Flexible multichannel multilayer electrode, its fabrication method, and electromyography signal acquisition device

Abstract

This invention discloses a flexible multichannel multilayer electrode, its fabrication method, and an electromyography (EMG) signal acquisition device. The fabrication method of the flexible multichannel multilayer electrode includes the following steps: etching and cleaning a silicon wafer; preparing an AgNW / NG solution as a conductive material and using SEBS powder to prepare an elastic substrate; fabricating a signal acquisition layer using the silicon wafer, conductive material, and SEBS powder; fabricating a wire shielding layer using the silicon wafer and SEBS powder; and fabricating an encapsulation layer and an interference signal shielding layer using the silicon wafer, conductive material, and SEBS powder; assembling the encapsulation layer, interference signal shielding layer, signal acquisition layer, and wire shielding layer sequentially from top to bottom, and connecting the signal acquisition layer to a flexible printed circuit board. This invention aims to solve the problems of high electrode impedance, low signal-to-noise ratio, and poor tensile strength of multichannel electrodes.

Description

Technical Field

[0001] This invention relates to the field of electrode fabrication, and more particularly to a flexible multichannel multilayer electrode, its fabrication method, and an electromyography signal acquisition device. Background Technology

[0002] From the perspective of data acquisition methods, muscle fatigue can be mainly divided into invasive and non-invasive methods. Invasive methods can acquire more precise physiological signals, but due to their lower practicality, the risk of wound damage and infection, they are not widely used in muscle fatigue research. Non-invasive methods, on the other hand, are easier to obtain through the human body surface while ensuring signal quality and are widely accepted. Currently, the mainstream non-invasive research method is surface electromyography (sEMG). When muscles are fatigued, their electromyographic signals show phenomena such as increased time-domain amplitude and left-shifted frequency spectrum. Therefore, surface electromyographic signals can be used to objectively and accurately assess muscle functional status.

[0003] To obtain higher resolution muscle state information, multi-channel electrodes are generally used to acquire sEMG signals and perform fatigue feature extraction and other algorithmic processing. Currently, multi-channel electromyography signal acquisition either uses multiple Ag / AgCl gel electrodes or multi-channel electrodes fabricated using polyimide (PI) material as a substrate, which have drawbacks such as high electrode impedance, low signal-to-noise ratio, and poor tensile strength. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a flexible multi-channel multilayer electrode, its preparation method, and an electromyography signal acquisition device to solve the problems of high electrode impedance, low signal-to-noise ratio, and poor tensile strength of multi-channel electrodes.

[0005] To address the above problems, this invention provides a method for fabricating a flexible multichannel multilayer electrode, comprising the following steps:

[0006] The silicon wafer is etched and then cleaned.

[0007] Preparation of AgNW / NG solution as a conductive material and preparation of elastic substrate using SEBS powder;

[0008] A signal acquisition layer is prepared using silicon wafers, conductive materials, and SEBS powder; a wire shielding layer is prepared using silicon wafers and SEBS powder; and an encapsulation layer and an interference signal shielding layer are prepared using silicon wafers, conductive materials, and SEBS powder.

[0009] The encapsulation layer, interference signal shielding layer, signal acquisition layer and wire shielding layer are fixedly assembled from top to bottom, and the flexible printed circuit board is connected through the signal acquisition layer.

[0010] Optionally, before the silicon wafer etching and cleaning steps, the following steps are also included:

[0011] The signal acquisition layer is designed as a serpentine electrode pattern with four rows and eight columns, wherein the electrode diameter is 4-6 mm, the row spacing is 10-12 mm, and the column spacing is 10-12 mm.

[0012] The conductor shielding layer is designed as an electrode pattern of four rows and eight columns, with an electrode diameter of 4-6 mm, a row spacing of 10-12 mm, a column spacing of 10-12 mm, and a cutout at the electrode.

[0013] Optionally, the steps of etching and cleaning the silicon wafer specifically include:

[0014] Grooves with 50-70 micrometer structured electrode patterns are etched into the silicon wafer for the deposition of conductive materials;

[0015] Place the silicon wafer in a beaker, add deionized water, acetone and isopropanol respectively, and clean it with ultrasonic power of 30-40W for 10-15 minutes. After cleaning, dry it with a nitrogen gun.

[0016] Optionally, the steps of preparing the AgNW / NG solution as a conductive material and preparing the elastic substrate using SEBS powder specifically include:

[0017] NG solution was prepared from NG powder and subjected to ultrasonic treatment at a power of 400-450W for 1-1.5h under ice bath conditions to separate the layered structure of the NG solution and collect the supernatant.

[0018] Take AgNW solution in a glass bottle and add the prepared NG solution to the glass bottle. Use ultrasonic treatment with a power of 40-50W for 3-5 minutes to mix the two materials and prepare an AgNW / NG solution with a concentration ratio of (6-8):(1-2) as a conductive material. Take SEBS powder and grind it in a mortar until uniform to prepare a SEBS solution with dichlorobenzene as solvent. The concentration of the SEBS solution is 220-280 mg / ml. Add magnetic beads to the SEBS solution and stir at 55-65℃ and 400-500 r / min for 1-2 hours until the white powdery solid is completely dissolved. Let it stand to remove air bubbles to obtain an elastic substrate.

