A bionic auricular point patch with self-adhesion and conductivity and a preparation method thereof

Abstract

This invention relates to the field of biomedical materials technology, specifically disclosing a biomimetic ear acupoint patch with self-adhesion and conductivity, and its preparation method. The biomimetic ear acupoint patch comprises, from the skin-adhesive side to the outer side, a biomimetic adhesive conductive layer, a flexible base layer, and an electrode interface layer. The biomimetic adhesive conductive layer is composed of photocurable resin, a photoinitiator, liquid metal microdroplets, and thiolized carbon nanotubes. The preparation method includes: preparing a conductive precursor solution, coating and pre-curing, hot-pressing and transferring a micropillar structure, curing and molding, and post-treatment. This invention utilizes a "thiol-ene" click chemistry reaction to construct a covalently bonded three-dimensional network between liquid metal, carbon nanotubes, and a resin matrix, solving the problems of filler agglomeration, interface debonding, and unstable conductivity in traditional physical mixing. This results in a patch with adhesive-free physical self-adhesion, high conductivity stability, and excellent biocompatibility, making it suitable for ear acupoint electrostimulation therapy.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, and relates to a biomimetic ear acupoint patch with self-adhesion and conductivity and its preparation method. Background Technology

[0002] Auricular therapy is an important part of Traditional Chinese Medicine (TCM), which uses stimulation of specific acupoints on the auricle to diagnose and treat diseases. Modern medicine has combined auricular therapy with physical stimulation (such as electrical stimulation) to develop various auricular therapy devices. Among them, auricular patches are widely used in clinical and home healthcare due to their convenience and non-invasiveness.

[0003] Currently used ear acupuncture patches are mostly ordinary medical tapes with conductive adhesive, which have obvious defects: (1) Adhesive problems: long-term use can easily lead to skin allergies and irritation, and may cause pain and damage to the skin when removed; (2) Contradiction between conductivity and adhesion: in order to pursue good conductivity, metal fillers are added, which often sacrifices the flexibility and adhesion of the material, making it easy to fall off on the complex curved surface of the auricle and dynamic skin, and the conductivity is unstable; (3) Single function: it only serves as an electrode and has no ability to actively adapt to the micro-movement of the skin and maintain a stable interface.

[0004] Therefore, developing an ear acupoint patch that requires no glue, has no risk of allergies, is highly conductive, and has a simple structure is of great significance for improving the efficacy, safety, and ease of use of ear acupoint therapy. Summary of the Invention

[0005] In view of the problems existing in the prior art, this invention provides a biomimetic ear acupoint patch with self-adhesion and conductivity, and its preparation method. This innovative approach utilizes a silane coupling agent to target the surface modification of liquid metal and carbon nanotubes. Through "thiol-ene" click chemistry and free radical copolymerization, an integrated three-dimensional conductive-reinforced cross-linked network is constructed in situ within a photocurable resin. Simultaneously, using a "semi-cured film hot-press transfer" manufacturing process, the aforementioned chemical cross-linked system is precisely replicated into a micron-scale biomimetic bristle array, thereby preparing a biomimetic ear acupoint patch that combines adhesive-free physical self-adhesion with precise low-impedance electrical stimulation conduction. This design aims to fundamentally solve the auricular allergy problem caused by traditional pressure-sensitive adhesive patches, providing a novel medical dressing solution that is adhesive-free, hypoallergenic, highly conductive, and durable for ear acupoint electrical stimulation therapy.

[0006] To achieve the above and other objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a biomimetic ear acupoint patch with self-adhesion and conductivity. The biomimetic ear acupoint patch includes, from the skin-adhesive side to the outer side, a biomimetic adhesive conductive layer, a flexible base layer, and an electrode interface layer. The biomimetic adhesive conductive layer is integrally formed with the bottom surface of the flexible base layer, and the electrode interface layer is fixed to the top surface of the flexible base layer and forms an electrical connection with the biomimetic adhesive conductive layer. The biomimetic adhesive conductive layer is composed of the following raw materials in parts by weight: 100 parts of photocurable resin, 1-3 parts of photoinitiator, 30-60 parts of liquid metal microdroplets, and 2-8 parts of mercapto-modified carbon nanotubes.

