Bionic tree root electronic tattoo skin electrode

Abstract

The application belongs to the technical field of flexible electronics, and specifically discloses an electronic tattoo skin electrode with a bionic tree root shape, wherein the electronic tattoo skin electrode is composed of a main electrode, a branch electrode and conductive nanowires; the main electrode, the branch electrode and the conductive nanowires respectively occupy the main root, the branch root and the fibrous root positions of the bionic tree root; the electronic tattoo skin electrode can obtain the maximum skin charge collection capacity through the minimum metal electrode area, and can improve the conductivity between the electrode and the skin through the composite carbon nanotube mode, thereby solving the technical problems of motion artifacts and the electrode area that cannot be fully utilized in the electrocardiogram, electromyogram and electroencephalogram signal monitoring. The electronic tattoo skin electrode with the bionic tree root shape can be applied to the charge collection on the skin or the surface of other organs, such as electrocardiogram, electroencephalogram and electromyogram.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics technology, and in particular to a biomimetic tree root electronic tattoo epidermal electrode. Background Technology

[0002] With the rapid development of electronic information technologies, represented by the Internet of Things (IoT), artificial intelligence (AI), and wearable smart devices, the connection between humans and the digital world is becoming increasingly close. As sensing technology advances, electronic information systems will acquire more comprehensive human body information. Human-machine interfaces, serving as a bridge for information transmission between humans and electronic information systems, are considered an efficient and feasible method for acquiring human body information. Regarding the acquisition of human body information signals, the skin, as the largest organ in the human body, contains a variety of physiological information that can reflect a person's health status, including bioelectrical signals, biophysical signals, and biochemical signals. Furthermore, population health monitoring systems that match big data have also seen corresponding developments, such as data interface access technologies, personal health data privacy protection mechanisms, health data service security management mechanisms and access technologies, research based on big data and AI technologies, personalized health profiling, and health assessment technologies. However, existing wearable devices still cannot compete with traditional big data IoT in terms of the amount of sensing data and the stability of data streams. Moreover, limited by the mechanical rigidity and size of functional chips, the flexibility and comfort of existing wearable devices do not yet meet the needs for long-term, efficient, and comfortable monitoring.

[0003] Flexible electronic devices have become a research hotspot in wearable electronic devices in recent years. However, fully flexible wearable devices are still hampered by factors such as manufacturing costs, production standardization conditions, and monitoring accuracy in practical production and application. There is an urgent need to research a design approach for flexible wearable devices suitable for large-scale production, thereby optimizing the commercial landscape for wearable vital sign detection devices. Based on the recognition and acquisition of this type of skin information through wearable human-machine interfaces, wearable electronic devices can interact with users and are widely used in many fields such as information energy, biomedicine, military defense, and smart homes, becoming a research hotspot for many researchers. Successful human-machine interaction relies on various acquisition and control interfaces, such as electrodes, touchpads, keyboards, and mice. However, with the increasing demand for multifunctional, intimate, and seamless interaction, these traditional rigid and cumbersome interfaces have gradually exposed many problems. On the one hand, due to incompatible mechanical characteristics, most existing wearable human-machine interfaces cannot establish a compliant connection with soft human skin, greatly reducing the user experience, increasing sensitivity to motion artifacts, and curbing the possibility of novel interactions. On the other hand, as a standard sensing interface for bio-information acquisition, gel electrodes will cause problems such as skin allergies and signal instability during long-term use, and are not suitable for long-term dynamic monitoring.

