By constructing a heterogeneous stacked friction pair consisting of a high-modulus PDMS / BST layer and a low-modulus Ecoflex / ZnO layer, the high sensitivity of hard materials to weak high-frequency signals and the compliantness of soft materials to strong low-frequency signals are fully utilized. The two work together to overcome the response blind spots of single-material sensors in certain frequency bands, enabling the complete capture of speech features from voiceless to voiced consonants, providing high-quality, high signal-to-noise ratio raw signals for backend speech recognition. Attached Figure Description

[0026] Figure 1 : A schematic diagram of the structure of a triboelectric sensor for an artificial larynx based on a modulus gradient heterojunction provided in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of an artificial throat triboelectric sensor in an embodiment of the present invention, wherein the gradient modulus transition layer comprises three sub-layers. Detailed Implementation

[0028] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0029] Example 1

[0030] like Figures 1-2As shown, in the first embodiment of the present invention, a triboelectric sensor for an artificial larynx based on a modulus gradient heterojunction is provided, including a first electrode layer 200 and a second electrode layer 600 disposed opposite to each other, and a first friction layer 300 and a second friction layer 500 located between the first electrode layer 200 and the second electrode layer 600. The first friction layer 300 is adjacent to and electrically connected to the first electrode layer 200, and the second friction layer 500 is adjacent to and electrically connected to the second electrode layer 600. The first friction layer 300 is a high-modulus friction layer composed of polydimethylsiloxane and barium strontium titanate nanoparticles, and the second friction layer 500 is... Layer 500 is a low-modulus friction layer composed of Ecoflex silicone rubber and zinc oxide nanowires; the first friction layer 300 and the second friction layer 500 form a heterogeneous stacked friction pair, and the Young's modulus of the first friction layer 300 is greater than that of the second friction layer 500; a gradient modulus transition layer 400 is provided between the first friction layer 300 and the second friction layer 500; the material composition of the gradient modulus transition layer 400 changes in a stepwise manner along its thickness direction, and the material composition of the side in contact with the first friction layer 300 is similar to the matrix material of the first friction layer 300, and the material composition of the side in contact with the second friction layer 500 is similar to the matrix material of the second friction layer 500.

[0031] It is worth mentioning that, in order to facilitate the fabrication of the sensor, a first flexible substrate 100 can be provided to support the first electrode layer 200 shown. If necessary, a second flexible substrate 700 layer can also be provided to support or encapsulate the second electrode layer 600.

[0032] In this embodiment, the mass fraction of the barium strontium titanate nanoparticles in the first friction layer 300 is 10% to 20%; and the mass fraction of the zinc oxide nanowires in the second friction layer 500 is 5% to 15%.

[0033] In this embodiment, the gradient modulus transition layer 400 bonds the first friction layer 300 and the second friction layer 500 together to form a seamless, integrated heterogeneous stacked structure; the first friction layer 300, the gradient modulus transition layer 400 and the second friction layer 500 respond together to external vibrations and achieve triboelectric power generation through periodic deformation inside the heterogeneous stacked structure.

[0034] In this embodiment, the gradient modulus transition layer 400 includes at least two sublayers composed of a mixture of polydimethylsiloxane and Ecoflex. From the first friction layer 300 to the second friction layer 500, the mass proportion of polydimethylsiloxane in the mixture decreases layer by layer, and the mass proportion of Ecoflex increases layer by layer.

[0035] In this embodiment, the gradient modulus transition layer 400 includes three sublayers: a first sublayer 401, in which the mass ratio of polydimethylsiloxane to Ecoflex is (6:4)-(8:2); a second sublayer 402, in which the mass ratio is (4:6)-(6:4); and a third sublayer 403, in which the mass ratio is (2:8)-(4:6).

[0036] In this embodiment, the first electrode layer 200 and the second electrode layer 600 are prepared on a flexible substrate of polyethylene terephthalate or polyimide.

[0037] In this embodiment, the sensor is entirely encapsulated in a biocompatible flexible encapsulation material, and its shape is configured to conform to the anatomical structure of the human throat.

[0038] In the first embodiment of the present invention, a method for preparing a triboelectric sensor is also provided, wherein the gradient modulus transition layer 400 is prepared by an alternating spin coating and ultraviolet step curing process, comprising the following steps:

[0039] On the surface of the completed first friction layer 300, a first layer of mixed slurry is spin-coated. The slurry contains polydimethylsiloxane prepolymer, Ecoflex component A and component B, with polydimethylsiloxane prepolymer having the highest proportion.

