A breathable dry electrode adherable in dry and wet states and a preparation method thereof

Abstract

This disclosure relates to a breathable dry electrode capable of adhesion in both dry and wet conditions, and its preparation method. This technology constructs a flexible, self-adhesive polymer substrate with a porous structure, endowing the substrate with excellent breathability and flexibility. By introducing an acrylic component that can form an interfacial interaction with the skin surface into the polymer system, the substrate can form stable adhesion to the skin without additional adhesive coating. The introduction of the hydrophobic component, dodecyl acrylate, enhances the interfacial stability of the substrate in sweaty or humid environments. Furthermore, by selectively encapsulating the conductive circuitry according to functional zones, the breathable channels of the substrate are preserved to the maximum extent while protecting the conductive circuitry. Ultimately, the dry electrode maintains good adhesion stability, wearing comfort, and electrophysiological signal acquisition performance under long-term wear, humid environments, and sports conditions.

Description

Technical Field

[0001] This disclosure relates to electrodes for monitoring electrophysiological signals, and more particularly to a breathable dry electrode that can adhere in both dry and wet conditions and a method for preparing the same. Background Technology

[0002] In the field of electrophysiological signal monitoring such as electrocardiogram (ECG), electromyography (EMG), and electroencephalography (EEG), electrodes serve as the direct interface between the human body and the signal acquisition system, and their performance directly affects signal acquisition quality, wearing comfort, and long-term monitoring stability. As applications shift from short-term hospital monitoring to home-based, continuous, and wearable devices, electrodes not only need low and stable skin contact impedance but also require good flexibility, skin conformability, breathability, adhesion stability, and anti-interference capabilities in dynamic usage environments. Currently, silver / silver chloride gel wet electrodes are widely used in clinical and commercial products. These electrodes rely on conductive gel to form a conductive interface between the electrode and the skin, offering good short-term detection performance. However, during prolonged wear, the gel is prone to water loss, drying, or uneven distribution, leading to interface impedance fluctuations and affecting signal quality. Furthermore, the gel layer and backing structure often hinder moisture dissipation from the skin surface, easily causing sweat accumulation, skin maceration, itching, or irritation. During sweating, activity, or bending and stretching, they are also prone to introducing interface slippage and motion artifacts, thus failing to meet the needs of long-term dynamic monitoring.

[0003] To overcome the shortcomings of traditional gel wet electrodes, researchers have proposed several flexible dry electrode technologies. Existing solutions mainly include: First, constructing microstructure arrays such as microneedles, micropillars, and microprotrusions on the electrode surface to enhance the mechanical interaction between the electrode and the stratum corneum of the skin and improve contact stability. Although dry electrodes with microstructure arrays can enhance interfacial contact to some extent, they usually suffer from problems such as a strong foreign body sensation, limited adaptability to sensitive skin, complex manufacturing processes, and insufficient long-term stability. Second, designing biomimetic surface topologies such as micropores, microgrooves, and microsuction cups to improve the adhesion of the electrode to the skin surface. However, these biomimetic surface topologies are prone to lubrication failure due to liquid film formation in sweaty or humid environments, leading to electrode lifting, displacement, or even detachment. Third, ... One approach involves using fabric substrates, porous membranes, fiber membranes, or three-dimensional interconnected network structures, and then laminating them with silver, carbon-based conductive materials, or conductive polymers to improve breathability and wearing comfort. However, their inherent self-adhesion is usually weak, often requiring additional adhesive layers, tapes, or other fixing structures, thus increasing structural complexity and potentially affecting the original breathability and wearing comfort. Another approach uses flexible polymers such as polydimethylsiloxane, polyurethane, polyvinyl alcohol, and styrene-based block copolymers as substrates, combined with conductive materials such as silver nanowires, carbon nanotubes, graphene, conductive carbon black, or poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid to construct conductive layers or conductive circuits, thus preparing flexible composite dry electrodes. While this approach offers good skin conformability, in practical applications it is often difficult to simultaneously achieve breathability, self-adhesion, wet-state stability, and interfacial reliability under dynamic deformation conditions. Especially after the conductive circuit is fully encapsulated, the breathability can easily decrease due to the encapsulation layer covering or blocking the pores. Summary of the Invention

