Flexible Bioelectric Dry Electrode and Its Preparation Method and Application

Abstract

The present invention discloses a flexible bioelectric dry electrode, a preparation method thereof and an application. The flexible bioelectric dry electrode includes a superhydrophilic layer, a hydrophobic layer and an electrode layer which are sequentially stacked, and the heterogeneous interfaces are tightly bonded through medical adhesive points. The superhydrophilic layer, the hydrophobic layer and the electrode layer all have a porous network structure and are interconnected, so as to form a plurality of heat-moisture transfer capillary channels in the flexible bioelectric dry electrode, ensuring that the electrode can spontaneously transport the sweat on the skin surface to its superhydrophilic outer layer and prevent the backflow of the discharged sweat in the reverse direction. The flexible bioelectric dry electrode provided by the embodiment of the present invention has an ultra-thin thickness, excellent electrical conductivity, good air permeability and unidirectional sweat permeability; it can achieve close adhesion to the complex texture of the skin surface, is comfortable to wear, can resist skin bending and the interference of skin sweat on its electrical properties, and can stably capture high-quality bioelectric signals for a long time under normal and skin sweating conditions.

Description

Technical Field

[0001] The present invention particularly relates to a flexible bioelectric dry electrode, a preparation method thereof, and an application thereof, belonging to the technical field of bioelectric dry electrodes. Background Art

[0002] The electrophysiological signals (such as electromyogram, electrooculogram, electrocardiogram, electroencephalogram, etc.) on the human body surface contain rich and important information about various physiological states of the human body, and have broad application prospects in the fields of health monitoring, sports management, medical care, and human-computer interaction interfaces. For example, through surface electromyogram signals, various neuromuscular diseases (such as muscle fatigue, myasthenia gravis, myotonia, and muscular atrophy, etc.) can be diagnosed, the movements and intensities of athletes' training can be analyzed, and decoding recognition can be performed according to their signal characteristics to achieve the control of prostheses and other motion machinery (such as robots); through electrocardiogram signals, various heart diseases such as arrhythmia, myocardial hypertrophy, and ischemia can be diagnosed and differentiated; through electroencephalogram signals, various brain diseases such as epilepsy, hypoxic-ischemic diseases, and hepatic encephalopathy can be diagnosed and guided in treatment, and external devices can be manipulated by means of the mind in combination with machine learning, etc.

[0003] The electrophysiological signals on the human body surface are generally relatively weak, and the signal amplitude is at the μV to mV level. Therefore, how to non-invasively and continuously collect high-quality electrophysiological signals from the human skin surface is the key to the research. At present, the most commonly used bioelectric electrode in clinical practice is the wet Ag / AgCl gel electrode, which is usually composed of an Ag / AgCl disk electrode, a conductive gel, and an adhesive. It has the characteristics of easy operation and use and excellent signal acquisition quality. However, the Ag / AgCl gel electrode can only be used for a short period of time. For long-term measurement, since the conductive gel in the wet Ag / AgCl gel electrode is used as an ionic electrolyte to transmit signals, the gel will continuously lose water and dry out under environmental conditions, resulting in continuous attenuation of the collected signal quality. In addition, the long-term attachment of the conductive gel to the human body will also cause skin irritation. Based on these problems, researchers and doctors are working hard to seek a new alternative method that can overcome the above problems and have the same diagnostic efficiency to achieve long-term monitoring of physiological electrical signals.

[0004] Bioelectric dry electrodes can directly contact the skin without using an electrolyte or gel as a conductive medium, so their performance will not decline over time, and they have received extensive attention from domestic and foreign researchers. Currently, the bioelectric dry electrodes on the market are generally made of rigid materials (usually precious metals). These electrodes cannot fit well with the rough skin surface, and the interface contact between the electrode and the skin is not stable during movement, which not only results in a low signal-to-noise ratio of the measured electrophysiological signals but also easily induces large dynamic noise.

[0005] To further improve the contact degree between the electrode and the skin surface, flexible bioelectric dry electrodes have emerged. Although significant progress has been made in the development of flexible bioelectric dry electrodes in recent years, most of them use non-porous solid flexible polymers as substrates, such as polydimethylsiloxane (PDMS), polyimide (PI), and polyethylene terephthalate (PET). Although these substrates have a low modulus, their air permeability and sweat permeability are relatively poor, seriously preventing the evaporation of sweat, the emission of volatile organic components from the human skin, and heat diffusion. Therefore, over time, the wearing comfort of the electrode gradually decreases, and in severe cases, it can even induce skin inflammatory reactions (such as skin itching, skin irritation, dry peeling, allergic redness, etc.). In addition, there is also evidence that the failure to drain sweat in time will cause sweat to accumulate between the skin and the electrode, seriously reducing the interfacial adhesion force between the skin and the electrode, resulting in skin-electrode interface delamination or even electrode detachment, leading to obvious artifacts or even signal loss in the collected signals. These above problems greatly limit the ability of flexible bioelectric dry electrodes to read signals for a long time in challenging environments (such as sweating, wound exudation, and high-temperature environments).

[0006] Therefore, the development of flexible bioelectric dry electrodes with high air permeability is of great significance for the long-term monitoring of electrophysiological signals. In recent years, researchers have reported some flexible bioelectric dry electrodes with excellent air permeability. For example, gold nanogrid electrodes, porous graphene electrodes based on porous elastomeric sponges, and serpentine gold electrodes based on microporous silica gels. Although the above existing electrodes have a certain air permeability under normal conditions, their air permeability is still difficult to meet the actual requirements. And when the wearer sweats profusely under hot and humid conditions or after exercise, the above electrodes will be soaked in sweat due to the inability to quickly evaporate sweat, making it impossible for the electrodes to collect stable electrophysiological signals. Summary of the Invention

[0007] The main object of the present invention is to provide a flexible bioelectric dry electrode, its preparation method and application to overcome the deficiencies in the prior art.

[0008] To achieve the foregoing invention object, the technical solutions adopted by the present invention include:

[0009] An embodiment of the present invention provides a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability, which includes a superhydrophilic layer, a hydrophobic layer, and an electrode layer stacked in sequence. The superhydrophilic layer, the hydrophobic layer, and the electrode layer are adhesively fixed to each other through medical adhesive points. The superhydrophilic layer, the hydrophobic layer, and the electrode layer all have a porous network structure, and the porous network structures contained in the superhydrophilic layer, the hydrophobic layer, and the electrode layer are interconnected, so as to form a plurality of heat-moisture transfer capillary channels in the flexible bioelectric dry electrode. The heat-moisture transfer capillary channels penetrate the flexible bioelectric dry electrode along the thickness direction.

