A flexible and stretchable stimulation electrode and its preparation method

Abstract

This application relates to the field of biointerface sensing technology, and particularly to a flexible, stretchable stimulation electrode and its fabrication method. The electrode comprises: a substrate, a conductive layer, an electrode pathway encapsulation layer, and a stimulation point encapsulation layer. The conductive layer is composed of a liquid metal electrode array disposed on the substrate. The conductive layer includes an electrode wire region and an electrode stimulation end. The electrode pathway encapsulation layer covers the electrode wire region. The stimulation point encapsulation layer covers the electrode stimulation end. The material of the electrode pathway encapsulation layer is polydimethylsiloxane. The material of the stimulation point encapsulation layer is a polydimethylsiloxane-carbon fiber composite elastomer. The purpose of this application is to provide a flexible, stretchable stimulation electrode to solve the technical problems of mechanical mismatch, biointerface instability, and insufficient stimulation precision that exist in existing stimulation electrodes during long-term use.

Description

Technical Field

[0001] This application relates to the field of biointerface sensing technology, and in particular to a flexible stretchable stimulation electrode and its preparation method. Background Technology

[0002] With the rapid development of wearable medical electronics, electronic skin, neural interfaces, and intelligent rehabilitation technologies, flexible and stretchable stimulation electrodes, as key components in human-computer interaction interfaces, have received widespread attention. These electrodes not only require good fit and comfort on complex biological surfaces (such as skin, muscle, or nerve tissue), but also need to maintain stable electrical stimulation performance and biocompatibility under dynamic stretching, bending, torsion, and other mechanical deformation conditions.

[0003] While traditional rigid metal electrodes offer excellent conductivity, their high mechanical rigidity leads to a modulus mismatch with human tissue, which can cause stimulation misalignment, signal instability, skin discomfort, and even micro-damage during long-term use, limiting their application in wearable and implantable neuromodulation. Therefore, developing flexible, stretchable electrodes with good mechanical compliance, excellent conductivity, and reliable electrical stimulation has become an important research direction in this field.

[0004] Existing skin stimulation electrode technology, when applied to human skin surfaces or flexible wearable devices, still suffers from several significant drawbacks, severely limiting its effectiveness in clinical rehabilitation, electrophysiological intervention, and wearable medical systems:

[0005] (1) Large electrode size and limited spatial resolution: Traditional stimulation electrodes usually adopt a large area design to reduce the impedance per unit area and enhance adhesion, but this leads to a decrease in their spatial positioning ability and makes it impossible to achieve precise stimulation of specific muscle groups or nerve areas.

[0006] (2) The electrode structure is rigid and cannot be stretched, resulting in poor adaptability: Most existing electrodes are made of rigid conductive materials such as stainless steel, platinum, and iridium, which lack flexibility and elasticity. There is a huge difference in modulus between them and soft human tissue. During long-term use, they are prone to damage to the surrounding tissue, thereby reducing the stability and comfort of stimulation.

[0007] (3) Insufficient precision of electrical stimulation makes it difficult to achieve efficient neuromodulation: Due to uneven contact, unstable signal coupling and the diffusion of stimulation current caused by structural rigidity, the existing electrodes have poor stimulation selectivity in multi-target or fine neurocontrol, which makes it difficult to meet the demand for high-precision and personalized electrical stimulation schemes, thus limiting their application in high-requirement scenarios such as precision rehabilitation treatment and functional reconstruction. Summary of the Invention

[0008] This application provides a flexible and stretchable stimulation electrode and its preparation method to solve the technical problems of existing stimulation electrodes during long-term use, such as mechanical mismatch, instability of biological interface, and insufficient stimulation precision.

[0009] To address the aforementioned technical problems, in a first aspect, embodiments of this application provide a flexible and stretchable stimulation electrode, comprising: a substrate, a conductive layer, an electrode pathway encapsulation layer, and a stimulation point encapsulation layer; the conductive layer is composed of a liquid metal electrode array disposed on the substrate; the conductive layer includes an electrode wire region and an electrode stimulation end; the electrode pathway encapsulation layer covers the electrode wire region; the stimulation point encapsulation layer covers the electrode stimulation end; the material of the electrode pathway encapsulation layer is polydimethylsiloxane; the material of the stimulation point encapsulation layer is polydimethylsiloxane-carbon fiber composite elastomer.