[0019] Optionally, the step of preparing the signal acquisition layer using silicon wafers, conductive materials, and SEBS powder specifically includes:

[0020] The prepared AgNW / NG solution was drop-coated onto the cleaned etched silicon wafer, and the silicon wafer with AgNW / NG solution was placed on a heating stage and dried at 45-50°C. After 2-3 hours, SEBS solution was spin-coated onto its surface.

[0021] Then place it on a heating table and anneal at 85-95℃ for 1-2 hours. After it has solidified into a film, use alcohol to help peel it off to obtain the signal acquisition layer.

[0022] Optionally, the step of preparing the encapsulation layer and the interference signal shielding layer using silicon wafers, conductive materials, and SEBS powder specifically includes:

[0023] The prepared AgNW / NG solution was drop-coated onto the cleaned silicon wafer, and then placed on a heating table to dry at 45-50℃ for 2-3 hours.

[0024] SEBS solution is spin-coated onto a dried silicon wafer. The silicon wafer with SEBS solution spin-coated is then placed on a heating stage and annealed at 85-95°C for 1-2 hours. After it has solidified into a film, alcohol is used to assist in the peeling process to obtain the encapsulation layer and the interference signal shielding layer.

[0025] Optionally, the step of preparing the wire shielding layer using silicon wafers and SEBS powder specifically includes:

[0026] Place the conductor shielding mask on the cleaned silicon wafer and fix it with tape. Spin-coat the conductor shielding layer onto the silicon wafer with SEBS solution. Then place it on a heating table and anneal at 85-95℃ for 1-2 hours. After it has cured into a film, use alcohol to help peel it off to obtain the conductor shielding layer.

[0027] Optionally, the step of fixing and assembling the encapsulation layer, interference signal shielding layer, signal acquisition layer, and wire shielding layer from top to bottom, and connecting the flexible printed circuit board through the signal acquisition layer, specifically includes:

[0028] Apply conductive silver paste to the signal pin connections of the signal acquisition layer;

[0029] Place the signal pins of the flexible printed circuit board on the signal pins after applying conductive silver paste to the signal acquisition layer, press lightly, and then place it on a heating table to anneal at 55-65℃ for 1-2 hours to anneal and cure the conductive silver paste.

[0030] A flexible multi-channel multilayer electrode is fabricated by mechanically laminating the encapsulation layer, interference signal shielding layer, signal acquisition layer, and wire shielding layer sequentially from top to bottom using the organic solvent dichlorobenzene.

[0031] The present invention also proposes a flexible multi-channel multilayer electrode, comprising an encapsulation layer, an interference signal shielding layer, a signal acquisition layer, and a wire shielding layer prepared by the flexible multi-channel multilayer electrode preparation method described above. The encapsulation layer, the interference signal shielding layer, the signal acquisition layer, and the wire shielding layer are mechanically laminated and fixed from top to bottom, and are connected to a flexible printed circuit board through the signal acquisition layer.

[0032] The present invention also proposes an electromyography signal acquisition device, comprising the flexible multi-channel multilayer electrode as described above.

[0033] The technical solution of this invention first involves etching and cleaning a silicon wafer; then, an AgNW / NG solution is prepared as a conductive material, and an elastic substrate is prepared using SEBS powder; a signal acquisition layer is prepared using the silicon wafer, conductive material, and SEBS powder; a wire shielding layer is prepared using the silicon wafer and SEBS powder; and an encapsulation layer and an interference signal shielding layer are prepared using the silicon wafer, conductive material, and SEBS powder. The encapsulation layer, interference signal shielding layer, signal acquisition layer, and wire shielding layer are then assembled sequentially from top to bottom, and a flexible printed circuit board is connected via the signal acquisition layer. Thus, the flexible multi-channel multilayer electrode manufactured by the above method has the advantages of low electrode impedance and high signal-to-noise ratio, and both AgNW / NG and SEBS materials possess good tensile properties, ensuring good consistency between the electrode's tensile curve and recovery curve. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0035] Figure 1 This is a schematic flowchart of an embodiment of the method for preparing flexible multichannel multilayer electrodes according to the present invention;

[0036] Figure 2 This is a schematic flowchart of another embodiment of the method for preparing the flexible multichannel multilayer electrode of the present invention;

[0037] Figure 3 This is a scanning electron microscope schematic diagram of an embodiment of the preparation method of the flexible multichannel multilayer electrode of the present invention, in which AgNW / NG is used as a conductive material;

[0038] Figure 4 This is a side scanning electron microscope schematic diagram of an embodiment of the signal acquisition layer in the fabrication method of the flexible multichannel multilayer electrode of the present invention;

[0039] Figure 5 This is a schematic diagram of the process for preparing the signal acquisition layer in the preparation method of the flexible multichannel multilayer electrode of the present invention;

