Ionic gel preparation method, and preparation method and application of flexible electrode patch

Abstract

The invention discloses a preparation method of ionic gel and a preparation method and application of a flexible electrode patch, and relates to the technical field of flexible electronics and biosensing, choline chloride and ethylene glycol are used for preparing a deep eutectic solvent as a conductive phase, gelatin is used as a matrix, tannic acid is used as a modifier, and the ionic gel which is stable and durable and low in bioelectric interface impedance is prepared. A stable interface can be provided for the dynamic deformation skin, the gelatin endows the skin with the characteristics of stretchability and the like, the eutectic solvent prevents the electrical performance from being reduced, and the tannic acid enhances the adhesion and flexibility. On the basis, the flexible array type electromyographic electrode patch is prepared by adopting an ink direct writing process, and the process is simple, easy to expand and customizable; a wireless acquisition circuit board is adopted to transmit signals, so that wired defects are avoided; the wearable electromyographic acquisition system composed of the flexible electrode patch and the acquisition circuit board can realize high-fidelity electromyographic signal measurement under dynamic movement, and provides an important tool for multiple fields.

Description

Technical Field

[0001] The present invention relates to the field of flexible electronics and biosensor technology, and in particular to a method for preparing an ion gel, a method for preparing a flexible electrode patch, and applications thereof. Background Art

[0002] Surface electromyography (sEMG), the bioelectrical signal generated by muscle cells, has demonstrated invaluable value in numerous fields, including rehabilitation and assistive technology, ergonomics, non-invasive diagnostics, sports science, and robotic control. However, while existing commercial rigid sEMG devices offer advantages such as high acquisition accuracy, clear and reliable results, and excellent repeatability, their rigid and bulky sensor components are prone to positional shifts, motion artifacts, and poor contact during muscle contraction or sweat secretion, making stable, continuous, high-quality, and efficient sEMG acquisition difficult. Furthermore, due to device size constraints, the area and density of muscle data that can be acquired with rigid devices are relatively limited. The Ag / AgCl patch electrodes commonly used in clinical practice also fail to meet the requirements for stretchability, long-term stability, and recyclability, and their signal acquisition density is low. Furthermore, the cumbersome wiring and cables of EMG devices not only hinder human movement but also easily lead to electrode detachment, displacement, and interference.

[0003] With the rapid development of flexible electronics, the development of flexible, wearable myoelectric sensing systems with high epidermal adhesion offers a novel option for high-fidelity recording of bioelectrical signals in dynamic environments. Surface electromyographic sensing systems primarily consist of myoelectric electrodes and signal processing circuitry. Direct contact between the electrodes and the skin is a key factor in determining the quality of the myoelectric signals. Currently developed and applied myoelectric electrode materials can be categorized into two types: dry and wet electrodes. Dry electrodes, such as metals, carbon materials, and conductive polymers, generally exhibit good biocompatibility and stability, enabling stable and long-term monitoring. However, due to their generally high Young's modulus and insufficient adhesion to the skin, they are prone to high interfacial impedance and motion artifacts on wrinkled and contracted skin surfaces. In contrast, wet electrode materials, such as hydrogels and conductive gels, possess properties similar to those of human tissue, capable of wetting the skin and forming seamless, low-impedance interfacial channels, thereby establishing a robust bioelectronic interface. However, gel electrodes have inherent drawbacks such as susceptibility to dehydration and mechanical softness, resulting in poor stability and durability. Therefore, how to design a stable, durable gel electrode with low bioelectric interface impedance to provide a stable and reliable interface between the dynamically deformed epidermis has become one of the urgent problems to be solved.

