Flexible multi-channel multi-layer electrode, preparation method and electromyographic signal collector

Abstract

The invention discloses a flexible multi-channel multi-layer electrode, a preparation method and an electromyographic signal collector. The preparation method of the flexible multi-channel multi-layer electrode comprises the following steps: etching a silicon wafer, and cleaning the silicon wafer; preparing an AgNW / NG solution as a conductive material, and preparing an elastic substrate by adopting SEBS powder; a signal acquisition layer is prepared from a silicon wafer, a conductive material and SEBS powder, a wire shielding layer is prepared from the silicon wafer and the SEBS powder, and a packaging layer and an interference signal shielding layer are prepared from the silicon wafer, the conductive material and the SEBS powder; the packaging layer, the interference signal shielding layer, the signal acquisition layer and the wire shielding layer are fixedly assembled in sequence from top to bottom, and are connected with the flexible printed circuit board through the signal acquisition layer. The invention aims to solve the problems of high electrode impedance value, low signal-to-noise ratio and poor stretchability of a multi-channel electrode.

Description

Technical Field

[0001] The invention relates to the field of electrode preparation, and in particular to a flexible multi-channel multi-layer electrode and a preparation method thereof, and an electromyographic signal collector. Background Art

[0002] From the perspective of acquisition methods, muscle fatigue phenomenon can be mainly divided into invasive methods and non-invasive methods. Invasive methods can collect more accurate physiological signals, but due to their low practicality, wound damage, and susceptibility to infection, they have not been widely used in the study of muscle fatigue. Non-invasive methods are easier to obtain through the human body surface while ensuring signal quality, and are widely recognized. The current mainstream non-invasive research method is the surface electromyography (sEMG) method. When muscle fatigue occurs, its electromyographic signal manifests as an increase in time domain amplitude and a left shift in the frequency domain spectrum. Therefore, surface electromyographic signals can be used to objectively and accurately evaluate muscle functional status.

[0003] In order to obtain higher resolution muscle status information, multi-channel electrodes are generally used to collect sEMG signals and perform fatigue feature extraction and other algorithm processing. At present, multi-channel electromyographic signal acquisition is either collected using multiple Ag / AgCl gel electrodes or multi-channel electrodes prepared with polyimide (PI) material as the substrate, which have the disadvantages of high electrode impedance, low signal-to-noise ratio and poor stretchability. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a flexible multi-channel multi-layer electrode and a preparation method and an electromyographic signal collector to solve the problems of high electrode impedance, low signal-to-noise ratio and poor stretchability of the multi-channel electrode.

[0005] In order to solve the above problems, the present invention provides a method for preparing a flexible multi-channel multi-layer electrode, comprising the following steps:

[0006] Etching and cleaning silicon wafers;

[0007] preparing AgNW / NG solution as conductive material and using SEBS powder to prepare elastic substrate;

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

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

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

[0011] The signal collection 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 wire shielding layer is designed as an electrode pattern of four rows and eight columns, wherein the electrode diameter is 4-6 mm, the row spacing is 10-12 mm, the column spacing is 10-12 mm, and the electrodes are hollowed out.

[0013] Optionally, the step of etching the silicon wafer and cleaning the silicon wafer specifically includes:

[0014] Carve 50-70 micron grooves of structured electrode patterns into silicon wafers for conductive material deposition;

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

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

[0017] The NG solution is prepared from the NG powder, and an ultrasonic treatment is performed at a power of 400-450 W for 1-1.5 h under ice bath conditions to separate the layered structure of the NG solution, and the supernatant is taken;

[0018] The AgNW solution is put into a glass bottle, and the prepared NG solution is added into the glass bottle. The two materials are mixed by ultrasonic treatment at a power of 40-50 W for 3-5 minutes to prepare an AgNW / NG solution with a concentration ratio of (6-8):(1-2) as a conductive material; SEBS powder is put into a mortar and ground until uniform, and a SEBS solution with dichlorobenzene as a solvent is prepared. The concentration of the SEBS solution is 220-280 mg / ml. Magnetic beads are added into the SEBS solution, and the solution is stirred at 55-65° C. and 400-500 r / min for 1-2 hours until the white powdery solid is completely dissolved, and the solution is allowed to stand to exhaust air bubbles to obtain an elastic substrate.