[0010] The embodiments of the present invention also provide a preparation method of a flexible bioelectric dry electrode with breathability and unidirectional sweat permeability, which includes:

[0011] Fabricating a super-hydrophilic polymer fiber membrane and a hydrophobic polymer fiber membrane which are stacked by means of electrospinning or 3D printing; and

[0012] Forming a conductive metal network thin film as an electrode layer on the surface of the hydrophobic polymer fiber membrane, and adhesively fixing the super-hydrophilic polymer fiber membrane, the hydrophobic polymer fiber membrane and the conductive metal network thin film through medical adhesive points, wherein the porous network structures contained in the super-hydrophilic polymer fiber membrane, the hydrophobic polymer fiber membrane and the conductive metal network thin film are interconnected, so as to form a plurality of heat-moisture transfer capillary channels in the formed flexible bioelectric dry electrode, and the heat-moisture transfer capillary channels penetrate through the flexible bioelectric dry electrode along the thickness direction.

[0013] The embodiments of the present invention also provide the use of the flexible bioelectric dry electrode described above or the flexible bioelectric dry electrode prepared by the preparation method in the non-invasive detection of electrophysiological signals on the human body surface.

[0014] The embodiments of the present invention also provide a wearable device, which includes the flexible bioelectric dry electrode with breathability and unidirectional sweat permeability described above.

[0015] Compared with the prior art, the advantages of the present invention include:

[0016] 1) A flexible bioelectric dry electrode with breathability and unidirectional sweat permeability provided by the embodiments of the present invention is stacked by multiple layers of porous network thin films with different hydrophilic and hydrophobic properties, and has a large number of heat-moisture transfer capillary channels inside, so as to have excellent breathability and unidirectional sweat permeability;

[0017] 2) In the flexible bioelectric dry electrode with breathability and unidirectional sweat permeability provided by the embodiments of the present invention, the porous network thin films of each layer are stably combined at the interface with the help of electrospinning medical adhesive points, ensuring that the electrode can maintain its structural stability and will not undergo interface delamination during the continuous transport of sweat;

[0018] 3) A flexible bioelectric dry electrode with breathability and unidirectional sweat permeability provided by the embodiments of the present invention has good mechanical properties and electrical durability;

[0019] 4) The preparation method of a flexible bioelectric dry electrode with breathability and unidirectional sweat permeability provided by the embodiments of the present invention has low cost, stable process and good repeatability. Description of the Drawings

[0020] Figure 1It is a schematic structural diagram of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability provided in a typical embodiment of the present invention;

[0021] Figure 2 It is a schematic structural diagram of the preparation process of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability provided in a typical embodiment of the present invention;

[0022] Figure 3 It is a scanning electron microscope image (SEM image) of the cross-section of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability provided in a typical embodiment of the present invention;

[0023] Figure 4 It is a picture of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability conformally attached to the forearm skin provided in a typical embodiment of the present invention;

[0024] Figure 5 It is a bar chart comparing the water vapor transmission rates (WVTR) of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability, a medical tape, and a wet Ag / AgCl gel electrode provided in a typical embodiment of the present invention;

[0025] Figure 6a 、 Figure 6b 、 Figure 6c They are respectively the unidirectional sweat permeability characterization test diagrams of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability provided in a typical embodiment of the present invention;

[0026] Figure 7a 、 Figure 7b They are respectively the normalized resistance curves of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability under different bending curvatures and performing bending-release cycles under a specific bending curvature provided in a typical embodiment of the present invention;

[0027] Figure 8a 、 Figure 8b 、 Figure 8c 、 Figure 8d They are respectively the electrocardiogram signal curves collected before and after sweating of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability and a wet Ag / AgCl gel electrode provided in a typical embodiment of the present invention. Detailed implementation manners

[0028] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. The following will further explain the technical solution, its implementation process, principles, etc.

[0029] The present invention mainly aims at the problems existing in the existing flexible bioelectric dry electrodes, such as low air permeability, poor long-term wearing comfort, low anti-interference performance against mechanical deformations such as skin bending, and obvious attenuation or even signal loss of the collected signal quality under sweating conditions. A flexible bioelectric dry electrode with excellent air permeability and unidirectional sweat permeability, which allows the timely penetration and rapid evaporation of body surface gas and sweat, is insensitive to mechanical deformations such as skin bending, can stably collect high-quality electrophysiological signals for a long time under normal conditions and skin sweating conditions, and a preparation method thereof are provided.

[0030] A flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability provided by an embodiment of the present invention is stacked by multiple layers of porous network films, from top to bottom in sequence: a super-hydrophilic polymer fiber film (super-hydrophilic layer), a medical adhesion point, a hydrophobic polymer fiber film (hydrophobic layer), a patterned conductive metal network film (electrode layer), and a medical adhesion point, wherein the heterogeneous interfaces of each layer of film are stably combined with the assistance of medical glue.

[0031] The air permeability of the bioelectric dry electrode with air permeability and unidirectional sweat permeability provided by an embodiment of the present invention is better than that of medical-grade tape, and can timely export the sweat generated on the skin surface and prevent the sweat from permeating in the reverse direction. The resistance of the electrode can maintain stability during the processes of skin bending and sweat penetration, and the signal quality of the electromyogram and electrocardiogram collected before and after sweating basically remains unchanged.

[0032] An embodiment of the present invention adopts the method of electrospinning combined with vacuum filtration to construct a flexible bioelectric dry electrode with ultra-light, ultra-thin, super-soft, high air permeability, and unidirectional sweat permeability, continuously transports sweat from the skin-electrode interface to the external environment and enables the discharged sweat to be quickly evaporated, realizing the long-term stable monitoring of high-quality electrophysiological signals under normal (non-sweating) and sweating conditions. And it provides a preparation method for the flexible bioelectric dry electrode with low cost, stable process, and good repeatability.

[0033] An embodiment of the present invention provides a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability, which includes a super-hydrophilic layer, a hydrophobic layer, and an electrode layer stacked in sequence. The super-hydrophilic layer, the hydrophobic layer, and the electrode layer are adhesively fixed to each other through medical adhesion points. The super-hydrophilic layer, the hydrophobic layer, and the electrode layer all have a porous network structure, and the porous network structures contained in the super-hydrophilic layer, the hydrophobic layer, and the electrode layer are interconnected, thereby forming a plurality of heat-moisture transfer capillary channels in the flexible bioelectric dry electrode. The heat-moisture transfer capillary channels penetrate through the flexible bioelectric dry electrode along the thickness direction.

[0034] In a specific embodiment, the electrode layer, the hydrophobic layer, and the super-hydrophilic layer are arranged in sequence in a direction away from the skin surface.

[0035] In a specific embodiment, the superhydrophilic layer and the hydrophobic layer, and the hydrophobic layer and the electrode layer are fixedly connected through a plurality of discrete medical adhesive points.

[0036] In a specific embodiment, the medical adhesive points include solvent-based adhesives.

[0037] In a specific embodiment, the medical adhesive points include oil-soluble adhesives.

[0038] In a specific embodiment, the material of the medical adhesive points includes acrylate pressure-sensitive adhesive, BC-1 type medical pressure-sensitive adhesive, or silicone pressure-sensitive adhesive, etc.