[0004] To address the aforementioned issues, the present invention aims to provide a breathable dry electrode that can adhere in both dry and wet conditions, and its preparation method. The electrode substrate possesses excellent breathability and flexibility, and is a porous, flexible, self-adhesive polymer membrane. During substrate preparation, by introducing acrylic monomers that can form interfacial interactions with the skin surface into the polymer system, the substrate can achieve stable adhesion to the skin without the need for additional adhesive coating. The introduction of the hydrophobic component, dodecyl acrylate, enhances interfacial stability in sweaty or humid environments. Furthermore, the conductive circuitry on the substrate is selectively encapsulated according to functional zones, achieving protection of the conductive circuitry while maximizing the preservation of the substrate's breathability. Ultimately, this allows the electrode to maintain excellent adhesion stability, wearing comfort, and electrophysiological signal acquisition performance even under long-term wear, humid environments, and sports activities.

[0005] To achieve the above technical objectives, this disclosure proposes a breathable dry electrode that can adhere in both dry and wet conditions. Specifically, it includes a porous self-adhesive polymer film, conductive lines, and a flexible printed circuit board connector. The porous self-adhesive polymer film is obtained based on a prepolymer solution, which includes urethane diacrylate and monomers in a mass ratio of 17:3. The monomers contain dodecyl acrylate in a mass ratio of 1:2 to acrylic monomers, 2% by mass of photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and 35% by mass of ethyl acetate. The conductive lines are located on the surface or in designated areas of the porous self-adhesive polymer film and are selectively encapsulated based on functional partitions. The encapsulation methods include: complete insulation encapsulation of conductive lines in non-sensing areas; modification of detection points in the sensor area with conductive hydrogel; thick brushing of conductive paste at the ends of the conductive lines to strengthen the contact areas; and fixing the pins of the flexible printed circuit board connector to the strengthened contact areas after dipping them in silver paste. Then, the other parts of the flexible printed circuit board connector are fixed to the porous self-adhesive polymer film on which the electrode has been constructed using adhesive.

[0006] In one embodiment of the above technical solution, during the preparation of the porous self-adhesive polymer membrane, a conductive material is directly added to the prepolymer solution, so that the conductive phase is distributed in the interior of the polymer matrix, the near-surface region, or the pore wall skeleton during the polymerization, curing, and phase separation process, so that the polymer film forms a porous self-adhesive polymer membrane with conductive function.

[0007] To achieve the above-mentioned technical objectives, this disclosure proposes a method for preparing the breathable dry electrode that can adhere in both dry and wet states. Specifically, the method includes: weighing urethane diacrylate and monomers at a mass ratio of 17:3, wherein the mass ratio of dodecyl acrylate to acrylic monomers in the monomers is 1:2; adding 2% by mass of the monomer as a photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO); adding 35% by mass of ethyl acetate; stirring until homogeneous to obtain a prepolymer solution; removing air bubbles from the prepolymer solution by standing or vacuum degassing; coating the prepolymer solution onto a mold, glass substrate, or release substrate; and then placing it in a UV curing apparatus for photocuring; immersing the resulting semi-cured composite film in a poor solvent for extraction and washing; after extraction, placing it at 40-60°C... A porous self-adhesive polymer film is obtained by drying to constant weight in a constant temperature oven based on a prepolymer solution. Conductive circuits are constructed on the surface or designated areas of the porous self-adhesive polymer film, and the conductive circuits are selectively encapsulated based on functional partitions, including: fully insulating the conductive circuits in non-sensing areas; modifying the detection points in the sensor area with conductive hydrogel; thickly brushing conductive paste onto the ends of the conductive circuits to strengthen the contact area; then dipping the pins of the flexible printed circuit board connector in silver paste and fixing them to the strengthened contact area; and finally fixing the other parts of the flexible printed circuit board connector to the porous self-adhesive polymer film with constructed electrodes using adhesive to form dry electrodes.