[0008] Furthermore, the preparation method of the liquid metal microdroplets is as follows: liquid metal is added to an anhydrous ethanol solution containing 3-(methacryloyloxy)propyltrimethoxysilane, and the reaction is carried out under inert gas protection in a water bath at 50-60°C with gentle stirring for 2-3 hours. After the reaction is completed, the microdroplets are separated by centrifugation and washed with anhydrous ethanol to obtain liquid metal microdroplets with a double-bonded siloxane shell on the surface.

[0009] Furthermore, the liquid metal is a medical-grade gallium indium tin alloy.

[0010] Furthermore, the thiolized carbon nanotubes are carboxylated multi-walled carbon nanotubes with 3-mercaptopropyltrimethoxysilane grafted onto their surface. The preparation method is as follows: carboxylated multi-walled carbon nanotubes are dispersed in an ethanol-water mixed solution containing 3-mercaptopropyltrimethoxysilane, and after being ultrasonically dispersed evenly, they are refluxed at 70-80℃ for 4-6 hours. After the reaction is completed, the nanotubes are centrifuged, washed, and dried to obtain thiolized carbon nanotubes.

[0011] Furthermore, the photocurable resin is a medical-grade polyurethane acrylate resin; the photoinitiator is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0012] Furthermore, the flexible base layer is a medical thermoplastic polyurethane film, and the electrode interface layer is electrically connected to the biomimetic adhesive conductive layer through medical conductive silver paste.

[0013] This invention also provides a method for preparing a biomimetic ear acupoint patch with self-adhesion and conductivity, specifically including the following steps:

[0014] S1. Preparation of conductive precursor solution: Photocurable resin, photoinitiator, liquid metal microdroplets and mercapto-modified carbon nanotubes are mixed and then placed in a vacuum planetary mixer and stirred and degassed at 40-50℃ for 1-2 hours to obtain conductive precursor solution. During this process, the mercapto groups on the surface of mercapto-modified carbon nanotubes and the carbon-carbon double bonds in the surface shell of liquid metal microdroplets and resin system achieve initial contact through physical mixing, laying the foundation for the subsequent "mercapto-alkene" click chemical reaction.

[0015] S2. Preparation of a uniform conductive film: The conductive precursor liquid obtained in step S1 is coated onto a flat PET release film. The thickness is controlled to be 50-100 μm by a doctor blade coating. Then, under nitrogen protection, it is pre-cured by 365 nm wavelength ultraviolet light for 5-10 seconds. The ultraviolet light activates the photoinitiator to generate a large number of free radicals, which causes the acrylate double bonds inside the film to undergo a rapid chain free radical polymerization reaction. At the same time, it further promotes the "thiol-alkene" click reaction, so that the system changes from a liquid state to a semi-cured state with flexibility and initial strength, forming a semi-cured conductive composite film.

[0016] S3. Micropillar structure hot press transfer: A conductive composite film is covered on a PDMS microstructure mold with micron-sized cylindrical pores, and then placed in a hot press device and held at 60-80℃ and 0.1-0.5MPa pressure for 1-2 minutes. Under these conditions, the semi-cured resin softens and flows when heated, and fully fills the micropores of the PDMS microstructure mold under pressure. At the same time, the click chemical reaction of "thiol-olefin" and the free radical polymerization reaction of the resin are further carried out to achieve deep cross-linking of chemical bonds and obtain a composite structure.

[0017] S4. Complete curing and demolding: The hot-pressed composite structure, together with the PDMS microstructure mold, is placed under 365nm ultraviolet light for final curing for 60-90 seconds to allow the resin to fully cure and set. After cooling, it is peeled off from the PDMS microstructure mold to obtain a biomimetic adhesive conductive layer with a biomimetic micropillar array on the surface.