[0004] To address these key challenges, wearable human-machine interfaces with superior mechanical and electrical properties should be developed. These interfaces should enable long-term, comfortable, and stable connections with the human body, driving the transformation of next-generation human-machine interaction products. This includes propelling traditional hospital-centric healthcare towards portability, intelligence, and personalization; improving the accuracy of electronic devices in capturing and sensing various biological information; and enhancing human-machine interaction and feedback to form a bidirectional, complete human-machine cycle. As a product of the fusion of flexible electronics and biomedicine, electronic tattoos, due to their unique material and structural characteristics, endow wearable interfaces with excellent flexibility and stretchability, demonstrating enormous potential in human-machine interaction applications. Specifically, an electronic tattoo is an ultra-thin, ultra-soft, and stretchable electronic device that can adhere closely to human skin. Leveraging its outstanding performance advantages, electronic tattoos can conform to skin deformation and adapt to localized strain, enabling interconnection and conduction of electronic devices and monitoring and collecting various biomarkers, such as electrophysiological signals, skin temperature, hydration, blood oxygen saturation, and even sweat analytes. However, as a typical disposable stretchable flexible electronic device, its manufacturing process is cumbersome and costly, and the fabricated size is only on the order of centimeters, making it difficult to transfer flexibly and without damage, and to achieve high-quality signal acquisition and transmission. Therefore, how to reduce manufacturing costs, improve the transfer and signal acquisition capabilities of electronic tattoos, and enable better human-computer interaction are important issues facing the commercial application of electronic tattoos. Currently, it is believed that improving the graphic design of epidermal electrodes is an effective way to solve motion artifacts and electronic noise. For example, Patent Document 1 discloses a flexible system that improves comfort and stretchability. Considering the overall package thickness, this system improves the overall stretchability of the system by replacing the connecting lines between circuits with multiple thin serpentine lines in parallel; it also reduces the stress on the skin from the circuit by using two buffer structures: a flexible boss array and an embedded fluid cavity, thus improving the comfort when wearing the packaged circuit. Patent Document 2 discloses a method for preparing a honeycomb electrode patch, as well as the honeycomb electrode patch and its application. The electrodes designed by this method have advantages such as breathability, flexible wearability, low interfacial impedance, and high anti-interference ability, and are expected to be used in the actual monitoring of athletes' electrophysiological signals, assisting in muscle tracking and scientific guidance during training.

[0005] However, the main drawbacks of the above technical solutions and existing major technical solutions are as follows: (1) Although the flexible interconnect adopts a serpentine or other hollow pattern wiring method, it can improve the stretch performance of the electrode following the skin to a certain extent and improve the breathability of the electrode on the human body surface, and reduce the influence of sweat on the electrode fit to a certain extent. However, in terms of the width of the electrode, it is generally consistent throughout the electrode, and lacks adaptive optimization design based on current density. This results in a larger resistance in the area of ​​higher current density in the electrode, which is not conducive to the rapid discharge of charge; while in the area of ​​lower current density, the electrode width is larger, which wastes the conductivity of the electrode and affects the breathability of the electrode; (2) Metal electrodes have better lateral conductivity, but due to the texture and grooves of the skin surface, the metal electrodes cannot be completely attached to the skin surface, and there will be a certain air gap at the texture, which in turn affects the charge discharge capability of the electrode in the direction perpendicular to the skin surface.

[0006] Related literature

[0007] Patent Document 1: Chinese Invention Patent Application, Publication No.: CN113194601A, Publication Date: 2021.07.30;

[0008] Patent document 2 Chinese invention patent application, publication number: CN114569135A, publication date: 2021.06.03. Summary of the Invention

[0009] The purpose of this invention is to propose a biomimetic tree root electronic tattoo epidermal electrode to obtain the maximum epidermal charge collection capacity with the least amount of metal electrode area, while improving the conductivity between the electrode and the skin through composite carbon nanotubes.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A biomimetic tree root-inspired electronic tattoo epidermal electrode, the electrode pattern of which adopts the shape of a biomimetic tree root;

[0012] The electronic tattoo epidermal electrode is composed of a main electrode, branch electrodes, and conductive nanowires; wherein the main electrode, branch electrodes, and conductive nanowires occupy the main root, branch root, and fibrous root positions of the biomimetic tree root, respectively.

[0013] Preferably, along the direction of charge conduction, the electronic tattoo epidermal electrodes gradually become thicker, eventually forming a biomimetic tree root shape.

[0014] Preferably, the charge collection process involves sequentially passing through conductive nanowires, branch electrodes, and the main electrode;

[0015] The main electrode has a width greater than 10 micrometers and less than 500 micrometers; the branch electrode has a width greater than 1 micrometer and less than 50 micrometers; and the conductive nanowire has a length greater than 1 micrometer and less than 50 micrometers.

[0016] Preferably, for the main electrode and the branch electrode, the ratio of the widest part to the narrowest part of each electrode is 2 to 5 times.

[0017] Preferably, the main electrode and the branch electrode are made of metal thin film; wherein the metal thin film is made of gold, silver, aluminum or copper.

[0018] Preferably, the conductive nanowires include single-walled carbon nanotubes, multi-walled carbon nanotubes, or metal nanowires.

[0019] Preferably, the shape of the tree root is abstracted from the shape of the naturally growing tree root, and this shape is used to design and manufacture a photomask for photolithography. The shape is then copied onto a planar metal electrode using the photomask.