[0039] In a specific embodiment, the medical adhesive points cannot be formed by electrospinning.

[0040] In a specific embodiment, the electrode layer can conformally contact the skin surface.

[0041] In a specific embodiment, the flexible bioelectric dry electrode can conformally adhere to the skin surface. It can be understood that the flexible bioelectric dry electrode can be directly attached to the skin surface, and the surface of the flexible bioelectric dry electrode conforms to the microstructures on the human body surface.

[0042] In a specific embodiment, the thickness of the flexible bioelectric dry electrode is 5 - 20 μm.

[0043] In a specific embodiment, the superhydrophilic layer includes a superhydrophilic polymer fiber membrane.

[0044] In a specific embodiment, the diameter of the superhydrophilic polymer fibers contained in the superhydrophilic polymer fiber membrane is 800 - 1400 nm.

[0045] In a specific embodiment, the porosity of the superhydrophilic polymer fiber membrane is > 75%, and the pore diameter of the contained pores is 2 - 14 μm.

[0046] In a specific embodiment, the thickness of the superhydrophilic polymer fiber membrane is 3 - 15 μm.

[0047] In a specific embodiment, the material of the superhydrophilic polymer fiber membrane includes polyacrylonitrile / silica, polyacrylic acid, or cellulose, etc.

[0048] In a specific embodiment, the hydrophobic layer includes a hydrophobic polymer fiber membrane.

[0049] In a specific embodiment, the diameter of the hydrophobic polymer fibers contained in the hydrophobic polymer fiber membrane is 1800 - 2800 nm.

[0050] In a specific embodiment, the porosity of the hydrophobic polymer fiber membrane is >80%, and the pore diameter of the contained mesh holes is 6 - 20 μm.

[0051] In a specific embodiment, the thickness of the hydrophobic polymer fiber membrane is 2 - 6 μm.

[0052] Preferably, the material of the hydrophobic polymer fiber membrane includes polyurethane, polydimethylsiloxane, polyethylene, etc.

[0053] In a specific embodiment, the electrode layer includes a conductive network thin film, preferably a conductive metal network thin film.

[0054] In a specific embodiment, the conductive metal network thin film is formed by the interweaving of metal nanowires. The diameter of the metal nanowires is 30 - 100 nm, and the aspect ratio is >3000.

[0055] In a specific embodiment, the porosity of the conductive metal network thin film is >90%, and the pore diameter of the contained mesh holes is 4 - 16 μm.

[0056] In a specific embodiment, the thickness of the conductive metal network thin film is 30 - 300 nm.

[0057] In a specific embodiment, the metal nanowires include silver nanowires, gold nanowires, copper nanowires, etc.

[0058] In a specific embodiment, the sheet resistance of the electrode layer is 2 - 15 Ω / sq -1 。

[0059] The embodiment of the present invention also provides a preparation method of a flexible bioelectric dry electrode with breathability and unidirectional sweat permeability, which includes:

[0060] Using electrospinning or 3D printing to fabricate a superhydrophilic polymer fiber membrane and a hydrophobic polymer fiber membrane arranged in layers; and

[0061] Forming a conductive metal network thin film as the electrode layer on the surface of the hydrophobic polymer fiber membrane, and adhesively bonding and fixing the superhydrophilic polymer fiber membrane, the hydrophobic polymer fiber membrane, and the conductive metal network thin film through medical adhesive points. The porous network structures contained in the superhydrophilic polymer fiber membrane, the hydrophobic polymer fiber membrane, and the conductive metal network thin film are interconnected, so as to form a plurality of heat - moisture transfer capillary channels in the formed flexible bioelectric dry electrode, and the heat - moisture transfer capillary channels penetrate through the flexible bioelectric dry electrode along the thickness direction.

[0062] In a specific embodiment, the preparation method is characterized in that it specifically includes:

[0063] Dissolve the superhydrophilic polymer precursor in an organic solvent to form a superhydrophilic polymer precursor solution, and use electrospinning or 3D printing to fabricate a superhydrophilic polymer fiber membrane with a porous network structure from the superhydrophilic polymer precursor solution.

[0064] In a specific embodiment, the concentration of the superhydrophilic polymer precursor solution is 10 - 25 wt%.

[0065] In a specific embodiment, the superhydrophilic polymer precursor includes polyacrylonitrile / silica, polyacrylic acid, cellulose, etc.

[0066] In a specific embodiment, the preparation method further includes: hydrolyzing the superhydrophilic polymer fiber membrane in an alkaline solution under a water bath condition of 40 - 80 °C for 5 - 30 min.

[0067] In a specific embodiment, the concentration of the alkaline solution is 1.5 - 3.5 mol L ～1 。

[0068] In a specific embodiment, the preparation method specifically includes: dissolving a hydrophobic polymer precursor in an organic solvent to form a hydrophobic polymer precursor solution, and using electrospinning or 3D printing to fabricate a hydrophobic polymer fiber membrane with a porous network structure from the hydrophobic polymer precursor solution.

[0069] In a specific embodiment, the concentration of the hydrophobic polymer precursor solution is 10 - 30 wt%.

[0070] In a specific embodiment, the hydrophobic polymer precursor includes polyurethane, polydimethylsiloxane, polyethylene, etc.

[0071] In a specific embodiment, the preparation method specifically includes: mixing metal nanowires with a solvent to form a metal nanowire solution, and using vacuum filtration to fabricate a conductive metal network thin film with a porous network structure from the metal nanowire solution.

[0072] In a specific embodiment, the concentration of the metal nanowire solution is 5 - 20 μg mL ～1 。

[0073] In a specific embodiment, the metal nanowires include silver nanowires, gold nanowires, copper nanowires, etc.

[0074] In a specific embodiment, the preparation method further includes: fabricating adhesive attachment points at the interface between the hydrophilic polymer fiber membrane and the hydrophobic polymer fiber membrane and / or on the surface of the conductive metal network thin film facing away from the hydrophobic polymer fiber membrane.

[0075] In a specific embodiment, the preparation method specifically includes: diluting a solvent-based adhesive into a solvent-based adhesive solution, and using electrospinning or 3D printing to form the medical adhesive points with the solvent-based adhesive solution.

[0076] In a specific embodiment, the concentration of the solvent-based adhesive solution is 0.45 - 0.75 g / mL ～1 .

[0077] In a specific embodiment, the solvent-based adhesive is an oil-soluble adhesive.

[0078] In a specific embodiment, the material of the solvent-based adhesive includes acrylate pressure-sensitive adhesive, BC-1 type medical pressure-sensitive adhesive, or silicone pressure-sensitive adhesive, etc.