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

[0020] The prepared AgNW / NG solution is dropped on the cleaned etched silicon wafer, and the silicon wafer with the AgNW / NG solution is placed on a heating table to dry at 45-50°C. After 2-3 hours, the SEBS solution is spin-coated on the surface;

[0021] Then place it on a heating table and anneal it at 85-95°C for 1-2 hours. After it solidifies into a film, use alcohol to assist in peeling to obtain the signal collection layer.

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

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

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

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

[0026] Place the wire shielding layer mask on the cleaned silicon wafer, use tape to assist in fixing, spin-coat SEBS solution on the wire shielding layer on the silicon wafer, then place it on a heating table and anneal it at 85-95°C for 1-2 hours. After it solidifies into a film, use alcohol to assist in peeling off to obtain the wire shielding layer.

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

[0028] Apply conductive silver paste to the signal pin connection of the signal collection layer;

[0029] Place the signal pin of the flexible printed circuit board on the signal pin on which the conductive silver paste is dotted on the signal collection layer, press it lightly, and then place it on a heating table to anneal at 55-65°C for 1-2 hours to anneal and solidify the conductive silver paste;

[0030] The packaging layer, the interference signal shielding layer, the signal collection layer and the wire shielding layer are mechanically laminated from top to bottom in sequence with the assistance of the organic solvent dichlorobenzene to obtain a flexible multi-channel multi-layer electrode.

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

[0032] The present invention also provides an electromyographic signal collector, comprising the flexible multi-channel multi-layer electrode as described above.

[0033] The technical solution of the present invention first etches the silicon wafer and cleans the silicon wafer; then prepares AgNW / NG solution as a conductive material and uses SEBS powder to prepare an elastic substrate; and prepares a signal acquisition layer through a silicon wafer, a conductive material and SEBS powder, prepares a wire shielding layer through a silicon wafer and SEBS powder, and prepares an encapsulation layer and an interference signal shielding layer through a silicon wafer, a conductive material and SEBS powder; then fixes and assembles the encapsulation layer, the interference signal shielding layer, the signal acquisition layer and the wire shielding layer from top to bottom, and connects the flexible printed circuit board through the signal acquisition layer. In this way, the flexible multi-channel multi-layer electrode manufactured by the above method has the advantages of low electrode impedance value and high signal-to-noise ratio, and both the AgNW / NG material and the SEBS material have good stretchability, which can ensure that the stretching curve and the recovery curve of the electrode also have good consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary personnel in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0035] Figure 1 It is a schematic flow chart of an embodiment of a method for preparing a flexible multi-channel multi-layer electrode according to the present invention;

[0036] Figure 2 It is a schematic flow chart of another embodiment of the method for preparing a flexible multi-channel multi-layer electrode of the present invention;

[0037] Figure 3 It is a scanning electron microscope schematic diagram of an embodiment of AgNW / NG as a conductive material in the method for preparing a flexible multi-channel multi-layer electrode of the present invention;

[0038] Figure 4 It is a side scanning electron microscope schematic diagram of an embodiment of a signal collection layer in the method for preparing a flexible multi-channel multi-layer electrode of the present invention;

[0039] Figure 5 It is a schematic diagram of the process of preparing the signal collection layer in the method for preparing the flexible multi-channel multi-layer electrode of the present invention;

[0040] Figure 6 This is a schematic diagram of the structural disassembly of an embodiment of a flexible multi-channel multi-layer electrode of the present invention;

[0041] Figure 7 is a schematic diagram of an embodiment of a flexible multi-channel multi-layer electrode of the present invention;

[0042] Figure 8 It is a recovery diagram of the flexible multi-channel multi-layer electrode of the present invention under different stress stretching;

[0043] Fig. 9 This is a comparison diagram of the contact impedance between the flexible multi-channel multi-layer electrode of the present invention and the Ag / AgCl electrode;

[0044] Fig.10 This is a comparison diagram of the signal-to-noise ratio of the flexible multi-channel multi-layer electrode of the present invention and the Ag / AgCl electrode when collecting electromyographic signals under forearm weight-bearing conditions;

[0045] Fig.11 It is a graph of electromyographic signals of static and dynamic muscle contraction collected in an embodiment of the flexible multi-channel electrode of the present invention;