[0020] Preferably, the electronic tattoo epidermal electrode is made using microelectronic technology.

[0021] Preferably, a portion of the conductive nanowire is embedded in the main electrode or a branch electrode.

[0022] Furthermore, this invention also proposes a method for preparing a biomimetic tree root electronic tattoo epidermal electrode, which facilitates the preparation of the aforementioned biomimetic tree root electronic tattoo epidermal electrode.

[0023] To achieve the above objectives, the present invention adopts the following technical solution:

[0024] A method for preparing a biomimetic tree root-inspired electronic tattoo epidermal electrode includes the following steps:

[0025] Step 1. Extract key design parameters based on the shape of the tree roots and complete the design of the electrode pattern;

[0026] Step 2. Spin-coating PVA adhesive (polyvinyl alcohol adhesive) onto the glass slide. The purpose is to temporarily fix the flexible electrode device during the fabrication process and maintain a plane that is compatible with microelectronic processes.

[0027] Step 3. Spin-coat PI acid (polyimide acid) onto the PVA adhesive. The purpose is to provide a certain strength to the planar electrode, prevent electrode breakage, and improve the stability and durability of the flexible device.

[0028] After spin-coating PI acid, polyimide will be applied to form a PI film with certain strength and toughness.

[0029] Step 4. Sputter (physical vapor deposition) a metal thin film and a corresponding adhesive layer (such as titanium or cadmium) onto the PI thin film. This layer is the main conductive thin film layer, and its thickness and mechanical properties have a significant impact on the performance of the device.

[0030] Step 5. Spin-coat photoresist, place it on a heating stage and heat it, then use a mask to perform photolithographic patterning; expose the area illuminated by the mask, and then place the exposed glass slide in the developer solution for development;

[0031] The image of the mask is obtained by using a biomimetic tree root shape;

[0032] Step 6. Use wet and dry etching methods to etch away unwanted electrodes to obtain the electrode pattern of the biomimetic tree root;

[0033] Step 7. Use resist remover to remove the photoresist and PVA adhesive, and the device will be detached from the glass substrate;

[0034] Step 8. Use chemical methods to fix the metal electrode and conductive nanowire.

[0035] The present invention has the following advantages:

[0036] The skin surface electrode prepared by this invention has high conductivity, good repeatability and strong adhesion. It has good adhesion performance to surfaces with different textures and can be patterned onto various flexible or rough substrates, making it widely applicable.

[0037] The biomimetic tree root electronic tattoo epidermal electrode proposed in this invention effectively achieves a balance between charge acquisition and conduction capabilities and electrode permeability, thus enabling better electrode mechanical properties and signal stability. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the design method of the electronic tattoo epidermal electrode for biomimetic tree roots in an embodiment of the present invention.

[0039] Figure 2 This is a flowchart illustrating the fabrication process of the biomimetic tree root electronic tattoo epidermal electrode in an embodiment of the present invention.

[0040] Figure 3 This is a schematic diagram of the epidermal electrode pattern of the biomimetic tree root electronic tattoo in an embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram of carbon nanotubes fixed on a metal surface in an embodiment of the present invention.

[0042] Figure 5 This is an electrocardiogram (ECG) signal collected using an electronic tattoo epidermal electrode made from biomimetic tree roots, as shown in an embodiment of the present invention. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0044] like Figure 3 As shown in the figure, this embodiment describes a biomimetic tree root electronic tattoo epidermal electrode. In terms of design, the electrode adopts a biomimetic electrode pattern design based on the hierarchical morphology and pattern distribution of the main root, branch roots and fibrous roots of a tree root.

[0045] The biomimetic technology in this embodiment refers to extracting the shape of a tree root and abstracting the shape of an electrode. Based on the shape of the tree root, it can be determined that the width of the electrode gradually increases along the direction of current collection.

[0046] Through the above biomimetic design, the overall structure of the electrode pattern forms a biomimetic tree root structure.

[0047] Specifically, the electronic tattoo epidermal electrode consists of a main electrode, branch electrodes, and conductive nanowires. The main electrode, branch electrodes, and conductive nanowires occupy the positions of the main root, branch roots, and fibrous roots of a biomimetic tree root, respectively.

[0048] In this embodiment, the main electrode and the branch electrode are metal thin film electrodes. The metal thin film electrodes are made of materials such as gold, silver, aluminum or copper, but are not limited to gold, silver or aluminum or copper. The metal thin film electrodes are metal sheet electrodes.

