Bioelectrodes

Abstract

A soft, textile-shaped bioelectrode that is highly comfortable to wear and does not readily shift. A bioelectrode that has a layered structure that comprises a fibrous base material layer and a conductor layer. The fibrous base material layer is formed from non-conductive fibers. The conductor layer is formed from a conductor that contains carbon black, a urethane resin, and an aqueous thickener.

Description

[Technical Field]

[0001] The present invention relates to a bioelectrode. [Background technology]

[0002] Various types of bioelectrodes are used to measure bioelectrical signals such as electroencephalograms, electrocardiograms, and electromyograms in humans and animals, or to apply electrical stimuli to living organisms, including gel electrodes, rubber electrodes, electrodes made of thin metal plates, and electrodes made of conductive fiber materials.

[0003] While the gel electrodes and rubber electrodes mentioned above have the advantage of being highly flexible, adhering closely to the surface of the living body, and enabling stable acquisition of biosignals, they have the problem of poor breathability, causing stuffiness at the contact points and causing rashes and other problems.

[0004] Furthermore, electrodes made of thin metal plates are hydrophobic and hard, making them unsuitable for contact with the body surface, which is rich in moisture and flexible. To ensure close contact with the body surface, high contact pressure or the use of a conductive paste (jelly) was required.

[0005] Conductive textile electrodes are considered to be effective as electrodes that can be directly attached to the surface of a living body without using conductive paste, etc., and various proposals have been made for them. Textile electrodes are strong against bending and can be deformed to fit the contours of the body surface.

[0006] To provide electrical conductivity to textile electrodes, metal-plated fibers, conductive polymer coatings, and carbon materials have been proposed. Carbon is widely used in industrial applications because it is less likely to cause allergic reactions or metal corrosion, and is inexpensive.

[0007] As a textile electrode using carbon, an electrode in which carbon black powder is added to silicone rubber has been proposed (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2006-512128 [Patent Document 2] International Publication No. 2017 / 199026 Summary of the Invention [Problem to be solved by the invention]

[0009] Both the bioelectrodes described in Patent Document 1 and Patent Document 2 have a substrate made of conductive thread such as stainless steel or a substrate made of conductive wire. These bioelectrodes also use silicone rubber (silicone rubber). Substrates made of conductive thread such as stainless steel and conductive wire tend to be less flexible than substrates made of non-conductive fibers. Furthermore, the silicone material contained in these bioelectrodes has excellent interfacial properties for release. Therefore, these bioelectrodes tend to come off the skin during use, and movement of the wearer during biosignal acquisition can cause the bioelectrode to shift position, potentially resulting in artifacts in bioelectrodes that acquire or input weak signals. On the other hand, using non-conductive fibers can sometimes result in insufficient conductivity.

[0010] In view of the above, an object of the present invention is to provide a textile-shaped bioelectrode that is flexible, comfortable to wear, and less likely to slip out of position. [Means for solving the problem]

[0011] The invention for solving the above problems and achieving the object is configured as follows. (1) A bioelectrode having a laminated structure of a fiber substrate layer made of non-conductive fibers and a conductive layer, the conductive layer being a layer formed of a conductive material containing carbon black, a urethane resin, and an aqueous thickener. (2) The bioelectrode according to (1), having a mixed layer in which fibers and conductors are mixed between the fiber substrate layer and the conductor layer. (3) A bioelectrode according to (2), wherein the mixed layer ratio, which is the value obtained by dividing the thickness of the mixed layer by the total thickness of the conductive layer, the mixed layer, and the fiber substrate layer provided in the bioelectrode and multiplying the result by 100, is 0.1 to 80%, and the conductive layer thickness is 1 to 200 μm. (4) The bioelectrode according to any one of (1) to (3) above, wherein the aqueous thickener is a polyacrylic acid compound. (5) The bioelectrode according to any one of (1) to (4) above, wherein the urethane resin includes at least one selected from the group consisting of an ether-based urethane resin and a carbonate-based urethane resin. (6) The volume resistivity of the bioelectrode is 1×10 6 The bioelectrode according to any one of (1) to (5) above, which has a resistance of Ω·cm or less. (7) The surface resistance of the fiber substrate layer is 1×10 10 The bioelectrode according to any one of (1) to (6) above, having a resistance of Ω or more. [Effects of the Invention]

[0012] The present invention provides a textile-shaped bioelectrode that is flexible, comfortable to wear, has excellent conductivity, and is less likely to slip out of position. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a conceptual diagram of a cross section of a bioelectrode showing one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the bioelectrode according to the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0015] <Bioelectrode> The bioelectrode of the present invention has a laminated structure of a fiber substrate layer made of non-conductive fibers and a conductor layer. The conductor layer serves as the contact surface with the living body and acquires and transmits biosignals. Here, the laminated structure may be a laminated structure in which the fiber substrate layer and the conductor layer are directly laminated, or a laminated structure of three or more layers, including a mixed layer in which fibers and conductors are mixed between the fiber substrate layer and the conductor layer. The conductor layer is a layer formed of a conductor containing carbon black, urethane resin, and an aqueous thickener, and the mixed layer is a layer in which fibers and conductors are mixed. The mixed layer is also formed by impregnating non-conductive fibers with the conductor. Figure 1 is a conceptual diagram showing the cross section of one embodiment of the bioelectrode of the present invention. For example, this embodiment can be obtained by applying a conductor 1 onto a fiber substrate 2. The bioelectrode has a laminated structure consisting of a conductor layer 3 composed only of a conductor (i.e., not including a fiber substrate), a mixed layer 4 containing a conductor and a fiber substrate, and a fiber substrate layer 5 composed only of a fiber substrate (i.e., not including a conductor).

[0016] <Conductive layer> In the present invention, the conductor layer is a layer that exhibits conductivity and is formed solely from a conductor (i.e., does not contain a fiber substrate). The conductor here refers to a compound that imparts conductivity to a bioelectrode and includes (A) carbon black, (B) a urethane resin, and (C) an aqueous thickener. The compound and the conductor layer may contain other components in addition to (A) carbon black, (B) a urethane resin, and (C) an aqueous thickener. Examples of other components include, but are not limited to, (D) a conductivity enhancer, (E) a flexibility imparting agent, (F) a surfactant and / or leveling agent, a crosslinking agent, a catalyst, and an antifoaming agent.

