Electrode with a structure of an electric double layer and a method for preparing and using the same

Abstract

This application relates to the technical field of epidermal signal acquisition equipment, and provides an ion-electric dual-layer structure epidermal electrode, its preparation method, and its application. The ion-electric dual-layer structure epidermal electrode includes an electronically conductive layer with a first surface that is uneven. An ion-electric conductive layer is disposed on the first surface of the electronically conductive layer, and an uneven ion-electric interface is formed between the electronically conductive layer and the ion-electric conductive layer. The ion-electric dual-layer structure epidermal electrode provided by this application improves the ion-electric coupling efficiency, reduces the interface impedance, and thus reduces the baseline noise level of electrophysiological signals, achieving high-fidelity electrophysiological signal acquisition.

Description

Technical Field

[0001] This application belongs to the technical field of epidermal signal acquisition equipment, and particularly relates to an ion-electric double-layer structure epidermal electrode, its preparation method and application. Background Technology

[0002] Electrophysiological signals are crucial information reflecting complex biological phenomena. Acquiring high-fidelity electrophysiological signals is of great significance for clinical diagnosis, health monitoring, and rehabilitation medicine. Electrophysiological signals are potential differences existing between different parts of the body due to differences in ion concentration across the cell membrane. Common electrophysiological signals include electrocardiograms (ECG), electroencephalograms (EEG), and electromyograms (EMG). Using electrodes to convert the ion potential generated by biological activity into an electronic potential in a measurement system is the most common method for detecting electrophysiological signals. Among these, epidermal electrodes are widely used for acquiring various types of electrophysiological signals because their use causes almost no damage to the human body.

[0003] However, electrophysiological signals are often difficult to measure accurately due to their weakness (microvolts to millivolts), high impedance of the signal source, and complex interfacial phenomena between the organism and the electrode. Impedance is a significant source of thermal noise, and the relationship between thermal noise and impedance can be expressed as V noise 2 = 4kTfZ, where k is the Boltzmann constant, T is the temperature, f is the bandwidth, and Z is the impedance. Therefore, it is essential to reduce the interfacial impedance between the electrode and the epidermis to improve the fidelity of the electrophysiological signal. Summary of the Invention

[0004] The purpose of this application is to provide an ion-electrostatic bilayer structure epidermal electrode, its preparation method and application, aiming to solve the problem of poor fidelity in the acquisition of electrophysiological signals by existing epidermal electrodes.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, this application provides an ion-electric dual-layer structure skin electrode, including an electronic conductive layer, the electronic conductive layer having a first surface with unevenness, an ion conductive layer disposed on the first surface of the electronic conductive layer, and an uneven ion-electric interface formed between the electronic conductive layer and the ion conductive layer.

[0007] Secondly, this application provides a method for preparing an ion-electrostatic bilayer structure skin electrode, comprising the following steps:

[0008] A mold is provided, the mold having a surface with an uneven structure;

[0009] An electronically conductive polymer solution is coated onto the surface of the uneven structure of the mold, and then dried to obtain the electronically conductive layer having the first surface.

[0010] An ion-conductive layer pre-curing solution is coated onto the first surface of the electronic conductive layer, and then cured to obtain the ion-conductive layer, resulting in an ion-conductive bilayer structure skin electrode with an uneven ion-conductive interface.

[0011] Thirdly, this application provides an application of an ion-electrostatic double-layered epidermal electrode, which is used to collect electrophysiological signals from the epidermis.

[0012] The first aspect of this application provides an ion-electric bilayer structure epidermal electrode, which employs a bilayer structure of an electronic conductive layer and an ion-electric conductive layer. By forming an uneven ion-electric interface between the electronic and ion-electric conductive layers, the integration of the electronic and ion-electric conductive layers is achieved. This increases the physical anchoring effect between the electronic and ion-electric conductive layers, thereby improving their bonding strength and reducing the possibility of interlayer separation. In addition, it increases the ion-electric interface area, improves the ion-electric coupling efficiency, and reduces the interface impedance. This, in turn, improves the conversion efficiency of ion signals to electronic signals near the interface between the ion-electric and electronic conductive layers, reduces the baseline noise level of electrophysiological signals, and enables the acquisition of high-fidelity electrophysiological signals.