[0040] Figure 6 This is a structural breakdown diagram of an embodiment of the flexible multichannel multilayer electrode of the present invention;

[0041] Figure 7 This is a schematic diagram of an embodiment of the flexible multichannel multilayer electrode of the present invention;

[0042] Figure 8 These are recovery diagrams of the flexible multichannel multilayer electrode of the present invention under different stress tensions;

[0043] Figure 9 This is a comparison diagram of the contact impedance between the flexible multichannel multilayer electrode of this invention and the Ag / AgCl electrode;

[0044] Figure 10 This is a comparison of the signal-to-noise ratio of the flexible multichannel multilayer electrode of this invention and the Ag / AgCl electrode when collecting electromyographic signals under forearm load conditions;

[0045] Figure 11 This is an electromyography (EMG) signal image of static and dynamic muscle contraction acquired in one embodiment of the flexible multichannel electrode of the present invention.

[0046] Figure 12 This is a schematic diagram of the electromyographic signals collected by the flexible multi-channel electrode of the present invention for static and dynamic muscle contraction. Detailed Implementation

[0047] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0048] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of the present invention involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0049] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0050] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0051] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0052] From the perspective of data acquisition methods, muscle fatigue can be mainly divided into invasive and non-invasive methods. Invasive methods can acquire more precise physiological signals, but due to their lower practicality, the risk of wound damage and infection, they are not widely used in muscle fatigue research. Non-invasive methods, on the other hand, are easier to obtain through the human body surface while ensuring signal quality and are widely accepted. Currently, the mainstream non-invasive research method is surface electromyography (sEMG). When muscles are fatigued, their electromyographic signals show phenomena such as increased time-domain amplitude and left-shifted frequency spectrum. Therefore, surface electromyographic signals can be used to objectively and accurately assess muscle functional status.

[0053] To obtain higher resolution muscle state information, multi-channel electrodes are generally used to acquire sEMG signals and perform fatigue feature extraction and other algorithmic processing. Currently, multi-channel EMG signal acquisition either uses multiple silver / silver chloride (Ag / AgCl) gel electrodes or multi-channel electrodes fabricated using polyimide (PI) materials as substrates. However, these methods suffer from drawbacks such as high electrode impedance, low signal-to-noise ratio, and poor tensile strength. They also present disadvantages such as complex wiring and poor adhesion.

[0054] To address the above problems, this invention proposes a method for fabricating flexible multichannel multilayer electrodes.

[0055] Reference Figure 1 In one embodiment, the fabrication method of the flexible multichannel multilayer electrode includes the following steps:

[0056] S100: Etch the silicon wafer and clean it.

[0057] S200, preparation of AgNW / NG solution as a conductive material and preparation of elastic substrate using SEBS powder;

[0058] S300, a signal acquisition layer 30 is prepared by means of silicon wafer, conductive material and SEBS powder, a wire shielding layer 40 is prepared by means of silicon wafer and SEBS powder, and an encapsulation layer 10 and an interference signal shielding layer 20 are prepared by means of silicon wafer, conductive material and SEBS powder.

[0059] S400, from top to bottom, the encapsulation layer 10, the interference signal shielding layer 20, the signal acquisition layer 30 and the wire shielding layer 40 are fixedly assembled, and the flexible printed circuit board 50 is connected through the signal acquisition layer 30.

[0060] In this embodiment, silicon wafer etching removes contaminants and oxide layers from the silicon wafer surface, ensuring good electrode contact and higher conductivity. Furthermore, silicon wafer etching also contributes to feature fabrication, increases surface area, improves adhesion, and optimizes electrical performance. Cleaning the silicon wafer removes contaminants, improves surface cleanliness to enhance electrode material adhesion and conductivity, promotes chemical reactions, improves signal stability, and ensures consistency, thereby improving experimental repeatability and reliability. Common cleaning methods include ultrasonic cleaning, acid cleaning, and alkaline cleaning; the specific choice depends on the nature of the contaminants and the desired cleaning effect.

[0061] In this embodiment, a solution of silver nanowires (AgNW) with high electrical conductivity and nanographite (NG) with superlubricating properties can be prepared as a conductive material. The concentration ratio of AgNW to NG can be (6-8):(1-2), and the concentration ratio of AgNW to NG can be finely adjusted according to the actual situation. Among them, silver nanowires have excellent electrical conductivity, which can effectively reduce the resistance of the electrode and improve the current conduction capability. In addition, silver nanowires also have good mechanical flexibility while maintaining high conductivity. Furthermore, the fine structure of silver nanowires provides a large surface area, which is beneficial to improving the reactivity of the electrode. Nanographite has high conductivity, and the material is lightweight and high-strength. Nanographite also has good chemical stability, making it suitable for use in a variety of chemical environments. Thus, using a mixed solution of silver nanowires and nanographite as a conductive material can also combine the advantages of both materials. An elastic substrate is then prepared using hydrogenated styrene-butadiene block copolymer (SEBS). SEBS is a thermoplastic elastomer with excellent flexibility, weather resistance, chemical resistance, and good processability. Thus, during electrode fabrication, the conductive network formed by AgNW / NG material, combined with the inherent network structure of SEBS, imparts excellent mechanical tensile properties to the electrode. Using SEBS as a substrate, its elastic modulus matches that of human skin tissue, thus providing the electrode with good flexibility. Figure 3This is a schematic diagram of a scanning electron microscope using AgNW / NG as the conductive material.