[0017] <(A) Carbon black> The carbon black (hereinafter sometimes referred to as CB) used in the present invention is a conductive material. When imparting conductivity using CB, it is important to consider the particle size forming the base of the CB (the particle size of the particles that make up the structure; hereinafter, these particles are sometimes referred to as primary particles, and the particle size is sometimes referred to as primary particle size), the structure, which is the chain structure of the primary particles, and the particle surface properties. When preparing a solution containing CB and a binder, it is particularly important to increase the specific surface area by modifying the particle surface properties. A large specific surface area means that there are many pores on the particle surface, which allows the binder to penetrate into the pores, reducing the interparticle distance and resulting in high conductivity.

[0018] The specific surface area can be measured by the BET method, and the BET specific surface area of ​​carbon black is 400 to 2000 m 2 The BET specific surface area of ​​carbon black is preferably 600 to 1600 m / g or more. 2 / g. It is more preferable that the BET specific surface area of ​​the carbon black is 400 m 2 / g or more, the interparticle distance becomes small enough to provide sufficient conductivity to the bioelectrode, and the 2 / g or more, even higher conductivity can be obtained. 2 / g or less, the structure can be maintained, and stable conductivity can be imparted to the bioelectrode. This effect is achieved when the BET specific surface area of ​​the carbon black is 1600 m 2 / g or less, the effect is more pronounced.

[0019] Furthermore, to obtain high conductivity, it is desirable that the primary particles of CB are small. The average particle size of the primary particles of CB is preferably in the range of 1 to 200 nm, more preferably 5 to 100 nm. A particle size of 1 nm or greater enhances the robustness of the bioelectrode against friction, while a particle size of 5 nm or greater provides high robustness. A particle size of 200 nm or less provides sufficient conductive performance to the bioelectrode, while a particle size of 100 nm or less provides high conductivity. The primary particle size is determined by observing an ultrathin section cut from a conductor using a transmission electron microscope (TEM) at an arbitrary magnification at which the primary particle diameter can be observed, determining the diameter of the circumscribing circle for multiple arbitrarily selected primary particles from the obtained image, and averaging these values.

[0020] To obtain high conductivity, it is desirable for the structure to be highly developed. The dibutyl phthalate (DBP) absorption, which is an index of the size of the structure, should be 100 to 600 cm 3 / 100g is preferable, 300-500cm 3 / 100g is more preferable. 3 By increasing the thickness to 100g or more, the conductive performance becomes apparent due to the development of the structure, and the 3 / 100g or more further improves the conductivity. 3 By keeping the density at 500cm / 100g or less, the viscosity can be kept low, allowing the material to penetrate fully into the fibers, and providing sufficient conductivity to the bioelectrode. 3 The effect is more pronounced when the dose is kept below 100g. The DBP absorption amount is measured using an absorptometer according to the method specified in JIS K 6217-4 (2017).

[0021] In the bioelectrode of the present invention, the content of (A) carbon black is not particularly limited, but the content of CB is preferably 1 to 60 parts by weight, and more preferably 5 to 40 parts by weight, per 100 parts by weight of the solid content of the conductor. When the content is 1 part by weight or more, the continuity of the carbon black makes the conductive performance of the bioelectrode more pronounced, and when the content is 5 parts by weight or more, the conductive performance is further improved. Furthermore, when the content of CB is 60 parts by weight or less, or even 40 parts by weight or less, the conductor layer can be made robust against friction.

[0022] <(B) Urethane resin> The conductor contains (A) carbon black and (B) urethane resin. Here, the role of (B) urethane resin is to act as a binder that supports the compound that constitutes the conductor on the fiber substrate. Because the binder significantly affects the flexibility of the bioelectrode, it is important that the binder is a urethane resin. Because urethane resin has superior flexibility compared to resins other than urethane resin, the bioelectrode of the present invention is flexible and comfortable to wear.

[0023] (B) The urethane resin prevents the compound constituting the conductor in the bioelectrode from falling off the fiber substrate, and further reduces the bioelectrode's separation from the skin, improving biosignal acquisition. From this point of view, one of the features of the present invention is that the conductor contains a urethane resin.

[0024] The conductor may contain urethane resin alone or one or more other resins as a binder, and preferred examples of the other resins include olefin resins, polyester resins, urethane resins, epoxy resins, silicone resins, vinyl chloride resins, nylon resins, and acrylic resins.

[0025] Urethane resins are classified into ether-based, ester-based, carbonate-based, modified polyol-based, ester / carbonate-based, or polymers combining these, depending on the polyol used as the raw material, and any of these can be used. From the viewpoint of hydrolysis resistance, it is particularly preferable to use at least one selected from the group consisting of ether-based urethane resins and carbonate-based urethane resins.

[0026] Examples of commercially available products that can be used as the urethane resin include the following: ether-based urethane resins such as "Rezamin (registered trademark) D-2040" (Dainichiseika Chemicals) and "Superflex (registered trademark) E-4800" (Dai-ichi Kogyo Seiyaku); carbonate-based urethane resins such as "Evaphanol (registered trademark) HA-107C" (Nicca Chemicals), "Rezamin (registered trademark) D-6300" (manufactured by Dainichiseika Chemicals), "Rezamin (registered trademark) D-6065NP" (Dainichiseika Chemicals), and "Superflex (registered trademark) 460" (manufactured by Dai-ichi Kogyo Seiyaku); and polyether / carbonate-based urethane resins such as "Rezamin (registered trademark) D-4080" (Dainichiseika Chemicals) and "Rezamin (registered trademark) D-4200" (Dainichiseika Chemicals).

[0027] Urethane resins include those derived from aromatic isocyanates and aliphatic isocyanates. However, from the viewpoint of toxicity and yellowing, urethane resins containing aliphatic isocyanates are desirable for bioelectrode applications that require skin contact and durability.