[0046] Fig.12 It is a schematic diagram of the flexible multi-channel electrode of the present invention collecting electromyographic signals of static muscle contraction and dynamic muscle contraction. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] In the embodiments and the scope of the patent application, unless the text specifically defines the article, "a", "an", "the" and "the" may also include plural forms. If there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0049] It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the 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 said to be "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there can also be intermediate elements. In addition, the "connection" or "coupling" used herein can include wireless connection or wireless coupling. The term "and / or" 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 (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0051] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0052] From the perspective of acquisition methods, muscle fatigue phenomenon can be mainly divided into invasive methods and non-invasive methods. Invasive methods can collect more accurate physiological signals, but due to their low practicality, wound damage, and susceptibility to infection, they have not been widely used in the study of muscle fatigue. Non-invasive methods are easier to obtain through the human body surface while ensuring signal quality, and are widely recognized. The current mainstream non-invasive research method is the surface electromyography (sEMG) method. When muscle fatigue occurs, its electromyographic signal manifests as an increase in time domain amplitude and a left shift in the frequency domain spectrum. Therefore, surface electromyographic signals can be used to objectively and accurately evaluate muscle functional status.

[0053] In order to obtain higher-resolution muscle status information, multi-channel electrodes are generally used to collect sEMG signals and perform fatigue feature extraction and other algorithm processing. At present, multi-channel electromyographic signal acquisition is either collected using multiple silver / silver chloride (Ag / AgCl) gel electrodes, or multi-channel electrodes prepared with polyimide (PI) materials as substrates, which have disadvantages such as high electrode impedance, low signal-to-noise ratio and poor stretchability. There are also disadvantages such as complex wiring and poor adhesion.

[0054] In order to solve the above problems, the present invention proposes a method for preparing a flexible multi-channel multi-layer electrode.

[0055] Reference Figure 1 In one embodiment, a method for preparing a flexible multi-channel multi-layer electrode comprises the following steps:

[0056] S100, etching the silicon wafer and cleaning the silicon wafer;

[0057] S200, preparing AgNW / NG solution as a conductive material and using SEBS powder to prepare an elastic substrate;

[0058] S300, preparing a signal collection layer 30 by using a silicon wafer, a conductive material and SEBS powder, preparing a wire shielding layer 40 by using a silicon wafer and SEBS powder, and preparing a packaging layer 10 and an interference signal shielding layer 20 by using a silicon wafer, a conductive material and SEBS powder;

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

[0060] In this embodiment, etching of silicon wafers can remove pollutants and oxide layers on the surface of silicon wafers, ensuring good contact of electrodes and higher conductivity. In addition, etching of silicon wafers also has the functions of characteristic structure, increasing surface area, improving adhesion, optimizing electrical properties, etc. Cleaning of silicon wafers can remove pollutants, improve surface cleanliness to improve adhesion and conductivity of electrode materials, promote chemical reactions, improve signal stability, ensure consistency, and thus improve repeatability and reliability of experiments. Common cleaning methods include ultrasonic cleaning, acid cleaning, alkaline cleaning, etc. The specific selection depends on the nature of the pollutants and the required cleaning effect.

[0061] In this embodiment, silver nanowires (AgNW for short) with high electrical conductivity and nanographite powder (NG for short) with super lubricity can be used to prepare AgNW / NG solution as 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 fine-tuned according to actual conditions. Among them, silver nanowires have excellent electrical conductivity, which can effectively reduce the resistance of the electrode and improve the current conduction capacity. In addition, while maintaining high electrical conductivity, silver nanowires also have good mechanical flexibility. The fine structure of silver nanowires also provides a large surface area, which is beneficial to improving the reaction activity of the electrode. Nanographite powder has high electrical conductivity, and the material is light and high-strength. Nanographite has good chemical stability and is suitable for use in a variety of chemical environments. In this way, the mixed solution of silver nanowires and nanographite powder is used as a conductive material, which can also have the advantages of both materials. Then, the elastic substrate is prepared with hydrogenated styrene-butadiene block copolymer (Styrene Ethylene Butylene Styrene, referred to as SEBS) material. SEBS is a thermoplastic elastomer with excellent flexibility, weather resistance, chemical resistance and good processability. In this way, during the electrode preparation process, the AgNW / NG material forms a conductive network and the network structure of the SEBS material can give the electrode good mechanical tensile properties. With SEBS material as the substrate, its elastic modulus matches that of human skin tissue, giving the electrode good flexibility. Figure 3Schematic diagram of scanning electron microscopy using AgNW / NG as conductive material.