[0018] S5. Post-processing: Apply a layer of medical-grade UV-curable adhesive to the flat back of the biomimetic adhesive conductive layer, cover it with a flexible base layer, and irradiate it with UV light again to firmly bond the two together, forming a patch body. Then, immerse it in 75% medical alcohol and ultrasonically clean it for 5-10 minutes to remove any low-molecular-weight substances that may remain on the surface. Then, dry it in a vacuum oven at 40-50℃ for 2-4 hours. Finally, apply medical conductive silver paste to the back of the flexible base layer by screen printing and attach electrode leads. After curing at room temperature, the self-adhesive and conductive biomimetic ear acupoint patch is obtained.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) In the prior art, the simple physical blending of liquid metal or carbon nanotubes into a polymer matrix has problems such as filler agglomeration, interfacial debonding, and unstable conductive network. The present invention innovatively adopts a "thiol-ene" click chemical reaction to covalently link surface double-bonded liquid metal microdroplets with thiolized carbon nanotubes, and simultaneously form chemical crosslinks with the photocurable resin matrix, thus constructing a three-in-one covalent bonded network of "liquid metal-carbon nanotube-resin". This chemical bonding fundamentally eliminates the interfacial slippage between the filler and the matrix, so that the conductive network remains stable during repeated bending and application, with minimal resistance fluctuation, laying a solid material foundation for achieving precise and repeatable auricular acupoint electrostimulation.

[0021] (2) Through the above-mentioned chemical cross-linking network design, the present invention achieves a deep synergistic effect of “conductivity and mechanical enhancement” at the micro level: carbon nanotubes are anchored in the resin network through chemical bonds, acting as “nano-steel bars” to greatly improve the compressive strength and elastic recovery rate of the micropillars, making them able to withstand the mechanical stress during hot pressing and demolding without collapsing, perfectly replicating the size effect of gecko bristles to achieve glue-free physical self-adhesion; at the same time, high-density liquid metal microdroplets are stably suspended in the network to form a continuous low-impedance electronic conduction pathway.

[0022] (3) The “uniform coating-UV pre-curing-hot pressing transfer” preparation process adopted in this invention first obtains a composite film with preliminary strength and precise control through pre-curing, and then perfectly replicates the micron-level cavity structure of the PDMS microstructure mold in the flow through hot pressing, thereby replicating a biomimetic micropillar array with a high aspect ratio and complete structure. This makes the invented ear acupoint patch not require any traditional adhesives, and can achieve firm and reversible skin adhesion by relying solely on the van der Waals force of the micropillar array, thus avoiding the risk of contact dermatitis caused by adhesives. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0025] The materials used in the following examples are medical-grade gallium indium tin alloy liquid metal, medical-grade polyurethane acrylate resin photocurable resin, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator, and other materials are commercially available medical-grade or analytical grade products unless otherwise specified.

[0026] Example 1: This example provides a biomimetic ear acupoint patch with self-adhesion and conductivity. The biomimetic ear acupoint patch includes, from the skin-adhesive side to the outer side, a biomimetic adhesive conductive layer, a flexible base layer, and an electrode interface layer. The biomimetic adhesive conductive layer is integrally formed with the bottom surface of the flexible base layer, and the electrode interface layer is fixed to the top surface of the flexible base layer and forms an electrical connection with the biomimetic adhesive conductive layer. The biomimetic adhesive conductive layer is composed of the following raw materials in parts by weight: 100 parts of photocurable resin, 1 part of photoinitiator, 30 parts of liquid metal microdroplets, and 2 parts of mercapto-modified carbon nanotubes.

[0027] The preparation method of the liquid metal microdroplets is as follows: 5g of medical-grade gallium indium tin alloy is weighed and added to 200mL of anhydrous ethanol solution containing 0.5g of 3-(methacryloyloxy)propyltrimethoxysilane. Under nitrogen protection, the mixture is gently stirred in a water bath at 50℃ for 2 hours. After the reaction is completed, the mixture is centrifuged at 8000rpm for 10 minutes and the precipitate is washed three times with anhydrous ethanol to obtain liquid metal microdroplets with a double-bonded siloxane shell on the surface.

[0028] The thiolized carbon nanotubes are carboxylated multi-walled carbon nanotubes with 3-mercaptopropyltrimethoxysilane grafted onto their surface. The preparation method is as follows: 2g of carboxylated multi-walled carbon nanotubes are weighed and dispersed in 200mL of an ethanol-water mixed solution containing 1g of 3-mercaptopropyltrimethoxysilane, wherein the volume ratio of ethanol to water is 3:1. The mixture is then ultrasonically dispersed at 200W for 30 minutes to make it uniform. The mixture is then placed in an oil bath and refluxed at 70℃ for 4 hours. After the reaction is completed, the solid is collected by centrifugation and washed three times each with ethanol and water. Finally, it is dried in a vacuum oven at 60℃ for 12 hours to obtain thiolized carbon nanotubes.