[0004] On the other hand, traditional bipolar intervertebral disc sEMG acquisition methods can only collect sEMG signals from a single measured area, which may contain multiple muscles or muscle groups, and thus cannot accurately reflect the specific muscle being analyzed. Multichannel surface electromyography (SEMG) overcomes the limitations of traditional differential electrodes, enabling quantitative analysis of spatially distinct muscle strength and temporal information. This holds important implications for human movement research and improving the accuracy of human-computer interaction. Currently developed multichannel sEMG sensing systems mostly use PET as a substrate, but the high modulus of the substrate is mechanically mismatched with skin tissue, leading to interface failures and discomfort during long-term wear. Furthermore, traditional wired signal transmission methods result in multichannel sensing systems with numerous, cumbersome, and redundant wires and cables, significantly restricting human mobility and limiting their practical application. Therefore, designing a wearable, fully flexible EMG acquisition system remains a key challenge in this field. This is crucial for achieving accurate, stable, and continuous sEMG monitoring during natural human activity. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for preparing an ion gel, a method for preparing a flexible electrode patch, and applications.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] <First Aspect>

[0008] The present invention provides a method for preparing an ion gel, comprising the following steps:

[0009] S11, mixing choline chloride and ethylene glycol, and stirring uniformly to obtain a deep eutectic solvent;

[0010] S12, adding gelatin to the deep eutectic solvent obtained in step S1, and stirring until the gelatin is completely dissolved in the mixed solution to form a transparent colloid;

[0011] S13, adding tannic acid to the transparent colloid obtained in step S2, removing bubbles in vacuo, and refrigerating for 4 to 10 hours to obtain the ion gel.

[0012] As an embodiment, the molar ratio of choline chloride to ethylene glycol is 1:2.

[0013] As an embodiment, the mass ratio of the deep eutectic solvent, gelatin and tannic acid is 100:(10-30):(0.5-15).

[0014] In some embodiments, the amount of gelatin added is 10% by weight of the deep eutectic solvent.

[0015] In some embodiments, the amount of tannic acid added is 6% by weight of the deep eutectic solvent.

[0016] As an embodiment, in step S12, after the gelatin is added to the deep eutectic solvent, it is heated and stirred at 60-100° C. until it becomes a transparent colloid.

[0017] In some embodiments, in step S12, the gelatin is added to the deep eutectic solvent and then heated and stirred at 80° C. until it becomes a transparent colloid.

[0018] As an embodiment, in step S13, the vacuum degree of the vacuum removal of bubbles is 0.08-0.1 MPa, the refrigeration temperature is 4° C., and the refrigeration time is 4 to 10 hours.

[0019] In some embodiments, in step S13, the vacuum degree of the vacuum removal of bubbles is 0.09 MPa, and the refrigeration time is 6 hours.

[0020] <Second Aspect>

[0021] The present invention provides a flexible electrode patch comprising the above-mentioned ion gel.

[0022] A flexible electrode patch, comprising, from bottom to top, a substrate layer, a conductor layer, an adhesive packaging layer, and an ion gel electrode, wherein:

[0023] The base layer is a flexible and stretchable film material;

[0024] The conductor layer includes a plurality of independent conductive lines arranged on the base layer, one end of each conductive line is connected to a disc electrode for transmitting epidermal physiological electrical signals, and the other end is connected to a flexible cable through a vertically conductive tape;

[0025] The adhesive packaging layer is used to cover the wire layer except the disc electrode;

[0026] The ion gel electrode is coated on the disk electrode.

[0027] As an embodiment, the material of the base layer includes any one of PU, PDMS, Ecoflex or medical tape.

[0028] In some embodiments, the base layer is made of TPU.

[0029] As an embodiment, the base layer has a thickness of no more than 1 mm.

[0030] In some embodiments, the base layer is TPU with a thickness of 0.025 mm.

[0031] As an embodiment, the material of the disk electrode is a flexible and stretchable conductor.

[0032] As an embodiment, the material of the disk electrode is one or more of silver, gallium-indium eutectic alloy, carbon nanotube, and graphene. As an embodiment, the disk electrode has a diameter of 2 to 20 mm and a thickness of 0.001 to 1 mm.

[0033] As an embodiment, the disk electrodes are distributed in an array on the substrate layer.