[0062] After etching and cleaning the silicon wafer, and preparing the conductive material and the elastic substrate, the signal collection layer 30, the interference signal shielding layer 20, the encapsulation layer 10 and the wire shielding layer 40 can be prepared. Specifically, the AgNW / NG solution or the SEBS solution can be dripped on the silicon wafer, and then dried or annealed to form a thin film as the corresponding signal collection layer 30, the interference signal shielding layer 20, the encapsulation layer 10 or the wire shielding layer 40. Specifically, the signal collection layer 30 can be prepared by silicon wafer, conductive material and SEBS powder, the wire shielding layer 40 can be prepared by silicon wafer and SEBS powder, and the encapsulation layer 10 and the interference signal shielding layer 20 can be prepared by silicon wafer, conductive material and SEBS powder. Then, the prepared signal collection layer 30, the interference signal shielding layer 20, the encapsulation layer 10 and the wire shielding layer 40 are mechanically laminated from top to bottom in sequence with the assistance of organic solvent dichlorobenzene, and the flexible printed circuit board 50 is connected to the flexible printed circuit board 50 through the signal collection layer 30, so as to obtain a complete flexible multi-channel multi-layer electrode.

[0063] The technical solution of the present invention first etches the silicon wafer and cleans the silicon wafer; then prepares AgNW / NG solution as a conductive material and uses SEBS powder to prepare an elastic substrate; and prepares a signal acquisition layer 30 through a silicon wafer, a conductive material and SEBS powder, prepares a wire shielding layer 40 through a silicon wafer and SEBS powder, and prepares a packaging layer 10 and an interference signal shielding layer 20 through a silicon wafer, a conductive material and SEBS powder; and then fixes and assembles the packaging layer 10, the interference signal shielding layer 20, the signal acquisition layer 30 and the wire shielding layer 40 from top to bottom, and connects the flexible printed circuit board 50 through the signal acquisition layer 30. In this way, the flexible multi-channel multi-layer electrode manufactured by the above method has the advantages of low electrode impedance value and high signal-to-noise ratio, and both the AgNW / NG material and the SEBS material have good stretchability, which can ensure that the stretching curve and the recovery curve of the electrode are also consistent.

[0064] In another embodiment, other materials can also be used as conductive materials and to prepare elastic substrates. For example, other conductive nanowires such as gold nanowires can be used as conductive materials, and 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 elastic substrates. MXene is usually composed of transition metal carbides, nitrides or carbonitrides in the form of Mn+1Xn(T), where M represents transition metals, X represents carbon or nitrogen, and T represents surface termination groups such as oxygen, fluorine or carboxyl groups; polyimide and the like can also be used as materials for elastic substrates; silicon wafers can also be replaced with aluminum plates, steel plates, etc.

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

[0066] The signal collection 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 wire shielding layer 40 is designed as an electrode pattern of four rows and eight columns, wherein the electrode diameter is 4-6 mm, the row spacing is 10-12 mm, the column spacing is 10-12 mm, and the electrodes are hollowed out.

[0068] In this embodiment, the electrode diameter of the signal acquisition layer 30 and the wire shielding layer 40 is 4-6mm, the row spacing is 10-12mm, and the column spacing is 10-12mm. The overall size of the electrode is designed to be (11-12)cm*(9-10)cm. The overall design is a differential structure with a total of 16 channels. Compared with single-ended input, differential input has a stronger ability to resist common-mode interference and is suitable for long-distance transmission; and 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 the quality and accuracy of the signal, and can also optimize the signal transmission path, reduce delay and loss, improve the system response speed, and ensure the reliability of the equipment under various working conditions. The design of the wire shielding layer 40 can effectively isolate electromagnetic interference and ensure that the signal is not affected by external noise; it can also improve signal integrity, ensure the integrity of the signal during transmission, reduce reflection and crosstalk; and protect the signal line and avoid ground loop problems, thereby improving the reliability of signal acquisition. Therefore, the design of the signal collection layer 30 structure and the design of the wire shielding layer 40 are both to improve the quality, integrity and reliability of the signal. It is understandable that the signal collection layer 30 adopts a serpentine structure design method, which can also give it good structural stretchability.