[0062] After etching and cleaning the silicon wafer, and preparing conductive materials and an elastic substrate, a signal acquisition layer 30, an interference signal shielding layer 20, an encapsulation layer 10, and a wire shielding layer 40 can be prepared. Specifically, AgNW / NG solution or SEBS solution can be drop-coated onto the silicon wafer, followed by drying or annealing to form a thin film, which serves as the corresponding signal acquisition layer 30, interference signal shielding layer 20, encapsulation layer 10, or wire shielding layer 40. Specifically, the signal acquisition layer 30 can be prepared using silicon wafers, conductive materials, and SEBS powder; the wire shielding layer 40 can be prepared using silicon wafers and SEBS powder; and the encapsulation layer 10 and interference signal shielding layer 20 can be prepared using silicon wafers, conductive materials, and SEBS powder. The prepared signal acquisition layer 30, interference signal shielding layer 20, encapsulation layer 10, and wire shielding layer 40 are then mechanically laminated from top to bottom using the organic solvent dichlorobenzene. Finally, the signal acquisition layer 30 is connected to the flexible printed circuit board 50, thus obtaining a complete flexible multi-channel multilayer electrode.

[0063] The technical solution of this invention first involves etching and cleaning a silicon wafer; then, an AgNW / NG solution is prepared as a conductive material, and an elastic substrate is prepared using SEBS powder; a signal acquisition layer 30 is prepared using the silicon wafer, conductive material, and SEBS powder; a wire shielding layer 40 is prepared using the silicon wafer and SEBS powder; and an encapsulation layer 10 and an interference signal shielding layer 20 are prepared using the silicon wafer, conductive material, and SEBS powder. The encapsulation layer 10, interference signal shielding layer 20, signal acquisition layer 30, and wire shielding layer 40 are then assembled sequentially from top to bottom, and a flexible printed circuit board 50 is connected via the signal acquisition layer 30. Thus, the flexible multi-channel multilayer electrode manufactured by the above method has the advantages of low electrode impedance and high signal-to-noise ratio, and both the AgNW / NG and SEBS materials have good tensile properties, ensuring good consistency between the electrode's tensile curve and recovery curve.

[0064] In another embodiment, other materials can also be used as conductive materials and to prepare the elastic substrate. For example, other conductive nanowires such as gold nanowires can be used as conductive materials, as gold nanowires also have excellent electrical conductivity, thermal conductivity and chemical stability; and two-dimensional layered materials such as MXene can be used to prepare the elastic substrate. MXene is usually composed of transition metal carbides, nitrides or carbonitrides, in the form of Mn+1Xn(T), where M represents a transition metal, X represents carbon or nitrogen, and T represents a surface termination group such as oxygen, fluorine or carboxyl; polyimide and other materials can also be used as materials for the elastic substrate; the silicon wafer can also be replaced with aluminum plate, steel plate, etc.

[0065] In one embodiment, prior to the steps of etching and cleaning the silicon wafer, the following steps are also included:

[0066] The signal acquisition layer 30 is designed as a serpentine electrode pattern with four rows and eight columns, wherein the electrode diameter is 4-6 mm, the row spacing is 10-12 mm, and the column spacing is 10-12 mm.

[0067] The conductor shielding layer 40 is designed as an electrode pattern of four rows and eight columns, wherein the electrode diameter is 4-6mm, the row spacing is 10-12mm, the column spacing is 10-12mm, and the electrode area is hollowed out.

[0068] In this embodiment, the electrode diameter of the signal acquisition layer 30 and the conductor shielding layer 40 is 4-6 mm, the row spacing is 10-12 mm, and the column spacing is 10-12 mm, resulting in an overall electrode size of (11-12) cm * (9-10) cm. The overall design is a pairwise differential structure with a total of 16 channels. Differential input has stronger anti-common-mode interference capability compared to single-ended input, making it suitable for long-distance transmission; the specific electrode diameter, spacing, and size design can also be adjusted according to actual conditions and user needs. A well-designed signal acquisition layer 30 can effectively reduce noise and interference, thereby improving signal quality and accuracy, optimizing the signal transmission path, reducing delay and loss, improving system response speed, and ensuring the reliability of the equipment under various operating conditions. The design of the conductor shielding layer 40 can effectively isolate electromagnetic interference, ensuring that the signal is not affected by external noise; it can also improve signal integrity, ensuring the integrity of the signal during transmission, reducing reflection and crosstalk; and it can protect the signal line and avoid ground loop problems, improving the reliability of signal acquisition. Therefore, the structural design of the signal acquisition layer 30 and the design of the conductor shielding layer 40 are both aimed at improving signal quality, integrity, and system reliability. Understandably, the serpentine structure design of the signal acquisition layer 30 also provides it with good structural stretchability.