[0040] The first layer of mixed slurry is pre-cured by ultraviolet light to form the first gradient sublayer;

[0041] On the surface of the first gradient sublayer, a second layer of mixed slurry is spin-coated, wherein the proportion of polydimethylsiloxane prepolymer in the slurry is reduced and the proportion of Ecoflex component is increased.

[0042] The second layer of mixed slurry is pre-cured by a second round of ultraviolet light to form a second gradient sublayer.

[0043] All coatings and the second friction layer 500 are subjected to final thermosetting to achieve interlayer chemical cross-linking and integrated molding.

[0044] In this embodiment, the wavelength of the light source for UV pre-curing is 365nm and the energy density is 200-500mJ / cm²; the final thermal curing temperature is 70-85℃ and the time is 1-2 hours.

[0045] In this embodiment, the total thickness of the gradient modulus transition layer 400 is controlled between 20 μm and 50 μm; and the viscosity of both the first layer mixing slurry and the second layer mixing slurry is adjusted to the range of 500 cP to 2000 cP to ensure the uniformity of spin-coating and the interface fusion quality between sublayers.

[0046] In this embodiment, the structure includes: a first friction layer (PDMS / BST) – a gradient modulus transition layer – a second friction layer (Ecoflex / ZnO). The gradient layer chemically bonds the upper and lower layers together, forming an integrated, gapless stacked structure. In this structure, there is no longer a physical space allowing for significant separation between the two layers. Its working principle changes from "large-scale contact-separation" to "minor interfacial shearing and deformation." Specifically:

[0047] Vibration transmission and internal stress:

[0048] Vibration of the skin in the throat is transmitted to the entire integrated sensor. Due to the different moduli of the heterogeneous materials, small, periodic shear stresses and compressive stresses are generated between the PDMS / BST layer, the gradient layer, and the Ecoflex / ZnO layer during vibration.

[0049] Interface micro-deformation and charge transfer:

[0050] These stresses cause minute, high-frequency "contact-slip" or "adhesion-release" interactions at the interface between the second friction layer (Ecoflex / ZnO) and the top surface of the gradient layer. Simultaneously, minute, high-frequency "contact-slip" or "adhesion-release" interactions also occur between the first friction layer and the bottom surface of the gradient layer, as well as within the gradient layer, thus forming a friction layer.

[0051] Although chemically bonded, polymer molecular chains can still undergo relative displacement and deformation at the microscopic level under external forces. This microscopic, nanoscale relative motion is sufficient to disrupt the charge balance at the interface, generating triboelectric charges. This structure offers higher structural reliability, eliminating mechanical gaps and preventing failures caused by dust or moisture entering the gaps, as well as avoiding interlayer adhesion or collision damage that may occur under intense movement. It also exhibits better linearity and stability: the relationship between the output signal and vibration amplitude is more linear because it is based on the bulk deformation of the material, rather than unstable collisions. Furthermore, it is easier to encapsulate and wear: the integrated structure greatly simplifies the encapsulation process, making the device thinner, more flexible, and more suitable for close-fitting wear.

[0052] Meanwhile, a heterogeneous stacked structure composed of a PDMS / BST high-modulus friction layer and an Ecoflex / ZnO low-modulus friction layer is employed. This structure utilizes the different mechanical and electrical properties of the two materials to synergistically respond to a wide-bandwidth (100-1000Hz) vibration signal in the throat, ranging from strong low-frequency to weak high-frequency. To further improve device reliability, a gradient modulus transition layer is introduced between the two friction layers. This transition layer is composed of a mixture of PDMS and Ecoflex in a proportionally stepped manner, achieving a smooth stress transition and effectively suppressing interface delamination. This demonstrates the TENG sensor structure and fabrication method, which exhibits wide-bandwidth response to throat vibrations and long-term mechanical stability.

[0053] Example 2: Preparation of heterogeneous laminated friction pairs

[0054] 1. Material preparation:

[0055] High modulus friction layer material: PDMS prepolymer and curing agent (Sylgard184), barium strontium titanate nanoparticles (BST, ~150nm).

[0056] Low modulus friction layer material: Ecoflex00-30 (A / B components), zinc oxide nanowires (ZnONWs).