[0029] The flexible base layer is a medical-grade thermoplastic polyurethane film.

[0030] This embodiment also provides a method for preparing a biomimetic ear acupoint patch with self-adhesion and conductivity, specifically including the following steps:

[0031] S1. Preparation of conductive precursor liquid: 100g of photocurable resin, 1g of photoinitiator, 30g of liquid metal microdroplets and 2g of mercapto-carbon nanotubes were mixed and placed in a vacuum planetary mixer. The mixture was stirred and degassed at 2000rpm for 1 hour at 40℃ to obtain a uniform conductive precursor liquid.

[0032] S2. Preparation of a uniform conductive film: The conductive precursor liquid obtained in step S1 is coated onto a flat PET release film. The coating thickness is controlled to be 50 μm using a doctor blade. Then, under a nitrogen protective atmosphere, it is subjected to ultraviolet light at a wavelength of 365 nm (intensity 20 mW / cm²). 2 Irradiation for 8 seconds to cure, resulting in a semi-cured conductive composite film;

[0033] S3. Micropillar structure hot press transfer: A conductive composite film is covered on a PDMS microstructure mold with micron-sized cylindrical holes, and then placed in a hot press device and held at 60°C and 0.1MPa pressure for 1 minute to obtain a composite structure;

[0034] S4. Complete curing and demolding: The hot-pressed composite structure, together with the PDMS microstructure mold, is placed under 365nm ultraviolet light for final curing for 60 seconds to allow the resin to fully cure and set. After cooling to room temperature, it is carefully peeled off from the PDMS microstructure mold to obtain a biomimetic adhesive conductive layer with a biomimetic micropillar array on the surface.

[0035] S5. Post-processing: A layer of medical-grade UV-curable adhesive is applied to the flat back of the biomimetic adhesive conductive layer, and a flexible base layer is covered. The two are then subjected to UV irradiation again to ensure firm adhesion and integral molding to obtain the patch body. After that, it is immersed in 75% medical alcohol for ultrasonic cleaning for 5 minutes. After cleaning, it is removed and dried in a vacuum oven at 40°C for 2 hours. Finally, medical conductive silver paste is applied to the back side of the flexible base layer by screen printing, and electrode leads are attached. After curing at room temperature for 24 hours, the biomimetic ear acupoint patch with self-adhesion and conductivity is obtained.

[0036] Example 2: This example provides a biomimetic ear acupoint patch with self-adhesion and conductivity. The biomimetic ear acupoint patch includes, from the skin-adhesive side to the outer side, a biomimetic adhesive conductive layer, a flexible base layer, and an electrode interface layer. The biomimetic adhesive conductive layer is integrally formed with the bottom surface of the flexible base layer, and the electrode interface layer is fixed to the top surface of the flexible base layer and forms an electrical connection with the biomimetic adhesive conductive layer. The biomimetic adhesive conductive layer is composed of the following raw materials in parts by weight: 100 parts of photocurable resin, 2 parts of photoinitiator, 45 parts of liquid metal microdroplets, and 5 parts of mercapto-modified carbon nanotubes.

[0037] The preparation method of the liquid metal microdroplets is as follows: 10g of medical-grade gallium indium tin alloy is weighed and added to 300mL of anhydrous ethanol solution containing 1.0g of 3-(methacryloyloxy)propyltrimethoxysilane. Under nitrogen protection, the mixture is gently stirred in a water bath at 55℃ for 2.5 hours. After the reaction is completed, the mixture is centrifuged at 8000rpm for 10 minutes and the precipitate is washed three times with anhydrous ethanol to obtain liquid metal microdroplets with a double-bonded siloxane shell on the surface.