[0069] Reference Figure 2 In one embodiment, the steps of etching and cleaning the silicon wafer specifically include:

[0070] S210. Grooves with 50-70 micrometer structured electrode patterns are etched in the silicon wafer for the deposition of conductive materials.

[0071] S220. Place the silicon wafer in a beaker, add deionized water, acetone and isopropanol respectively, and clean it with ultrasonic for ten minutes. After cleaning, dry it with a nitrogen gun.

[0072] In this embodiment, the grooves of the 50-70 micrometer structured electrode pattern etched in the silicon wafer can be etched according to the designed serpentine electrode pattern of the signal acquisition layer 30 for subsequent fabrication of the signal acquisition layer 30. The specific groove depth can also be adjusted according to the actual needs of the signal acquisition layer 30. The silicon wafer can be cleaned using a three-step cleaning method, which typically includes the following steps to ensure the cleanliness and high performance of the electrode surface: Preliminary cleaning: The electrodes are initially cleaned using deionized water, acetone, isopropanol, or ultrapure water to remove large particulate impurities and soluble contaminants from the surface. This can be done by ultrasonic cleaning or immersion to ensure that there is no obvious dirt on the surface. Chemical cleaning: Depending on the properties of the electrode material, the electrodes are chemically cleaned using appropriate chemical reagents (such as acidic or alkaline solutions). This step can remove metal oxides, grease, and other organic contaminants. Commonly used cleaning agents include nitric acid, hydrochloric acid, hydrofluoric acid, or surfactant solutions. After cleaning, the electrodes should be thoroughly rinsed again with deionized water to remove any residual cleaning agent. Drying and post-treatment: Dry the cleaned electrode in an oven or under a nitrogen atmosphere to prevent re-adhesion of airborne contaminants. After drying, subsequent treatments can be performed as needed, such as coating a protective layer or performing electrochemical activation. The above three-step cleaning method helps improve the electrochemical performance and repeatability of the electrode.

[0073] In one embodiment, the steps of preparing the conductive material and preparing the elastic substrate specifically include:

[0074] NG solution was prepared from NG powder and subjected to ultrasonic treatment at a power of 400-450W for 1-1.5h under ice bath conditions to separate the layered structure of the NG solution and collect the supernatant.

[0075] Take AgNW solution into a glass bottle, add prepared NG solution into the glass bottle, and use ultrasonic treatment with a power of 40-50W for 3-5 minutes to mix the two materials, so as to prepare an AgNW / NG solution with a concentration ratio of (6-8):(1-2) as a conductive material.

[0076] Take SEBS powder and grind it in a mortar until uniform. Prepare a SEBS solution with dichlorobenzene as solvent. The concentration of the SEBS solution is 220-280 mg / ml. Add magnetic beads to the SEBS solution and stir at 55-65℃ and 400-500 r / min for 1-2 hours until the white powdery solid is completely dissolved. Let it stand to remove air bubbles to obtain an elastic substrate.

[0077] In this embodiment, ultrasonic treatment with a power of 400-450W under ice bath conditions can effectively promote the formation and collapse of bubbles in the solution, thereby accelerating the dispersion and mixing of substances. The concentrations of NG solution, AgNW solution, and SEBS solution can be adjusted according to actual conditions and requirements. It should be noted that in this embodiment, the concentration ratio of AgNW solution to NG solution in the AgNW / NG solution is (6-8):(1-2), where (6-8) and (1-2) represent that the ratio of AgNW solution to NG solution can be adjusted within the ranges of 6 to 8 and 1 to 2, respectively. The AgNW / NG solution obtained by mixing NG solution and AgNW / NG solution has the advantages of strong conductivity, large-area coverage, high mechanical strength and flexibility, promotion of charge transport, good chemical stability, high specific surface area, and strong controllability. Furthermore, the temperature, rotation speed, and stirring time during the preparation of the elastic substrate can be adjusted within the given range according to actual conditions to prepare an elastic substrate with good flexibility.

[0078] In one embodiment, the step of fabricating the signal acquisition layer 30 using silicon wafers, conductive materials, and SEBS powder specifically includes:

[0079] The prepared AgNW / NG solution was drop-coated onto the cleaned etched silicon wafer, and the silicon wafer with AgNW / NG solution was placed on a heating stage and dried at 45-50°C. After 2-3 hours, SEBS solution was spin-coated onto its surface.

[0080] Then place it on a heating table and anneal at 85-95℃ for 1-2 hours. After it has solidified into a film, use alcohol to help peel it off to obtain the signal acquisition layer 30.