[0034] In some embodiments, the disk electrodes are silver electrodes with a diameter of 8 mm and a thickness of 0.04 mm, and are distributed on the substrate layer in a pattern of four rows and four columns.

[0035] As an embodiment, the conductive line is made of a flexible and stretchable conductor.

[0036] As an embodiment, the conductive line is made of one or more materials selected from the group consisting of silver, gallium-indium eutectic alloy, carbon nanotubes, and graphene.

[0037] In some embodiments, the conductive lines are made of silver.

[0038] As an embodiment, the conductive lines are conductively connected to the flexible wiring electrodes.

[0039] As an embodiment, the material of the adhesive encapsulation layer is a composite polymer material based on polydimethylsiloxane monomer with the addition of a curing agent and a plasticizer.

[0040] In some embodiments, the polydimethylsiloxane monomer and its supporting curing agent are Sylgard 184, and the plasticizer is polyethylene glycol.

[0041] As an embodiment, the thickness of the adhesive packaging layer is 0.05 to 5 mm.

[0042] In some embodiments, the adhesive encapsulation layer has a thickness of 0.08 mm.

[0043] As an embodiment, the thickness of the ion gel is 0.05 to 5 mm.

[0044] In some embodiments, the ion gel has a thickness of 1 mm.

[0045] <Third Aspect>

[0046] The present invention provides a method for preparing a flexible electrode patch, comprising the following steps:

[0047] S31, preparing a conductive line on the surface of the substrate layer using a liquid metal conductor, connecting one end of the conductive line to the disk electrode, and adhering a vertical conductive tape to the other end, which is then connected to the flexible cable;

[0048] S32, setting an electrode shield on the surface of the disk electrode, and then evenly spin-coating an adhesive on the wire layer to encapsulate the wire lines and the interface between the wire lines and the flexible cable, then removing the shield on the surface of the disk electrode to expose the disk electrode, and then placing it in an oven to heat and cure the adhesive;

[0049] S33. After heating and dissolving the ion gel, drop it on the disc electrode and wait for it to cool and gel to obtain a flexible electrode patch.

[0050] As an embodiment, in step S31, the conductive lines are prepared by screen printing or 3D printing.

[0051] In some embodiments, the liquid metal is silver paste, and the silver paste is printed onto the TPU substrate according to the planned conductor layer arrangement structure through 3D printing ink direct writing technology.

[0052] As an embodiment, the step of setting a shield on the disk electrode is: preparing Ecoflex, dripping uncured liquid Ecoflex onto the surface of the disk electrode, and forming a shield on the surface of the disk electrode after curing.

[0053] In some embodiments, the Ecoflex is Smooth on Ecoflex 0030.

[0054] As an embodiment, the adhesive is prepared by mixing a polymer matrix material with a curing agent, adding a plasticizer, stirring the mixture evenly, and removing bubbles generated during the stirring process to obtain an uncured adhesive.

[0055] In some embodiments, the polymer matrix material is polydimethylsiloxane monomer and its supporting curing agent model is Sylgard 184, and the plasticizer is polyethylene glycol.

[0056] <Fourth Aspect>

[0057] The present invention provides an application of a flexible electrode patch in an electromyography acquisition system.

[0058] A wireless fully flexible multi-channel electromyography acquisition system includes a flexible electrode patch, a flexible cable and a wireless acquisition circuit, wherein:

[0059] One end of the flexible cable is connected to the conductive line of the flexible electrode patch through a flexible cable, and the other end of the flexible cable is connected to the wireless acquisition circuit, which is used to transmit the electrical signal generated by the disk electrode array in the flexible electrode patch to the wireless acquisition circuit;

[0060] The wireless acquisition circuit integrates a wireless transmission module and a flexible circuit board with an analog front end, which is used to receive electrical signals from the flexible electrode patch and convert them into digital signals.