[0038] The thiolized carbon nanotubes are carboxylated multi-walled carbon nanotubes with 3-mercaptopropyltrimethoxysilane grafted onto their surface. The preparation method is as follows: 3g of carboxylated multi-walled carbon nanotubes are weighed and dispersed in 300mL of an ethanol-water mixed solution containing 2g of 3-mercaptopropyltrimethoxysilane, wherein the volume ratio of ethanol to water is 9:1. The mixture is then ultrasonically dispersed at 300W for 30 minutes to make it uniform. The mixture is then placed in an oil bath and refluxed at 75℃ for 5 hours. After the reaction is completed, the solid is collected by centrifugation and washed three times each with ethanol and water. Finally, it is dried in a vacuum oven at 60℃ for 12 hours to obtain thiolized carbon nanotubes.

[0039] The flexible base layer is a medical-grade thermoplastic polyurethane film.

[0040] This embodiment also provides a method for preparing a biomimetic ear acupoint patch with self-adhesion and conductivity, specifically including the following steps:

[0041] S1. Preparation of conductive precursor liquid: 100g of photocurable resin, 2g of photoinitiator, 45g of liquid metal microdroplets and 5g of mercapto-carbon nanotubes were mixed and placed in a vacuum planetary mixer. The mixture was stirred and degassed at 2000rpm for 1.5 hours at 45℃ to obtain a uniform conductive precursor liquid.

[0042] S2. Preparation of a uniform conductive film: The conductive precursor liquid obtained in step S1 is coated onto a flat PET release film. The coating thickness is controlled to be 80 μm using a doctor blade. Then, under a nitrogen protective atmosphere, it is subjected to ultraviolet light at a wavelength of 365 nm (intensity 20 mW / cm²). 2 Irradiation for 9 seconds to cure, resulting in a semi-cured conductive composite film;

[0043] S3. Micropillar structure hot press transfer: A conductive composite film is covered on a PDMS microstructure mold with micron-sized cylindrical holes, and then placed in a hot press device and held at 70°C and 0.3MPa pressure for 1.5 minutes to obtain a composite structure;

[0044] S4. Complete curing and demolding: The hot-pressed composite structure, together with the PDMS microstructure mold, is placed under 365nm ultraviolet light for final curing for 75 seconds to allow the resin to fully cure and set. After cooling to room temperature, it is carefully peeled off from the PDMS microstructure mold to obtain a biomimetic adhesive conductive layer with a biomimetic micropillar array on the surface.

[0045] S5. Post-processing: A layer of medical-grade UV-curable adhesive is applied to the flat back of the biomimetic adhesive conductive layer, and a flexible base layer is covered. The two are then subjected to UV irradiation again to ensure firm adhesion and integral molding to obtain the patch body. After that, it is immersed in 75% medical alcohol for ultrasonic cleaning for 8 minutes. After cleaning, it is removed and dried in a vacuum oven at 45°C for 3 hours. Finally, medical conductive silver paste is applied to the back side of the flexible base layer by screen printing, and electrode leads are attached. After curing at room temperature for 24 hours, the biomimetic ear acupoint patch with self-adhesion and conductivity is obtained.

[0046] Example 3: This example provides a biomimetic ear acupoint patch with self-adhesion and conductivity. The biomimetic ear acupoint patch includes, from the skin-adhesive side to the outer side, a biomimetic adhesive conductive layer, a flexible base layer, and an electrode interface layer. The biomimetic adhesive conductive layer is integrally formed with the bottom surface of the flexible base layer, and the electrode interface layer is fixed to the top surface of the flexible base layer and forms an electrical connection with the biomimetic adhesive conductive layer. The biomimetic adhesive conductive layer is composed of the following raw materials in parts by weight: 100 parts of photocurable resin, 3 parts of photoinitiator, 60 parts of liquid metal microdroplets, and 8 parts of mercapto-modified carbon nanotubes.

[0047] The preparation method of the liquid metal microdroplets is as follows: 15g of medical-grade gallium indium tin alloy is weighed and added to 400mL of anhydrous ethanol solution containing 2.0g of 3-(methacryloyloxy)propyltrimethoxysilane. Under nitrogen protection, the mixture is gently stirred in a water bath at 60℃ for 3 hours. After the reaction is completed, the mixture is centrifuged at 8000rpm for 10 minutes and the precipitate is washed three times with anhydrous ethanol to obtain liquid metal microdroplets with a double-bonded siloxane shell on the surface.