[0010] In some exemplary embodiments, the liquid metal electrode array is composed of gallium-based liquid metal microspheres that have been ultrasonically treated.

[0011] In some exemplary embodiments, the electrode pathway encapsulation layer covers the electrode wire area while exposing the electrode stimulation end, preventing bodily fluids from corroding the wire and improving biocompatibility; the thickness of the electrode pathway encapsulation layer is 50~100μm.

[0012] In some exemplary embodiments, the electrode has a thickness of 0.1 mm to 0.3 mm and a certain degree of stretchability.

[0013] In some exemplary embodiments, the substrate material is polydimethylsiloxane.

[0014] Secondly, embodiments of this application also provide a method for preparing a flexible and stretchable stimulation electrode, comprising the following steps: providing a substrate; forming a conductive layer on the substrate; the conductive layer being composed of a liquid metal electrode array; the conductive layer including an electrode wire region and an electrode stimulation end; encapsulating the electrode wire region and the electrode stimulation end of the conductive layer respectively to form an electrode pathway encapsulation layer and a stimulation point encapsulation layer; the material of the electrode pathway encapsulation layer is polydimethylsiloxane; the material of the stimulation point encapsulation layer is polydimethylsiloxane-carbon fiber composite elastomer.

[0015] In some exemplary embodiments, forming a conductive layer on a substrate includes: preparing liquid metal micro / nano particle ink; printing an electrode pattern on a PET film using screen printing; and transferring the electrode pattern from the PET film to the substrate using the liquid metal micro / nano particle ink via a transfer method.

[0016] In some exemplary embodiments, the electrode wire region of the conductive layer is encapsulated to form an electrode pathway encapsulation layer, including: preparing a 50μm~100μm thick polydimethylsiloxane film using a spin coater, and covering the electrode stimulation point and the rear wiring with the polydimethylsiloxane film; then spin coating a 50μm thick polydimethylsiloxane layer onto the electrode surface as an encapsulation layer using a spin coater, with the spin coating speed parameter set to 600 rpm / 60 s; after spin coating is completed, the film covering the electrode stimulation point is peeled off, and the electrode is placed in a 60°C oven to dry for 2 hours. After the polydimethylsiloxane has cured, the electrode pathway encapsulation layer is formed.

[0017] In some exemplary embodiments, encapsulating the electrode stimulation end to form an encapsulation layer at the stimulation point includes: using a planetary mixer to mix 15% carbon fiber and polydimethylsiloxane by mass to remove bubbles, and after uniform mixing, adding a curing agent to obtain an uncured polydimethylsiloxane-carbon fiber composite elastomer; according to the required size of the encapsulation layer at the stimulation point, using an ultraviolet laser marking machine to make a mask, and using a scraping method to uniformly cover the surface of the electrode stimulation point with the uncured composite elastomer material; after the scraping is completed, placing the electrode in a 60°C oven to dry for 2 hours to form an encapsulation layer at the stimulation point.

[0018] In some exemplary embodiments, the mass ratio of polydimethylsiloxane to curing agent is 15:1.

[0019] The technical solution provided in this application has at least the following advantages:

[0020] This application provides a flexible and stretchable stimulation electrode and its preparation method. The electrode includes: a substrate, a conductive layer, an electrode pathway encapsulation layer, and a stimulation point encapsulation layer; the conductive layer is composed of a liquid metal electrode array disposed on the substrate; the conductive layer includes an electrode wire region and an electrode stimulation end; the electrode pathway encapsulation layer covers the electrode wire region; the stimulation point encapsulation layer covers the electrode stimulation end; the material of the electrode pathway encapsulation layer is polydimethylsiloxane; the material of the stimulation point encapsulation layer is polydimethylsiloxane-carbon fiber composite elastomer.