[0061] <Fifth Aspect>

[0062] The present invention provides an application of a myoelectricity acquisition system in a wearable sensor.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] 1) The present invention first designs and prepares an ion gel using choline chloride and ethylene glycol as a low eutectic solvent as the conductive phase, gelatin as the matrix, and tannic acid as the modifier. The gel has the characteristics of stable, durable electrodes and low bioelectric interface impedance, and can provide a stable and reliable interface between the epidermis with dynamic deformation. Gelatin, as the skeleton of the gel, has high stretchability, excellent biocompatibility and self-adhesion, and its heat-softening properties help to build a seamless low-impedance channel between the skin and the circuit. The low eutectic solvent DES, as the conductive phase, has the advantages of biosafety and non-volatility, thereby avoiding the degradation of the electrical performance of the gel due to dehydration and drying. In addition, further doping with tannic acid can effectively enhance the adhesion and flexibility of the electrode material, and significantly improve the dynamic stability of the electrode in collecting electromyographic signals.

[0065] 2) Based on ion gel flexible electrodes, this invention designs and manufactures flexible myoelectric electrode patches (specifically, 16-channel flexible array myoelectric electrode patches) through a direct ink writing process. This process does not involve any complex process flows or processing equipment and has excellent scalability, enabling customized design for target muscles based on application requirements. The flexible substrate has skin-like softness and excellent stretchability, allowing direct attachment to the skin to stably record sEMG signals without causing any discomfort.

[0066] 3) The present invention adopts a wireless acquisition circuit board for signal transmission, avoiding the restrictions of wired connection on human activities, as well as the problems of noise enhancement and motion artifacts caused by the shaking of wires during activities, thereby improving the robustness of the system in recording electromyographic signals during dynamic movement.

[0067] 4) The present invention utilizes flexible electrode patches and a flexible collection circuit board to form a wearable electromyographic acquisition system. The electromyographic acquisition system has the characteristics of bendability, portability, and dynamic stability. It can meet the needs of scenarios where it is worn on the human body and provide high-fidelity electromyographic signal measurement capabilities under dynamic motion. It provides a potential important tool for scenarios such as sports science, human-computer interaction, intention recognition, and clinical diagnosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0069] Figure 1 This is a graph showing the interface impedance test between the ion gel prepared in Example 1 of the present invention and human skin;

[0070] Figure 2 This is a schematic structural diagram of a flexible array electrode patch provided in Example 2 of the present invention;

[0071] Figure 3 This is a schematic diagram of the structure of the myoelectric acquisition system provided in Example 3 of the present invention;

[0072] Figure 4 This is the electromyographic signal recorded by the electromyographic acquisition system provided in Example 4 of the present invention, wherein the abscissa represents time and the ordinate represents the voltage after the physiological potential is amplified;

[0073] Figure 5 The myoelectric acquisition system provided in Example 4 of the present invention records the myoelectric signals of the ulnar flexor carpi muscle of the human body over a long period of time, wherein the abscissa represents time and the ordinate represents the voltage after the physiological potential is amplified.

[0074] In the figure: 1. Ion gel electrode; 2. Viscous packaging layer; 3. Wire layer; 4. Matrix layer; 5. 16-channel flexible array electrode patch; 6. Flexible cable; 7. Wireless acquisition circuit. DETAILED DESCRIPTION

[0075] The present invention will be described in detail below with reference to the examples. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several adjustments and improvements without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0076] This specific embodiment provides a method for preparing an ion gel, which is introduced through Example 1.

[0077] Example 1

[0078] A method for preparing an ion gel comprises the following steps:

[0079] S11, mixing choline chloride as a hydrogen bond acceptor and ethylene glycol as a hydrogen bond donor in a molar ratio of 1:2, and stirring to obtain a deep eutectic solvent;

[0080] S12, adding gelatin to the deep eutectic solvent obtained in step S1, heating and stirring at 80° C. until the gelatin is completely dissolved in the mixed solution to form a transparent colloid;

[0081] S13. Add tannic acid to the transparent colloid obtained in step S2, remove bubbles in a vacuum, and then refrigerate for 4 to 10 hours to obtain an ion gel. In this embodiment, the vacuum degree for removing bubbles is 0.09 MPa, the refrigeration temperature is 4° C., and the refrigeration time is 6 hours.