[0013] The method for preparing an ion-electric bilayer skin electrode provided in the second aspect of this application involves coating an electronically conductive polymer solution onto a mold with an uneven surface. After drying, the electronically conductive polymer solution forms an electronically conductive layer while simultaneously forming a first uneven surface. Next, an ion-electric bilayer pre-curing solution is coated onto the first surface of the electronically conductive layer. Through curing, an ion-electric conductive layer is formed, and simultaneously, an uneven ion-electric interface is created between the electronically and ion-electric conductive layers, allowing the electronically and ion-electric conductive layers to integrate and obtain the ion-electric bilayer skin electrode. Furthermore, this method increases the ion-electric interface area, improves the ion-electric coupling efficiency, and reduces the interface impedance, thereby improving the conversion efficiency of ion signals to electron signals near the interface between the ion-electric and electronically conductive layers, reducing the baseline noise level of the electrophysiological signal, and achieving high-fidelity electrophysiological signal acquisition.

[0014] The application of the ion-electric bilayer structure epidermal electrode provided in the third aspect of this application can be used to collect electrophysiological signals from the epidermis. Due to the presence of a highly conductive electronic and ion-conductive layer, the ion-electric bilayer structure epidermal electrode provides a high carrier concentration for conducting electrophysiological signals, providing a material basis for converting the ionic form of electrophysiological signals from the human body into electronic signals of the circuit. Furthermore, the uneven ion-electric interface greatly reduces the interface impedance and baseline noise level of the ion-electric bilayer structure epidermal electrode, enabling the acquisition of high-fidelity electrophysiological signals. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the ion-electric double-layer skin electrode provided in the embodiments of this application;

[0017] Figure 2 This is a schematic flowchart of the preparation method of the ion-electrostatic double-layer structure skin electrode provided in the embodiments of this application;

[0018] Figure 3 This is a comparison diagram of the interfacial impedance between the ion-electrostatic bilayer structure skin electrode prepared in Example 1 of this application and the commercial Ag / AgCl electrode.

[0019] The following are the labeling elements in the figure:

[0020] 1-Electrically conductive layer; 2-Ionically conductive layer; 3-Ion-electric interface. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0023] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0024] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0027] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0028] Epidermal electrodes are electrodes applied to the skin of an organism to test its electrophysiological signals. The organism can be any animal (such as a mammal) or a human.

[0029] The first aspect of this application provides an ion-electric dual-layer structure skin electrode, including an electronic conductive layer 1, the electronic conductive layer 1 having a first surface with unevenness, an ion conductive layer 2 disposed on the first surface of the electronic conductive layer 1, and an uneven ion-electric interface 3 formed between the electronic conductive layer 1 and the ion conductive layer 2.

[0030] The aforementioned uneven first surface is a surface with a microscopically uneven or textured structure, thereby forming an uneven ion-electric interface 3 at the junction of the electronic conductive layer 1 and the ion conductive layer 2.

[0031] The ion-electric bilayer structure epidermal electrode provided in this application adopts a bilayer structure of electronic conductive layer 1 and ion conductive layer 2. By forming an uneven ion-electric interface 3 between electronic conductive layer 1 and ion conductive layer 2, the integration of electronic conductive layer 1 and ion conductive layer 2 is achieved, which can increase the physical anchoring effect between electronic conductive layer 1 and ion conductive layer 2, thereby improving their bonding strength and reducing the possibility of interlayer separation. In addition, the area of ​​ion-electric interface 3 is increased, improving ion-electric coupling efficiency and reducing interface impedance, thereby improving the conversion efficiency of ion signal to electronic signal near the interface between ion conductive layer 2 and electronic conductive layer 1, reducing the baseline noise level of electrophysiological signal, and realizing the acquisition of high-fidelity electrophysiological signal.

[0032] In some embodiments, the first surface may be formed by a roughening process. Here, "roughening process" refers to a process that creates or adds microscopic irregularities or textures to the surface of a material.

[0033] In some embodiments, the Ra value of the first surface is greater than 0.15 μm. The Ra value of the first surface refers to the arithmetic mean roughness of the first surface, which is the average height of protrusions and depressions on the first surface measured over a certain length. The larger the Ra value, the rougher the surface; the smaller the Ra value, the smoother the surface.