[0049] Conductive nanowires can be, but are not limited to, single-walled carbon nanotubes, multi-walled carbon nanotubes, or various metal nanowires.

[0050] In this embodiment, the selection of materials is related to the preparation process, and factors such as the preparation process time, the cost of the materials, and the Young's modulus, ductility, thickness, and corrosion resistance of the prepared materials need to be considered.

[0051] The conductive nanowires are embedded within the aforementioned metal sheet electrode. In this embodiment, the conductive nanowires have two functions: firstly, to increase the skin's ability to collect electrical charges; and secondly, to fill in the grooves and crevices of the skin texture.

[0052] The function of the metal electrode plate is to transfer the charge on the surface of a biological organism or organ out of the electrode and into the signal reading circuit to form a corresponding signal. It can generally be used for the acquisition of electrical signals from electrocardiogram, electroencephalogram and electromyography.

[0053] In signal acquisition, a key technical challenge is how to improve signal acquisition efficiency while simultaneously increasing electrode permeability. The balance between permeability and charge collection capacity refers to the fact that a larger planar electrode area results in stronger charge collection and discharge capabilities. However, a larger planar electrode area leads to decreased permeability due to its larger surface area, significantly impacting electrode adhesion. This makes it difficult for sweat and other fluids from the skin to evaporate, causing the electrode to easily detach and generating significant motion artifacts, which is detrimental to signal stability.

[0054] This embodiment uses biomimetic tree root technology, which adopts the tree root structure that has evolved over a long period of time in nature. In the process of obtaining water and nutrients from the soil, the tree root perfectly balances its volume and absorption and coverage capacity.

[0055] The design and graphic design of this electrode are based on the biomimetic technology of tree roots. The graphic of the metal sheet electrode is generally divided into two levels. The first level electrode is biomimetic to the main root of a tree root. The graphic is relatively wide, which facilitates the rapid discharge of large charge densities and reduces the resistivity in areas with high charge density. The second level electrode is connected to the wider first level electrode. Its metal sheet electrode is smaller in width but more numerous, and its shape is biomimetic to the branch root shape of a tree root.

[0056] In the design of the planar electrode in this embodiment, the shape of the biomimetic tree root needs to be considered to determine the direction of the electrode, so as to make it easier to determine the width ratio of the designed electrode at different positions according to the different positions of the tree root.

[0057] Along the direction of charge conduction, the electrodes on the surface of the electronic tattoo gradually become thicker, eventually forming the shape of a biomimetic tree root.

[0058] The charge collection process involves sequentially passing through conductive nanowires, branch electrodes, and the main electrode.

[0059] The main electrode has a width greater than 10 micrometers and less than 500 micrometers; the branch electrode has a width greater than 1 micrometer and less than 50 micrometers; and the conductive nanowire has a length greater than 1 micrometer and less than 50 micrometers.

[0060] Preferably, for the main electrode and the branch electrode, the ratio of the widest part to the narrowest part of each electrode is 2 to 5 times.

[0061] A portion of the conductive nanowire is embedded inside the metal electrode. The conductive nanowire is embedded into the metal electrode during the fabrication process. According to this approach, the metal electrode can be fabricated using physical vapor deposition, chemical vapor deposition, electroplating, and other methods.

[0062] In this embodiment, when using the electronic tattoo epidermal electrode, one side of the electrode with conductive nanowires is attached to the skin surface or organ surface. The conductive nanowires are responsible for absorbing the epidermal charge into the planar electrode in the longitudinal direction, giving full play to the good conductivity of the nanowires along the axial direction. Furthermore, due to the flexible nature of the conductive nanowires, they can be better embedded into the texture grooves of the skin, reducing the air gap capacitance between the skin and the electrode and increasing the conductivity of the electrode.

[0063] The fabrication of planar electrodes typically employs microelectronic fabrication processes, which generally follow the following steps:

[0064] First, conductive nanowires are sprayed or brushed onto the surface of a substrate. Then, metal electrodes are fabricated on the substrate coated with conductive nanowires using physical vapor deposition, chemical vapor deposition, electroplating, or other methods. This method allows a portion of the conductive nanowires to be embedded into the metal electrode. Subsequently, a root-shaped planar metal electrode is fabricated using photolithography and etching.