[0028] In the bioelectrode of the present invention, from the viewpoint of flexibility of the resulting bioelectrode, the glass transition temperature (Tg) of the urethane resin is preferably -60 to ±0°C. The glass transition temperature (Tg) is measured by the following method. First, a resin solution is poured into a stainless steel box and dried at 60°C for 1 hour and then at 120°C for 2 hours to prepare a film with a thickness of approximately 0.3 mm. Using this film, the dynamic viscoelasticity is measured from -100 to 200°C using a viscoelasticity measuring device DMS6100 (manufactured by Seiko Instruments Inc.), and the peak temperature (T°C) of the obtained loss viscoelastic modulus is taken as the glass transition temperature (Tg). The measurement is performed at a temperature rise rate of 5°C / min and a measurement frequency of 1 Hz.

[0029] From the viewpoint of the abrasion resistance of the resulting bioelectrode, the tensile strength of the urethane resin alone is preferably 5 to 50 MPa. When the tensile strength of the urethane resin alone is 5 MPa or more, the bioelectrode is robust against abrasion, and when the tensile strength of the urethane resin alone is 50 MPa or less, the flexibility characteristic of textiles can be more reliably maintained in the bioelectrode.

[0030] In the bioelectrode of the present invention, the content of the urethane resin is not particularly limited, but is preferably 40 to 98 parts by weight, more preferably 60 to 95 parts by weight, per 100 parts by weight of the solid content of the conductor. When the content of the urethane resin is 40 parts by weight or more, the carbon black (A) contained in the bioelectrode becomes less likely to fall off. On the other hand, when the content of the urethane resin is 98 parts by weight or less, contact points between the carbon black particles in the bioelectrode are secured, and sufficient conductivity can be ensured when used as an electrode member, which is preferable.

[0031] <(C) Water-based thickener> In addition to the above-mentioned (A) carbon black and (B) urethane resin, the conductor further contains (C) an aqueous thickener. The role of the (C) aqueous thickener is to impart viscosity characteristics to the solution (coating liquid) formed from the components that make up the conductor layer, thereby controlling the coating thickness and the penetration of the coating liquid into the fibrous substrate when the coating liquid is applied to form the conductor layer. Controlling the coating thickness allows for the control of the thickness of the conductor layer, resulting in a bioelectrode with excellent conductivity. Furthermore, controlling the penetration of the coating liquid into the fibrous substrate allows for the control of the thickness of the mixed layer (described below), resulting in a bioelectrode with excellent conductivity.

[0032] The aqueous thickener (C) contains an aqueous solvent from the viewpoint of reducing VOCs during production. One type of aqueous thickener may be used, or two or more types may be used in combination.

[0033] Examples of aqueous thickeners include the following: inorganic thickeners such as silicates and montmorillonite, and organic thickeners such as cellulose-based thickeners like carboxymethyl cellulose, methyl cellulose, and hydroxyethyl cellulose, vinyl-based thickeners like polyvinyl alcohol, polyvinylpyrrolidone, and polyvinylbenzyl ether copolymers, polyacrylic acid-based thickeners like polyacrylic acid or polyacrylates, poly(meth)acrylic acid-(meth)acrylic acid ester copolymers, and crosslinked core carboxylic acid emulsions, polyurethane-based thickeners like polyether-modified urethane compounds and hydrophobically modified polyoxyethylene polyurethane copolymers, and urea-based thickeners like urethane-urea compounds.

[0034] Among these, polyacrylic acid compounds are preferably used because they can thicken and impart thixotropy to the coating solution. A coating solution that has been thickened and thixotropic by a polyacrylic acid compound exhibits excellent properties, such as preventing settling during storage and improving workability by reducing viscosity during coating.

[0035] In the bioelectrode of the present invention, the content of the aqueous thickener (C) is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the solid content of the conductor. When the content of the aqueous thickener is 0.1 part by weight or more, thickening and thixotropy can be imparted to the coating liquid forming the conductor of the bioelectrode, improving coatability, and when it is 10 parts by weight or less, coating defects due to excessive thickening can be suppressed, which is preferable.

[0036] <Other ingredients> As described above, in the bioelectrode of the present invention, the conductor may contain other components in addition to (A) carbon black, (B) urethane resin, and (C) aqueous thickener, such as (D) conductivity improver, (E) flexibility imparting agent, (F) surfactant and / or leveling agent, crosslinking agent, catalyst, and antifoaming agent.

[0037] <(D) Conductivity improver> A (D) conductivity improver may be added to the conductor. The (D) conductivity improver is not particularly limited, but examples include compounds having a boiling point of 100°C or higher and two or more hydroxyl groups in the molecule, compounds having a boiling point of 100°C or higher and at least one sulfinyl group in the molecule, compounds having a boiling point of 60°C or higher and at least one carbonyl group in the molecule, and compounds having a boiling point of 100°C or higher and at least one amide group in the molecule. These (D) conductivity improvers may be used alone or in combination of two or more.

[0038] Examples of compounds having a boiling point of 100°C or higher and two or more hydroxyl groups in the molecule include ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, β-thiodiglycol, triethylene glycol, tripropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, catechol, cyclohexanediol, cyclohexanedimethanol, glycerin, erythritol, imamartol, lactitol, maltitol, mannitol, sorbitol, xylitol, sucrose, etc. These may be used alone or in combination of two or more.

[0039] An example of a compound having a boiling point of 100° C. or higher and at least one sulfinyl group in the molecule is dimethyl sulfoxide.

[0040] Examples of compounds having a boiling point of 60°C or higher and at least one carbonyl group in the molecule include acrylic acid, methacrylic acid, methanoic acid, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid, decanoic acid, dodecanoic acid, benzoic acid, p-toluic acid, p-chlorobenzoic acid, p-nitrobenzoic acid, 1-naphthoic acid, 2-naphthoic acid, phthalic acid, isophthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, maleic acid, fumaric acid, etc. These may be used alone or in combination of two or more.

[0041] Examples of compounds having a boiling point of 100° C. or higher and at least one amide group in the molecule include N,N-dimethylacetamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-ethylacetamide, N-phenyl-N-propylacetamide, benzamide, etc. These may be used alone or in combination of two or more.