[0034] When the Ra value of the first surface is greater than 0.15 μm, it can be considered that the first surface is rougher than the surface of the conventional electronic conductive layer. By using a roughened first surface, a roughened ion-electric interface 3 can be formed between the electronic conductive layer 1 and the ion conductive layer 2, thereby increasing the area of ​​the ion-electric interface 3 and thus improving the conversion efficiency of ion signal to electron signal near the interface between the ion conductive layer 2 and the electronic conductive layer 1.

[0035] In some embodiments, the total thickness of the electronic conductive layer 1 and the ion conductive layer 2 is 0.1 mm to 5 mm.

[0036] By controlling the total thickness of the electronically conductive layer 1 and the ionically conductive layer 2, the signal transmission efficiency of the epidermal electrode can be ensured while preventing the electrode from becoming too thick and affecting its conformity to the skin surface, thus avoiding potential impacts on signal acquisition accuracy. Furthermore, excessively thick electronically conductive layer 1 and ionically conductive layer 2 increase material costs, while excessively thin layers significantly increase the difficulty of epidermal electrode fabrication and make the electrode prone to cohesive failure, affecting its durability and reliability.

[0037] In some embodiments, the raw materials for preparing the electronically conductive layer 1 include a polymer substrate and a conductive material.

[0038] In the formulation system of electronic conductive layer 1, the conductive material provides conductivity, and the polymer substrate provides dispersion, mechanical support and elasticity, thereby obtaining a flexible electronic conductive layer 1.

[0039] In some embodiments, the mass ratio of the conductive material to the water-soluble polymer substrate is (0.2–5):10. Specifically, the mass ratio of the conductive material to the water-soluble polymer substrate can be 0.2:10, 0.5:10, 0.75:10, 1:10, 1.25:10, 2:10, 5:10, or any value between these adjacent values.

[0040] In some embodiments, the conductive material includes poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid.

[0041] Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) is a conductive polymer. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conductive polymer with a conjugated structure, exhibiting high electrical conductivity and good chemical stability. Polystyrene sulfonate (PSS) is a water-soluble polymer. When used together, PEDOT:PSS exhibits good water dispersibility.

[0042] In some embodiments, the polymeric substrate includes at least one of polyvinyl alcohol and styrene-butadiene rubber.

[0043] Polyvinyl alcohol (PVA) and styrene-butadiene rubber (SBR) can provide good mechanical strength and flexibility.

[0044] In some embodiments, the raw materials for preparing the electronically conductive layer 1 include PEDOT:PSS, PVA, and SBR, wherein the mass ratio of PEDOT:PSS, PVA, and SBR is (0.75–1.25):1.5:8.5. Specifically, the mass ratio of PEDOT:PSS, PVA, and SBR can be 0.75:1.5:8.5, 1:1.5:8.5, 1.25:1.5:8.5, or any value between these adjacent values.

[0045] In the formulation system of the electronic conductive layer 1, the specific mass ratio of conductive materials and polymer substrates can ensure the high conductivity and good conformality of the electronic conductive layer 1. An appropriate amount of polyvinyl alcohol provides mechanical support and dispersion, forming a stable conductive network and ensuring the continuity and stability of the conductive path. An appropriate amount of styrene-butadiene rubber ensures the elasticity of the electronic conductive layer 1.

[0046] In some embodiments, the raw materials for preparing the ion-conducting layer 2 include the following components in parts by weight:

[0047] 1-20 parts of 3-methacrylamide;

[0048] Photoinitiator 0.5–10 parts;

[0049] 80-120 parts acrylic acid;

[0050] Deep eutectic solvent 20-200 parts.

[0051] In the formulation of ion-conducting layer 2, the photoinitiator initiates the copolymerization of acrylic acid and 3-methacrylamide to form a polymer network by absorbing light energy, providing adhesion and stability to ion-conducting layer 2. The deep eutectic solvent is a low-melting-point mixture formed by two or more components through hydrogen bonding. Adding the deep eutectic solvent provides conductivity and high moisture retention to ion-conducting layer 2, thereby obtaining an ion-conducting layer 2 with high ion concentration, low volatility, and high ion conductivity.