[0057] Electrode and substrate: PET film with sputtered gold electrodes.

[0058] 2. Sensor fabrication:

[0059] First friction layer 300: 15 wt% BST nanoparticles are dispersed in PDMS prepolymer, stirred evenly and degassed. It is then spin-coated onto the first PET / gold electrode and cured at 80°C for 2 hours to form a film with a thickness of approximately 100 μm.

[0060] Second friction layer 500: 8 wt% ZnONWs are dispersed in Ecoflex A+B mixed prepolymer, stirred evenly and degassed. It is then spin-coated onto the second PET / gold electrode and cured at room temperature for 30 minutes to form a film with a thickness of approximately 120 μm.

[0061] Device assembly: The two parts are separated by a flexible gasket and encapsulated with the friction layer facing each other to form a contact-separated TENG.

[0062] Example 3: Fabrication of an integrated sensor with a gradient modulus transition layer 400

[0063] 1. Fabrication of gradient modulus transition layer 400:

[0064] Based on Example 2, this embodiment prepares a gradient modulus transition layer 400 on the cured PDMS / BST first friction layer 300.

[0065] Slurry Preparation: Three co-curable slurries of PDMS and Ecoflex were prepared. To ensure that all layers eventually undergo chemical cross-linking, all slurries used the same curing mechanism. Specific preparation methods are as follows:

[0066] Slurry A (7:3): Take 7g of PDMS prepolymer, 0.7g of PDMS curing agent, 2.1g of Ecoflex A component, and 0.9g of Ecoflex B component, and mix them evenly.

[0067] Slurry B (5:5): Take 5g of PDMS prepolymer, 0.5g of PDMS curing agent, 3.5g of Ecoflex A component, and 1.5g of Ecoflex B component, and mix them evenly.

[0068] Slurry C (3:7): Take 3g of PDMS prepolymer, 0.3g of PDMS curing agent, 4.9g of Ecoflex A component, and 2.1g of Ecoflex B component, and mix them evenly.

[0069] It is worth mentioning that this formulation contains both the PDMS curing component and the Ecoflex A / B curing components in all slurries, ensuring the formation of a uniform cross-linked network during final thermosetting. The viscosity of each slurry is adjusted to approximately 1500 cP by adding an appropriate amount of diluent.

[0070] Spin coating and stepped curing:

[0071] First, slurry A is spin-coated onto the first friction layer 300 (3000 rpm, 60 s) to form a wet film of approximately 15 μm. Immediately afterwards, it is irradiated under a UV lamp (365 nm, 400 mJ / cm²) for 30 seconds to pre-gel. This process causes a sharp increase in the viscosity of the slurry, fixing its shape, but not completely curing it.

[0072] Next, slurry B was spin-coated onto the surface of slurry A (3000 rpm, 60 s) to form a wet film of about 15 μm, and then UV pregeling was performed under the same conditions.

[0073] Then, slurry C was spin-coated onto the surface of slurry B (3000 rpm, 60 s) to form a wet film of approximately 15 μm, and pre-gelled under the same conditions using UV light. At this point, the total wet film thickness of the gradient transition layer was approximately 45 μm.

[0074] Preparation and final integrated curing of the second friction layer 500:

[0075] Ecoflex / ZnO slurry was spin-coated onto the gradient layer (same as in Example 2).

[0076] The entire device was placed in a 75°C oven for thermosetting for 1.5 hours. During this process, the unreacted PDMS and Ecoflex prepolymers in all layers fully crosslinked, forming strong chemical bonds at the interface, achieving an integrated structure from the PDMS / BST layer to the Ecoflex / ZnO layer. The final total dry thickness of the gradient layer was approximately 30 μm.

[0077] 2. Durability Tests and Results:

[0078] The sensor of this embodiment was compared with a comparative example (without a gradient layer, Ecoflex / ZnO was directly spin-coated and cured onto PDMS / BST) in a fatigue test (5Hz, 2mm stroke). After 10,000 cycles, the sensor of this embodiment maintained an electrical signal output retention rate of over 95%. In contrast, the comparative example sensor's output began to significantly decrease after 1569 cycles and failed after 2680 cycles due to obvious delamination. Upon disassembly, the comparative example showed a clear and easily peelable interface, while the layers of this embodiment were fused together and could not be mechanically separated. This demonstrates the decisive role of the gradient transition layer structure and the fabrication method in improving the mechanical durability of the device.