[0042] When the conductor contains (D) the conductivity enhancer, its content is not particularly limited, but is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of the solid content of the conductor. When the content of (D) the conductivity enhancer is 0.01 part by weight or more, a sufficient conductivity enhancing effect can be obtained, and when it is 20 parts by weight or less, the drying properties of the bioelectrode are good.

[0043] <(E) Softening agent> A (E) flexibility-imparting agent may be added to the conductor. The (E) flexibility-imparting agent is not particularly limited, but examples thereof include glycerol, sorbitol, polyglycerin, polyethylene glycol, and polyethylene glycol-polypropylene glycol copolymer. These may be used alone or in combination of two or more.

[0044] When the conductor contains (E) a softening agent, its content is not particularly limited, but is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of the solid content of the conductor. When the content of (E) a softening agent is 0.01 part by weight or more, sufficient softness is obtained, and when it is 20 parts by weight or less, the conductivity and strength of the bioelectrode are excellent and washing resistance is not significantly reduced.

[0045] <(F) Surfactant and / or Leveling Agent> In the present invention, a surfactant for uniformly dispersing the compound constituting the conductor in the conductor, or a leveling agent for uniforming the surface tension of the bioelectrode when it dries, may be added to the conductor. Note that in the bioelectrode of the present invention, one compound may correspond to both the surfactant and the leveling agent. Furthermore, when the surfactant and the leveling agent are different compounds, the surfactant and the leveling agent may be used in combination.

[0046] The surfactant is preferably one that has the ability to disperse solid components in a solvent, and specific examples thereof include siloxane compounds such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyetherester-modified hydroxyl group-containing polydimethylsiloxane, polyether-modified acrylic group-containing polydimethylsiloxane, polyester-modified acrylic group-containing polydimethylsiloxane, perfluoropolydimethylsiloxane, perfluoropolyether-modified polydimethylsiloxane, and perfluoropolyester-modified polydimethylsiloxane; perfluoroalkylcarboxylic acid, perfluoroalkylpolyoxyethyleneethoxysilane; Examples of surfactants include fluorine-containing organic compounds such as ethanol; polyether compounds such as polyoxyethylene alkylphenyl ether, propylene oxide polymer, and ethylene oxide polymer; carboxylic acids such as coconut oil fatty acid amine salts and gum rosin; ester compounds such as castor oil sulfates, phosphate esters, alkyl ether sulfates, sorbitan fatty acid esters, sulfonates, and succinates; sulfonate compounds such as alkylarylsulfonic acid amine salts and dioctyl sodium sulfosuccinate; phosphate compounds such as sodium lauryl phosphate; amide compounds such as coconut oil fatty acid ethanolamide; and acrylic compounds. These surfactants may be used alone or in combination of two or more.

[0047] The leveling agent is not particularly limited, and examples thereof include siloxane compounds such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyetherester-modified hydroxyl group-containing polydimethylsiloxane, polyether-modified acrylic group-containing polydimethylsiloxane, polyester-modified acrylic group-containing polydimethylsiloxane, perfluoropolydimethylsiloxane, perfluoropolyether-modified polydimethylsiloxane, and perfluoropolyester-modified polydimethylsiloxane; fluorine compounds such as perfluoroalkylcarboxylic acid and perfluoroalkylpolyoxyethyleneethanol; Examples of the leveling agent include: an organic compound containing an alkyl group; polyether compounds such as polyoxyethylene alkylphenyl ether, propylene oxide polymer, and ethylene oxide polymer; carboxylic acids such as coconut oil fatty acid amine salts and gum rosin; ester compounds such as castor oil sulfates, phosphate esters, alkyl ether sulfates, sorbitan fatty acid esters, sulfonate esters, and succinate esters; sulfonate compounds such as alkylarylsulfonic acid amine salts and dioctyl sodium sulfosuccinate; phosphate compounds such as sodium lauryl phosphate; and amide compounds such as coconut oil fatty acid ethanolamide. These leveling agents may be used alone or in combination of two or more.

[0048] <Fiber base material layer> The fibers constituting the fiber substrate layer of the bioelectrode of the present invention are non-conductive fibers, and do not include metal fibers such as stainless steel, aluminum, aluminum alloy, and copper, metal-coated fibers coated with metals such as silver, or conductive fibers spun from resins kneaded with metals or carbon. 10 The non-conductive fibers have a surface resistance of Ω or more. Non-conductive fibers tend to be more readily available than conductive fibers, and the bioelectrode of the present invention has excellent productivity.

[0049] The non-conductive fibers constituting the fiber substrate layer used in the present invention may be natural fibers or chemical fibers. Examples of natural fibers include cellulosic fibers such as cotton and hemp, and protein fibers such as wool and silk. Examples of chemical fibers include regenerated fibers such as rayon, semi-synthetic fibers such as acetate, and synthetic fibers. From the viewpoint of processability, it is preferable that the fibers constituting the fiber substrate layer used in the present invention are synthetic fibers.

[0050] Examples of synthetic fibers include polyamide fibers such as nylon and aramid, polyester fibers such as polyethylene terephthalate, acrylic fibers such as polyacrylonitrile, polyolefin fibers such as polyethylene and polypropylene, polyvinyl alcohol fibers, polyvinyl chloride fibers, polyurethane fibers, heterocyclic polymer fibers such as polyimide fibers, etc. From the viewpoint of being able to impart high flexibility to the bioelectrode, it is particularly preferable to use one or more of polyamide fibers, polyester fibers, and polyolefin fibers.

[0051] In the bioelectrode of the present invention, the cross-sectional shape of the fibers constituting the fiber substrate layer may be round, triangular, flat, polygonal, hollow, or other irregular cross-sectional shapes with a high degree of irregularity, and is not particularly limited.

[0052] Examples of the form of the fiber substrate layer according to the present invention include mesh, paper, woven fabric, knitted fabric, nonwoven fabric, ribbon, string, etc. The form is not particularly limited as long as it is suitable for the intended use, but nonwoven fabric or woven fabric is preferable from the viewpoints of conductivity and processability.

[0053] For nonwoven fabrics, it is desirable for the fabric to have high water pressure resistance. It is preferable for the fabric to have a performance of 50 mmH2O (490 Pa) or more, and even more preferable for it to have a performance of 100 mmH2O (980 Pa) or more. Means for achieving water pressure resistance within the above range include a laminated structure of a spunbond layer and a meltblown layer, increasing the basis weight of the nonwoven fabric, and embossing.