[0079] In a specific embodiment, the preparation method specifically includes:

[0080] 1) Dissolving a super-hydrophilic polymer precursor in an organic solvent to form a super-hydrophilic polymer precursor solution with a concentration of 10 - 25 wt%, and the super-hydrophilic polymer precursor includes polyacrylonitrile / silica, polyacrylic acid, or cellulose;

[0081] Placing the super-hydrophilic polymer precursor solution in a syringe of an electrospinning device, setting the distance between the metal spinneret of the syringe and the receiving substrate placed on a roller to 10 - 20 cm, and applying a high-voltage electrostatic field with a voltage of 9.5 - 13.5 kV between the metal spinneret of the syringe and the receiving substrate placed on a roller, so as to electrospin a super-hydrophilic polymer fiber membrane with a porous network structure on the receiving substrate; wherein, the diameter of the metal spinneret is 0.3 - 0.7 mm, the rotation speed of the roller is 50 - 150 rpm, and the electrospinning time is 10 - 120 min;

[0082] 2) Providing a solvent-based adhesive solution with a concentration of 0.45 - 0.75 g / mL ～1 The solvent-based adhesive solution contains a solvent-based adhesive including acrylate pressure-sensitive adhesive, BC-1 type medical pressure-sensitive adhesive, or silicone pressure-sensitive adhesive;

[0083] Place the solvent-based adhesive solution in the syringe of the electrospinning equipment. Fix the superhydrophilic polymer fiber membrane prepared in step 1) on the roller. Apply a high-voltage electrostatic field with a voltage of 8.5 - 12.5 kV between the metal spinneret of the syringe and the superhydrophilic polymer fiber membrane, so as to deposit medical adhesion points on the superhydrophilic polymer fiber membrane to enhance the interfacial adhesion with the hydrophobic polymer fiber membrane. Among them, the diameter of the metal spinneret is 0.3 - 0.7 mm, the rotation speed of the roller is 30 - 100 rpm, and the electrospinning time is 10 - 70 min;

[0084] 3) Dissolve the hydrophobic polymer precursor in an organic solvent to form a hydrophobic polymer precursor solution with a concentration of 10 - 30 wt%. The hydrophobic polymer precursor includes polyurethane, polydimethylsiloxane or polyethylene;

[0085] Place the hydrophobic polymer precursor solution in the syringe of the electrospinning equipment. Set the distance between the metal spinneret of the syringe and the receiving substrate placed on the roller to 10 - 20 cm. Fix the composite fiber membrane prepared in step 2) on the roller. And apply a high-voltage electrostatic field with a voltage of 8.5 - 12.5 kV between the metal spinneret of the syringe and the composite fiber membrane placed on the roller, so as to electrospin a hydrophobic polymer fiber membrane with a porous network structure on the composite fiber membrane. Among them, the diameter of the metal spinneret is 0.3 - 0.7 mm, the rotation speed of the roller is 50 - 150 rpm, and the electrospinning time is 10 - 70 min;

[0086] 4) Mix the metal nanowires with a solvent to form a metal nanowire solution with a concentration of 5 - 20 μg mL ～1 . The metal nanowires include silver nanowires, gold nanowires or copper nanowires. The aspect ratio of the metal nanowires is > 3000. The solvent includes water;

[0087] Use the hydrophilic microporous membrane as the support layer and place it at the bottom of the composite fiber membrane prepared in step 3). Use the prepared composite fiber membrane as the filter membrane and place it on the all-glass sand core filtration device. Pour 10 - 60 mL of the metal nanowire dispersion on the filter membrane. Use a vacuum pump to evacuate to 0.02 - 0.08 MPa. Based on the pore size screening principle of the filter membrane, the ultra-large aspect ratio metal nanowires in the metal nanowire dispersion are uniformly retained on the surface of the hydrophobic polymer fiber membrane of the composite fiber membrane instead of penetrating into the interior of the nanofiber-based flexible bio-dry electrode, so as to form a conductive metal network thin film on the surface of the hydrophobic polymer fiber membrane;

[0088] 5) Dry the composite fiber film prepared in step 4) at 60 - 100 °C for 2 - 5 min, then fix it on a roller. Place the solvent-based adhesive solution in step 2) into the syringe of the electrospinning device, and apply a high-voltage electrostatic field with a voltage of 8.5 - 12.5 kV between the metal spinneret of the syringe and the composite fiber film, so as to deposit medical adhesive points on the conductive metal network film, thereby stably adhering the conductive metal network film to the surface of the hydrophobic polymer fiber membrane; wherein, the diameter of the metal spinneret is 0.3 - 0.7 mm, the rotation speed of the roller is 30 - 100 rpm, and the electrospinning time is 10 - 70 min, finally obtaining a flexible bioelectric dry electrode with breathability and unidirectional sweat permeability.

[0089] It should be noted that the organic solvents used in the present invention can be solvents that can effectively dissolve and disperse the superhydrophilic polymer precursor and the hydrophobic polymer precursor. For example, the organic solvent can be DMF (N,N-dimethylformamide), etc.

[0090] The embodiment of the present invention also provides the use of the flexible bioelectric dry electrode with breathability and unidirectional sweat permeability or the flexible bioelectric dry electrode prepared by the preparation method in the non-invasive detection of electrophysiological signals on the human body surface.

[0091] The embodiment of the present invention also provides a wearable device, which includes the flexible bioelectric dry electrode with breathability and unidirectional sweat permeability.

[0092] In a specific embodiment, the wearable device includes an electrophysiological signal monitoring device.

[0093] The following will further explain the technical solution, its implementation process and principle in combination with the drawings and specific implementation cases. Unless otherwise specified, the electrospinning device, vacuum filtration device, etc. in the embodiments of the present invention can all be those known to those skilled in the art.

[0094] Please refer to Figure 1 , a flexible bioelectric dry electrode with breathability and unidirectional sweat permeability, which successively includes a superhydrophilic layer, a hydrophobic layer and an electrode layer (or called a conductive layer) from top to bottom. Among them, the superhydrophilic layer is at least used to continuously suck out the sweat on the skin surface; the hydrophobic layer is at least used to keep the skin surface dry; the conductive layer is at least used to collect the electrophysiological signals on the skin surface;

[0095] Moreover, the super-hydrophilic layer, the hydrophobic layer, and the electrode layer all have a porous network structure, and the porous network structures contained in the super-hydrophilic layer, the hydrophobic layer, and the electrode layer are interconnected, thereby forming a breathable and one-way moisture-permeable thermal-humidity transfer capillary channel between the super-hydrophilic layer, the hydrophobic layer, and the electrode layer, so as to continuously export sweat from the skin surface without sweat permeating in the reverse direction (the reverse direction is the direction from the super-hydrophilic layer to the electrode layer).

[0096] In an embodiment of the present invention, the interface bonding force between layers of the flexible bioelectric dry electrode is enhanced by medical adhesive points formed by electrospinning, so as to achieve good structural stability and electrical stability of the electrode during the continuous penetration of sweat from the electrode-hydrophobic layer to the super-hydrophilic layer and during the bending of the skin.