[0048] The thiolized carbon nanotubes are carboxylated multi-walled carbon nanotubes with 3-mercaptopropyltrimethoxysilane grafted onto their surface. The preparation method is as follows: 5g of carboxylated multi-walled carbon nanotubes are weighed and dispersed in 400mL of an ethanol-water mixed solution containing 4g of 3-mercaptopropyltrimethoxysilane, wherein the volume ratio of ethanol to water is 9:1. The mixture is then ultrasonically dispersed at 300W for 30 minutes to make it uniform. The mixture is then placed in an oil bath and refluxed at 80℃ for 6 hours. After the reaction is completed, the solid is collected by centrifugation and washed three times each with ethanol and water. Finally, it is dried in a vacuum oven at 60℃ for 12 hours to obtain thiolized carbon nanotubes.

[0049] The flexible base layer is a medical-grade thermoplastic polyurethane film.

[0050] This embodiment also provides a method for preparing a biomimetic ear acupoint patch with self-adhesion and conductivity, specifically including the following steps:

[0051] S1. Preparation of conductive precursor liquid: 100g of photocurable resin, 3g of photoinitiator, 60g of liquid metal microdroplets and 8g of mercapto-carbon nanotubes were mixed and placed in a vacuum planetary mixer. The mixture was stirred and degassed at 2000rpm for 2 hours at 50℃ to obtain a uniform conductive precursor liquid.

[0052] S2. Preparation of a uniform conductive film: The conductive precursor liquid obtained in step S1 is coated onto a flat PET release film. The coating thickness is controlled to be 100 μm using a doctor blade. Then, under a nitrogen protective atmosphere, it is subjected to ultraviolet light at a wavelength of 365 nm (intensity 20 mW / cm²). 2 Irradiation for 10 seconds to cure, resulting in a semi-cured conductive composite film;

[0053] S3. Micropillar structure hot press transfer: A conductive composite film is covered on a PDMS microstructure mold with micron-sized cylindrical holes, and then placed in a hot press device and held at 80°C and 0.5MPa pressure for 2 minutes to obtain a composite structure;

[0054] S4. Complete curing and demolding: The hot-pressed composite structure, together with the PDMS microstructure mold, is placed under 365nm ultraviolet light for final curing for 90 seconds to allow the resin to fully cure and set. After cooling to room temperature, it is carefully peeled off from the PDMS microstructure mold to obtain a biomimetic adhesive conductive layer with a biomimetic micropillar array on the surface.

[0055] S5. Post-processing: A layer of medical-grade UV-curable adhesive is applied to the flat back of the biomimetic adhesive conductive layer, and a flexible base layer is covered. The two are then subjected to UV irradiation again to ensure firm adhesion and integral molding to obtain the patch body. After that, it is immersed in 75% medical alcohol for ultrasonic cleaning for 10 minutes. After cleaning, it is removed and dried in a vacuum oven at 50°C for 4 hours. Finally, medical conductive silver paste is applied to the back side of the flexible base layer by screen printing, and electrode leads are attached. After curing at room temperature for 24 hours, the biomimetic ear acupoint patch with self-adhesion and conductivity is obtained.

[0056] Comparative Example 1: This comparative example provides a comparative ear acupoint patch with the same structure as Example 2, but the raw materials for preparing the biomimetic adhesive conductive layer are different. The raw materials are: 100 parts of photocurable resin, 2 parts of photoinitiator, and 5 parts of thiolized carbon nanotubes. The corresponding preparation method is modified as follows: S1. Preparation of precursor liquid: The photocurable resin, photoinitiator, and thiolized carbon nanotubes are mixed and placed in a vacuum planetary mixer. The mixture is stirred and degassed at 2000 rpm for 1.5 hours at 45°C to obtain the precursor liquid; S2. Preparation of uniform conductive film layer: The precursor liquid obtained in step S1 is coated on a flat PET release film. The coating thickness is controlled to be 80 μm using a doctor blade. Then, under a nitrogen protective atmosphere, it is cured by irradiation with 365 nm wavelength ultraviolet light for 9 seconds to obtain a semi-cured composite film; The remaining steps are the same as in Example 2.