[0054] For woven fabrics, the cover factor, calculated by multiplying the square root of the fineness by the yarn density, should desirably be between 1500 and 3000 for the sum of the warp and weft cover factors. If the cover factor is too small, the coating agent may reach the back surface, preventing the fiber substrate layer from functioning as an insulating layer. On the other hand, fabrics with a cover factor of over 3000 have poor weaving properties.

[0055] The fiber may be in the form of a monofilament yarn, a multifilament yarn, or a staple yarn.

[0056] The single fiber fineness is not particularly limited, and may be, for example, about 0.0001 dtex to 300 dtex.

[0057] In addition to fiber entanglement and raising, the fiber substrate layer may be subjected to a variety of treatments, such as shrinkage, shape fixation, compression, dyeing and finishing, oiling, heat setting, solvent removal, shape fixation agent removal, combing, polishing, flat (roll) pressing, and high-performance short-cut shearing (cutting of raised nap), which may be combined appropriately in each step. However, there are no limitations on the types of treatments that may be performed as long as they do not impair the performance of the electrode.

[0058] The fiber base layer has a basis weight of 5 g / m 2 More than 500g / m 2 It is preferable that the basis weight is 5 g / m or less. 2 By exceeding this limit, the fabric is not too thin, the bioelectrode has sufficient strength, and the fabric weight is 500 g / m 2 When the density is less than 10 g / m, good flexibility is obtained. 2 More than 250g / m 2 The following is the result.

[0059] Furthermore, when the surface resistance of the fiber substrate layer is measured by the method described below, it is 1×10 10 It is preferable that the surface resistance is 1×10 Ω or more. 10By setting the surface resistance to 1×10 or more, it is possible to further suppress the stiffness of the bioelectrode when a conductive layer is applied, resulting in better comfort when wearing the clothing. Note that, when a conductive thread or conductive wire such as stainless steel is used, the resistance value of the fiber substrate itself decreases, and the surface resistance value is 1×10 10 The surface resistance tends to be less than 1×10 10 Ω or more, that is, when the conductivity of the fiber substrate itself is low, the fiber substrate layer can be more effectively used as an insulating layer. 18 In addition to the above, from the viewpoint of improving the coatability of the processing agent, the surface resistance value is set to 1 × 10 18 The surface resistance of the fiber substrate alone can be controlled by selecting the polymer from which the fiber substrate is formed or by limiting the amount of conductive material added during or after the formation of the substrate.

[0060] <Mixed layer> In the present invention, the conductor layer is supported on the fiber substrate layer, and a mixed layer is preferably present between the conductor layer and the fiber substrate layer. Here, the mixed layer is a layer in which fibers and conductors are mixed, with the conductors penetrating the gaps between the fibers. The presence of the mixed layer strengthens the adhesion between the conductor layer and the fiber substrate layer, making peeling between the layers less likely to occur during use. The mixed layer is preferably provided so that the mixed layer ratio, as measured by the method described below, is 80% or less. The mixed layer ratio is more preferably 0.1% or more and 80% or less, and even more preferably 0.5% or more and 50% or less. Here, as described below, the mixed layer ratio refers to the value obtained by dividing the thickness of the mixed layer by the sum of the thicknesses of the conductor layer, mixed layer, and fiber substrate layer provided in the bioelectrode, and multiplying this value by 100.

[0061] <Other configurations of bioelectrodes> In the bioelectrode of the present invention, a resin layer may be laminated on the surface opposite to the conductive layer, which is the living body contact surface, or a fiber, film, etc. The resin, fiber, or film can be laminated for purposes such as insulation from electrical stimulation, moisture permeability, and moisture retention.

[0062] <Mixed layer ratio and conductive layer thickness in bioelectrodes> The mixed layer ratio and conductor layer thickness of the bioelectrode of the present invention can be controlled by the selection of the thickener, the amount of thickener in the coating liquid, and the selection, fineness, and density of the polymer that constitutes the fiber substrate. When the mixed layer ratio is measured by the measurement method described in the Examples section below, the mixed layer ratio is preferably 0.1% or more and 80% or less, and more preferably 0.5% or more and 50% or less.

[0063] The mixed layer ratio here specifically refers to the value obtained by dividing the thickness of the mixed layer of the bioelectrode by the total thickness of the conductor layer, mixed layer, and fiber substrate layer of the bioelectrode, and multiplying this value by 100.

[0064] If the mixed layer ratio is too high, the insulating properties of the fiber substrate will increase the resistance of the bioelectrode, resulting in reduced conductivity, which is undesirable. By setting the mixed layer ratio to 80% or less, the bioelectrode of the present invention can maintain low resistance and provide an electrode with better conductivity. A mixed layer ratio of 50% or less is more preferable. On the other hand, a low mixed layer ratio is undesirable, as it tends to cause peeling between the conductor layer and the fiber substrate layer. By setting the mixed layer ratio to 0.1% or more, more preferably 0.5% or more, the bioelectrode of the present invention can suppress peeling between the conductor layer and the fiber substrate layer.

[0065] Furthermore, when the thickness of the conductor layer is measured using the measurement method described in the Examples section below, it is preferably 1 to 200 μm. If the conductor layer thickness is too thin, the insulating properties of the fiber substrate will have a strong effect, which will likely increase the resistance of the bioelectrode and, as a result, will likely decrease the conductivity, which is undesirable. If the conductor layer thickness is too thick, the flexibility of the fiber substrate will likely be lost, resulting in rigidity and the risk of reducing comfort when wearing the garment. By setting the conductor layer thickness to 1 to 200 μm, it is possible to provide a bioelectrode of the present invention that combines higher levels of conductivity and flexibility.

[0066] Furthermore, from the viewpoints of being able to provide an electrode having low resistance, better conductivity, suppressing the occurrence of peeling between the conductive layer and the fiber substrate layer, and also having excellent flexibility, it is particularly preferable that the mixed layer ratio is 0.1 to 80% and the conductive layer thickness is 1 to 200 μm.