[0097] In an embodiment of the present invention, the super-hydrophilic layer is a super-hydrophilic polymer fiber membrane, the thickness of the super-hydrophilic polymer fiber membrane is 3 - 15 μm, the diameter of the super-hydrophilic polymer fibers contained in the super-hydrophilic polymer fiber membrane is 800 - 1400 nm, the porosity of the super-hydrophilic polymer fiber membrane > 75%, and the pore diameter of the contained mesh holes is 2 - 14 μm. Among them, the material of the super-hydrophilic polymer fiber membrane includes polyacrylonitrile / silica, polyacrylic acid, or cellulose, etc.

[0098] In an embodiment of the present invention, the hydrophobic layer includes a hydrophobic polymer fiber membrane, the thickness of the hydrophobic polymer fiber membrane is 2 - 6 μm; the diameter of the hydrophobic polymer fibers contained in the hydrophobic polymer fiber membrane is 1800 - 2800 nm; the porosity of the hydrophobic polymer fiber membrane > 80%, and the pore diameter of the contained mesh holes is 6 - 20 μm. The material of the hydrophobic polymer fiber membrane includes polyurethane, polydimethylsiloxane, or polyethylene, etc.

[0099] In an embodiment of the present invention, the electrode layer includes a conductive metal network thin film, the thickness of the conductive metal network thin film is 30 - 300 nm, the conductive metal network thin film is formed by the interweaving of metal nanowires, the diameter of the metal nanowires is 30 - 100 nm, the aspect ratio is > 3000, the porosity of the conductive metal network thin film > 90%, and the pore diameter of the contained mesh holes is 4 - 16 μm. Among them, the metal nanowires include silver nanowires, gold nanowires, or copper nanowires, etc.

[0100] In an embodiment of the present invention, the adhesive points include solvent-based adhesives. Preferably, the adhesive points include oil-soluble adhesives. Among them, the material of the adhesive points includes acrylate pressure-sensitive adhesives, BC-1 type medical pressure-sensitive adhesives, or silicone pressure-sensitive adhesives, etc.

[0101] Please refer to Figure 2, A preparation method of a flexible bioelectric dry electrode with breathability and unidirectional sweat permeability, comprising the following process steps:

[0102] 1) Uniformly disperse silica (SiO2, 2 wt%) in N,N-dimethylformamide (DMF, 90 wt%) by magnetic stirring and ultrasonic treatment, and then add polyacrylonitrile (PAN, 8 wt%) and continuously stir to ensure its complete dissolution, thereby obtaining a PAN-SiO2 solution;

[0103] Transfer the obtained PAN-SiO2 solution to a 5 mL plastic syringe with a metal needle (the aforementioned metal spinneret, the same hereinafter, with an inner diameter of 0.5 mm). Fix the aluminum foil (i.e., the aforementioned receiving substrate) on the roller, set the rotation speed of the roller to 100 rpm, set the distance between the metal needle of the syringe and the aluminum foil placed on the roller to 15 cm, and apply a high-voltage electrostatic field with a voltage of 11.0 kV between the metal needle of the syringe and the aluminum foil placed on the roller, and electrospin for 80 min to prepare a PAN-SiO2 nanofiber membrane with a porous network structure on the surface of the aluminum foil;

[0104] To further increase the wettability of the fiber membrane, place the obtained PAN-SiO2 fiber membrane in a 2.5 M NaOH solution (C2H5OH∶H2O = 7∶3 v / v) and hydrolyze it at a temperature of 50 °C for 15 min. Rinse the obtained hydrolyzed membrane (HPAN fiber membrane, superhydrophilic layer) with distilled water until neutral, and then place it in a vacuum oven at 70 °C for drying;

[0105] 2) Dilute the oil-soluble acrylate pressure-sensitive adhesive by 1.5 times, transfer the diluted oil-soluble acrylate pressure-sensitive adhesive to a 5 mL plastic syringe with a metal needle (inner diameter of 0.5 mm). Fix the HPAN fiber membrane prepared in step (1) on the roller, set the rotation speed of the roller to 50 rpm, apply a high-voltage electrostatic field with a voltage of 10.6 kV between the metal needle of the syringe and the HPAN fiber membrane, and electrospin for 40 min to uniformly deposit medical adhesive attachment points on the surface of the superhydrophilic HPAN fiber membrane to enhance the interfacial adhesion with the hydrophobic PU fiber membrane;

[0106] 3) Completely dissolve polyurethane (PU, 22 wt%) in DMF (78 wt%) to obtain a PU solution;

[0107] The obtained PU solution was transferred into a 5 mL plastic syringe with a metal needle (with an inner diameter of 0.5 mm), and the composite fiber membrane prepared in step (3) was immediately fixed on the roller, the rotation speed of the roller was set to 100 rpm, the distance between the metal needle of the syringe and the receiving substrate placed on the roller was set to 15 cm, and a high-voltage electrostatic field with a voltage of 10.3 kV was applied between the metal needle of the syringe and the composite fiber membrane placed on the roller, and electrospinning was performed for 40 minutes, thereby uniformly depositing a PU nanofiber membrane (hydrophobic layer) on the surface of the composite fiber membrane;

[0108] 4) Dilute the silver nanowire / water dispersion (AgNW diameter is 50nm, length is 100-200μm) to 10μgmL -1 The concentration of the composite fiber membrane prepared in step 3) is set at a hydrophilic PES microporous filter membrane as a support layer, and the prepared composite fiber membrane is placed on a full glass sand core filter device as a filter membrane. 40 mL of the ultra-large aspect ratio silver nanowire / water dispersion is poured on the filter membrane, and the air is evacuated to 0.08 MPa with a vacuum pump. Based on the pore size screening principle of the filter membrane, the ultra-large aspect ratio silver nanowires in the silver nanowire / water dispersion are uniformly retained on the surface of the hydrophobic polymer fiber membrane of the composite fiber membrane instead of penetrating into the interior of the flexible biological dry electrode based on nanofibers, thereby forming a uniformly distributed AgNW conductive network film (electrode layer) on the surface of the hydrophobic polymer fiber membrane;

[0109] 5) The composite fiber membrane prepared in step 4) is placed at 70° C. for drying for 2 to 5 minutes, and then fixed on a roller, and the oil-soluble acrylic pressure-sensitive adhesive diluted in step 2) is used as a casting liquid, the rotation speed of the rotating shaft is set to 50 rpm, and a high-voltage electrostatic field with a voltage of 10.6 kV is applied between the metal needle of the syringe and the composite fiber membrane placed on the roller, and electrospinning is performed for 40 minutes, thereby depositing medical adhesive adhesion points on the AgNW conductive network film, so as to stably adhere the AgNW conductive network film to the surface of the hydrophobic PU fiber membrane, and finally obtain a flexible bioelectric dry electrode with stable heterogeneous interface bonding, air permeability and unidirectional sweat permeability.