[0021] This application provides a flexible and stretchable stimulation electrode. The electrode uses PDMS as a substrate and gallium-based liquid metal as the conductive material. Good electrode performance is achieved by encapsulating a conductive elastic composite material layer on the surface of the stimulation point and electrodepositing a conductive polymer layer. The electrode has an overall thickness of approximately 0.3 mm and possesses a certain degree of stretchability, maintaining good stimulation efficiency even under large deformations. Attached Figure Description

[0022] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0023] Figure 1 This is a schematic diagram of the structure of a flexible and stretchable stimulation electrode provided in one embodiment of this application.

[0024] Figure 2 This is a schematic diagram of the impedance variation of an electrode provided in an embodiment of this application within a frequency range of 1-100kHz.

[0025] Figure 3 A schematic diagram of the cyclic voltammetry (CV) characteristic curve of an electrode provided in an embodiment of this application in the range of -1V to 1V. Detailed Implementation

[0026] As the background technology shows, traditional rigid metal electrodes, due to their high mechanical rigidity, have a modulus mismatch with human tissue, which can easily lead to stimulation position displacement, signal instability, or skin discomfort, and may even cause micro-damage during long-term use, thus limiting their application in wearable and implantable neuromodulation.

[0027] The related technology provides a liquid metal-based implantable soft neural electrode for deep brain stimulation, demonstrating implantable soft macroelectrodes made of biocompatible liquid metal for brain stimulation. These probes can be easily fabricated by simply filling polymer tubes with liquid metal, providing a direct method for manufacturing brain stimulation devices. They can be customized in different lengths and diameters and can also be used as recording microelectrodes. The electrode tips are treated with platinum nanoclusters to achieve low impedance and efficient charge injection while preventing liquid metal from seeping into brain tissue. In vivo experiments in a rat model of neuropathic pain demonstrated the stability and effectiveness of these probes in simultaneously performing neural stimulation and recording.

[0028] Another related technology provides an ultra-highly ductile and dynamically deformable electronic device for monitoring dynamically moving organs. It introduces a scalable manufacturing method for creating implantable electronic devices with inherent ductility and implantability. These devices utilize liquid metal components, exhibiting ultra-high ductility with tensile strain up to 400% and excellent resistance to repeated deformation. The device architecture also demonstrates long-term stability under physiological conditions, the ability to fit snugly to internal organs, and low interfacial impedance. Successful electrophysiological mapping on a rapidly beating heart demonstrates the potential of inherently ductile electronic devices for a wide range of applications in health monitoring, disease diagnosis, and medical treatment.

[0029] In applications such as neuromodulation, muscle function rehabilitation, and pain management, achieving efficient and safe electrical stimulation of the human body is crucial. Traditional rigid stimulation electrodes, when in contact with skin or tissue, often lead to stimulation position displacement, unstable electrical contact, and even tissue discomfort due to the significant difference in modulus between mechanical rigidity and human tissue, especially during dynamic movement. Therefore, this application aims to develop a novel stretchable flexible stimulation electrode to achieve stable, precise, and comfortable electrical stimulation output to specific areas of the human body. This application aims to solve the following key technical problems:

[0030] (1) Develop a stretchable flexible stimulation electrode that has high conductivity, high tensile strength and excellent biocompatibility to achieve stable electrical stimulation output under large strain conditions.

[0031] (2) Construct a skin-electrode interface structure with low impedance and long-term adhesion to reduce interface resistance and improve stimulation efficiency and safety.

[0032] To address the aforementioned technical problems, this application provides a flexible and stretchable stimulation electrode, comprising: a substrate, a conductive layer, an electrode pathway encapsulation layer, and a stimulation point encapsulation layer; the conductive layer is composed of a liquid metal electrode array disposed on the substrate; the conductive layer includes an electrode wire region and an electrode stimulation end; the electrode pathway encapsulation layer covers the electrode wire region; the stimulation point encapsulation layer covers the electrode stimulation end; the electrode pathway encapsulation layer is made of polydimethylsiloxane; the stimulation point encapsulation layer is made of polydimethylsiloxane-carbon fiber composite elastomer. This application provides a flexible and stretchable stimulation electrode and its preparation method to solve the technical problems of mechanical mismatch, biointerface instability, and insufficient stimulation precision that exist in existing stimulation electrodes during long-term use.