[0067] <Method of manufacturing bioelectrodes> The bioelectrode of the present invention can be obtained by, for example, applying a coating liquid of a conductor containing (A) carbon black, (B) a urethane resin, and (C) an aqueous thickener to the surface of a fiber substrate layer, thereby forming a laminated structure of the fiber substrate layer and the conductor layer. The coating liquid is preferably a dispersion containing (A) carbon black, (B) a urethane resin, and (C) an aqueous thickener, or a solution containing (A) carbon black, (B) a urethane resin, and (C) an aqueous thickener, and is applied to the surface of the fiber substrate layer. In this specification, there is no distinction between a solvent that completely dissolves all components contained in the conductor (i.e., a "solvent") and a solvent that disperses insoluble components (i.e., a "dispersion medium"), and both are referred to as "solvent." Solvents are described below.

[0068] <Solvent> The solvent is not particularly limited, and examples thereof include water; alcohols such as methanol, ethanol, 2-propanol, 1-propanol, and glycerin; ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether; glycol ether acetates such as ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate; propylene glycol, dipropylene glycol, Examples of suitable solvents include propylene glycols such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, propylene glycol diethyl ether, and dipropylene glycol diethyl ether; propylene glycol ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, and dipropylene glycol monoethyl ether acetate; tetrahydrofuran; acetone; acetonitrile, etc. These solvents may be used alone or in combination of two or more.

[0069] The solvent is preferably water or a mixture of water and an organic solvent. When water is used as the solvent, the content of water is not particularly limited, but is preferably 10 to 1,000 parts by weight, and more preferably 20 to 500 parts by weight, per 100 parts by weight of the solid content of the conductor. When the water content is 10 parts by weight or more, the fluidity of the compound in the solution is ensured, improving handling, while when the water content is 1,000 parts by weight or less, the compound concentration does not become too low, and the amount of coating liquid used does not increase too much.

[0070] In the present invention, the conductive coating liquid can be applied to the fiber substrate layer by a conventional method such as dipping, coating, or spraying, and the coating liquid can be laminated on the fiber substrate and then heated to obtain a bioelectrode. The coating method is preferred because it allows the conductive coating liquid to be applied to a uniform thickness.

[0071] It is desirable that (A) carbon black be mixed with (E) surfactant in advance and uniformly dispersed in the solvent, and that the dispersibility be maintained even when (B) urethane resin is mixed in. Methods for uniformly dispersing carbon black in a solvent include, but are not limited to, a ball mill, a bead mill, a planetary ball mill, a vibrating ball mill, a sand mill, a colloid mill, an attritor, a roll mill, high-speed impeller dispersion, a disperser, a homogenizer, a high-speed impact mill, ultrasonic dispersion, and mechanical stirring using a stirring blade, a stirrer, or the like.

[0072] <How to use bioelectrodes> Preferred embodiments of the bioelectrode of the present invention include those that can directly contact a living body to acquire an electrical signal and / or impart an electrical signal or electrical stimulation, such as an electrode member that acquires electrical signals from a living body, such as cardiac potential, myoelectric potential, and electroencephalogram, or an electrode member that imparts electrical stimulation to a living body, such as low frequency, high frequency, or EMS.

[0073] Specific examples of the shape of the electrode include, but are not limited to, electrodes including the bioelectrode, electric wires, clothing, pants, gloves, socks, brassieres, headbands, wristbands, neckbands, hats, bellybands, supports, shoes, sheets, glasses, headbands, hair accessories, headphones, watches, chairs, toilet seats, handlebars, beds, carpets, various covers, and other items that come into direct contact with the skin. For example, by attaching a sensor or an electrical stimulation device to some of these products so that they are electrically connected to the bioelectrode, various products can be made to function as electrode members.

[0074] In the case of electrodes, the electrodes alone and / or in combination with the above-mentioned electrodes that come into direct contact with the skin can be suitably used. The shape of the electrodes alone may be any shape, such as a circle or a polygon, and is not limited thereto.

[0075] The size of the electrode is not limited as long as it has a contact area that allows the desired biosignal to be acquired. To improve adhesion to the living body, a typical flat electrode may have a three-dimensional structure such as a loop so that it can be easily linked to movement, or may be inflated with air.

[0076] When used as an electrode in combination with other structures such as clothing, wiring may be attached to the bioelectrode so that electrical signals from the desired area can be obtained.The bioelectrode can also be attached with buttons, hooks, magnets, hook-and-loop fasteners such as Velcro (registered trademark), etc., making it suitable for use in a shape that can be attached to and detached from clothing.

[0077] <Static friction resistance of bioelectrodes> The static friction resistance of the bioelectrode of the present invention can be controlled by appropriately selecting the binder resin. When the static friction resistance (Fs) described below was measured, it was 0.16 N / cm 2It is desirable that the static friction resistance of the bioelectrode is at least 100%. If the static friction resistance of the bioelectrode is small, the movement of the wearer while acquiring biosignals may cause the bioelectrode to shift position, which may result in artifacts in the bioelectrode that acquires or inputs weak signals. The bioelectrode of the present invention has a large static friction resistance, which makes it possible to prevent the bioelectrode from shifting position due to the movement of the wearer.

[0078] <Volume resistivity of bioelectrodes> The volume resistivity of the bioelectrode of the present invention can be controlled by the properties of the CB (BET specific surface area and DBP adhesion amount), the amount of CB in the conductor, the mixed layer ratio, and the like.

[0079] The volume resistivity of the bioelectrode of the present invention is 1×10 when measured by the method described below. 6 It is preferably Ω·cm or less, and more preferably 1×10 -2 Ω cm or more 1×10 6 The volume resistivity is 1×10 Ω·cm or less. 6 A volume resistivity of 1×10 Ω·cm or less improves the bioelectrode's biosignal acquisition capabilities. -2 By ensuring that the electrical resistance is Ω·cm or higher, the amount of binder supporting the CB increases, resulting in an improved retention of the CB in the bioelectrode and further preventing the CB from falling off from the bioelectrode. [Example]

[0080] Next, the bioelectrode of the present invention will be described in detail using examples. The bioelectrode of the present invention is not limited to these examples. The measured values ​​in the examples and comparative examples were obtained by the following methods.