[0081] In this embodiment, a pre-designed structured pattern for the signal acquisition layer 30, with a depth of 50-70 micrometers, is first etched onto a silicon wafer. Then, a prepared conductive material, namely an AgNW / NG solution, is drop-coated into the etched grooves on the silicon wafer. After annealing and drying on a heated platform, an elastic substrate material, SEBS, is spin-coated onto the silicon wafer using a spin coater. During the heating and curing process, the conductive material embeds into the surface of the elastic substrate. Finally, an alcohol-assisted peeling process is used to obtain the flexible electrode. This method allows for large-scale device fabrication, and the patterned silicon wafer can be reused after the device is removed from the wafer, simplifying the electrode fabrication process and reducing the overall device fabrication cost. The amount of AgNW / NG solution drop-coated onto the etched silicon wafer can be 3-5 ml, which can be adjusted according to user requirements. Furthermore, the annealing temperature and annealing stirring time during the preparation of the signal acquisition layer 30 can be adjusted within the given range based on actual conditions. Figure 4This is a side scanning electron microscope (SEM) schematic diagram of the signal acquisition layer 30 prepared in the fabrication method of the flexible multichannel multilayer electrode in this embodiment. The signal acquisition layer 30 includes an SEBS layer formed after SEBS curing and an AgNW / NG layer formed after AgNW / NG solution curing. The thickness of the SEBS layer is 33.3 micrometers, and the thickness of the AgNW / NG layer ranges from 6.35 micrometers to 6.55 micrometers. The specific fabrication process of the signal acquisition layer 30 can be referred to... Figure 5 .

[0082] In one embodiment, the step of preparing the encapsulation layer 10 and the interference signal shielding layer 20 using silicon wafers, conductive materials, and SEBS powder specifically includes:

[0083] The prepared AgNW / NG solution was drop-coated onto the cleaned silicon wafer, and then placed on a heating table to dry at 45-50℃ for 2-3 hours.

[0084] SEBS solution is spin-coated onto a dried silicon wafer. The spin-coated silicon wafer is then placed on a heating table and annealed at 85-95°C for 1-2 hours. After curing into a film, alcohol is used to assist in the peeling process to obtain the encapsulation layer 10 and the interference signal shielding layer 20.

[0085] In this embodiment, AgNW / NG solution is drop-coated onto a cleaned, smooth silicon wafer. After drying on a heating stage, SEBS solution is spin-coated onto it, followed by annealing and curing on a heating stage. After curing into a film, alcohol-assisted peeling is used to obtain the encapsulation layer 10 and the interference signal shielding layer 20. It should be noted that in this embodiment, the encapsulation layer 10 and the interference signal shielding layer 20 are prepared using an integrated method. The interference signal shielding layer 20 is embedded in the encapsulation layer, and the outer encapsulation layer 10 provides protection, preventing interference or damage to the electrode interior. The interference signal shielding layer 20 can shield external interference signals, improving the quality of electromyographic signals. It should be noted that because the interference signal shielding layer 20 is a powder of the conductive material AgNW / NG solution after drying on the silicon wafer, the added SEBS solution, after drying, will embed the conductive powder into the dried SEBS film. Furthermore, in this embodiment, the amount of AgNW / NG solution used to prepare the interference signal shielding layer 20 is 5-7 ml.

[0086] In one embodiment, the step of preparing the wire shielding layer 40 using silicon wafers and SEBS powder specifically includes:

[0087] Place the conductor shielding layer 40 mask on the cleaned silicon wafer and fix it with tape. Spin-coat the conductor shielding layer 40 on the silicon wafer with SEBS solution. Then place it on a heating table and anneal at 85-95℃ for 1-2 hours. After it has cured into a film, use alcohol to help peel it off to obtain the conductor shielding layer 40.

[0088] In this embodiment, the structural design of the wire shielding layer 40 in the above embodiments can be a design of a mask for the wire shielding layer 40. The mask for the wire shielding layer 40 is placed on a cleaned, smooth silicon wafer, fixed with adhesive tape, and then a SEBS solution is spin-coated onto it. Afterward, it is placed on a heating stage, and once cured into a film, it is peeled off with alcohol to obtain the wire shielding layer 40. The wire shielding layer 40 is a perforated thin film made of SEBS material, which can shield the electrode wires from errors introduced during electromyography (EMG) signal acquisition, improving the accuracy of EMG signal acquisition. Furthermore, the annealing temperature and annealing time of the wire shielding layer 40 can be adjusted within a given range according to actual conditions.

[0089] In one embodiment, the step of fixing and assembling the encapsulation layer 10, interference signal shielding layer 20, signal acquisition layer 30, and wire shielding layer 40 from top to bottom, and connecting the flexible printed circuit board 50 through the signal acquisition layer 30, specifically includes:

[0090] Apply conductive silver paste to the signal pin connection points of the signal acquisition layer 30;

[0091] Place the signal pins of the flexible printed circuit board 50 on the signal pins of the signal acquisition layer 30 after applying conductive silver paste, press it slightly, and then place it on a heating table to anneal at 55-65℃ for 1-2 hours to anneal and cure the conductive silver paste.

[0092] A flexible multi-channel multilayer electrode is fabricated by mechanically laminating the encapsulation layer 10, interference signal shielding layer 20, signal acquisition layer 30, and wire shielding layer 40 sequentially from top to bottom using the organic solvent dichlorobenzene.