[0052] In some embodiments, the photoinitiator includes at least one selected from α-ketoglutaric acid, photoinitiator 127, photoinitiator 2959, and benzophenone. Photoinitiator 127 is composed of 1,1'-(methylenedi-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propanone], and photoinitiator 2959 is composed of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylpropanone. Both are novel, highly efficient, and non-yellowing ultraviolet photoinitiators capable of initiating the polymerization of monomers containing unsaturated double bonds to form polymers. In the formulation system of the ion-conducting layer in this application embodiment, the photoinitiator generates primary free radicals under ultraviolet light triggering. These primary free radicals initiate the monomers (3-methacryloyldopamine and acrylic acid) to generate monomer free radicals. The monomer free radicals and monomers continue to react, achieving chain growth, ultimately yielding an ion-conducting layer composed of a polymer and a deep eutectic solvent.

[0053] In some embodiments, the deep eutectic solvent comprises hydrogen bond acceptors and hydrogen bond donors in a molar ratio of 1:(1–3). The hydrogen bond acceptors and hydrogen bond donors form the deep eutectic solvent through hydrogen bonding. Specifically, the molar ratio of hydrogen bond acceptors to hydrogen bond donors can be 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:3, or any value between these adjacent values.

[0054] In some embodiments, the hydrogen bond donor includes at least one of ethylene glycol, glycerol, urea, and diethylene glycol. All of these substances can act as hydrogen bond donors in the formulation system, forming a deep eutectic solvent with the hydrogen bond acceptor.

[0055] In some embodiments, the hydrogen bond acceptor includes at least one of choline chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, and tetrabutylammonium iodide. All of these substances can act as hydrogen bond acceptors to form deep eutectic solvents with hydrogen bond donors. Furthermore, as ion-conducting media, they can form ion channels in the polymer, enhancing the ion conductivity of the ion-conducting layer 2.

[0056] The second aspect of this application provides a method for preparing an ion-electrostatic double-layer structured epidermal electrode, comprising the following steps:

[0057] Provide a mold with a surface featuring an uneven texture;

[0058] An electronically conductive polymer solution is coated onto the surface of the uneven structure of a mold and dried to obtain an electronically conductive layer 1 having a first surface.

[0059] The ion-conducting layer pre-curing solution is coated on the first surface of the electronically conductive layer 1, and then cured to obtain the ion-conducting layer 2, thus obtaining the ion-electric bilayer structure skin electrode.

[0060] The method for preparing an ion-electric bilayer skin electrode provided in this application involves coating an electron-conductive polymer solution onto a mold with an uneven surface. After drying, the electron-conductive polymer solution forms an electron-conductive layer 1 while simultaneously forming a first uneven surface. Next, an ion-conductive pre-curing solution is coated onto the first surface of the electron-conductive layer 1, and in-situ cured to form an ion-conductive layer 2. Simultaneously, an uneven ion-electric interface 3 is formed between the electron-conductive layer 1 and the ion-conductive layer 2, allowing the electron-conductive layer 1 and the ion-conductive layer 2 to be stably integrated, thus obtaining an ion-electric bilayer skin electrode. Furthermore, this method increases the ion-electric interface area, improves the ion-electric coupling efficiency, and reduces the interface impedance, thereby improving the conversion efficiency of ion signals to electron signals near the interface between the ion-conductive layer 2 and the electron-conductive layer 1, reducing the baseline noise level of the electrophysiological signal, and achieving high-fidelity electrophysiological signal acquisition.

[0061] In some embodiments, the liquid film thickness of the electronically conductive polymer solution is 20 μm to 5000 μm. Specifically, the liquid film thickness of the electronically conductive polymer solution can be 20 μm, 50 μm, 100 μm, 200 μm, 500 μm, 1000 μm, 2000 μm, or 5000 μm, or any value between these adjacent values. The mass concentration of the conductive material in the electronically conductive polymer solution is 2 wt% to 50 wt%.

[0062] In some embodiments, the liquid film thickness of the ion-conductive layer pre-curing solution is 25 μm to 5000 μm. Specifically, the liquid film thickness of the ion-conductive layer pre-curing solution can be 25 μm, 75 μm, 150 μm, 500 μm, 1000 μm, 2000 μm, or 5000 μm, or any value between these adjacent values.