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

[0070] S210, carving grooves of 50-70 micrometer structured electrode patterns in the silicon wafer for conductive material deposition;

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

[0072] In this embodiment, the grooves of the 50-70 micron structured electrode pattern engraved in the silicon wafer can be etched according to the designed serpentine electrode pattern of the signal collection layer 30, so as to prepare the signal collection layer 30 later. The specific groove depth can also be adjusted and set according to the signal collection layer 30 required in actual conditions. The three-step cleaning method can be used to clean the silicon wafer. The three-step cleaning method generally includes the following steps to ensure the cleanliness and high performance of the electrode surface: Preliminary cleaning: Use deionized water, acetone, isopropanol or ultrapure water to preliminarily clean the electrode to remove large particle impurities and soluble contaminants on the surface. It can be done by ultrasonic cleaning or soaking to ensure that there is no obvious dirt on the surface. Chemical cleaning: According to the properties of the electrode material, use appropriate chemical reagents (such as acidic or alkaline solutions) to chemically clean the electrode. This step can remove metal oxides, grease and other organic contaminants. Common cleaning agents include nitric acid, hydrochloric acid, hydrofluoric acid or surfactant solutions. After cleaning, it should be thoroughly rinsed again with deionized water to remove residual cleaning agents. Drying and post-treatment: Dry the cleaned electrode in an oven or blow dry it in a nitrogen atmosphere to prevent air pollutants from attaching again. 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 to 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] The NG solution is prepared from the NG powder, and an ultrasonic treatment is performed at a power of 400-450 W for 1-1.5 h under ice bath conditions to separate the layered structure of the NG solution, and the supernatant is taken;

[0075] The AgNW solution is placed in a glass bottle, and the prepared NG solution is added to the glass bottle, and the two materials are mixed by ultrasonic treatment at a power of 40-50 W for 3-5 minutes 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 it is 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, stir at 55-65°C and 400-500 r / min for 1-2 hours until the white powdery solid is completely dissolved, and let it stand to exhaust 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 rupture of bubbles in the solution, thereby accelerating the dispersion and mixing of the substances. The concentrations of NG solution, AgNW solution and SEBS solution can be adjusted according to actual conditions and needs; it should be noted that the concentration ratio of AgNW solution to NG solution in the AgNW / NG solution of this embodiment 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 range of 6 to 8 and 1 to 2, respectively. The AgNW / NG solution obtained by mixing the NG solution and the AgNW / NG solution has the advantages of strong conductivity, large area coverage, high mechanical strength and high flexibility, promotion of charge transfer, good chemical stability, high specific surface area, and strong controllable performance. In addition, the temperature, rotation speed and stirring time when preparing 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 preparing the signal collection layer 30 by using silicon wafers, conductive materials and SEBS powder specifically includes:

[0079] The prepared AgNW / NG solution is dropped on the cleaned etched silicon wafer, and the silicon wafer with the AgNW / NG solution is placed on a heating table to dry at 45-50°C. After 2-3 hours, the SEBS solution is spin-coated on the surface;

[0080] Then, the layer is placed on a heating platform and annealed at 85-95° C. for 1-2 hours. After the layer is solidified into a film, alcohol-assisted peeling is used to obtain the signal collection layer 30 .

[0081] In this embodiment, the designed signal collection layer 30 structured pattern is first etched on the silicon wafer, with a depth of 50-70 microns, and then the prepared conductive material, that is, the AgNW / NG solution, is dripped into the pattern grooves etched on the silicon wafer, and after being placed on a heating table for annealing and drying, the elastic base material SEBS is spin-coated on the above silicon wafer using a glue spreader. During the heating and curing process, the conductive material is embedded in the surface of the elastic base, and finally the flexible electrode is obtained by stripping the film with alcohol assistance. This method can be used for large-scale device preparation, and after the device is peeled off from the silicon wafer, the silicon wafer with a graphic structure can be reused, which simplifies the electrode preparation process and reduces the process cost of the entire device preparation. The amount of AgNW / NG solution dripped on the etched silicon wafer can be 3-5 ml, which can be adjusted according to user needs. In addition, the annealing temperature and annealing stirring time when preparing the signal collection layer 30 can be adjusted within the given range according to actual conditions. Figure 4The side scanning electron microscope diagram of the signal collection layer 30 prepared in the method for preparing the flexible multi-channel multi-layer electrode in this embodiment, wherein the signal collection layer 30 includes a SEBS layer formed after SEBS is cured and an AgNW / NG layer formed after AgNW / NG solution is cured, the thickness of SEBS is 33.3 microns, and the thickness of the AgNW / NG layer ranges from 6.35 microns to 6.55 microns. The specific preparation process of the signal collection 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 by using silicon wafers, conductive materials and SEBS powder specifically includes:

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

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

[0085] In this embodiment, the AgNW / NG solution can be dripped onto the cleaned smooth silicon wafer, and after being placed on a heating table to dry, the SEBS solution can be spin-coated thereon, and then it can be placed on a heating table for annealing and curing. After it is cured into a film, the encapsulation layer 10 and the interference signal shielding layer 20 can be obtained by using alcohol-assisted peeling. It should be noted that in this embodiment, the encapsulation layer 10 and the interference signal shielding layer 20 are prepared by an integrated method, and the interference signal shielding layer 20 is embedded in the encapsulation layer. The external encapsulation layer 10 can play a protective role to prevent the electrode from being interfered or damaged. The interference signal shielding layer 20 can shield external interference signals and improve the quality of the electromyographic signal. It should be noted that because the interference signal shielding layer 20 is a powder after the conductive material AgNW / NG solution is dried, it is in a powder state after drying on the silicon wafer. At this time, the SEBS solution is added on it. After the SEBS solution is dried, the conductive powder will be embedded in the dried SEBS film. And in this embodiment, the amount of AgNW / NG solution used when preparing the interference signal shielding layer 20 is 5-7ml.

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

[0087] Place the mask of the wire shielding layer 40 on the cleaned silicon wafer, fix it with tape, spin-coat the SEBS solution on the wire shielding layer 40 on the silicon wafer, and then place it on a heating table to anneal at 85-95°C for 1-2 hours. After it solidifies into a film, use alcohol to assist in peeling to obtain the wire shielding layer 40.

[0088] In this embodiment, the structural design of the wire shielding layer 40 in the above embodiment can be the design of the mask of the wire shielding layer 40, so that the mask of the wire shielding layer 40 is placed on a smooth silicon wafer after cleaning, and is fixed with an adhesive tape, and a SEBS solution is spin-coated thereon, and then it is placed on a heating table, and after it is cured into a film, alcohol is used to assist in peeling off the wire shielding layer 40. The wire shielding layer 40 is a hollow film made of SEBS material, which can shield the electrode wire from errors caused by the electromyographic signal collection process and improve the accuracy of the electromyographic signal collection. And the annealing temperature and annealing time of the wire shielding layer 40 can be adjusted within the given range according to actual conditions.

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

[0090] Applying conductive silver paste to the signal pin connection of the signal collection layer 30;

[0091] The signal pin of the flexible printed circuit board 50 is placed on the signal pin on which the conductive silver paste is dotted on the signal collection layer 30, and after slight pressing, it is placed on a heating table and annealed at 55-65° C. for 1-2 hours to anneal and solidify the conductive silver paste;

[0092] The packaging layer 10, the interference signal shielding layer 20, the signal collection layer 30 and the wire shielding layer 40 are mechanically laminated in sequence from top to bottom with the assistance of dichlorobenzene, an organic solvent, to obtain a flexible multi-channel multi-layer electrode.

[0093] In this embodiment, the signal acquisition layer 30 can be connected to the signal pin of the flexible printed circuit board 50 with the aid of conductive silver paste. Then, using the organic solvent dichlorobenzene as an aid, the encapsulation layer 10, the interference signal shielding layer 20, the signal acquisition layer 30 and the wire shielding layer 40 are mechanically laminated from top to bottom to obtain a complete flexible multi-channel multi-layer electrode. The flexible electrode is connected to the wires of the flexible printed circuit board 50 through conductive silver paste, and then the wires of the flexible printed circuit board 50 are connected to the hardware system by a card slot, which simplifies the wiring process of the signal from the electrode to the hardware acquisition system and avoids the risk of misconnection and missed connection. In addition, the annealing temperature and annealing time of the conductive silver paste can be adjusted within the given range according to actual conditions.

[0094] In one embodiment, if Figure 8 The flexible multi-channel multi-layer electrode was tested for recovery in the range of 40%, 60%, 80%, and 100%. Even within the stress range of 100%, the tensile curve and recovery curve of the flexible multi-channel multi-layer electrode made of SEBS-AgNW / NG material showed good consistency. Figure 7 The sub-figure in FIG. 1 is an enlarged view of the recovery at 40% stress stretching.

[0095] like Fig. 9 The electrode-skin contact impedance tests were carried out on the flexible multi-channel multilayer electrodes made of SEBS-AgNW / NG materials and the Ag / AgCl electrodes. At a frequency of 100Hz, the impedance value of the SEBS-AgNW / NG electrode was reduced by 54.2% compared with the Ag / AgCl electrode.