[0033] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0034] See Figure 1 This application provides a flexible and stretchable stimulation electrode, comprising: a substrate 1, a conductive layer 2, an electrode pathway encapsulation layer 3, and a stimulation point encapsulation layer 4; the conductive layer 2 is composed of a liquid metal electrode array disposed on the substrate 1; the conductive layer 2 includes an electrode wire region and an electrode stimulation end; the electrode pathway encapsulation layer 3 covers the electrode wire region; the stimulation point encapsulation layer 4 covers the electrode stimulation end; the material of the electrode pathway encapsulation layer 3 is polydimethylsiloxane; the material of the stimulation point encapsulation layer 4 is polydimethylsiloxane-carbon fiber composite elastomer.

[0035] The purpose of this application is to provide a flexible and stretchable stimulation electrode to solve the technical problems of existing stimulation electrodes during long-term use, such as mechanical mismatch, biointerface instability, and insufficient stimulation precision. Traditional implantable electrodes mostly use metal wires or rigid electrode structures, which are prone to interfacial stress concentration under dynamic physiological environments (such as muscle contraction, organ movement, etc.), leading to tissue damage, inflammatory response, or electrode migration, thereby affecting the stimulation effect and biocompatibility, and limiting their application in the fields of neuromodulation, cardiac pacing, and spinal cord stimulation.

[0036] In some embodiments, the liquid metal electrode array is composed of ultrasonically treated gallium-based liquid metal microspheres.

[0037] In some embodiments, the electrode pathway encapsulation layer 3 covers the electrode wire area while exposing the electrode stimulation end, preventing body fluids from corroding the wire and improving biocompatibility; the thickness of the electrode pathway encapsulation layer 3 is 50~100μm.

[0038] In some embodiments, the electrode has a thickness of 0.1 mm to 0.3 mm and a certain degree of stretchability.

[0039] In some embodiments, the material of substrate 1 is polydimethylsiloxane.

[0040] This application also provides a method for preparing a flexible and stretchable stimulation electrode, comprising the following steps: providing a substrate; forming a conductive layer on the substrate; the conductive layer being composed of a liquid metal electrode array; the conductive layer including an electrode wire region and an electrode stimulation end; encapsulating the electrode wire region and the electrode stimulation end of the conductive layer respectively to form an electrode pathway encapsulation layer and a stimulation point encapsulation layer; the material of the electrode pathway encapsulation layer is polydimethylsiloxane; the material of the stimulation point encapsulation layer 4 is polydimethylsiloxane-carbon fiber composite elastomer.

[0041] In some embodiments, forming a conductive layer on a substrate includes: preparing liquid metal micro / nano particle ink; printing an electrode pattern on a PET film using screen printing; and transferring the electrode pattern from the PET film to the substrate using the liquid metal micro / nano particle ink via a transfer method.

[0042] In some embodiments, the electrode wire region of the conductive layer is encapsulated to form an electrode pathway encapsulation layer, including: preparing a 50μm~100μm thick polydimethylsiloxane film using a spin coater, and covering the electrode stimulation point and the rear wiring with the polydimethylsiloxane film; then spin coating a 50μm thick polydimethylsiloxane layer onto the electrode surface as an encapsulation layer using a spin coater, with the spin coating speed parameter set to 600 rpm / 60 s; after spin coating is completed, the film covering the electrode stimulation point is peeled off, and the electrode is placed in a 60°C oven to dry for 2 hours. After the polydimethylsiloxane has cured, the electrode pathway encapsulation layer is formed.