[0063] By controlling the liquid film thickness of the electronically conductive polymer solution, the liquid film thickness of the ion-conductive layer pre-cured solution, and the solid content in the electronically conductive polymer solution, the thicknesses of electronically conductive layer 1 and ion-conductive layer 2 can be controlled. The resulting electronically conductive layer thickness is comparable to the ion-conductive layer thickness, ensuring a balance in the transmission of electrons and ions within the ion-conductive bilayer structure's outer electrode, thereby ensuring efficient signal acquisition.

[0064] In some embodiments, the preparation of the electronically conductive polymer solution includes the following steps: subjecting the conductive material and the polymer substrate to a first mixing treatment.

[0065] In some embodiments, the preparation of the ion-conductive layer pre-curing solution includes the following steps: subjecting 3-methacrylamide dopamine, photoinitiator, acrylic acid and deep eutectic solvent to a second mixing treatment.

[0066] In some embodiments, the deep eutectic solvent includes the following preparation steps: mixing a hydrogen bond acceptor and a hydrogen bond donor under heating conditions to obtain a deep eutectic solvent.

[0067] In some embodiments, the heating temperature is 78°C to 95°C, and the heating time is 1.5 to 2.5 hours. Specifically, the heating temperature can be 78°C, 80°C, 82°C, 85°C, 90°C, and 95°C, or any value between these adjacent values. The heating time can be 1.5 hours, 1.8 hours, 2 hours, and 2.5 hours, or any value between these adjacent values.

[0068] In some embodiments, the preparation of the mold includes the following steps: coating an elastomer material solution onto 1000-20000 grit sandpaper, curing it, and then demolding it to obtain the mold.

[0069] Specifically, the elastomer material includes SYLGARD. TM 184. At least one of Ecoflex and Dragon Skin. SYLGARD TM184 is a two-component, room-temperature curing silicone rubber, mainly composed of polydimethylsiloxane and a curing agent. Ecoflex and Dragon Skin are both commonly used silicone materials. These substances can be used to prepare molds. In mold preparation, the elastomer material is first prepared into a solution, then coated onto sandpaper and cured. After removing the sandpaper, a surface with a rough microstructure is obtained on the mold.

[0070] In some embodiments, the grit of the sandpaper can be 1000 grit, 2000 grit, 5000 grit, 6000 grit, 7000 grit, 10000 grit, 11000 grit, 12000 grit, 15000 grit, 18000 grit, and 20000 grit, or any value between the above adjacent values.

[0071] In some embodiments, the drying step includes: natural drying for 3 to 12 hours.

[0072] In some embodiments, the curing step includes: UV curing for 3 to 10 minutes.

[0073] Please see Figure 2 , Figure 2 A method for preparing an ion-electrostatic bilayer structure epidermal electrode provided in this application embodiment, as shown in the figure, includes the following steps:

[0074] S10. Provide a mold, the mold having a surface with an uneven structure;

[0075] S20. The conductive material and the polymer substrate are subjected to a first mixing treatment to obtain an electronically conductive polymer solution;

[0076] S30. The electronically conductive polymer solution is coated onto the surface of the uneven structure of the mold and dried to obtain an electronically conductive layer with a first surface.

[0077] S40. 3-Methylacrylamide dopamine, photoinitiator, acrylic acid and deep eutectic solvent are mixed in a second process to obtain an ion-conductive layer pre-cured solution.

[0078] S50. The ion-conducting layer pre-curing solution is coated on the first surface of the electronically conductive layer and cured to obtain the ion-conducting layer, thus obtaining the ion-electric double-layer structure skin electrode.

[0079] The third aspect of this application provides an application of an ion-electrostatic double-layered epidermal electrode, which is used to collect electrophysiological signals from the epidermis.

[0080] The ion-electric bilayer structure epidermal electrode provided in this application embodiment can be used to collect electrophysiological signals from the epidermis. Due to the presence of a highly conductive electronic conductive layer and an ion conductive layer, it provides a high carrier concentration for the conduction of electrophysiological signals by the epidermal electrode, providing a material basis for converting the ionic form of electrophysiological signals from the human body into electronic signals of the circuit. Furthermore, the uneven ion-electric interface greatly reduces the interface impedance and baseline noise level of the epidermal electrode, enabling the acquisition of high-fidelity electrophysiological signals.