[0057] Comparative Example 2: This comparative example provides a comparative ear acupoint patch. The difference between the other two examples is that the thiolized carbon nanotubes are replaced with an equal amount of ordinary carboxylated multi-walled carbon nanotubes in the preparation of the biomimetic adhesive conductive layer. The corresponding preparation method is modified as follows: S1. Preparation of conductive precursor liquid: The photocurable resin, photoinitiator, liquid metal microdroplets and ordinary carboxylated multi-walled carbon nanotubes are mixed and placed in a vacuum planetary mixer. The mixture is stirred and degassed at 2000 rpm at 45°C for 1.5 hours to obtain the conductive precursor liquid. The remaining steps are the same as in Example 2.

[0058] Comparative Example 3: This comparative example provides a comparative ear acupoint patch, which differs from Example 2 in that the biomimetic adhesive conductive layer is composed of the following raw materials in parts by weight: 100 parts of photocurable resin, 2 parts of photoinitiator, 45 parts of liquid metal microdroplets, and 5 parts of multi-walled carbon nanotubes. The liquid metal microdroplets are prepared by directly ultrasonically breaking up liquid metal in ethanol. The preparation method of this comparative ear acupoint patch is modified as follows: S1. Preparation of precursor liquid: The photocurable resin, photoinitiator, liquid metal microdroplets, and multi-walled carbon nanotubes are mixed and placed in a vacuum planetary mixer. The mixture is stirred and degassed at 2000 rpm at 45°C for 1.5 hours to obtain the precursor liquid. The remaining steps are the same as in Example 2.

[0059] To verify the effectiveness of the present invention, the following performance tests were conducted on the biomimetic auricular acupoint patches prepared in Examples 1-3 and Comparative Examples 1-3.

[0060] Adhesion performance test: Fresh detached pig ear skin was used as the substrate (simulating human ear skin). The sample was cut into 30mm×50mm sizes and a 90° peel test was performed using a universal testing machine at a peel speed of 10mm / min. The peel strength (N / cm) was recorded. At the same time, the peel strength retention rate of the sample after 50 cycles of repeated adhesion and peeling was tested to evaluate the adhesion durability. The results are shown in Table 1.

[0061] Table 1 Adhesion performance test results

[0062]

[0063] Conductivity test: The four-probe method was used to measure the surface sheet resistance (Ω / sq) of the biomimetic adhesive conductive layer of the sample. At the same time, the sample was stretched to 50% strain using a tensile testing machine, and the resistance change was monitored in real time. The resistance change rate (ΔR / R0) was calculated to evaluate the conductivity stability under auricle deformation. The results are shown in Table 2.

[0064] Table 2. Conductivity test results

[0065]

[0066] Interfacial bonding test: The sample was immersed in PBS buffer (pH=7.4) and shaken at 150 rpm for 24 hours in a constant temperature shaker at 37℃. The surface morphology was observed and the change in conductivity after shaking was measured. The results are shown in Table 3.

[0067] Table 3. Results of interfacial bonding test

[0068]

[0069] As shown in Table 1, Examples 1-3 exhibited excellent initial adhesion, maintaining over 87% adhesion even after 50 repeated adhesion cycles. In contrast, Comparative Example 1 (without liquid metal) showed the lowest adhesion, indicating that the liquid metal microdroplets, acting as a filler, helped increase the physical contact area between the micropillars and the skin. Comparative Examples 2 and 3, lacking "thiol-ene" chemical bonds, had insufficient micropillar structural toughness, leading to easy breakage or filler detachment during repeated adhesion, resulting in a significant decrease in adhesion retention. This demonstrates that the present invention effectively improves the mechanical stability of the structure through "thiol-ene" chemical crosslinking. Table 2 shows that Examples 1-3 all achieved high conductivity and exhibited a small resistance change rate under 50% strain, demonstrating excellent tensile conductivity stability. This indicates that the surface-modified liquid metal microdroplets and thiolized carbon nanotubes formed a stable conductive framework through chemical bonds, maintaining the continuity of conductive pathways even under deformation. Under the rigorous testing of simulated bodily fluid environment, the samples of Examples 1-3 once again demonstrated excellent stability. This result further proves that the present invention, through the covalent bond network formed by "thiol-ene" click chemistry, firmly anchors liquid metal microdroplets and carbon nanotubes in the resin matrix, significantly improving the hydrolysis resistance and interfacial bonding stability of the material in physiological environment.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0071] The present invention and its embodiments have been described above. This description is not restrictive, and the actual application is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and, without departing from the spirit of the invention, design similar methods and embodiments to this technical solution without creative effort, all such designs should fall within the protection scope of the present invention.