[0043] In some embodiments, the electrode stimulation end is encapsulated to form an encapsulation layer at the stimulation point, including: using a planetary mixer to mix 15% carbon fiber and polydimethylsiloxane by mass to remove bubbles, and after mixing evenly, adding a curing agent to obtain an uncured polydimethylsiloxane-carbon fiber composite elastomer; according to the required size of the encapsulation layer at the stimulation point, using an ultraviolet laser marking machine to make a mask, and using a scraping method to evenly cover the surface of the electrode stimulation point with the uncured composite elastomer material; after the scraping is completed, the electrode is placed in a 60°C oven to dry for 2 hours to form an encapsulation layer at the stimulation point.

[0044] In some embodiments, the mass ratio of polydimethylsiloxane to curing agent is 15:1.

[0045] The following detailed description of the flexible stretchable stimulation electrode and its preparation method provided in this application is based on specific embodiments.

[0046] The flexible and stretchable stimulation electrode provided in this application, such as Figure 1 As shown, from bottom to top, the layers consist of: a substrate (PMDS), a conductive layer (EGaln), an electrode pathway encapsulation layer (PMDS), and a stimulation point encapsulation layer (composite carbon fiber elastomer). The substrate is prepared using commercially available polydimethylsiloxane (PDMS) elastomer. Specifically, a layer of PMDS is spin-coated using a transfer method to form the substrate layer. The flexibility of the substrate ensures that the electrode can adhere well to the tissue surface (such as nerve fibers). The electrode conductive layer is composed of ultrasonically treated gallium-based liquid metal microspheres. When not activated, the conductive layer is non-conductive; after activation, the resistance rapidly decreases to within 100 ohms, exhibiting excellent conductivity.

[0047] Encapsulation layer: The electrode lead area is covered with 50-100μm thick PDMS, exposing only the electrode stimulation end, to prevent body fluids from corroding the lead and improve biocompatibility.

[0048] Encapsulated conductive layer at the stimulation point: This elastic composite material layer has three functions: conductivity, stretchability, and encapsulation. First, this layer has good conductivity, serving as an electrical stimulation interface for tissues to achieve stable electrical signal transmission. Second, it has excellent tensile properties and flexibility, buffering stress changes caused by tissue movement and improving fit and stimulation stability. Third, it acts as a physical barrier for the liquid metal conductive layer, effectively preventing liquid metal leakage and direct contact with biological tissue, thus enhancing the biosafety of the electrode.

[0049] This application provides a method for preparing a flexible and stretchable stimulation electrode, comprising the following steps:

[0050] Preparation of liquid metal micro / nanoparticle ink: 6 g of gallium-indium alloy (EGaIn, 75% gallium, 25% indium) and 1 mL of n-decanol were weighed using an electronic balance and added to a 10 mL centrifuge tube. The mixture was ultrasonically sonicated at 50% amplitude for 3-5 min using an ultrasonic cell disruptor. The entire sonication process was performed in a water bath to prevent the n-decanol from evaporating due to heating. An ultrasonic amplitude transformer with a diameter of 5 mm or 1 cm was inserted 1 cm below the surface of the n-decanol for sonication, using a 2-second sonication followed by a 2-second pause to reduce the wear and tear on the instrument due to high temperature. Under ultrasonic action, the liquid metal transformed from a continuous state into micro / nanoparticles, resulting in a suspension of liquid metal particles in n-decanol, which is the liquid metal ink for screen printing.

[0051] Preparation of the liquid metal electrode array: A 200-mesh screen printing mask was used to ensure the processing accuracy of the neural electrode pattern. The screen and squeegee were cleaned with anhydrous ethanol and allowed to air dry before use. The screen was fixed on a manual screen printing machine. A polyethylene terephthalate (PET) film was adhered to the screen printing table using medical tape as a printing substrate. Then, liquid metal micro / nanoparticle ink prepared by ultrasonication was dropped onto the edge of the screen for screen printing. The printed electrode pattern was placed in a ventilated area to dry, removing any residual n-decyl alcohol solvent, thus obtaining the liquid metal particle neural electrode pattern. A polymethylsiloxane solution (PDMS, PDMS to curing agent ratio 15:1) was poured onto the surface of the neural electrode pattern using a spin coater. The spin coater speed was set to 600 rpm / 60 s to obtain the electrode substrate of ideal thickness. After spin coat, the substrate was allowed to stand for 30 min–1 h to allow the PDMS solution and liquid metal micro / nanoparticles to completely coat the substrate. The electrode samples were dried in a 60°C oven for 2 hours to allow the PDMS to cure completely. The PDMS film was then peeled off from the PET substrate to obtain a liquid metal electrode array transferred onto the PDMS substrate.