[0065] This embodiment abstracts the shape of a tree root from the shape of a naturally growing tree root, and uses this shape to design and manufacture a photomask for photolithography, using the photomask to copy the shape onto a planar metal electrode.

[0066] The biomimetic tree root electronic tattoo epidermal electrode of this invention can obtain the maximum epidermal charge collection capacity with the least amount of metal electrode area. At the same time, the conductivity between the electrode and the skin is improved by using composite carbon nanotubes, which solves the problems of motion artifacts and insufficient utilization of electrode area in ECG, EMG and EEG signal monitoring.

[0067] The electrode of this invention can be applied to charge collection on the surface of skin or other organs, such as electrocardiogram, electroencephalogram, and electromyography.

[0068] Furthermore, this invention also proposes a method for preparing a biomimetic tree root electronic tattoo epidermal electrode, used to prepare the aforementioned biomimetic tree root electronic tattoo epidermal electrode, such as... Figure 1 and Figure 2 As shown.

[0069] The preparation method includes the following steps:

[0070] Step 1. Preparation of the sacrificial layer.

[0071] The dried glass slide 101 was placed at room temperature to cool for about 10 minutes. Polyvinyl alcohol was then spin-coated onto the glass slide 101 as a sacrificial layer 102. The spin-coating speeds were 500 rpm for 10 seconds, 2000 rpm for 15 seconds, 3500 rpm for 10 seconds, and 3500 rpm for 20 seconds.

[0072] The preparation process of polyvinyl alcohol is as follows: a polyvinyl alcohol solution with a mass ratio of 1:10 is prepared by stirring with a heated magnetic stirrer at a speed of 1200 rpm and a water temperature of 90℃ for 40 min.

[0073] Step 2. PI film attachment.

[0074] A 5μm thick PI film 103 is smoothly attached to a heated magnetic stirrer using a cotton scraper, and then coated with the prepared PVA solution. The cotton scraper effectively improves the wrinkle-free properties of the PI film without damaging it.

[0075] Then, the glass slide is placed on a heating table (80℃) and heated for 15 minutes to allow the PVA and PI film to adhere better.

[0076] Step 3. Deposition of the metal layer.

[0077] First, a base vacuum of 10 is established using mechanical and molecular pumps. -4 In a Pa environment, argon gas, a reaction gas, is continuously introduced into the chamber at a flow rate of 30 sccm, which is controlled by a flow display.

[0078] Then, a Ti layer with a thickness of 70 nm and an Au layer with a thickness of 350 nm were sputtered at powers of 150 W and 210 W respectively to obtain a composite layer 104, which includes a metal layer, a PI layer, a PVA layer and a substrate.

[0079] Here, the Ti layer improves the adhesion between the Au layer and the PI film.

[0080] Step 4. Pattern the metal layer.

[0081] Spin-coat photoresist 105 (positive photoresist) at a spin speed of 500 rpm for 10 seconds and 2000 rpm for 30 seconds. Place it on a heating stage (100°C) and heat for 3 minutes. Then use mask 106 to perform photolithographic patterning.

[0082] The image of this mask is obtained by mimicking the shape of a tree root, such as... Figure 3 As shown.

[0083] Expose the area visible through the mask (exposure time is 10s), place the exposed glass slide in the developer for 50s, then rinse the glass slide and observe the patterning under an electron microscope.

[0084] Step 5. Wet etching.

[0085] First, prepare the etching solution. Place the glass slide in the etching solution and shake it for 1 minute to 20 seconds. Then rinse it with clean water and soak it in clean water for 3 minutes. After that, place it on a heating table (80℃ for 5 minutes) to dry the glass slide, thereby removing the metal layer except for the desired pattern.

[0086] In this embodiment, the etching solution is, for example, KI:I:H2O = 4g:1g:40ml.

[0087] Step 6. Dry etching.

[0088] The glass slide is placed in the RIE plasma etching chamber, and a base vacuum of 10 is constructed using mechanical and molecular pumps. - 4 In a vacuum environment, etching is performed for 35 minutes (AC self-bias voltage of 150W and start-up voltage of about 3Pa) to remove the surface photoresist and PI film, thus completing the patterning of the metal layer.