Claims

1. A biomimetic ear acupoint patch with self-adhesion and conductivity, characterized in that, The biomimetic auricular patch comprises, from the skin-adhering side to the outer side, a biomimetic adhesive conductive layer, a flexible base layer, and an electrode interface layer in sequence. The biomimetic adhesive conductive layer is integrally formed with the bottom surface of the flexible base layer, and the electrode interface layer is fixed to the top surface of the flexible base layer and forms an electrical connection with the biomimetic adhesive conductive layer. The biomimetic adhesive conductive layer is composed of the following raw materials in parts by weight: 100 parts of photocurable resin, 1-3 parts of photoinitiator, 30-60 parts of liquid metal microdroplets, and 2-8 parts of mercapto-modified carbon nanotubes. The liquid metal microdroplets are prepared by adding liquid metal to an anhydrous ethanol solution containing 3-(methacryloyloxy)propyltrimethoxysilane and stirring the reaction. After the reaction is completed, the mixture is centrifuged and washed to obtain liquid metal microdroplets with a double-bonded siloxane shell on the surface. The mercapto-modified carbon nanotubes are carboxylated multi-walled carbon nanotubes grafted with 3-mercaptopropyltrimethoxysilane on their surface.

2. The biomimetic ear acupoint patch with self-adhesion and conductivity according to claim 1, characterized in that, The method for preparing the thiolized carbon nanotubes is as follows: carboxylated multi-walled carbon nanotubes are dispersed in an ethanol-water mixed solution containing 3-mercaptopropyltrimethoxysilane, and after ultrasonic dispersion, the mixture is refluxed for reaction. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain thiolized carbon nanotubes.

3. The biomimetic ear acupoint patch with self-adhesion and conductivity according to claim 1, characterized in that, The liquid metal is a medical-grade gallium indium tin alloy.

4. The biomimetic ear acupoint patch with self-adhesion and conductivity according to claim 1, characterized in that, The photocurable resin is a medical-grade polyurethane acrylate resin.

5. The biomimetic ear acupoint patch with self-adhesion and conductivity according to claim 1, characterized in that, The photoinitiator is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

6. A biomimetic ear acupoint patch with self-adhesion and conductivity according to claim 1, characterized in that, The flexible base layer is a medical thermoplastic polyurethane film; the electrode interface layer is electrically connected to the biomimetic adhesive conductive layer through medical conductive silver paste.

7. A method for preparing a biomimetic ear acupoint patch with self-adhesion and conductivity according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Preparation of conductive precursor liquid: Photocurable resin, photoinitiator, liquid metal microdroplets and mercaptoized carbon nanotubes are mixed in proportion and stirred to remove bubbles to obtain conductive precursor liquid; S2. Preparation of uniform conductive film: The conductive precursor liquid is coated on the PET release film, and the thickness is controlled by the doctor blade coating. Then, it is pre-cured by ultraviolet light to form a conductive composite film. S3. Micropillar structure hot pressing transfer: A conductive composite film is covered on a PDMS microstructure mold, and then hot-pressed to obtain a composite structure; S4. Complete curing and demolding: The composite structure, together with the PDMS microstructure mold, is placed under ultraviolet light again for final curing. After shaping and cooling, it is peeled off from the PDMS microstructure mold to obtain a biomimetic adhesive conductive layer with a biomimetic micropillar array on the surface. S5. Post-processing: Apply UV-curable adhesive to the flat back of the biomimetic adhesive conductive layer, cover it with a flexible base layer, and irradiate it with UV light again to form the patch body in one piece. Then clean and dry it. Finally, apply medical conductive silver paste to the back side of the flexible base layer and attach electrode leads. After curing at room temperature, the biomimetic ear acupoint patch with self-adhesion and conductivity is obtained.

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