[0052] Electrode encapsulation: PDMS and PDMS-carbon fiber composite elastomer were used as encapsulation materials for different applications. For insulating encapsulation of conductive paths, PDMS with matching tensile properties was selected. A PDMS film with a thickness of 50-100 μm was prepared in advance using a spin coater and applied to the stimulation point and the rear wiring. Then, a 50 μm thick PDMS layer was spin-coated onto the electrode surface as an encapsulation layer using a spin coater at a speed of 600 rpm for 60 s. After spin coating, the film covering the stimulation point was peeled off, and the electrode was placed in a 60°C oven to dry for 2 hours. After the PDMS cured, the encapsulated stretchable stimulation electrode was obtained. For insulating encapsulation at the stimulation point, PDMS-carbon fiber composite elastomer was selected as the encapsulation material. Carbon fiber and PDMS (15% by mass) were mixed and degassed using a planetary mixer. After thorough mixing, a curing agent (PDMS to curing agent ratio of 15:1) was added to obtain an uncured PDMS-carbon fiber composite elastomer. A mask was fabricated using a UV laser marking machine according to the required encapsulation layer size at the stimulation point. The uncured composite elastomer material was then uniformly coated onto the stimulation point surface using a scraping method. After coating, the electrode was dried in a 60℃ oven for 2 hours to obtain the encapsulated electrode.

[0053] Electrodeposition of conductive polymer: A three-electrode system was used to electrodeposit polypyrrole, with a stretchable stimulating electrode array as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode. 300 μL of distilled pyrrole monomer was added to 45 mL of electrodeposition solution containing sodium dodecylbenzenesulfonate (0.3 M) and p-toluenesulfonic acid (0.1 M) and stirred. The solution was then sonicated in a water bath for 30 minutes to ensure homogeneity. Electrochemical deposition was performed at 0°C (ice bath) with a constant voltage of 0.8 V for 400 seconds. The resulting electrode was washed three times each with deionized water and anhydrous ethanol to obtain a usable electrode product.

[0054] The improvements in this application mainly include the following aspects:

[0055] (1) Flexible and stretchable electrode structure design: The overall electrode structure of this application has good flexibility and stretchability, which can adapt to the dynamic deformation of tissues in the implantation environment and maintain long-term stable tissue adhesion and electrical stimulation performance.

[0056] (2) Stimulation interface layer composed of conductive elastic composite material: A layer of elastic composite material with good conductivity and mechanical flexibility is set at the stimulation point to serve as the contact interface for electrical stimulation output, while improving stress adaptability and interface stability.

[0057] (3) Liquid metal conductive core and its encapsulation and isolation structure: Liquid metal is used as the main conductive channel inside the electrode. The conductive elastic material on the outside conducts electrical signals and provides physical isolation to prevent liquid metal leakage and direct contact with tissue, thereby improving the biosafety of the implantation system.

[0058] (4) Composition and configuration of conductive material system: Use composite conductive materials with high conductivity and good mechanical flexibility, such as carbon nanotube-PDMS composite materials.

[0059] (5) Electrode substrate material: The electrode substrate material is commercial PDMS silicone, which is a flexible electrode material with medical material grade.

[0060] (6) Transfer method: In the manufacturing process of the stretchable stimulation electrode made by this invention, the transfer method is used to transfer the electrode pattern from the PET film material to the PDMS flexible substrate.