[0082] In this embodiment, the mass ratio of the deep eutectic solvent, gelatin and tannic acid is 100:10:6.

[0083] It should be noted that the stirring process in step S11 can be carried out at room temperature or between room temperature and 80° C. Heating can increase the solid dissolution rate.

[0084] Example 2

[0085] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0086] The mass ratio of the deep eutectic solvent, gelatin and tannic acid is 100:20:6.

[0087] Example 3

[0088] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0089] The mass ratio of the deep eutectic solvent, gelatin and tannic acid is 100:30:12.

[0090] Example 4

[0091] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0092] The mass ratio of the deep eutectic solvent, gelatin and tannic acid is 100:10:0.5.

[0093] Example 5

[0094] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0095] The mass ratio of the deep eutectic solvent, gelatin and tannic acid is 100:10:15.

[0096] Example 6

[0097] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0098] In step S2, the stirring temperature is 100°C.

[0099] Example 7

[0100] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0101] In step S2, the stirring temperature is 60°C.

[0102] Example 8

[0103] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0104] In step S3, the refrigeration time is 4 hours.

[0105] Example 9

[0106] This embodiment provides a method for preparing an ion gel. The steps are basically the same as those in Example 1, except that:

[0107] In step S3, the refrigeration time is 10 hours.

[0108] Detection and Analysis

[0109] The interface impedance between the ion gel prepared in each of the above embodiments and human skin was tested by an electrochemical workstation at 100 Hz. The test curve of Example 1 is as follows: Figure 1 The interface impedance values ​​of various embodiments are shown in Table 1.

[0110] Table 1

[0111] Example Interface impedance kΩ Example 1 14 Example 2 26 Example 3 40 Example 4 20 Example 5 18 Example 6 15 Example 7 14.6 Example 8 13.9 Example 9 14.3

[0112] This specific embodiment also provides a flexible electrode patch, which is introduced through Example 10.

[0113] Example 10

[0114] A flexible electrode patch, such as Figure 2 As shown, it includes, from bottom to top, a base layer 4, a wire layer 3, an adhesive packaging layer 2 and an ion gel electrode 1, wherein:

[0115] The base layer 4 is a flexible stretchable film material, including any one of TPU, PU, ​​PDMS, Ecoflex or medical tape, with a thickness not exceeding 1 mm. In this embodiment, the base layer 4 is TPU with a thickness of 0.025 mm;

[0116] The conductor layer 3 includes a plurality of independent conductive lines arranged on the base layer 4. One end of each conductive line is connected to a disc electrode for transmitting epidermal physiological electrical signals, and the other end is connected to a flexible cable via a vertically conductive tape;

[0117] The adhesive encapsulation layer 2 is used to cover the wire layer 3 except the disc electrode. In this embodiment, the adhesive encapsulation layer 2 is made of an adhesive containing PDMS and polyethylene glycol;

[0118] The ion gel electrode 1, located on the disk electrode, is made of the ion gel prepared in Example 1 above.

[0119] Furthermore, the disk electrodes have a diameter of 2 to 20 mm and a thickness of 0.001 to 1 mm, and are distributed in an array on the base layer 4 .

[0120] In this embodiment, the disk electrodes are silver electrodes with a diameter of 8 mm and a thickness of 0.04 mm, and are distributed on the base layer 4 in a manner of four rows and four columns. That is, this embodiment provides a 16-channel flexible array electrode patch 5 .

[0121] Furthermore, the conductive lines are conductively connected to the flexible wiring electrodes.

[0122] Furthermore, the thickness of the adhesive packaging layer 2 is 0.05-5 mm. In this embodiment, the thickness of the adhesive packaging layer 2 is 0.08 mm.

[0123] Furthermore, the thickness of the ion gel is 0.05 to 5 mm. In this embodiment, the thickness of the ion gel is 1 mm.