[0008] In one embodiment of the above technical solution, before removing bubbles from the system by standing or vacuum degassing, the conductive material is directly added to the prepolymer solution, so that the conductive phase is distributed in the interior of the polymer matrix, the near-surface region or the pore wall skeleton during the polymerization, curing and phase separation process, so that the polymer film forms a porous self-adhesive polymer film with conductive function.

[0009] In one embodiment of the above technical solution, the detection point is a circular area with a radius of 2 mm, the width of the conductive line is 1 mm, and a 2 mm × 4 mm area is reserved at the end of the conductive line for connecting the flexible printed circuit board connector.

[0010] The beneficial technical effects of this disclosure are as follows.

[0011] (1) In this invention, the substrate of the dry electrode is prepared using a specific polymer, forming an interconnected porous structure inside. This structure can provide... The system provides channels for air and moisture exchange, thereby improving breathability and comfort at the skin-electrode interface under long-term wear. Compared to solutions that achieve breathability through perforation, the substrate in this solution itself has a continuous porous network, resulting in more direct breathability.

[0012] (2) The substrate of the dry electrode in this invention has self-adhesive ability and can achieve stable adhesion to the skin without the need for additional adhesive layer. Compared with the existing solutions that require additional glue, double-sided tape or external fixing structure, this solution can not only simplify the electrode preparation process, but also avoid the covering and clogging of the porous structure by the additional adhesive layer, thus making it more conducive to preserving the original breathability of the material.

[0013] (3) The substrate of the dry electrode in this invention has better interfacial stability in a humid environment. Compared with flexible electrodes that rely solely on the dry interface, the present invention is less prone to significant reduction in adhesion performance due to the formation of an interfacial liquid film in a humid environment, and is therefore more suitable for electrode applications under conditions of sweating, moisture, or prolonged wear.

[0014] (4) The substrate of the dry electrode in this invention has both flexibility, deformation adaptability and electrode application basis, which is conducive to maintaining good skin conformal contact under bending, stretching and movement, thus providing a basis for stable acquisition of 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 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 actual acquisition of electromyographic signals using a dual-channel electrode in one embodiment.

[0017] Figure 2 This is a schematic diagram illustrating the water vapor permeability characteristics of a porous base membrane in one embodiment. Detailed Implementation

[0018] While existing traditional gel electrodes for electrophysiological signal acquisition have low initial contact impedance, they typically rely on the conductive gel to form an interface with the skin, resulting in poor breathability. During prolonged wear, sweat can easily accumulate at the skin-electrode interface, hindering moisture dissipation and causing skin maceration, irritation, and discomfort, thus limiting their application in long-term continuous monitoring.

[0019] Meanwhile, while existing flexible dry electrodes avoid the problem of conductive gels drying out easily, they still generally have the following shortcomings: First, some dry electrode substrates themselves do not have self-adhesive capabilities and usually require additional adhesive coating or external fixing structures to adhere to the skin surface, which not only increases the complexity of preparation but also easily affects the breathability and long-term wearing comfort of the electrode; Second, in environments such as sweating and humidity, the liquid film on the skin surface weakens the interfacial interaction between the electrode and the skin, causing the electrode to shift position, curl up, or fall off, thereby resulting in a decrease in signal quality; Third, some existing dry electrodes lack flexibility and stretch adaptability, making it difficult to maintain stable conformal contact with the skin under conditions of limb bending, stretching, or strenuous exercise, easily producing motion artifacts and failing to meet the requirements for stable acquisition of electrophysiological signals in dynamic scenarios.

[0020] Therefore, the present invention aims to provide a breathable dry electrode that can adhere in both dry and wet conditions and its preparation method, in order to solve the problems of insufficient breathability, poor comfort during long-term wear, insufficient adhesion stability in humid environments, and unstable interfacial contact during movement of existing electrodes. This invention achieves a dry electrode that combines breathability, self-adhesion, stability in wet conditions, and good flexibility, thereby improving the stability and reliability of long-term monitoring of electrophysiological signals.