[0096] like Fig.10 The signal-to-noise ratio of the flexible multi-channel multi-layer electrode made of SEBS-AgNW / NG material was compared with that of the Ag / AgCl electrode. The signal-to-noise ratio of each segment of the electromyographic signal when the muscle was loaded with 1-5kg was calculated and plotted into a bar graph. In this scheme, the flexible multi-channel multi-layer electrode made of SEBS-AgNW / NG material has a higher signal-to-noise ratio than the Ag / AgCl electrode.

[0097] like Figure 11 to Figure 12 , 16 channels of electromyographic signals of static and dynamic muscle contraction were measured by loading the forearm with a 3kg dumbbell. The collected high-quality electromyographic signals can be used for further processing to extract muscle fatigue features and detect muscle fatigue status. For specific signal diagrams, please refer to Fig.11 For the actual application of electromyographic signal acquisition, please refer to Fig.12 .

[0098] The present invention also provides a flexible multi-channel multi-layer electrode.

[0099] Reference Figure 6 to Figure 7In one embodiment, the flexible multi-channel multi-layer electrode can be prepared by the preparation method of the flexible multi-channel multi-layer electrode as described above. Referring to the contents in the above embodiment, it can be known that the flexible multi-channel multi-layer electrode in this embodiment comprises four parts, namely, an encapsulation layer 10, an interference signal shielding layer 20, a signal collection layer 30, and a wire shielding layer 40. The encapsulation layer 10 is a layer of SEBS film, which can play a protective role to prevent the inside of the electrode from being interfered or damaged. The interference signal shielding layer 20 is made of AgNW / NG mixed material, which can shield external interference signals and prevent them from affecting the quality of the electromyographic signal. The signal collection layer 30 is made of SEBS-AgNW / NG material and is used to collect electromyographic signals on the surface of the human body. The serpentine structure design method is adopted to give it good structural stretchability. The wire shielding layer 40 is a hollow film made of SEBS material, which can shield the electrode wire from errors caused by the electromyographic signal collection process and improve the accuracy of the electromyographic signal collection. In the assembly of the multi-layer structure, the organic solvent dichlorobenzene is used to assist in mechanical lamination to obtain a complete flexible multi-channel multi-layer electrode. The flexible electrode is connected to the wires of the flexible printed circuit board 50 through conductive silver paste, and then the wires of the flexible printed circuit board 50 are connected to the hardware system by means of a card slot, which simplifies the wiring process of the signal from the electrode to the hardware acquisition system and avoids the risk of wrong connection or missed connection. Figure 6 This is the structural diagram of the decomposed flexible multi-channel multi-layer electrode. Figure 7 It is an overall structural diagram of the flexible multi-channel multi-layer electrode after assembly. It can be understood that since the flexible multi-channel multi-layer electrode of the present invention is prepared by the above-mentioned method for preparing the flexible multi-channel multi-layer electrode, the embodiment of the flexible multi-channel multi-layer electrode of the present invention includes all technical solutions of all embodiments of the above-mentioned method for preparing the flexible multi-channel multi-layer electrode, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0100] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a flexible multi-channel multi-layer electrode, characterized in that: The following steps are involved: Etching and cleaning silicon wafers; preparing AgNW / NG solution as conductive material and using SEBS powder to prepare elastic substrate; A signal collection layer is prepared by using silicon wafers, conductive materials and SEBS powder, a wire shielding layer is prepared by using silicon wafers and SEBS powder, and a packaging layer and an interference signal shielding layer are prepared by using silicon wafers, conductive materials and SEBS powder; The packaging layer, the interference signal shielding layer, the signal collection layer and the wire shielding layer are fixedly assembled from top to bottom, and the flexible printed circuit board is connected through the signal collection layer.

2. The method for preparing a flexible multi-channel multi-layer electrode according to claim 1, characterized in that: Before etching the silicon wafer and cleaning the silicon wafer, the following steps are also included: The signal collection 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 wire shielding layer is designed as an electrode pattern of four rows and eight columns, wherein the electrode diameter is 4-6 mm, the row spacing is 10-12 mm, the column spacing is 10-12 mm, and the electrodes are hollowed out.