[0081] Specifically, the obtained ion-electric double-layer skin electrode is processed into the required area and shape using a laser cutting machine, and metal wires are integrated onto the electronically conductive layer using conductive silver paste. In use, the ion-conductive layer of the ion-electric double-layer skin electrode is adhered to the skin directly above the muscle, and an external electrical device is connected to the metal wires to collect electromyographic signals from the epidermis. Multiple patches can be used, with a spacing of 1-2 cm between adjacent patches.

[0082] The following description is based on specific embodiments.

[0083] Example 1

[0084] An ion-conducting dual-layer skin electrode is disclosed, comprising a stacked electronically conductive layer and an ion-conducting layer, with an overall thickness of approximately 0.5 mm. The electronically conductive layer has a first surface with an uneven surface and an Ra value of 0.846 μm, forming an uneven ion-conducting interface between the electronically conductive layer and the ion-conducting layer.

[0085] The electronically conductive polymer solution consists of an aqueous dispersion of PEDOT:PSS with a mass concentration of 1 wt%, an aqueous PVA solution with a mass concentration of 10 wt%, and an aqueous SBR dispersion with a mass concentration of 50 wt%, wherein the mass ratio of PEDOT:PSS, PVA, and SBR is 1:1.5:8.5.

[0086] The ion-conductive layer pre-curing solution consists of 5 parts 3-methacrylamide, 1 part photoinitiator (α-ketoglutarate), 100 parts acrylic acid, and 115 parts deep eutectic solvent (composed of hydrogen bond acceptor (choline chloride) and hydrogen bond donor (ethylene glycol) in a molar ratio of 1:2).

[0087] This ion-electrostatic bilayer structure skin electrode was prepared by the following steps:

[0088] Making the mold: SYLGARD TM An elastomer material solution prepared with 184 is coated onto 10,000-grit sandpaper. After curing, the sandpaper is removed from the mold to obtain a mold with a surface having an uneven structure.

[0089] Preparation of electronically conductive polymer solution: Polyvinyl alcohol was dissolved in water at 80°C to prepare a 10wt% aqueous solution. PEDOT:PSS aqueous dispersion, PVA aqueous solution and SBR aqueous dispersion were shaken and mixed together to form an electronically conductive polymer solution.

[0090] Preparation of the electronically conductive layer: The electronically conductive polymer solution is coated on the surface of the uneven structure of the mold. The liquid film thickness of the electronically conductive polymer solution is 1 mm. It is then placed in the air to dry naturally for 12 hours to obtain the electronically conductive layer, which has an uneven first surface.

[0091] Preparation of the ion-conducting layer pre-curing solution: First, choline chloride and ethylene glycol are mixed at 80°C to form a deep eutectic solvent. Then, α-ketoglutaric acid, 3-methacrylamide, acrylic acid, and the deep eutectic solvent are shaken and mixed to form the ion-conducting layer pre-curing solution.

[0092] Preparation of ion-conductive layer and ion-electric bilayer structure skin electrode: The ion-conductive layer pre-curing liquid is coated on the first surface of the electronic conductive layer. The total thickness of the electronic conductive layer and the ion-conductive layer pre-curing liquid is controlled to be 0.5 mm using silicone pads and glass plates. The ion-conductive layer pre-curing liquid is cured in situ under ultraviolet light for 5 minutes to form the ion-conductive layer, thus obtaining the ion-electric bilayer structure skin electrode.

[0093] Application of this ion-electrode double-layer structure epidermal electrode: A 1cm diameter electrode is cut using a laser cutting machine. 2 A sensor patch is used to attach above a muscle to collect electromyographic signals.

[0094] Example 2

[0095] An ion-electrode bilayer structure epidermal electrode differs from Example 1 in that the mass ratio of PEDOT:PSS, PVA, and SBR is 0.75:1.5:8.5. The rest is the same as Example 1.

[0096] Example 3

[0097] An ion-electrode bilayer structure epidermal electrode differs from Example 1 in that the mass ratio of PEDOT:PSS, PVA, and SBR is 1.25:1.5:8.5. The rest is the same as Example 1.

[0098] Example 4

[0099] An ion-electrode bilayer structure skin electrode differs from Example 1 in that glycerol is used instead of ethylene glycol as the hydrogen bond donor in the deep eutectic solvent. The rest is the same as in Example 1.

[0100] Example 5

[0101] An ion-conductive double-layer skin electrode differs from Example 1 in that photoinitiator 127 is used instead of α-ketoglutarate as the photoinitiator in the ion-conductive layer pre-curing solution. The rest is the same as in Example 1.