[0124] It should be noted that the array arrangement can achieve high-density electrode patch placement in a neat and beautiful manner; in actual implementation, the layout of the patch electrodes can be flexibly designed according to different muscle shapes and positions.

[0125] This specific embodiment also provides a method for preparing a flexible electrode patch, which is introduced through Example 11.

[0126] Example 11

[0127] A method for preparing a flexible electrode patch, used to prepare the electrode patch described in Example 10 above, comprising the following steps:

[0128] S31, preparing conductive lines on the surface of the base layer 4 using a liquid metal conductor, connecting one end of the conductive line to the disk electrode, and adhering a vertical conductive tape to the other end, which is then connected to the flexible cable;

[0129] S32. An electrode shield is provided on the surface of the disk electrode. Then, an adhesive is evenly spin-coated on the wire layer 3 to encapsulate the wire lines and the interface between the wire lines and the flexible cable. The shield is then removed from the surface of the disk electrode to expose the disk electrode. The disk electrode is then heated in an oven to cure the adhesive, resulting in a structure covered with a viscous encapsulation layer 2.

[0130] S33. After heating and dissolving the ion gel obtained in Example 1, the ion gel is dropped onto the disk electrode, and after cooling and gelation, a flexible electrode patch is obtained.

[0131] Furthermore, a disk electrode is provided on the base layer 4 by using a 3D printing ink direct writing technology.

[0132] Furthermore, the disk electrodes are distributed in an array.

[0133] Furthermore, in step S31 , the conductive lines are prepared by screen printing, 3D printing, or the like.

[0134] In this embodiment, the liquid metal is silver paste, model: Elec-L705, viscosity: 20000mPa·S (cP), and the silver paste is printed onto the TPU substrate according to the planned conductor layer 3 arrangement structure at room temperature through 3D printing ink direct writing technology. The printing speed is 1mm / s and the printing pressure is 90kPa.

[0135] Furthermore, the step of setting a shield on the disk electrode is as follows: preparing Ecoflex (purchased from Smooth On), dropping uncured liquid Ecoflex onto the surface of the disk electrode, and forming a shield on the surface of the disk electrode after curing.

[0136] Ecoflex can use products with item numbers 0010, 0020, and 0030. In this embodiment, item number 0030 is selected.

[0137] Furthermore, the adhesive is prepared by mixing the polymer matrix material with the curing agent, adding the plasticizer, stirring the mixture evenly, and removing bubbles generated during the stirring process to obtain an uncured adhesive.

[0138] In this embodiment, the polymer matrix material is PDMS monomer and its matching curing agent model is Sylgard 184, and the mass ratio of monomer to curing agent is 10:1; the plasticizer is polyethylene glycol, and the mass ratio of polyethylene glycol to the polymer matrix material is 1:1:25.

[0139] This specific embodiment also provides an application of a flexible electrode patch in an electromyography acquisition system.

[0140] Example 12

[0141] A wireless, fully flexible, multi-channel electromyography acquisition system, such as Figure 3 As shown, it includes the flexible electrode patch, flexible cable 6 and wireless acquisition circuit 7 of embodiment 10, wherein,

[0142] One end of the flexible cable 6 is connected to the conductive line of the flexible electrode patch through a flexible cable, and the other end of the flexible cable 6 is connected to the wireless acquisition circuit 7, which is used to transmit the electrical signal generated by the disk electrode array in the flexible electrode patch to the wireless acquisition circuit 7;

[0143] The wireless acquisition circuit 7 integrates a wireless transmission module and a flexible circuit board of an analog front end, which is used to receive the electrical signals from the flexible electrode patch and convert them into digital signals.

[0144] In this way, the converted digital signal is transmitted wirelessly to other devices, such as mobile phones, tablet computers, computers, central receiving devices, or cloud devices, etc. through the wireless transmission module.