3. The method for preparing a flexible multi-channel multi-layer electrode according to claim 1, characterized in that: The steps of etching the silicon wafer and cleaning the silicon wafer specifically include: Carve 50-70 micron grooves of structured electrode patterns into silicon wafers for conductive material deposition; Place the silicon wafer in a beaker, add deionized water, acetone and isopropanol respectively, clean it with 30-40W ultrasonic wave for 10-15 minutes, and blow it dry with a nitrogen gun after cleaning.

4. The method for preparing a flexible multi-channel multi-layer electrode according to claim 1, characterized in that: The steps of preparing the AgNW / NG solution as the conductive material and using SEBS powder to prepare the elastic substrate specifically include: The NG solution is prepared from the NG powder, and an ultrasonic treatment is performed at a power of 400-450 W for 1-1.5 h under ice bath conditions to separate the layered structure of the NG solution, and the supernatant is taken; The AgNW solution is placed in a glass bottle, and the prepared NG solution is added to the glass bottle, and the two materials are mixed by ultrasonic treatment at a power of 40-50 W for 3-5 minutes to 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 it is 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, stir at 55-65°C and 400-500 r / min for 1-2 hours until the white powdery solid is completely dissolved, and let it stand to exhaust air bubbles to obtain an elastic substrate.

5. The method for preparing a flexible multi-channel multi-layer electrode according to claim 4, characterized in that: The step of preparing the signal collection layer by using silicon wafers, conductive materials and SEBS powder specifically includes: The prepared AgNW / NG solution is dropped on the cleaned etched silicon wafer, and the silicon wafer with the AgNW / NG solution is placed on a heating table to dry at 45-50°C. After 2-3 hours, the SEBS solution is spin-coated on the surface; Then place it on a heating table and anneal it at 85-95°C for 1-2 hours. After it solidifies into a film, use alcohol to assist in peeling to obtain the signal collection layer.

6. The method for preparing a flexible multi-channel multi-layer electrode according to claim 4, characterized in that: The step of preparing the encapsulation layer and the interference signal shielding layer by using silicon wafers, conductive materials and SEBS powder specifically includes: The prepared AgNW / NG solution was dropped onto the cleaned silicon wafer, and then placed on a heating table to dry at 45-50°C for 2-3 hours; The SEBS solution is spin-coated on the dried silicon wafer, and then the silicon wafer with the SEBS solution is placed on a heating table and annealed at 85-95°C for 1-2 hours. After it is solidified into a film, it is stripped with alcohol to obtain the encapsulation layer and the interference signal shielding layer.

7. The method for preparing a flexible multi-channel multi-layer electrode according to claim 4, characterized in that: The step of preparing the wire shielding layer by using silicon wafers and SEBS powder specifically comprises: Place the wire shielding layer mask on the cleaned silicon wafer, use tape to assist in fixing, spin-coat SEBS solution on the wire shielding layer on the silicon wafer, then place it on a heating table and anneal it at 85-95°C for 1-2 hours. After it solidifies into a film, use alcohol to assist in peeling off to obtain the wire shielding layer.

8. The method for preparing a flexible multi-channel multi-layer electrode according to claim 1, characterized in that: The steps of fixing and assembling the packaging layer, the interference signal shielding layer, the signal collection layer and the wire shielding layer in order from top to bottom, and connecting the flexible printed circuit board through the signal collection layer specifically include: Apply conductive silver paste to the signal pin connection of the signal collection layer; Place the signal pin of the flexible printed circuit board on the signal pin on which the conductive silver paste is dotted on the signal collection layer, press it lightly, and then place it on a heating table to anneal at 55-65°C for 1-2 hours to anneal and solidify the conductive silver paste; The packaging layer, the interference signal shielding layer, the signal collection layer and the wire shielding layer are mechanically laminated from top to bottom in sequence with the assistance of the organic solvent dichlorobenzene to obtain a flexible multi-channel multi-layer electrode.

9. A flexible multi-channel multi-layer electrode, characterized in that: It comprises a packaging layer, an interference signal shielding layer, a signal collection layer and a wire shielding layer prepared by the preparation method of a flexible multi-channel multi-layer electrode as described in any one of claims 1 to 8, wherein the packaging layer, the interference signal shielding layer, the signal collection layer and the wire shielding layer are mechanically laminated and fixed in sequence from top to bottom, and connected to a flexible printed circuit board through the signal collection layer.

10. A myoelectric signal collector, characterized in that: Comprising the flexible multi-channel multi-layer electrode as described in claim 9.

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