[0102] Example 6

[0103] An ion-electrode bilayer structure skin electrode differs from Example 1 in that: in the electron-conductive polymer solution, the aqueous dispersion of the conductive material is an aqueous dispersion of carbon nanotubes with a mass concentration of 16.2 wt%, and the mass ratio of the conductive material to the polymer substrate is the same. The rest is the same as in Example 1.

[0104] Performance testing

[0105] 1. Conductivity test of the electronic conductive layer: The conductivity of the electronic conductive layer of the ion-electric bilayer structure skin electrode prepared in Examples 1-6 was tested using the four-probe method. The test results are shown in Table 1.

[0106] 2. Conductivity test of ion-conducting layer: The conductivity of the ion-conducting layer of the ion-conducting bilayer structure skin electrode prepared in Examples 1-6 was measured by AC impedance spectroscopy using an electrochemical workstation. The test results are shown in Table 1.

[0107] Table 1. Conductivity Test Results

[0108]

[0109]

[0110] As shown in Table 1, the ion-electric bilayer structure skin electrode prepared using the embodiments of this application has a high-conductivity electronic conductive layer and a high-conductivity ion conductive layer. Among them, the electronic conductive layer prepared using carbon nanotube solution as the conductive material has a conductivity as high as 3.4 S cm⁻¹. -1 The conductivity of the ion-conducting layer in each embodiment can reach 0.06 mS / cm. -1 This highly conductive electronic conductive layer and highly conductive ionic conductive layer provide a high carrier concentration for the conduction of electrophysiological signals by the epidermal electrodes, and provide a material basis for converting the electrophysiological signals in the ionic form of the human body into electronic signals of the circuit.

[0111] 3. Interface impedance test: A 1cm section was cut from the ion-electrostatic bilayer structure skin electrode prepared in Example 1. 2 Two patches of the sensing area were applied 2 cm apart directly above an arm muscle, and the interfacial impedance was measured using an electrochemical workstation. A commercial Ag / AgCl electrode was simultaneously tested using the same method for comparison. The test results are as follows: Figure 3 As shown. From Figure 3It can be seen that the interface impedance of the ion-electric bilayer structure skin electrode in Example 1 is reduced by an order of magnitude compared with the interface impedance of the commercial Ag / AgCl electrode. This indicates that the embodiments of this application, through the ion-electric bilayer structure and the roughening treatment of the interface between the electronic conductive layer and the ion conductive layer, can improve the conversion efficiency of ion signal to electronic signal near the interface between the ion conductive layer and the electronic conductive layer, that is, improve the ion-electric coupling efficiency and reduce the interface impedance.

[0112] 4. Electromyography (EMG) signal testing: Baseline noise and signal-to-noise ratio (SNR) tests were performed on Examples 1 and 4-6, respectively. Simultaneously with the experiments in Examples 1 and 4-6, conventional smooth-surfaced molds were used for synchronous comparative experiments. The surface Ra value of the electronically conductive layer was 0.118 μm, resulting in epidermal electrodes with unroughened interfaces. Baseline noise and SNR tests were performed on these unroughened interfaces. Additionally, commercially available Ag / AgCl electrodes were used for baseline noise and SNR testing.

[0113] a. Baseline noise test: Cut a 1cm diameter section from the epidermal electrode. 2 For the sensor patch samples, two patches were attached directly above the arm muscles, 2 cm apart. Resting signal was measured during muscle relaxation, and baseline noise data was calculated. The baseline noise data was calculated as follows: Each sample value of the baseline signal was taken, squared, and the average of all squared values ​​was calculated. The square root of this average was then taken. The formula is as follows: The data results are shown in Table 2.

[0114] b. Signal-to-noise ratio test: Cut a 1cm section from the epidermal electrode. 2 Two patches of the sensing area were attached to the arm muscles, 2 cm apart, directly above the muscles. The signals during muscle contraction and relaxation were measured. The muscle relaxation segment was selected as the noise data segment, and the muscle contraction segment as the signal data segment. The signal-to-noise ratio (SNR) was calculated. The SNR was calculated by: calculating the root mean square (RMS) value of the baseline noise segment and the root mean square (RMS) value of the signal segment. The formula is: The data results are shown in Table 2.