[0021] The following will clearly and completely describe how the technical solution of this case is implemented. Obviously, the described implementation methods are only a part of the implementation methods of this case, and not all of them. Based on the implementation methods in this case, all other implementation methods obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0022] The fabrication process of the air-permeable dry electrode based on the porous self-adhesive polymer substrate mainly includes (i) the preparation of the porous self-adhesive polymer substrate material, (ii) the construction of the conductive circuit, and (iii) the encapsulation of the conductive circuit and the modification of the detection points, so that the electrode obtained after the fabrication is completed has air permeability, self-adhesion, wet interface stability, flexibility and stretchability, and stable electrophysiological signal acquisition capability.

[0023] (I) Preparation of porous self-adhesive polymer substrate materials The porous self-adhesive polymer substrate is prepared using an elastic polymer system. It employs a combination of photoinitiated polymerization and solvent-inducible phase separation techniques, utilizing the synergistic effects of polar monomers, hydrophobic monomers, crosslinking agents, photoinitiators, and pore-forming components to form an interconnected porous structure within the substrate. This substrate serves not only as a flexible support layer for conductive circuits but also as a direct interface layer in contact with the skin. Therefore, it must simultaneously possess properties such as flexibility, breathability, self-adhesion, and resistance to failure in humid environments.

[0024] Specifically, a prepolymer solution is first prepared. The prepolymer system includes a crosslinking agent, a polar monomer, a hydrophobic monomer, a photoinitiator, and pore-forming components. The crosslinking agent is preferably urethane diacrylate (UDA), used to construct a flexible three-dimensional polymer network, giving the resulting substrate good mechanical integrity, flexibility, and tensile adaptability. The polar monomer is specifically an acrylic monomer, used to introduce polar groups into the polymer network to enhance the interfacial interaction between the substrate and the skin surface, thereby improving the substrate's adhesion. Dodecyl acrylate, as a hydrophobic monomer, is used to regulate the interfacial energy and water absorption behavior of the polymer surface, reducing the adverse effects of sweat or humid environments on adhesion performance and improving the interfacial stability of the electrode under humid conditions. The photoinitiator is preferably diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) to ensure that the prepolymer system has high initiation efficiency and good curing depth. The pore-forming components can be achieved through a pore-forming agent and a poor solvent. The pore-forming agent can be ethyl acetate, and the poor solvent can be water or other media compatible with the pore-forming agent but with low compatibility with the polymer network. Weigh out urethane diacrylate and monomers at a mass ratio of 17:3, wherein the mass ratio of dodecyl acrylate to acrylic monomers in the monomers is 1:2. Add 2% by mass of the photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and 35% by mass of the total solution. After mixing the components according to the set ratio, stir thoroughly under light-protected conditions to form a homogeneous prepolymer solution, and remove air bubbles from the system by standing or vacuum degassing.

[0025] Subsequently, a porous self-adhesive polymer film is obtained based on the prepolymer solution. The obtained prepolymer solution is spread onto a mold, glass substrate, or release substrate using methods such as molding, doctor blade coating, spin coating, or casting. The release substrate can be surface-treated release paper or polyethylene terephthalate (PET) release film. By controlling the coating thickness, the thickness of the resulting substrate can be adjusted within a wide range according to the application, for example, a wet film thickness of 100 micrometers to 15 millimeters. Then, the mold or substrate coated with the prepolymer solution is placed in a UV curing system and irradiated with UV light under set wavelength and radiation intensity conditions to induce photo-initiated polymerization. As the polymerization reaction proceeds, the polymer molecular weight gradually increases, the system compatibility changes, and the pore-forming components originally dispersed in the system gradually separate from the polymer network, thus forming a microscopic separation structure of a polymer-rich phase and a pore-forming agent-rich phase. After UV curing, the resulting semi-cured composite film is immersed in a poor solvent for extraction and washing. The unsuitable solvent is one that is compatible with the porogen but incompatible or has low compatibility with the formed polymer network. During the washing process, the porogen retained in the polymer network is gradually dissolved and carried away from the system, thereby forming an interconnected microporous network inside the substrate. After extraction, the obtained porous substrate is dried in a constant temperature oven at 40–60 °C until constant weight, thus obtaining a porous self-adhesive polymer film.