[0081] <Static friction resistance of bioelectrodes> The static friction resistance of the bioelectrode was measured by the following method.

[0082] Using a surface property measuring instrument, Tribogear (TYPE: HEIDON-14DR) manufactured by Shinto Chemical Co., Ltd., the electrode was fixed to a flat indenter (area 30 x 28 mm) at a moving speed of 60 mm / min and a load of 255 g (2.50 N), and the static friction resistance force (N) was measured by sliding the electrode against a SUS plate with a surface roughness of 0.8 μm in the perpendicular direction. The static friction resistance force was measured at three points, and the averaged static friction resistance force was divided by the surface area of ​​the flat indenter to obtain the static friction resistance force per unit area (N / cm 2 The load was set to a value equivalent to the contact pressure in proportion to the area of ​​the flat indenter.

[0083] <Surface resistance value of fiber substrate layer> The surface resistance (Ω) of the fiber substrate layer of the bioelectrode was measured using a surface resistivity tester (Megaresta H0709 manufactured by Shishido Electrostatics) at 20°C and 40% RH for 60 seconds at 500 V. Three measurements were taken and averaged.

[0084] <Mixed layer ratio of bioelectrodes> The mixed layer ratio of the bioelectrode was measured as follows. The electrode was cut with a single-edged blade, and a cross-sectional image was taken at 100x magnification using a microscope (Keyence VHX-2000). Using the measurement mode, the thickness (μm) of the conductor layer formed only of the conductor, the thickness (μm) of the fiber substrate layer formed only of the fiber substrate, and the thickness (μm) of the mixed layer between the conductor layer and the fiber substrate layer, where the conductor and fiber were mixed, were measured.

[0085] The specific method for measuring the thickness of each layer from a cross-sectional image is described in detail with reference to Figure 1. Three locations where the conductor penetrates from the surface of the conductor layer toward the fiber substrate layer are selected, and the combined thickness of the conductor layer and mixed layer is measured at each location. The average value is designated as A. Three other locations where the conductor penetrates the fiber substrate are selected, and the combined thickness of the fiber substrate layer and mixed layer is measured. The average value is designated as B. Three other locations are selected, and the combined thickness of the conductor layer, mixed layer, and fiber substrate layer (bioelectrode thickness) is measured from the surface of the conductor layer to the surface of the fiber substrate layer. The average value is designated as C. The mixed layer thickness is calculated as (A + B) - C and designated as D. The conductor layer thickness is calculated as AD. The fiber substrate layer thickness is calculated as BD. The mixed layer ratio (%) is calculated by dividing the mixed layer thickness by the sum of the thicknesses of the conductor layer, mixed layer, and fiber substrate layer of the bioelectrode, and multiplying this value by 100. If the surface of the substrate has irregularities such as embossments and the layer thickness varies depending on the location, an image is taken at the location that comes into contact with the living body, and the layer thickness is measured.

[0086] <Resistance and volume resistivity of bioelectrodes> Measurements were performed using the five-point measurement method specified in JIS K 7194 (1994). The resistance (Ω) of the bioelectrode was measured using a Mitsubishi Analytec four-probe resistance meter (Loresta-AX MCP-T370) at 20°C and 40% RH. The thickness of the bioelectrode used to calculate the volume resistivity was the sum of the thicknesses of the conductor layer and the mixed layer. The electrode was cut with a single-edged blade, and images were captured at 100x magnification using a microscope (Keyence VHX-2000). Using the measurement mode, the thickness of the conductor layer (μm), which is made up of only the conductor, and the thickness of the mixed layer (μm), which is made up of both the conductor and the fiber substrate layer, were measured. The volume resistivity (Ω·cm) was calculated from the obtained resistance value, thickness, and the correction factor specified in JIS.

[0087] <Bioelectrode bending resistance change ratio> The bending resistance change ratio of the bioelectrode was calculated by measuring the bending resistance (mm) of the bioelectrode and the bending resistance (mm) of the fiber substrate before conductive processing in accordance with the bending resistance A method (45° cantilever method) of JIS L 1096 (Fabric testing methods for woven and knitted fabrics) (1999), and then dividing the bending resistance of the bioelectrode by the bending resistance of the fiber substrate. The bending resistance measurement sample was collected so that the longitudinal direction or the well direction was the long side, and measurements were taken on both sides and then averaged.

[0088] <Peeling strength of conductive layer> The peel strength test was conducted using the following method, based on the JIS L 1066 (2004) peel strength test method. Three 15 x 2.5 cm test pieces were prepared, with the longitudinal direction aligned with the vertical direction of the sample. For each test piece, the conductive layer was peeled off from the test piece by exactly 5 cm in the longitudinal direction of the test piece. Using a low-speed extension tensile tester with a self-recording device, the peeled conductive layer and the remaining substrate were gripped at a gripping distance of 5 cm. The conductive layer was peeled off by an additional 5 cm at a tensile speed of 10 cm / min, and the load (N) was measured. From the load-peel distance curve, the three largest maximum values ​​(N) and the three smallest minimum values ​​(N) were taken, and their averages were calculated. This was repeated for each test piece, and the average was calculated to determine the peel strength. If the peel strength is 30cN / cm or more, it is rated as A, and if the peel strength is less than 30cN / cm, it is rated as B. If it is rated as A, it is determined that the electrode has sufficient peel strength for use as a bioelectrode.

[0089] [Example 1] A smooth circular knit fabric was produced using 84 dtex-72F polyester filaments on a circular knitting machine. The resulting circular knit fabric was scoured with a 3% by mass aqueous solution of sodium hydroxide (80°C for 20 minutes), washed with water (50°C for 10 minutes), and heat-set in a dry heat treatment machine (180°C for 1 minute) to obtain a fiber base material. The resulting fiber base material had a basis weight of 150 g / m 2The obtained fiber substrate was coated with a mixed solution containing (A) 400 g / L of "Lion Paste (registered trademark)" W-311N (Ketjen black dispersion, manufactured by Lion Specialty Chemical Co., Ltd.), which contains carbon black as a conductive material, (B) 500 g / L of "Evaphanol (registered trademark) HA-107C" (Nicca Chemical Co., Ltd., water-based urethane resin) as a binder, and (C) 40 g / L of "SN Thickener 920" (San Nopco Co., Ltd., acrylate salt) as a water-based thickener, using a bar coater, and heated at 130 °C to obtain a bioelectrode. The materials used and the properties of the obtained bioelectrode are shown in Table 1.