[0079] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A triboelectric sensor for an artificial larynx based on a modulus gradient heterojunction, characterized in that, The system includes a first electrode layer and a second electrode layer disposed opposite to each other, and a first friction layer and a second friction layer located between the first electrode layer and the second electrode layer. The first friction layer is adjacent to and electrically connected to the first electrode layer, and the second friction layer is adjacent to and electrically connected to the second electrode layer. The first friction layer is a high-modulus friction layer composed of polydimethylsiloxane and barium strontium titanate nanoparticles, and the second friction layer is a low-modulus friction layer composed of Ecoflex silicone rubber and zinc oxide nanowires. The first friction layer and the second friction layer form a heterogeneous stacked friction pair, and the Young's modulus of the first friction layer is greater than that of the second friction layer. A gradient modulus transition layer is disposed between the first friction layer and the second friction layer. The material composition of the gradient modulus transition layer changes in a stepwise manner along its thickness direction, and the material composition of the side in contact with the first friction layer is similar to the matrix material of the first friction layer, while the material composition of the side in contact with the second friction layer is similar to the matrix material of the second friction layer. The gradient modulus transition layer comprises three sublayers composed of a mixture of polydimethylsiloxane and Ecoflex silicone rubber. From the first friction layer to the second friction layer, the mass ratio of polydimethylsiloxane in the mixture decreases layer by layer, while the mass ratio of Ecoflex silicone rubber increases layer by layer. Specifically, in the first sublayer, the mass ratio of polydimethylsiloxane to Ecoflex silicone rubber is (6:4) to (8:2); in the second sublayer, the mass ratio of polydimethylsiloxane to Ecoflex silicone rubber is (4:6) to (6:4); and in the third sublayer, the mass ratio of polydimethylsiloxane to Ecoflex silicone rubber is (2:8) to (4:6).

2. The sensor according to claim 1, characterized in that, The mass fraction of the barium strontium titanate nanoparticles in the first friction layer is 10% to 20%; the mass fraction of the zinc oxide nanowires in the second friction layer is 5% to 15%.

3. The sensor according to claim 1, characterized in that, The gradient modulus transition layer bonds the first friction layer and the second friction layer together to form a seamless, integrated heterogeneous stacked structure. The first friction layer, the gradient modulus transition layer and the second friction layer respond together to external vibrations and achieve triboelectric power generation through periodic deformation within the heterogeneous stacked structure.

4. The sensor according to claim 1, characterized in that, The first electrode layer and the second electrode layer are prepared on a flexible substrate of polyethylene terephthalate or polyimide.

5. The sensor according to claim 1, characterized in that, The sensor is entirely encapsulated in a biocompatible flexible encapsulation material, and its shape is configured to conform to the anatomical structure of the human throat.

6. A method for preparing the sensor as described in any one of claims 1-5, characterized in that, The gradient modulus transition layer is prepared by an alternating spin-coating and UV-cured stepwise process, including the following steps: On the surface of the completed first friction layer, a first layer of mixed slurry is spin-coated. The slurry contains polydimethylsiloxane prepolymer, component A and component B of Ecoflex silicone rubber, with polydimethylsiloxane prepolymer having the highest proportion. The first layer of mixed slurry is pre-cured by ultraviolet light to form the first gradient sublayer; On the surface of the first gradient sublayer, a second layer of mixed slurry is spin-coated, wherein the proportion of polydimethylsiloxane prepolymer in the slurry is reduced and the proportion of Ecoflex silicone rubber in the slurry is increased; The second layer of mixed slurry is pre-cured by a second round of ultraviolet light to form a second gradient sublayer. All coatings and the second friction layer are subjected to final thermosetting to achieve interlayer chemical cross-linking and integrated molding.

7. The method according to claim 6, characterized in that, The wavelength of the light source for UV pre-curing is 365nm, and the energy density is 200-500mJ / cm²; the final thermal curing temperature is 70-85℃, and the time is 1-2 hours.

8. The method according to claim 6, characterized in that, The total thickness of the gradient modulus transition layer is controlled between 20 μm and 50 μm; and the viscosity of the first layer mixed slurry and the second layer mixed slurry are both adjusted to the range of 500 cP to 2000 cP to ensure the uniformity of spin coating and the interface fusion quality between sublayers.

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