[0093] In this embodiment, the signal acquisition layer 30 can be connected to the signal pins of the flexible printed circuit board 50 using conductive silver paste. Then, using the organic solvent dichlorobenzene as an aid, the encapsulation layer 10, interference signal shielding layer 20, signal acquisition layer 30, and wire shielding layer 40 are mechanically laminated sequentially from top to bottom to obtain a complete flexible multi-channel multilayer electrode. The flexible electrode is connected to the lines of the flexible printed circuit board 50 via conductive silver paste, and the lines of the flexible printed circuit board 50 are then connected to the hardware system using a slot method, simplifying the wiring process from the electrode to the hardware acquisition system and avoiding the risk of incorrect or missing connections. Furthermore, the annealing temperature and annealing time of the conductive silver paste can be adjusted within a given range according to actual conditions.

[0094] In one embodiment, such as Figure 8 Recovery tests were conducted on the flexible multichannel multilayer electrode in the range of 40%, 60%, 80%, and 100%. Even within the 100% stress range, the tensile curve and recovery curve of the flexible multichannel multilayer electrode made of SEBS-AgNW / NG material showed good consistency. Figure 7 The subplot in the image is a magnified view of the resilience under 40% stress tension.

[0095] like Figure 9 Electrode-skin contact impedance tests were conducted on flexible multichannel multilayer electrodes and Ag / AgCl electrodes made of SEBS-AgNW / NG material. At a frequency of 100Hz, the impedance value of the SEBS-AgNW / NG electrode was reduced by 54.2% compared with that of the Ag / AgCl electrode.

[0096] like Figure 10 The signal-to-noise ratio (SNR) of a flexible multichannel multilayer electrode made of SEBS-AgNW / NG material was compared with that of an Ag / AgCl electrode. Electromyographic signals of muscles under a load of 1-5 kg ​​were collected, and the SNR of each signal segment was calculated and plotted as a bar graph. In this scheme, the flexible multichannel multilayer electrode made of SEBS-AgNW / NG material has a higher SNR than the Ag / AgCl electrode.

[0097] like Figures 11 to 12 The electromyography (EMG) signals of 16 channels were measured by loading a 3kg dumbbell onto the forearm to measure static and dynamic muscle contractions. The high-quality EMG signals acquired can be used for further processing to extract muscle fatigue characteristics and detect muscle fatigue status. Specific signal diagrams can be found in [reference needed]. Figure 11 For practical applications of electromyography (EMG) signal acquisition, please refer to... Figure 12 .

[0098] This invention also proposes a flexible multichannel multilayer electrode.

[0099] Reference Figures 6 to 7In one embodiment, the flexible multichannel multilayer electrode can be prepared using the method described above. Referring to the above embodiments, the flexible multichannel multilayer electrode in this embodiment comprises four parts: an encapsulation layer 10, an interference signal shielding layer 20, a signal acquisition layer 30, and a wire shielding layer 40. The encapsulation layer 10 is a SEBS thin film, which provides protection and prevents interference or damage to the electrode interior. The interference signal shielding layer 20 is made of AgNW / NG hybrid material, which shields external interference signals and prevents them from affecting the quality of electromyography (EMG) signals. The signal acquisition layer 30 is made of SEBS-AgNW / NG material and is used to acquire EMG signals from the human body surface. Its serpentine structure design provides good structural stretchability. The wire shielding layer 40 is a perforated thin film made of SEBS material, which shields the electrode wires from introducing errors during EMG signal acquisition, improving the accuracy of EMG signal acquisition. In the assembly of the multilayer structure, the organic solvent dichlorobenzene is used as an aid for mechanical lamination, thus obtaining a complete flexible multichannel multilayer electrode. The flexible electrode and the line of the flexible printed circuit board 50 are connected by conductive silver paste, and then the line of the flexible printed circuit board 50 is connected to the hardware system by a slot method, which simplifies the wiring process from the electrode to the hardware acquisition system and avoids the risk of incorrect or missing connections. Figure 6 This is a structural diagram of a flexible multichannel multilayer electrode. Figure 7 This is a diagram of the overall structure of the assembled flexible multichannel multilayer electrode. It is understood that since the flexible multichannel multilayer electrode of this invention is prepared using the aforementioned method, the embodiments of the flexible multichannel multilayer electrode of this invention include all the technical solutions of all embodiments of the aforementioned method for preparing flexible multichannel multilayer electrodes, and the achieved technical effects are completely identical, so they will not be repeated here.