[0090] [Example 2] A bioelectrode was manufactured in the same manner as in Example 1, except that the fiber substrate was changed to nylon jersey. For the nylon jersey, a circular knit fabric was made using 70d-24F and 78T / 2-24F nylon 6 filaments for the well and course, and the same processing as in Example 1 was carried out to obtain a fiber substrate. The obtained fiber substrate had a basis weight of 260 g / m 2 The materials used and the properties of the resulting bioelectrode are shown in Table 1.

[0091] [Example 3] A bioelectrode was manufactured in the same manner as in Example 1, except that a three-layer laminated nonwoven fabric consisting of a polypropylene meltblown fiber web, a spunbond fiber web, and a meltblown fiber web was used as the fiber substrate. The basis weight of the fiber substrate was 65 g / m 2 The water pressure resistance was 1091 mmH2O. The materials used and the characteristics of the obtained bioelectrode are shown in Table 1.

[0092] [Example 4] A bioelectrode was manufactured in the same manner as in Example 3, except that the binder was changed to "Superflex (registered trademark)" E-4800 (Dai-ichi Kogyo Seiyaku Co., Ltd., polyether-based urethane resin). The materials used and the properties of the obtained bioelectrode are shown in Table 1.

[0093] [Example 5] Except for changing the mixed layer ratio to 0.4%, a bioelectrode was manufactured by the same manufacturing method as in Example 4. Table 1 shows the materials used and the properties of the obtained bioelectrode.

[0094] [Example 6] Except for changing the mixed layer ratio to 57%, a bioelectrode was manufactured by the same manufacturing method as in Example 1. Table 1 shows the materials used and the properties of the obtained bioelectrode.

[0095] [Example 7] A bioelectrode was manufactured using the same manufacturing method as in Example 1, except that the fiber substrate was changed to a polyester woven fabric and the mixed layer ratio was changed to 24%. The fiber substrate was made of 84 dtex-72F polyester filaments, and a plain weave fabric was produced on a loom. The resulting fabric was scoured in an aqueous solution of 0.5 g / L of surfactant and 0.7 g / L of sodium hydroxide (80°C for 20 minutes), washed with water (50°C for 10 minutes), and heat-set in a dry heat treatment machine (180°C for 1 minute) to obtain a fiber substrate. The resulting fiber substrate had a basis weight of 110 g / m 2 The cover factor of the obtained fiber substrate was 2300. The materials used and the properties of the obtained bioelectrode are shown in Table 1.

[0096] [Comparative Example 1] Except for not adding a thickener, a bioelectrode was manufactured in the same manner as in Example 1. The materials used and the properties of the obtained bioelectrode are shown in Table 2.

[0097] Comparative Example 2 A bioelectrode was manufactured using the same manufacturing method as in Example 3, except that the binder was changed to "High Resin SD-319" (Takamatsu Yushi, silicone resin). The materials used and the properties of the obtained bioelectrode are shown in Table 2.

[0098] Comparative Example 3 A bioelectrode was manufactured in the same manner as in Example 3, except that the binder was changed to "KM-9772" (Shin-Etsu Chemical Co., Ltd., silicone rubber). The materials used and the properties of the obtained bioelectrode are shown in Table 2.

[0099] [Table 1]

[0100] [Table 2]

[0101] The bioelectrodes of the examples contain an aqueous thickener, which reduces the ratio of mixed layers in the electrode and achieves excellent volume resistivity. This is believed to provide high sensitivity for biosignal acquisition. Furthermore, the extremely high static friction resistance is expected to prevent misalignment when worn and prevent artifacts from occurring during biosignal acquisition. Furthermore, the use of a non-conductive fiber substrate and a flexible urethane resin as a binder provides excellent comfort. On the other hand, Comparative Example 1 does not contain a thickener, resulting in a high ratio of mixed layers in the electrode and a high volume resistivity, raising concerns about reduced biosignal acquisition performance compared to the examples. Furthermore, Comparative Examples 2 and 3 do not use a urethane binder, resulting in low static friction resistance, which can cause misalignment when worn and potentially lead to artifacts during biosignal acquisition. [Industrial Applicability]

[0102] The bioelectrode of the present invention is suitably used as a bioelectrode for measuring bioelectric signals such as electroencephalograms, electrocardiograms, and electromyograms of humans and animals, and for applying electrical stimulation to living organisms. [Explanation of symbols]

[0103] 1. Conductor 2. Fiber base material 3 Conductive layer 4 mixed layer 5 Fiber base material layer

Claims

1. A bioelectrode having a laminated structure of a fiber substrate layer made of non-conductive fibers and a conductor layer, the conductor layer being a layer formed of a conductor containing carbon black, a urethane resin, and an aqueous thickener, the fiber substrate layer being in the form of a woven fabric, a knitted fabric, or a nonwoven fabric, and having a mixed layer between the fiber substrate layer and the conductor layer, in which fibers and a conductor are mixed, the mixed layer ratio being 0.5 to 50%, which is a value obtained by dividing the thickness value of the mixed layer by the total thickness of the conductor layer, the mixed layer, and the fiber substrate layer provided in the bioelectrode, and multiplying the result by 100, the conductor layer having a thickness of 1 to 200 μm, and having a static friction resistance force (Fs) of 0.16 N / cm 2 or more.

2. The bioelectrode according to claim 1 , wherein the aqueous thickener is a polyacrylic acid compound.

3. The bioelectrode according to claim 1 or 2, wherein the urethane resin comprises at least one selected from the group consisting of an ether-based urethane resin and a carbonate-based urethane resin.

4. The volume resistivity of the bioelectrode is 1×10 ６ The bioelectrode according to any one of claims 1 to 3, having a resistance of Ω cm or less.

5. The surface resistance of the fiber substrate layer is 1×10 １０ The bioelectrode according to any one of claims 1 to 4, wherein the resistance is Ω or more.

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