[0026] The substrate prepared by the above method has the following characteristics: First, due to the use of photoinitiated polymerization combined with non-solvent-induced phase separation, the synergistic effect of polar monomers, hydrophobic monomers, crosslinking agents, photoinitiators, and pore-forming components forms an interconnected porous structure inside the material, which is conducive to air and water vapor exchange and can improve the breathability and comfort of the skin-electrode interface during long-term electrode wear; Second, the crosslinked polymer network endows the substrate with good flexibility and a certain tensile adaptability, enabling it to maintain good skin conformity under bending, stretching, and movement, thus providing a basis for stable acquisition of electrophysiological signals; Third, the introduction of polar monomers and hydrophobic monomers, where polar monomers can enhance interfacial interaction, the resulting porous material can be directly used as a skin-adhesive interface, reducing the need for additional adhesive layers to achieve stable adhesion to the skin, while hydrophobic monomers regulate the interfacial energy and water absorption behavior of the material surface, enabling the material to maintain a relatively stable adhesion state under sweating or humid conditions. Through the synergistic effect of polar and hydrophobic monomers, the substrate can maintain relatively stable interfacial adhesion in both dry and humid environments, thus providing a basic material for the subsequent construction of breathable dry electrodes.

[0027] (II) Construction of conductive circuits Conductive layers, conductive regions, or patterned conductive lines are constructed on the surface or localized areas of a pre-fabricated porous self-adhesive polymer membrane. The conductive layer can be formed by methods such as spraying, blade coating, screen printing, stencil printing, inkjet printing, aerosol printing, transfer printing, vacuum evaporation, magnetron sputtering, electroplating, or chemical plating. For example, a metal nanowire dispersion can be sprayed onto the membrane surface to form a conductive network; an ultrathin metal nanofilm can be deposited on the surface by evaporation or sputtering; and conductive silver paste, nanowire ink, carbon-based conductive ink, or conductive polymer ink can be printed in localized areas to form detection points and conductive lines. Preferably, this surface construction method ensures that the conductive phase is mainly distributed on the surface layer or a designated area of ​​the porous self-adhesive polymer membrane to reduce blockage of internal pores and preserve the material's permeability and flexibility as much as possible.

[0028] Furthermore, the conductive material can be directly added to the prepolymer solution, and participate in the structural formation together with the polymer phase during the polymer film formation process. This allows the conductive phase to be distributed in the interior of the polymer matrix, the near-surface region, or the pore wall skeleton during polymerization, curing, and phase separation, thereby forming a porous composite electrode material—a porous self-adhesive polymer film with conductive function. Then, on the surface or in a local area of ​​the porous self-adhesive polymer film with conductive function, a conductive layer, a conductive region, or a patterned conductive circuit can be constructed in the manner described above. The conductive material can be selected from metal nanowires, such as silver nanowires, gold nanowires, copper nanowires, etc., with an average diameter of 5–200 nm and an average length of 1–200 μm, and the addition amount accounts for 0.1–2 wt% of the prepolymer; carbon-based conductive materials, such as carbon nanotubes, graphene, conductive carbon black, etc., wherein the addition amount of carbon nanotubes with an average diameter of 5–100 nm and an average length of 0.5–100 μm accounts for 0.1–2 wt% of the prepolymer, the addition amount of graphene with a transverse dimension of 0.05–50 μm and a thickness of 0.34–50 nm accounts for 0.5–5 wt% of the prepolymer, and the addition amount of carbon black with a primary particle size of 10–100 nm and an aggregate equivalent particle size of 50–1000 nm accounts for 5–20 wt% of the prepolymer; conductive polymers, such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid, etc., with a hydrodynamic particle size of 10–800 nm in colloidal or gel particles, accounts for 1–6 wt% of the prepolymer by dry weight. One or more of transparent conductive materials, wt% or with an average particle size of 5–200 nm. By controlling the type, size, amount, and dispersion state of the conductive material in the polymer system, the resulting composite structure can form a stable conductive pathway while maintaining porosity, flexibility, and self-adhesion properties.