[0061] (7) Encapsulation material: The stretchable stimulation electrode described in this application is encapsulated with an ultra-thin film in all electrode areas except for the part of the electrode that needs to be exposed, in order to avoid leakage. The encapsulation layer material is a micron-thick film material with good biocompatibility and good insulation.

[0062] (8) Multi-channel design: The stretchable stimulation electrode described in this application is a multi-channel design with 1 to 100 channels, preferably 2 to 50, and can be processed by screen printing combined with transfer printing.

[0063] The feasibility of this application has been proven through experiments and use. Figure 2 and Figure 3 As shown, the electrode exhibits low impedance and good charge storage capacity, as indicated by the cyclic voltammetry (CV) curve. In experiments, the electrode stably adhered to the nerve surface and induced a significant physiological response in mice after the application of an electrical signal, demonstrating its excellent electrical stimulation function. Furthermore, the electrode maintained stable conductivity during repeated stimulation without mechanical damage or signal attenuation, exhibiting excellent conductive stability and mechanical compliance. No significant inflammatory response was observed in tissue observation, further demonstrating the biocompatibility and safety of this application and indicating its promising practical application prospects in implantable applications such as neuromodulation.

[0064] The flexible, stretchable, multi-channel stimulation electrode provided in this application exhibits significant advantages over existing technologies in terms of functional integration, structural compliance, and electrical performance, specifically in the following aspects:

[0065] (1) Multi-channel array design improves the spatial accuracy and functional flexibility of neural modulation.

[0066] This application employs a multi-channel electrode array structure, which can be designed in linear arrangement, two-dimensional matrix, or ring distribution according to different application requirements, to achieve independent or synergistic electrical stimulation control of multiple target tissue regions. Compared with traditional single-channel or few-channel electrodes, it significantly improves spatial resolution and the flexibility of stimulation protocols, making it particularly suitable for scenarios such as complex neural network modulation, large-scale functional recovery, or high-precision disease model research.

[0067] (2) Construct an ultra-thin patch structure to enhance tissue adhesion and signal stability.

[0068] The electrode has an overall thickness of less than 500 μm and a flexible, highly compliant structure that allows it to adhere closely to the surfaces of soft tissues such as brain tissue, myocardium, and spinal cord. This patch structure not only effectively reduces the mechanical mismatch between the tissue and the electrode but also alleviates interfacial stress changes caused by tissue movement (such as pulsation and peristalsis), reducing problems such as electrode detachment and displacement, thereby improving the mechanical stability under long-term implantation.

[0069] (3) Introduce liquid metal conductive materials to achieve a synergistic unity of high conductivity and high tensile strength.

[0070] This application introduces gallium-based liquid metal particles, modified by ultrasonic treatment and microsphere formation, into the conductive path. In its unactivated state, these particles are insulating; after sintering and activation, their resistance drops dramatically to the hundreds of ohms, ensuring efficient electrical signal transmission. Furthermore, this liquid metal conductor maintains low resistivity even under large deformation conditions such as stretching and bending, far superior to traditional rigid metals or silver nanowire conductors, making it particularly suitable for applications in dynamic environments such as implantable organ electrical stimulation.

[0071] Based on the above technical solutions, this application provides a flexible and stretchable stimulation electrode and its preparation method. The electrode includes: a substrate, a conductive layer, an electrode pathway encapsulation layer, and a stimulation point encapsulation layer; the conductive layer is composed of a liquid metal electrode array disposed on the substrate; the conductive layer includes an electrode wire region and an electrode stimulation end; the electrode pathway encapsulation layer covers the electrode wire region; the stimulation point encapsulation layer covers the electrode stimulation end; the material of the electrode pathway encapsulation layer is polydimethylsiloxane; the material of the stimulation point encapsulation layer is polydimethylsiloxane-carbon fiber composite elastomer.

[0072] This application provides a flexible and stretchable stimulation electrode. The electrode uses PDMS as a substrate and gallium-based liquid metal as the conductive material. Good electrode performance is achieved by encapsulating a conductive elastic composite material layer on the surface of the stimulation point and electrodepositing a conductive polymer layer. The electrode has an overall thickness of approximately 0.3 mm and possesses a certain degree of stretchability, maintaining good stimulation efficiency even under large deformations.