[0110] The inventors of this case have conducted characterization tests on the prepared flexible bioelectric dry electrode (hereinafter referred to as electrode), wherein the cross-sectional SEM image of the flexible bioelectric dry electrode obtained in the embodiment of the present invention is as follows: Figure 3 As shown by Figure 3It can be seen that the flexible bioelectric dry electrode is composed of multiple layers of porous network films stacked together. Under a typical condition, the thickness of the flexible bioelectric dry electrode prepared in the embodiment of the present invention is only 15 μm. The electrode thickness can be further reduced by reducing the electrospinning time of each layer. In addition, the presence of medical glue can be clearly seen on the surface of AgNWs and at the interface between AgNWs and the PU nanofiber membrane.

[0111] A photograph of the flexible bioelectric dry electrode obtained in the embodiment of the present invention attached to the skin of a human forearm is as Figure 4 shown, and from Figure 4 it can be seen that in the electrode-covered area, the irregular topological texture of the epidermis is clearly visible, indicating that the electrode has achieved conformal contact with the human skin, which is of great benefit to improving the signal-to-noise ratio and stability of the collected electrophysiological signals.

[0112] The breathability is evaluated by measuring the weight loss of water in a bottle sealed by the target sample. The inventors of this case placed the bottles covered with different samples (the flexible bioelectric dry electrode provided in the embodiment of the present invention, commercial medical tape 1 (3M, porous medical tape), commercial medical tape 2 (ZhenDe, cotton-type medical tape), and commercial Ag / AgCl gel electrode) at the same temperature and humidity for one week, and calculated the water vapor transmission rate (WVTR) based on the daily water loss. The results are as Figure 5 shown, Figure 5 showing that the WVTR of the flexible bioelectric dry electrode provided in the embodiment of the present invention is comparable to that of the open system, and is 15%, 129%, and 697% higher than commercial medical tape 1 (3M, porous medical tape), commercial medical tape 2 (ZhenDe, cotton-type medical tape), and commercial Ag / AgCl gel electrode respectively. Thus, it can be confirmed that the flexible bioelectric dry electrode provided in the embodiment of the present invention has excellent breathability.

[0113] The wettability difference between the superhydrophilic layer and the hydrophobic layer endows the flexible bioelectric dry electrode with directional water transport performance. As Figure 6a shown, when water droplets are added to the electrode layer - hydrophobic layer surface, the water quickly penetrates from the electrode layer - hydrophobic layer side to the superhydrophilic layer side; when the electrode is flipped so that the superhydrophilic layer side is upward and water droplets are added to the superhydrophilic layer surface, the water droplets added to the superhydrophilic layer side immediately spread instead of penetrating from the superhydrophilic layer side to the electrode layer - hydrophobic layer side (as Figure 6b ); in practical applications, absorbing sweat from the skin surface is against gravity. Therefore, the directional water transport performance of the electrode provided in the embodiment of the present invention under anti-gravity conditions was further evaluated. As expected, once the water contacts the bottom electrode layer - hydrophobic layer surface, it will penetrate upward to reach the top superhydrophilic layer (as Figure 6c shown); from Figure 6a , Figure 6b ,Figure 6c These results clearly show that the multi-layer stacked composite fiber membranes with different wettabilities have the ability of spontaneous directional water transport, and the discharged sweat will not re-permeate in the reverse direction.

[0114] Stability and robustness are also crucial for the long-term use of electrodes. Therefore, the inventors of this case tested the resistance changes of the flexible bioelectric dry electrodes provided in the embodiments of the present invention during bending and cyclic bending: First, the flexible bioelectric dry electrodes were self-adhered to a 100-μm-thick PET substrate, clamped and bent by a stepping motor, and the normalized resistances of the electrodes corresponding to bending at different bending curvatures and performing bending-release cycles at a specific bending curvature are as Figure 7a 、 Figure 7b shown; as the bending curvature increases, the resistance of the electrode remains almost unchanged. Even when the maximum bending curvature is 500 m -1 , the resistance change is only 1.1% (as Figure 7a ); in addition, Figure 7b The long-term test results in prove that the flexible bioelectric dry electrodes in the embodiments of the present invention have excellent anti-cyclic bending durability. After bending 4200 times at a bending curvature of 333 m -1 , the resistance of SRCN only increased by 1.5%.

[0115] To clarify the advantages of the flexible bioelectric dry electrodes in electrophysiological signal monitoring, the inventors of this case also tested the influence of skin sweating on electrocardiogram signals: The electrocardiogram signals were collected using the flexible bioelectric dry electrodes and Ag / AgCl gel electrodes in the embodiments of the present invention before and during sweating, and the results are respectively as Figure 8a 、 Figure 8b 、 Figure 8c 、 Figure 8d shown. Generally speaking, a typical electrocardiogram waveform includes three characteristic peaks, namely the "P" wave, the "QRS" complex, and the "T" wave, as Figure 8a 、 Figure 8b 、 Figure 8c 、 Figure 8d marked. A ratio of the amplitudes of the T and R waves (T / R ratio) close to 1 / 3 means high signal quality. The T / R ratios of the electrocardiogram signals collected by the Ag / AgCl gel electrodes and the flexible bioelectric dry electrodes before sweating are 0.305 and 0.332 respectively (see Figure 8a and 8c ), while after sweating, the T / R ratios become 0.230 and 0.310 respectively ( Figure 8b and 8d ). Thus, it can be seen that the influence of skin sweating on the T / R ratio of the flexible bioelectric dry electrodes is negligible compared with that of the Ag / AgCl gel electrodes.

[0116] On the other hand, the inventors of this case also observed the changes in the baseline of the electrocardiogram signal. The results showed that before sweating, the electrocardiogram signal collected by the Ag / AgCl gel electrode was highly stable, with a baseline drift of only 0.005 mV( Figure 8a ). However, after sweating, the electrocardiogram signal fluctuated significantly, rising and falling vertically, and the corresponding baseline drift rapidly increased to 0.230 mV( Figure 8b ). It is worth noting that the baseline drift value in the electrocardiogram collected by the flexible bioelectric dry electrode before and after sweating remained basically unchanged, with a change as low as 0.003 mV( Figure 8c and 8d ). The above experimental results confirm that the bioelectric dry electrode provided by the embodiments of the present invention can stably collect high-quality electrophysiological signals under normal and sweating conditions.

[0117] A flexible bioelectric dry electrode with breathability and unidirectional sweat permeability provided by an embodiment of the present invention is a unidirectional sweat-permeable epidermal electrode, mainly used for collecting bioelectric signals on the skin surface. And because it has unidirectional sweat permeability, when sweating, it can timely export the sweat generated on the skin surface and prevent the penetration of sweat in the reverse direction. Therefore, the flexible bioelectric dry electrode can still accurately collect bioelectric signals when the skin is sweating (the signal quality of the electromyogram and electrocardiogram collected before and after sweating remains basically unchanged, which could not be achieved before), while the flexible electrodes in the prior art can only achieve efficient capture and collection of water droplets.