[0029] This disclosure does not limit the specific method of constructing the conductive lines. For example, conductive fillers can be introduced into the polymer system to form an initial conductive framework, and then metal nanowires can be locally sprayed, conductive patterns can be printed, or ultrathin metal films can be deposited on the membrane surface to further improve conductivity and signal acquisition stability. As long as the resulting electrode structure can provide a stable conductive path while maintaining the air permeability and flexibility of the porous self-adhesive polymer material, it falls within the protection scope of this invention.

[0030] (III) Conductive circuit packaging The dry electrode of this invention is a breathable electrode. Traditional integral packaging would seal the pores, leading to a failure in breathability. Therefore, this solution adopts a strategy of selective packaging based on functional zones. For conductive lines in non-sensing areas (such as wire sections), complete insulation packaging is performed to prevent external electromagnetic interference and sweat corrosion. During insulation packaging, a secondary printing method is used to cover the conductive lines with a layer of insulating ink or polyurethane film, isolating the electrolyte solution outside the conductive traces while retaining the through-pores in the non-packaged areas (sensor array area). In the sensing area, the detection points are modified with conductive hydrogel to ensure close contact between the electrode points and the skin, thereby reducing the contact resistance at the interface. At the ends of the conductive lines, unlike the above packaging method, a thick layer of conductive paste is applied to strengthen the contact area, and then a flexible printed circuit board connector (FPC) is used to fix it to the strengthened contact area.

[0031] In use, polyimide (PI) with copper foil etched on its surface is selected as a flexible printed circuit board. The dry electrode is connected to the corresponding interface of the multi-channel physiological signal acquisition system to perform signal acquisition and complete signal transmission.

[0032] The following experimental examples demonstrate the effectiveness of the method of the present invention.

[0033] First, a porous flexible substrate is prepared.

[0034] 1. Preparation of prepolymer solution.

[0035] First, weigh out urethane diacrylate (UDA) and monomers at a mass ratio of 17:3, wherein the mass ratio of hydrophobic monomer to polar monomer is 1:2. The polar monomer is an acrylic monomer. The hydrophobic monomer is dodecyl acrylate.

[0036] Subsequently, 2% by mass of the monomer photoinitiator diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) was added, followed by ethyl acetate as a porogen, bringing its total mass to 35%. The resulting mixture was thoroughly stirred at room temperature and in the dark to ensure uniform mixing of all components, yielding a prepolymer solution.

[0037] (2) Preparation of porous membranes.

[0038] The release paper surface was treated with plasma surface treatment equipment for 1 minute to improve its surface wettability. Subsequently, the prepolymer solution was uniformly coated onto the release paper surface using a 200 μm coater. The coated sample was then placed in a UV curing chamber at 60% power (total power 750 mW / cm²). 2 The film was irradiated for 60 seconds to induce photocuring. After curing, the resulting film was placed in water for 6 hours for displacement. After displacement, the film was removed and dried in a forced-air drying oven until all moisture was removed. The final result was a porous substrate with a thickness of approximately 200 μm and pore sizes in the hundreds of nanometers.

[0039] 2. Preparation of electrode patterns.

[0040] Electrode pattern templates were fabricated on polyethylene terephthalate (PET) sheets using a laser cutting machine. The detection points were circular areas with a radius of 2 mm, the conductive lines were 1 mm wide, and a 2 mm × 4 mm area was reserved at the end of the lines for connection to a flexible printed circuit board connector. The cut mask was tightly fitted onto the porous substrate surface, minimizing gaps between the template and the substrate. Conductive silver paste was then dropped onto the mask surface and scraped using a scraper to transfer the paste to the porous substrate surface, forming the predetermined pattern. After printing, the samples were dried in a forced-air drying oven to obtain electrodes with conductive patterns.

[0041] 3. Electrode testing.

[0042] (1) Electrophysiological signal acquisition test.