[0073] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A method for preparing a flexible and stretchable stimulation electrode, characterized in that, Includes the following steps: Provide a base; A conductive layer is formed on the substrate; the conductive layer is composed of a liquid metal electrode array; the conductive layer includes an electrode wire region and an electrode stimulation end; The electrode wire region and the electrode stimulation end of the conductive layer are encapsulated to form an electrode pathway encapsulation layer and a stimulation point encapsulation layer, respectively; the material of the electrode pathway encapsulation layer is polydimethylsiloxane. The encapsulation layer at the stimulation point is made of polydimethylsiloxane-carbon fiber composite elastomer. Forming a conductive layer on the substrate includes: Preparation of liquid metal micro / nano particle ink; Electrode patterns are printed on PET film using screen printing. Electrode patterns are transferred from a PET film to the substrate using liquid metal micro / nano particle ink via a transfer method. The electrode wire region of the conductive layer is encapsulated to form an electrode path encapsulation layer, including: A 50μm~100μm thick polydimethylsiloxane film was prepared using a spin coater and then applied to the electrode stimulation point and the rear wiring. A 50μm thick polydimethylsiloxane layer was then spin-coated onto the electrode surface as an encapsulation layer using a spin coater at a speed of 600 rpm for 60 seconds. After spin coating, the thin film covering the electrode stimulation point was peeled off, and the electrode was placed in a 60℃ oven for 2 hours to dry. Once the polydimethylsiloxane had cured, an electrode pathway encapsulation layer was formed. The electrode stimulation end is encapsulated to form an encapsulation layer at the stimulation point, including: Carbon fiber and polydimethylsiloxane (15% by mass) were mixed and defoamed using a planetary mixer. After uniform mixing, a curing agent was added to obtain an uncured polydimethylsiloxane-carbon fiber composite elastomer. Based on the required size of the encapsulation layer at the stimulation point, a mask was made using a UV laser marking machine. The uncured composite elastomer material was then uniformly coated onto the surface of the electrode stimulation point using a scraping method. After the scraping was completed, the electrode was placed in a 60°C oven and dried for 2 hours to form the encapsulation layer at the stimulation point.

2. The method for preparing the flexible and stretchable stimulation electrode according to claim 1, characterized in that, The mass ratio of polydimethylsiloxane to curing agent is 15:

1.

3. A flexible and stretchable stimulation electrode, wherein the electrode is prepared by the method for preparing a flexible and stretchable stimulation electrode as described in any one of claims 1 to 2, characterized in that, The electrode includes: Substrate, conductive layer, electrode pathway encapsulation layer, and stimulation point encapsulation layer; The conductive layer is composed of a liquid metal electrode array disposed on the substrate; the conductive layer includes an electrode wire region and an electrode stimulation end; The electrode pathway encapsulation layer covers the electrode wire area; the encapsulation layer at the stimulation point covers the electrode stimulation end; The material of the electrode pathway encapsulation layer is polydimethylsiloxane; the material of the encapsulation layer at the stimulation point is polydimethylsiloxane-carbon fiber composite elastomer.

4. The flexible stretchable stimulation electrode according to claim 3, characterized in that, The liquid metal electrode array is composed of gallium-based liquid metal microspheres that have been ultrasonically treated.

5. The flexible stretchable stimulation electrode according to claim 3, characterized in that, The electrode pathway encapsulation layer covers the electrode wire area while exposing the electrode stimulation end, preventing body fluids from corroding the wire and improving biocompatibility. The thickness of the electrode pathway encapsulation layer is 50~100μm.

6. The flexible stretchable stimulation electrode according to claim 3, characterized in that, The thickness of the electrode is 0.1mm~0.3mm.

7. The flexible stretchable stimulation electrode according to claim 3, characterized in that, The substrate is made of polydimethylsiloxane.

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