[0100] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for fabricating a flexible multichannel multilayer electrode, characterized in that, Includes the following steps: The signal acquisition layer is designed as a serpentine electrode pattern with four rows and eight columns, wherein the electrode diameter is 4-6 mm, the row spacing is 10-12 mm, and the column spacing is 10-12 mm. The conductor shielding layer is designed as an electrode pattern of four rows and eight columns, wherein the electrode diameter is 4-6mm, the row spacing is 10-12mm, the column spacing is 10-12mm, and the electrode area is hollowed out. The process includes etching and cleaning the silicon wafer; specifically, the steps of etching and cleaning the silicon wafer include: Grooves with 50-70 micrometer structured electrode patterns are etched into the silicon wafer for the deposition of conductive materials; Place the silicon wafer in a beaker, add deionized water, acetone and isopropanol respectively, and clean it with ultrasonic power of 30-40W for 10-15 minutes. After cleaning, dry it with a nitrogen gun. The preparation of AgNW / NG solution as a conductive material and the preparation of an elastic substrate using SEBS powder; specifically, the steps of preparing AgNW / NG solution as a conductive material and preparing an elastic substrate using SEBS powder include: NG solution was prepared from NG powder and subjected to ultrasonic treatment at a power of 400-450W for 1-1.5h under ice bath conditions to separate the layered structure of the NG solution and collect the supernatant. Take AgNW solution into a glass bottle, add prepared NG solution into the glass bottle, and use ultrasonic treatment with a power of 40-50W for 3-5 minutes to mix the two materials, so as to prepare an AgNW / NG solution with a concentration ratio of (6-8):(1-2) as a conductive material. SEBS powder was ground in a mortar until homogeneous, and a SEBS solution with dichlorobenzene as solvent was prepared. The concentration of the SEBS solution was 220-280 mg / ml. Magnetic beads were added to the SEBS solution, and the mixture was stirred at 55-65℃ and 400-500 r / min for 1-2 hours until the white powdery solid was completely dissolved. The mixture was allowed to stand to remove air bubbles to obtain an elastic substrate. The thickness of the SEBS was 33.3 μm, and the thickness of the AgNW / NG layer ranged from 6.35 μm to 6.55 μm. A signal acquisition layer is prepared using silicon wafers, conductive materials, and SEBS powder; a wire shielding layer is prepared using silicon wafers and SEBS powder; and an encapsulation layer and an interference signal shielding layer are prepared using silicon wafers, conductive materials, and SEBS powder. A flexible multi-channel multilayer electrode is fabricated by mechanically laminating the encapsulation layer, interference signal shielding layer, signal acquisition layer, and wire shielding layer in sequence from top to bottom using the organic solvent dichlorobenzene. The electrode is then connected to a flexible printed circuit board via the signal acquisition layer.

2. The method for fabricating a flexible multichannel multilayer electrode as described in claim 1, characterized in that, The step of preparing the signal acquisition layer using silicon wafers, conductive materials, and SEBS powder specifically includes: The prepared AgNW / NG solution was drop-coated onto the cleaned etched silicon wafer, and the silicon wafer with AgNW / NG solution was placed on a heating stage and dried at 45-50℃. After 2-3 hours, SEBS solution was spin-coated onto its surface. Then place it on a heating table and anneal at 85-95℃ for 1-2 hours. After it has solidified into a film, use alcohol to help peel it off to obtain the signal acquisition layer.

3. The method for fabricating a flexible multichannel multilayer electrode as described in claim 1, characterized in that, The steps of preparing the encapsulation layer and interference signal shielding layer using silicon wafers, conductive materials, and SEBS powder specifically include: The prepared AgNW / NG solution was drop-coated onto the cleaned silicon wafer, and then placed on a heating table to dry at 45-50℃ for 2-3 hours. SEBS solution is spin-coated onto a dried silicon wafer. The spin-coated silicon wafer is then placed on a heating stage and annealed at 85-95°C for 1-2 hours. After the solution has solidified into a film, alcohol is used to assist in the peeling process to obtain the encapsulation layer and the interference signal shielding layer.

4. The method for fabricating a flexible multichannel multilayer electrode as described in claim 1, characterized in that, The step of preparing the wire shielding layer using silicon wafers and SEBS powder specifically includes: Place the conductor shielding mask on the cleaned silicon wafer and fix it with tape. Spin-coat the conductor shielding layer onto the silicon wafer with SEBS solution. Then place it on a heating table and anneal at 85-95℃ for 1-2 hours. After it has cured into a film, use alcohol to help peel it off to obtain the conductor shielding layer.

5. The method for fabricating a flexible multichannel multilayer electrode as described in claim 1, characterized in that, The step of fixing and assembling the encapsulation layer, interference signal shielding layer, signal acquisition layer, and wire shielding layer sequentially from top to bottom, and connecting the flexible printed circuit board through the signal acquisition layer, specifically includes: Apply conductive silver paste to the signal pin connections of the signal acquisition layer; Place the signal pins of the flexible printed circuit board onto the signal pins after applying conductive silver paste to the signal acquisition layer. After pressing lightly, place it on a heating table and anneal at 55-65℃ for 1-2 hours to cure the conductive silver paste.

6. A flexible multichannel multilayer electrode, characterized in that, The invention includes an encapsulation layer, an interference signal shielding layer, a signal acquisition layer, and a wire shielding layer prepared by the method for preparing a flexible multi-channel multilayer electrode as described in any one of claims 1-5. The encapsulation layer, the interference signal shielding layer, the signal acquisition layer, and the wire shielding layer are mechanically laminated and fixed from top to bottom, and are connected to a flexible printed circuit board through the signal acquisition layer.

7. An electromyography (EMG) signal acquisition device, characterized in that, Including the flexible multichannel multilayer electrode as described in claim 6.

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