[0043] The brachioradialis muscle region of the forearm was selected as the test site. The skin was first cleaned with alcohol. After connecting the dry electrode to the lead wire, the electrode was attached to the skin surface and connected to the acquisition device. Once the signal stabilized, the subject clenched their fist, and the acquired electromyographic signals were recorded. Experimental results show that this dry electrode can be used for electromyographic signal acquisition. Figure 1 The figure shows the electromyographic signals from two channels acquired using a dry electrode. This dry electrode can acquire high-quality electromyographic signals with a low signal-to-noise ratio, and the waveforms conform to electromyographic characteristics.

[0044] (2) Wet adhesion performance test.

[0045] Electrodes were attached to areas prone to sweating, such as the chest, and subjects performed cycling exercises for 20 minutes. After the exercise, the electrode condition was observed. The results showed no significant lifting or detachment of the electrodes, and considerable force was required to peel them off the skin. After removal, only a small amount of sweat remained on the skin and electrode surface, and the electrodes maintained a certain degree of stickiness, indicating that the electrodes exhibited good interfacial adhesion stability even under sweating conditions.

[0046] (3) Air permeability test.

[0047] Two glass bottles were filled with water. The opening of one bottle was covered with the prepared porous substrate, while the other served as a control. The initial weight of the water in each bottle was measured, and both were then placed in the same environment to stand. The weights of both bottles were then measured and recorded every 12 hours, for a total of six times. The air permeability of the prepared porous substrate could be evaluated by comparing the weight loss of the two groups of samples. Figure 2 The first curve at the top of the figure is the control group with the bottle opening uncovered. This curve shows the trend of water vapor permeation in the bottle. It can be seen that the bottle opening covered with a porous base membrane also has the same water vapor permeation characteristics.

[0048] In summary, this disclosure proposes a method for preparing a breathable dry electrode that can adhere in both dry and wet states. Specifically, the method includes: weighing urethane diacrylate and monomers at a mass ratio of 17:3, wherein the mass ratio of dodecyl acrylate to acrylic monomers in the monomers is 1:2; adding 2% by mass of the monomer as a photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO); adding 35% by mass of ethyl acetate; stirring until homogeneous to obtain a prepolymer solution; removing air bubbles from the prepolymer solution by standing or vacuum degassing; coating the prepolymer solution onto a mold, glass substrate, or release substrate; and then curing it in a UV curing apparatus; immersing the resulting semi-cured composite film in a poor solvent for extraction and washing; and after extraction, placing it at 40–60 °C. A porous self-adhesive polymer film is obtained by drying to constant weight in a constant temperature oven based on a prepolymer solution. Conductive circuits are constructed on the surface or designated areas of the porous self-adhesive polymer film, and the conductive circuits are selectively encapsulated based on functional partitions, including: fully insulating the conductive circuits in non-sensing areas; modifying the detection points in the sensor area with conductive hydrogel; thickly brushing conductive paste onto the ends of the conductive circuits to strengthen the contact area; then dipping the pins of the flexible printed circuit board connector in silver paste and fixing them to the strengthened contact area; and finally fixing the other parts of the flexible printed circuit board connector to the porous self-adhesive polymer film with constructed electrodes using adhesive to form dry electrodes.

[0049] The dry electrodes prepared by the above method can maintain good adhesion stability, wearing comfort, and electrophysiological signal acquisition performance under long-term wear, humid environments, and sports conditions. The breathable dry electrode specifically includes a porous self-adhesive polymer film, conductive lines, and a flexible printed circuit board connector. The porous self-adhesive polymer film is obtained based on a prepolymer solution, which includes urethane diacrylate and monomers in a mass ratio of 17:3. The monomers contain dodecyl acrylate in a mass ratio of 1:2 to acrylic monomers, 2% by mass of photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and 35% by mass of ethyl acetate. The conductive lines are located on the surface or in designated areas of the porous self-adhesive polymer film and are selectively encapsulated based on functional partitions. The encapsulation methods include: complete insulation encapsulation of conductive lines in non-sensing areas; modification of detection points in the sensor area with conductive hydrogel; thick brushing of conductive paste at the ends of the conductive lines to strengthen the contact areas; and fixing the pins of the flexible printed circuit board connector to the strengthened contact areas after dipping them in silver paste. The remaining parts of the flexible printed circuit board connector are then fixed to the porous self-adhesive polymer film containing the electrode using adhesive.