[0118] A flexible bioelectric dry electrode with breathability and unidirectional sweat permeability provided by an embodiment of the present invention adds an electrospun medical glue layer (that is, the bonding point) between two heterogeneous fiber membranes, which not only enhances the bonding force between the interfaces of the heterogeneous fiber membranes (the improvement of the bonding strength between the two heterogeneous fiber membranes was not available before); but also enables the AgNW to be cold-welded to the fiber membrane (the AgNW nodes are fixed by the electrospun bonding point), so that the flexible bioelectric dry electrode keeps its resistance unchanged during bending and liquid penetration processes (although it seems common to use metal nanowires as the electrode layer, in the present invention, after preparing the electrode layer, an electrospun medical glue adhesion point layer is added to make the AgNW adhered or cold-welded to the fiber membrane, so as to keep its resistance stable during bending and liquid penetration processes).

[0119] A flexible bioelectric dry electrode with breathability and unidirectional sweat permeability provided by an embodiment of the present invention is thinner (5 - 20 microns), can be conformally attached and self-adhered to the skin surface (the electrode can be directly attached to the human body surface and conform to the skin micro-structure), and the flexible bioelectric dry electrode provided by the embodiments of the present invention has good breathability, and its breathability is better than that of the medical gel electrode and better than that of the medical-grade tape (it does not affect the skin homeostasis function when worn).

[0120] A flexible bioelectric dry electrode provided by an embodiment of the present invention is stacked by multi-layer porous network films with different hydrophilic and hydrophobic properties, and has a large number of thermal-humidity transfer capillary channels inside, so it has excellent air permeability and unidirectional sweat permeability, enabling sweat, volatile organic components and heat generated on the skin surface to diffuse to the outside in a timely manner, and the discharged sweat will not re-permeate in the reverse direction, so that the skin surface can continuously maintain a dry state, is comfortable to wear, and is suitable for long-term monitoring of electrophysiological signals in normal environments and harsh environments (such as sweating, wound exudation and high-temperature environments).

[0121] In a flexible bioelectric dry electrode provided by an embodiment of the present invention, the multi-layer porous network films are stably bonded at the interface with the help of electrospun medical adhesive points, ensuring that the electrode can maintain its structural stability during the continuous transport of sweat without interface delamination. In addition, in a flexible bioelectric dry electrode provided by an embodiment of the present invention, a patterned conductive metal network film is adhered to a hydrophobic polymer fiber membrane, avoiding the problem that its electrical properties change due to slippage when subjected to external stress. Therefore, the electrode has good mechanical properties and electrical durability.

[0122] A flexible bioelectric dry electrode provided by an embodiment of the present invention has an ultra-thin thickness, excellent electrical conductivity, excellent air permeability and unidirectional sweat permeability; it can achieve close adhesion to the complex texture of the skin surface, is comfortable to wear, can resist skin bending and the interference of skin sweat on the electrical properties of the electrode, and can stably capture high-quality bioelectric signals for a long time under normal and sweating conditions. Moreover, the preparation method of a flexible bioelectric dry electrode provided by an embodiment of the present invention has low cost, stable process and good repeatability.

[0123] It should be understood that the above embodiments are only for explaining the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability, characterized in that Comprising: 1) Dissolve a superhydrophilic polymer precursor in an organic solvent to form a superhydrophilic polymer precursor solution with a concentration of 10-25 wt%, where the superhydrophilic polymer precursor includes polyacrylonitrile / silica, polyacrylic acid, or cellulose. Use electrospinning or 3D printing to fabricate a superhydrophilic polymer fiber membrane with a porous network structure from the superhydrophilic polymer precursor solution; 2) Provide a solvent-based adhesive solution with a concentration of 0.45~0.75 g / mL -1 The solvent-based adhesive contained in the solvent-based adhesive solution includes acrylate pressure-sensitive adhesive, BC-1 type medical pressure-sensitive adhesive or silicone pressure-sensitive adhesive. The solvent-based adhesive solution is deposited on the super-hydrophilic polymer fiber membrane by electrospinning or 3D printing to form a plurality of discrete medical adhesion points; 3) Dissolve a hydrophobic polymer precursor in an organic solvent to form a hydrophobic polymer precursor solution with a concentration of 10-30 wt%, where the hydrophobic polymer precursor includes polyurethane, polydimethylsiloxane, or polyethylene. Use electrospinning or 3D printing to fabricate a hydrophobic polymer fiber membrane with a porous network structure on the superhydrophilic polymer fiber membrane. The hydrophobic polymer fiber membrane and the superhydrophilic polymer fiber membrane are bonded and fixed through medical adhesive attachment points; 4) Mix the metal nanowires with a solvent to form a metal nanowire solution with a concentration of 5 - 20 μg mL -1 . The metal nanowires include silver nanowires, gold nanowires or copper nanowires. The aspect ratio of the metal nanowires > 3000. The solvent includes water. By means of vacuum filtration, the metal nanowires with an ultra-large aspect ratio in the metal nanowire dispersion are uniformly retained on the surface of the hydrophobic polymer fiber membrane, thereby forming a conductive metal network thin film, and the conductive metal network thin film can conformally contact the skin surface; 5) Provide the solvent-based adhesive solution in step 2). Use electrospinning or 3D printing to deposit the solvent-based adhesive solution on the conductive metal network thin film to form a plurality of discretely distributed medical adhesive attachment points. The conductive metal network thin film and the hydrophobic polymer fiber membrane are bonded and fixed through the plurality of discretely distributed medical adhesive attachment points; The porous network structures contained in the superhydrophilic polymer fiber membrane, hydrophobic polymer fiber membrane, and conductive metal network thin film are interconnected, thereby forming a plurality of heat-moisture transfer capillary channels within the formed flexible bioelectric dry electrode. The heat-moisture transfer capillary channels penetrate the flexible bioelectric dry electrode in the thickness direction, and the thickness of the flexible bioelectric dry electrode is 5-20 μm.

2. The preparation method according to claim 1, wherein, The preparation method further includes: hydrolyzing the superhydrophilic polymer fiber membrane in an alkaline solution under a water bath condition of 40-80 °C for 5-30 min.

3. The preparation method according to claim 2, characterized in that: The concentration of the alkaline solution is 1.5 to 3.5 mol / L -1 .

4. The preparation method according to claim 1, wherein: The solvent-based adhesive solution is obtained by diluting a solvent-based adhesive, and the solvent-based adhesive is an oil-soluble adhesive.