[0115] Table 2 Results of Electromyography (EMG) Signal Testing

[0116]

[0117] Note: The roughness of the interface in Table 2 is defined as Ra, which is greater than 0.15 μm.

[0118] As shown in Table 2, the embodiments of this application, by roughening the interface between the electronically conductive layer and the ionically conductive layer, can significantly reduce the baseline noise level of the epidermal electrode and significantly improve its signal-to-noise ratio. Specifically, the baseline noise level and signal-to-noise ratio of Examples 1 to 5 are significantly better than those of commercial Ag / AgCl electrodes. Furthermore, comparing Examples 1 and 6 reveals that although Example 6 has significantly better conductivity in the electronically conductive layer than Example 1, in terms of electromyography (EMG) signal testing, Example 6 is less effective than Example 1 in reducing the baseline noise level. Therefore, considering both conductivity and EMG signal testing, under the same conditions, the ion-electric bilayer structure epidermal electrode prepared using PEDOT:PSS as the conductive material to fabricate the electronically conductive layer exhibits better overall performance.

[0119] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An off-electric double layer structure skin electrode, characterized by, It includes a flexible electronically conductive layer, the flexible electronically conductive layer having a first surface with a microstructure, an in-situ solidified ion-conductive layer being disposed on the first surface of the flexible electronically conductive layer, and a rough ion-conductive interface being formed between the flexible electronically conductive layer and the ion-conductive layer.

2. The ion-electrostatic double-layer structure skin electrode as described in claim 1, characterized in that, The Ra value of the first surface microstructure is greater than 0.15 μm; and / or, The total thickness of the electronic conductive layer and the ion conductive layer is 0.1 mm to 5 mm.

3. The ion-electrostatic double-layer structure skin electrode as described in claim 1, characterized in that, The raw materials for preparing the electronic conductive layer include a polymer substrate and a conductive material.

4. The ion-electrostatic double-layer structure skin electrode as described in claim 3, characterized in that, The mass ratio of the conductive material to the polymer substrate is (0.2~5):10; and / or, The conductive material comprises poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid; and / or, The polymeric substrate includes at least one of polyvinyl alcohol and styrene-butadiene rubber.

5. The ion-electrostatic double-layer structure skin electrode as described in any one of claims 1-4, characterized in that, The raw materials for preparing the ion-conductive layer include the following components in parts by weight: 1-20 parts of 3-methacrylamide; Photoinitiator 0.5-10 parts; 80-120 parts acrylic acid; Deep eutectic solvent 20-200 parts.

6. The ion-electrostatic double-layer structure skin electrode as described in claim 5, characterized in that, The photoinitiator includes at least one of α-ketoglutaric acid, photoinitiator 127, photoinitiator 2959, and benzophenone; and / or, The deep eutectic solvent includes hydrogen bond acceptors and hydrogen bond donors in a molar ratio of 1:(1~3).

7. A method for preparing an ion-electrostatic bilayer structure skin electrode as described in any one of claims 1-6, characterized in that, Includes the following steps: A mold is provided, the mold having a surface with an uneven structure; An electronically conductive polymer solution is coated onto the surface of the uneven structure of the mold, and then dried to obtain the electronically conductive layer having the first surface. The ion-conductive layer pre-curing solution is coated onto the first surface of the electronic conductive layer, and then cured in situ to obtain the ion-conductive layer, resulting in an ion-conductive bilayer structure skin electrode with an uneven ion-conductive interface.

8. The preparation method according to claim 7, characterized in that, The preparation of the electronically conductive polymer solution includes the following steps: subjecting the conductive material and the polymer substrate to a first mixing treatment; and / or; The preparation of the ion-conductive layer pre-curing solution includes the following steps: a second mixing treatment of 3-methacrylamide, photoinitiator, acrylic acid and deep eutectic solvent.

9. The preparation method according to claim 7 or 8, characterized in that, The preparation of the mold includes the following steps: The mold is obtained by coating an elastomer material solution onto 1000-20000 grit sandpaper, curing it, and then demolding it.

10. An application of the ion-electrostatic double-layer structure epidermal electrode as described in any one of claims 1-6, characterized in that, Application of the described ion-electrostatic double-layer structure epidermal electrode in the acquisition of epidermal electrophysiological signals.

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