[0145] The myoelectric acquisition system prepared by the 16-channel flexible array electrode patch 5 provided in Example 2 is used to record the current signal generated by human muscle activity. The recorded myoelectric signal at the muscle-tendon junction of the biceps brachii when the human muscle exerts force is as follows: Figure 4 Further testing of the myoelectric acquisition system to record the myoelectric signals of the human ulnar flexor carpi muscle for a long time, the results are as follows Figure 5 As shown, the system can also maintain a low noise amplitude when working continuously for 168 hours, indicating that the myoelectric acquisition system provided by the present invention has excellent stability and durability.

[0146] This specific embodiment also provides an application of the myoelectric acquisition system in a wearable myoelectric sensor.

[0147] Example 13

[0148] A wearable myoelectric sensor comprises the above-mentioned myoelectric acquisition system.

[0149] In summary, the present invention connects the flexible electrode patch to a flexible circuit board with multi-channel data acquisition and wireless transmission capabilities via a flexible cable 6 to form a wireless, fully flexible, multi-channel electromyography acquisition system. The designed flexible array electromyography acquisition device is portable and dynamically stable, which is conducive to the efficient collection of rich muscle movement information of humans in natural activity states. The system is bendable and portable, and can provide high-fidelity electromyography signal measurement capabilities, showing broad application prospects in the fields of sports science, human-computer interaction, intention recognition, clinical diagnosis, etc.

[0150] In summary, the key issue focused on by the present invention is to provide an electromyographic electrode material with low interfacial impedance, high skin compliance, stability and durability. In order to achieve stability and durability, gelatin is used as the skeleton, and a low eutectic solvent that is not easily volatile is used as an ionic liquid as a conductive agent; in order to achieve low impedance and compliance with the skin, tannic acid is used as a modifier. Tannic acid can form hydrogen bonds with gelatin molecules, thereby destroying the original dense molecular network structure of gelatin and turning it into a loose network. This change in network state from a tight to a loose state reduces the modulus of gelatin (a decrease in modulus means that the compliance of gelatin with the skin will increase), and the adhesion will be further increased (reducing the interfacial contact impedance between the skin and the gel), thereby achieving low interfacial impedance and increased compliance with the skin.

[0151] The present invention aims to obtain myoelectric electrode materials with low interfacial impedance. The low impedance between the skin and the electrode is related to three factors:

[0152] (1) Electrode conductivity: the higher the conductivity, the lower the impedance;

[0153] (2) Electrode compliance (low modulus). The better the electrode's compliance to the skin, the more conducive it is to forming a seamless interface between the skin and the electrode, thus reducing the interfacial impedance.

[0154] (3) The adhesion between the electrode and the skin. The stronger the adhesion, the more conducive it is to forming a seamless interface between the skin and the electrode, thereby reducing the interface impedance.

[0155] The three factors restrict each other. The present invention achieves a dynamic balance among the three through optimization, and finally obtains a myoelectric electrode material with low impedance, low modulus and high adhesion, so as to meet the requirements of deformation synchronization between the electrode and the skin, stable interface electrical conduction and structural durability when adapting to skin deformation / wrinkle / twist during use.

[0156] Furthermore, the present invention utilizes the above-mentioned electromyographic electrode material for flexible electrode patches, and applies it to electromyographic acquisition systems. Flexible wires and flexible electrodes are both made of liquid silver paste and are printed on a flexible substrate material through 3D printing (ink direct writing) technology. The preparation process does not involve any complicated process flow or processing equipment, and is highly flexible in the array design of the electrode, and can be customized for the target muscle according to application requirements. Compared to metal electrodes, the liquid metal electrode also has higher softness and a more skin-friendly mechanical modulus, so it has better wearing comfort and is expected to have a more stable electromyographic monitoring effect.

[0157] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing an ion gel, characterized in that: The following steps are involved: S11, mixing choline chloride and ethylene glycol, and stirring uniformly to obtain a deep eutectic solvent; S12, adding gelatin to the deep eutectic solvent obtained in step S1, and stirring until the gelatin is completely dissolved in the mixed solution to form a transparent colloid; S13, adding tannic acid to the transparent colloid obtained in step S2, removing bubbles in a vacuum, and refrigerating to obtain the ion gel; The mass ratio of the deep eutectic solvent, gelatin and tannic acid is 100:(10-30):(0.5-15).