5. The preparation method according to claim 1, wherein: Step 1) specifically includes: Place the superhydrophilic polymer precursor solution in the syringe of an electrospinning device. Set the distance between the metal spinneret of the syringe and the receiving substrate placed on the roller to 10-20 cm, and apply a high-voltage electrostatic field with a voltage of 9.5-13.5 kV between the metal spinneret of the syringe and the receiving substrate placed on the roller, thereby electrospinning to form a superhydrophilic polymer fiber membrane with a porous network structure on the receiving substrate; wherein, the diameter of the metal spinneret is 0.3-0.7 mm, the rotation speed of the roller is 50-150 rpm, and the electrospinning time is 10-120 min; Step 2) specifically includes: placing a solvent-based adhesive solution in a syringe of an electrospinning device, fixing the super-hydrophilic polymer fiber membrane prepared in step 1) on a roller, and applying a high-voltage electrostatic field with a voltage of 8.5-12.5 kV between the metal spinneret of the syringe and the super-hydrophilic polymer fiber membrane, thereby depositing medical adhesive adhesion points on the super-hydrophilic polymer fiber membrane; wherein the diameter of the metal spinneret is 0.3-0.7 mm, the rotation speed of the roller is 30-100 rpm, and the electrospinning time is 10-70 min; Step 3) specifically includes: placing a hydrophobic polymer precursor solution in a syringe of an electrospinning device, setting the distance between the metal spinneret of the syringe and the receiving substrate placed on the roller to 10-20 cm, fixing the composite fiber membrane prepared in step 2) on the roller, and applying a high-voltage electrostatic field with a voltage of 8.5-12.5 kV between the metal spinneret of the syringe and the composite fiber membrane placed on the roller, thereby electrospinning a hydrophobic polymer fiber membrane with a porous network structure on the composite fiber membrane; wherein the diameter of the metal spinneret is 0.3-0.7 mm, the rotation speed of the roller is 50-150 rpm, and the electrospinning time is 10-70 min; Step 4) specifically includes: using a hydrophilic microporous filter membrane as a support layer, placing it at the bottom of the composite fiber membrane prepared in step 3), using the prepared composite fiber membrane as a filter membrane, placing it on a filter device, pouring 10-60 mL of a metal nanowire dispersion on the filter membrane, and evacuating the air to 0.02-0.08 MPa with a vacuum pump. Based on the pore size screening principle of the filter membrane, the metal nanowires with a large aspect ratio in the metal nanowire dispersion are uniformly retained on the surface of the hydrophobic polymer fiber membrane of the composite fiber membrane, thereby forming a conductive metal network film; Step 5) specifically includes: drying the composite fiber film prepared in step 4) at 60-100°C for 2-5 min, fixing it on a roller, placing the solvent-based adhesive solution in step 2) in a syringe of an electrospinning device, applying a high-voltage electrostatic field of 8.5-12.5 kV between the metal spinneret of the syringe and the composite fiber film, thereby depositing medical adhesive adhesion points on the conductive metal network film to stably adhere the conductive metal network film to the surface of the hydrophobic polymer fiber membrane; wherein the diameter of the metal spinneret is 0.3-0.7 mm, the rotation speed of the roller is 30-100 rpm, and the electrospinning time is 10-70 min, and finally a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability is obtained.

6. A flexible bioelectric dry electrode with breathability and unidirectional sweat permeability, characterized in that, The flexible bioelectric dry electrode is prepared by the preparation method of a flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability according to any one of claims 1 to 5, and the flexible bioelectric dry electrode comprises: a super hydrophilic layer, a hydrophobic layer and an electrode layer stacked in sequence, the electrode layer, the hydrophobic layer and the super hydrophilic layer are arranged in sequence in a direction away from the skin surface, the electrode layer can be in conformal contact with the skin surface, the super hydrophilic layer and the hydrophobic layer and the hydrophobic layer and the electrode layer are fixedly connected by a plurality of discretely distributed medical adhesive adhesion points, the super hydrophilic layer, the hydrophobic layer and the electrode layer all have a porous network structure, and the porous network structures contained in the super hydrophilic layer, the hydrophobic layer and the electrode layer are interconnected, thereby forming a plurality of heat-moisture transfer capillary channels in the flexible bioelectric dry electrode, and the heat-moisture transfer capillary channels penetrate the flexible bioelectric dry electrode along the thickness direction.

7. The flexible bioelectric dry electrode according to claim 6, wherein: The flexible bioelectric dry electrode can be conformally attached to the skin surface.

8. The flexible bioelectric dry electrode according to claim 6, wherein: The super hydrophilic layer comprises a super hydrophilic polymer fiber membrane.

9. The flexible bioelectric dry electrode according to claim 8, wherein: The diameter of the super-hydrophilic polymer fibers contained in the super-hydrophilic polymer fiber membrane is 800-1400 nm.

10. The flexible bioelectric dry electrode according to claim 8, characterized in that: The porosity of the super hydrophilic polymer fiber membrane is greater than 75%, and the pore size of the contained mesh is 2-14 μm.

11. The flexible bioelectric dry electrode according to claim 8, characterized in that: The thickness of the super hydrophilic polymer fiber membrane is 3-15 μm.

12. The flexible bioelectric dry electrode according to claim 8, wherein: The material of the super hydrophilic polymer fiber membrane includes polyacrylonitrile / silicon dioxide, polyacrylic acid or cellulose.

13. The flexible bioelectric dry electrode according to claim 6, characterized in that: The hydrophobic layer includes a hydrophobic polymer fiber membrane.

14. The flexible bioelectric dry electrode according to claim 13, wherein: The diameter of the hydrophobic polymer fibers contained in the hydrophobic polymer fiber membrane is 1800-2800 nm.

15. The flexible bioelectric dry electrode according to claim 13, wherein: The porosity of the hydrophobic polymer fiber membrane is greater than 80%, and the pore size of the contained mesh is 6-20 μm.

16. The flexible bioelectric dry electrode according to claim 13, characterized in that: The thickness of the hydrophobic polymer fiber membrane is 2-6 μm.

17. The flexible bioelectric dry electrode according to claim 13, wherein: The material of the hydrophobic polymer fiber membrane includes polyurethane, polydimethylsiloxane or polyethylene.

18. The flexible bioelectric dry electrode according to claim 6, wherein: The electrode layer includes a conductive network film.

19. The flexible bioelectric dry electrode according to claim 18, wherein: The electrode layer includes a conductive metal network film.

20. The flexible bioelectric dry electrode according to claim 19, wherein: The conductive metal network film is formed by metal nanowires interwoven with each other, the diameter of the metal nanowires is 30-100 nm, and the aspect ratio is >3000.

21. The flexible bioelectric dry electrode according to claim 19, wherein: The porosity of the conductive metal network film is greater than 90%, and the pore size of the mesh contained therein is 4-16 μm.

22. The flexible bioelectric dry electrode according to claim 19, wherein: The thickness of the conductive metal network film is 30-300 nm.

23. The flexible bioelectric dry electrode according to claim 20, wherein: The metal nanowires include silver nanowires, gold nanowires or copper nanowires.

24. The flexible bioelectric dry electrode according to claim 19, wherein: The sheet resistance of the electrode layer is 2 to 15 Ω / sq −1 .

25. Use of the flexible bioelectric dry electrode according to any one of claims 6 to 24 or the flexible bioelectric dry electrode prepared by the preparation method according to any one of claims 1 to 5 in non-invasive detection of electrophysiological signals on the surface of the human body.

26. A wearable device, characterized in that A flexible bioelectric dry electrode with air permeability and unidirectional sweat permeability comprising any one of claims 6-24.

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