[0089] Step 7. Treat the gold electrode surface with a 2.2 g / L 11-mercaptoundecyl acid (11-MUA) 107 ethanol solution and let it stand at room temperature for 24 hours. Figure 4 As shown. MUA is a thiol compound containing -SH and -COOH. The -SH108 spontaneously forms a covalent bond with the gold electrode, thereby forming a self-assembled monolayer. The hydroxyl groups can form peptide bonds with the amino groups modified on the carbon nanotubes, thus completing the fixation of the carbon nanotubes (conductive nanowires).

[0090] Step 8. Use a mixed solution of 0.2 mol / L l-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS) (which allows the amino groups on the carbon nanotubes to form peptide bonds with the hydroxyl groups on the MUA, thus immobilizing the amino-modified carbon nanotubes 110 on the gold electrode in a covalent manner), with phosphate buffer PBS (pH = 7.2, 0.01 M) solution as the solvent, and let it stand at room temperature for 1 h.

[0091] Step 9. Non-destructive transfer of the device.

[0092] Since the cured 1788L PVA dissolves in water, the electronic tattoo epidermal electrode in this embodiment can be transferred to human skin without damage simply by wetting the microstructure electrode. ECG signals can then be tested. Figure 5 As shown.

[0093] Of course, the above description is only a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. It should be noted that any equivalent substitutions or obvious modifications made by those skilled in the art under the guidance of this specification fall within the scope of this specification and should be protected by the present invention.

Claims

1. A biomimetic tree root-inspired electronic tattoo epidermal electrode, characterized in that, The electrode pattern of the electronic tattoo epidermal electrode adopts a biomimetic tree root shape; The electronic tattoo epidermal electrode is composed of a main electrode, branch electrodes, and conductive nanowires; wherein, the main electrode, branch electrodes, and conductive nanowires occupy the positions of the main root, branch root, and fibrous root of the biomimetic tree root, respectively. Looking along the direction of charge conduction, the electrodes on the surface of the electronic tattoo gradually become thicker, eventually forming the shape of a biomimetic tree root; The charge collection process involves sequentially passing through conductive nanowires, branch electrodes, and the main electrode. The main electrode has a width greater than 10 micrometers and less than 500 micrometers; the branch electrode has a width greater than 1 micrometer and less than 50 micrometers; and the conductive nanowire has a length greater than 1 micrometer and less than 50 micrometers.

2. The biomimetic tree root electronic tattoo epidermal electrode according to claim 1, characterized in that, For the main electrode and the branch electrode, the ratio of the widest part to the narrowest part of each electrode is 2 to 5 times.

3. The biomimetic tree root electronic tattoo epidermal electrode according to claim 1, characterized in that, The main electrode and the branch electrode are made of metal thin film; wherein the metal thin film is made of gold, silver, aluminum or copper.

4. The biomimetic tree root electronic tattoo epidermal electrode according to claim 1, characterized in that, The conductive nanowires include single-walled carbon nanotubes, multi-walled carbon nanotubes, or metal nanowires.

5. The biomimetic tree root electronic tattoo epidermal electrode according to claim 1, characterized in that, The shape of a tree root is abstracted from its natural growth shape, and this shape is used to design and manufacture a photomask for photolithography. The shape is then copied onto a planar metal electrode using the photomask.

6. The biomimetic tree root electronic tattoo epidermal electrode according to claim 1, characterized in that, The electronic tattoo epidermal electrode is made using microelectronic technology.

7. The biomimetic tree root electronic tattoo epidermal electrode according to claim 5, characterized in that, The conductive nanowires are partially embedded in the main electrode or the branch electrode.

8. The method for preparing the biomimetic tree root electronic tattoo epidermal electrode as described in claim 1, characterized in that, Includes the following steps: Step 1. Extract key design parameters based on the shape of the tree roots and complete the design of the electrode pattern; Step 2. Spin-coat PVA adhesive onto the glass slide; Step 3. Spin-coat PI acid onto the PVA adhesive. After spin-coating, polyimide will be applied to form a PI film. Step 4. Sputter a metal film and a corresponding adhesive layer onto the PI film; Step 5. Spin-coat photoresist, place it on a heating stage and heat it, then use a mask to perform photolithographic patterning; expose the area illuminated by the mask, and then place the exposed glass slide in the developer solution for development; The image of the mask is obtained by using a biomimetic tree root shape; Step 6. Use wet and dry etching methods to etch away unwanted electrodes to obtain the electrode pattern of the biomimetic tree root; Step 7. Use resist remover to remove the photoresist and PVA adhesive, and the device will be detached from the glass substrate; Step 8. Use chemical methods to fix the metal electrode and conductive nanowire.

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