[0050] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or application, should be considered within the scope of protection of the present invention.

[0051] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles of the embodiments, their practical application, or technical improvements in the market, or to enable others skilled in the art to understand the embodiments disclosed herein. The scope of the invention is defined by the appended claims.

Claims

1. A breathable dry electrode that can adhere in both dry and wet states, characterized in that, This includes porous self-adhesive polymer films, conductive lines, and flexible printed circuit board connectors, among which: The porous self-adhesive polymer membrane is obtained based on a prepolymer solution, which includes urethane diacrylate and monomers in a mass ratio of 17:

3. The mass ratio of dodecyl acrylate to acrylic monomers in the monomers is 1:

2. The monomers contain 2% by mass of photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and 35% by mass of ethyl acetate. The conductive lines are located on the surface or in a designated area of ​​a porous self-adhesive polymer film and are selectively encapsulated based on functional partitions. The encapsulation methods include: fully insulating the conductive lines in non-sensing areas; modifying the detection points in the sensor area with conductive hydrogel; and thickly brushing conductive paste onto the ends of the conductive lines to strengthen the contact area. After the pins of the flexible printed circuit board connector are dipped in silver paste, they are fixed to the reinforced contact area. Then, the other parts of the flexible printed circuit board connector are fixed to the porous self-adhesive polymer film with the electrodes already constructed using adhesive.

2. The air-permeable dry electrode according to claim 1, characterized in that, In the preparation process of porous self-adhesive polymer membranes, conductive materials are directly added to the prepolymer solution, so that the conductive phase is distributed in the interior of the polymer matrix, the near-surface region, or the pore wall skeleton during polymerization, curing, and phase separation, so that the polymer film forms a porous self-adhesive polymer membrane with conductive function.

3. The air-permeable dry electrode according to claim 1, characterized in that, The detection point is a circular area with a radius of 2 mm. The width of the conductive line is 1 mm. A 2 mm × 4 mm area is reserved at the end of the conductive line for connecting the flexible printed circuit board connector.

4. A method for preparing a breathable dry electrode that can adhere in both dry and wet states as described in any one of claims 1-3, characterized in that, include: Weigh urethane diacrylate and monomers at a mass ratio of 17:3, wherein the mass ratio of dodecyl acrylate to acrylic monomers in the monomers is 1:

2. Add 2% by mass of photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and 35% by mass of ethyl acetate. Stir until homogeneous to obtain a prepolymer solution. Remove air bubbles from the prepolymer solution by standing or vacuum degassing. Coat the prepolymer solution onto a mold, glass substrate, or release substrate and place it in a UV curing oven for photocuring. Immerse the resulting semi-cured composite film in a poor solvent for extraction and washing. After extraction, dry it in a constant temperature oven at 40–60 °C until constant weight to obtain a porous self-adhesive polymer film based on the prepolymer solution. Conductive lines are constructed on the surface or designated areas of a porous self-adhesive polymer film, and the conductive lines are selectively encapsulated based on functional partitions, including: fully insulating the conductive lines in non-sensing areas; modifying the detection points in the sensor area with conductive hydrogel; thickly brushing conductive paste onto the ends of the conductive lines to strengthen the contact area; then dipping the pins of the flexible printed circuit board connector in silver paste and fixing them to the strengthened contact area; and finally fixing the other parts of the flexible printed circuit board connector to the porous self-adhesive polymer film with constructed electrodes using adhesive to form dry electrodes.

5. The method according to claim 4, characterized in that, Before removing air bubbles from the system by standing or vacuum degassing, the conductive material is directly added to the prepolymer solution, so that the conductive phase is distributed in the interior of the polymer matrix, the near-surface region or the pore wall skeleton during polymerization, curing and phase separation, so that the polymer film forms a porous self-adhesive polymer film with conductive function.

6. The method according to claim 4, characterized in that, The detection point is a circular area with a radius of 2 mm. The width of the conductive line is 1 mm. A 2 mm × 4 mm area is reserved at the end of the conductive line for connecting the flexible printed circuit board connector.

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