2. A flexible electrode patch, characterized in that: The structure includes from bottom to top a substrate layer, a wire layer, an adhesive packaging layer and an ion gel electrode, wherein the ion gel electrode is Prepared according to the method of claim 1, wherein: The base layer is a flexible and stretchable film material; The conductor layer includes a plurality of independent conductive lines arranged on the base layer, one end of each conductive line is connected to a disc electrode for transmitting epidermal physiological electrical signals, and the other end is connected to a flexible cable through a vertically conductive tape; The adhesive packaging layer is used to cover the wire layer except the disc electrode; The ion gel electrode is coated on the disk electrode.

3. The flexible electrode patch according to claim 2, characterized in that: It also includes one or more of the following technical features: A. The material of the base layer includes any one of PU, PDMS, Ecoflex, and medical tape; B. The material of the disk electrode is a flexible and stretchable conductor; C. The conductive line is made of a flexible and stretchable conductor; D. The adhesive encapsulation layer is a composite polymer material based on polydimethylsiloxane monomer with the addition of a curing agent and a plasticizer.

4. The flexible electrode patch according to claim 2, characterized in that: It also includes one or more of the following technical features: A. The base layer has a thickness of no more than 1 mm; B. The disk electrode has a diameter of 2 to 20 mm and a thickness of 0.001 to 1 mm; C. The thickness of the adhesive encapsulation layer is 0.05 to 5 mm; D. The thickness of the ion gel is 0.05 to 5 mm; E. There are multiple disk electrodes distributed in an array on the substrate layer.

5. A method for preparing the flexible electrode patch according to any one of claims 2 to 4, characterized in that: The following steps are involved: S31, preparing a conductive line on the surface of the substrate layer using a liquid metal conductor, connecting one end of the conductive line to the disk electrode, and adhering a vertical conductive tape to the other end, which is then connected to the flexible cable; S32, setting an electrode shield on the surface of the disk electrode, and then evenly spin-coating an adhesive on the wire layer to encapsulate the wire lines and the interface between the wire lines and the flexible cable, then removing the shield on the surface of the disk electrode to expose the disk electrode, and then placing it in an oven to heat and cure the adhesive; S33. After heating and dissolving the ion gel, drop it on the disc electrode and wait for it to cool and gel to obtain a flexible electrode patch.

6. The method for preparing the flexible electrode patch according to claim 5, characterized in that: In step S31 , the conductive lines are prepared by screen printing or 3D printing.

7. The method for preparing the flexible electrode patch according to claim 5, characterized in that: The steps of setting the shield on the disk electrode are: configuring Ecoflex, dripping uncured liquid Ecoflex onto the surface of the disk electrode, and forming the shield on the surface of the disk electrode after curing.

8. The method for preparing the flexible electrode patch according to claim 5, wherein: The adhesive is prepared by mixing a polymer matrix material with a curing agent, adding a plasticizer, mixing and stirring the mixture evenly, and removing bubbles generated during the stirring process to obtain an uncured adhesive.

9. Application of the flexible electrode patch according to any one of claims 2 to 4 in an electromyography acquisition system, characterized in that: It includes flexible electrode patches, flexible cables and wireless acquisition circuits, among which, One end of the flexible cable is connected to the conductive line of the flexible electrode patch through a flexible cable, and the other end of the flexible cable is connected to the wireless acquisition circuit, which is used to transmit the electrical signal generated by the disk electrode in the flexible electrode patch to the wireless acquisition circuit; The wireless acquisition circuit integrates a wireless transmission module and a flexible circuit board with an analog front end, which is used to receive electrical signals from the flexible electrode patch and convert them into digital signals.

10. Application of the myoelectric acquisition system according to claim 9 in a wearable sensor.

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