WO2024070906A1 - Électrode adhésive pour acquérir un biosignal et biocapteur - Google Patents

Électrode adhésive pour acquérir un biosignal et biocapteur Download PDF

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Publication number
WO2024070906A1
WO2024070906A1 PCT/JP2023/034379 JP2023034379W WO2024070906A1 WO 2024070906 A1 WO2024070906 A1 WO 2024070906A1 JP 2023034379 W JP2023034379 W JP 2023034379W WO 2024070906 A1 WO2024070906 A1 WO 2024070906A1
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Prior art keywords
adhesive
acquiring
electrode
meth
adhesive electrode
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PCT/JP2023/034379
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English (en)
Japanese (ja)
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慶音 西山
千春 矢野
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日東電工株式会社
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25—Bioelectric electrodes therefor
    • A61B5/251—Means for maintaining electrode contact with the body
    • A61B5/257—Means for maintaining electrode contact with the body using adhesive means, e.g. adhesive pads or tapes
    • A61B5/259—Means for maintaining electrode contact with the body using adhesive means, e.g. adhesive pads or tapes using conductive adhesive means, e.g. gels
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25—Bioelectric electrodes therefor
    • A61B5/263—Bioelectric electrodes therefor characterised by the electrode materials
    • A61B5/268—Bioelectric electrodes therefor characterised by the electrode materials containing conductive polymers, e.g. PEDOT:PSS polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/12—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters

Definitions

  • the present invention relates to an adhesive electrode and a biosensor for acquiring biosignals.
  • biosensors that acquire bioinformation such as electrocardiogram waveforms, pulse waves, brain waves, and electromyography are used in hospitals, clinics, and other medical institutions, nursing homes, and homes.
  • the biosensor is equipped with adhesive electrodes (bioelectrodes) for acquiring biosignals that come into contact with a living body to acquire the subject's bioinformation.
  • biosensor is attached to the subject's skin and electrical signals related to the bioinformation are acquired by the bioelectrodes, thereby measuring the bioinformation.
  • an adhesive sheet has been disclosed that has an adhesive layer containing a conductive organic polymer compound and an adhesive material, and is used to attach the wiring board to the skin surface (see, for example, Patent Document 1).
  • Patent Document 1 does not consider the skin irritation and flexibility of the adhesive sheet. Because the conductive organic polymer compound used to form the adhesive layer of the adhesive sheet of Patent Document 1 has strong acid properties, the resulting adhesive layer also tends to have strong acid properties. As a result, there is a problem in that when the adhesive layer comes into contact with the skin during use of the adhesive sheet, it causes strong irritation to the skin.
  • bioelectrodes are often attached to the skin or other biological surfaces for long periods of time. Therefore, in order for the bioelectrode to stably acquire electrical signals related to biological information from the skin or other biological surfaces for long periods of time, it is important that it can remain stably attached to the biological surface even if the skin surface stretches due to bodily movement.
  • One aspect of the present invention aims to provide an adhesive electrode for acquiring biosignals that reduces irritation to the living body, has excellent flexibility, and maintains adhesion to the living body with low resistance.
  • One aspect of the adhesive electrode for acquiring a biological signal according to the present invention is It contains a conductive polymer, a water-based emulsion adhesive, a moisturizer and a neutralizer.
  • the pH at 25°C is 3.5 to 7.5.
  • One embodiment of the adhesive electrode for acquiring biological signals according to the present invention reduces irritation to the living body, has excellent flexibility, and maintains adhesion to the living body with low resistance.
  • FIG. 1 is a perspective view showing an example of an adhesive electrode for acquiring a biological signal according to an embodiment of the present invention.
  • FIG. 1 is a diagram showing the relationship between the imidazole concentration and the sheet resistance of the electrode sheets of an example and a comparative example 1.
  • FIG. 1 is a graph showing the relationship between the imidazole concentration and the breaking elongation of the electrode sheets of an example and a comparative example 1.
  • the adhesive electrode for acquiring a biological signal will be described.
  • the biological body refers to the human body (person) and animals such as cows, horses, pigs, chickens, dogs, and cats.
  • the biological sensor according to the present embodiment can be suitably used for biological bodies, particularly for the human body. In the present embodiment, the case where the biological body is a human will be described as an example.
  • the adhesive electrode for acquiring biosignals is a bioelectrode that is attached to a part of a living body (e.g., the skin, scalp, or forehead) to detect bioinformation.
  • a part of a living body e.g., the skin, scalp, or forehead
  • biosignals are electrical signals that represent, for example, electrocardiogram waveforms, brain waves, pulse rates, etc.
  • FIG. 1 is a perspective view showing an adhesive electrode for acquiring a biosignal according to this embodiment.
  • the adhesive electrode for acquiring a biosignal 1 has a sheet-like shape, and in a plan view, one side (one end) in the longitudinal direction of the adhesive electrode for acquiring a biosignal 1 may be formed in a substantially rectangular shape, and the other side (the other end) in the longitudinal direction may be formed in a substantially arc shape.
  • the adhesive electrode for acquiring a biosignal 1 can be used, for example, by being attached to and in contact with skin 2, which is an example of a living body, to measure the potential difference (polarization voltage) between the skin 2 and the adhesive electrode for acquiring a biosignal 1, and to detect an electrical signal (biosignal) related to the bioinformation of the subject.
  • skin 2 which is an example of a living body
  • the adhesive electrode 1 for acquiring a biological signal may have other shapes, such as a rod shape, in addition to the sheet shape.
  • the shape of the adhesive electrode 1 for acquiring a biological signal in a plan view is not limited to the shape shown in FIG. 1, and may be designed into any shape appropriate for the application, etc., and may be formed into any shape, such as a substantially rectangular, substantially polygonal, substantially circular, or substantially elliptical shape.
  • the adhesive electrode 1 for acquiring biosignals may have two through holes 11 on its main surface 1a. Of the two through holes 11, the through hole 11A may be provided on one end side of the adhesive electrode 1 for acquiring biosignals and may be formed in a thin, approximately oval shape. The through hole 11B may be provided on the other end side of the adhesive electrode 1 for acquiring biosignals and may be formed in a approximately circular shape.
  • the number, position and shape of the through holes 11 provided on the main surface 1a of the adhesive electrode 1 for acquiring a biosignal are not particularly limited and may be set appropriately depending on the size of the main surface 1a of the adhesive electrode 1 for acquiring a biosignal.
  • the number of through holes 11 may be one or three or more.
  • the position of the through hole 11 may be other than one end and the other end of the main surface 1a of the adhesive electrode 1 for acquiring a biosignal, or may be in the central part.
  • the shape of the through hole 11 may be approximately rectangular, etc.
  • the thickness of the adhesive electrode 1 for acquiring biosignals may be any appropriate thickness depending on the application, size, etc., within a range that ensures strength, flexibility, low resistance, and conductivity.
  • the thickness of the adhesive electrode 1 for acquiring biosignals refers to the length in the direction perpendicular to the surface of the adhesive electrode 1 for acquiring biosignals.
  • the thickness of the adhesive electrode 1 for acquiring biosignals is, for example, the thickness when an arbitrary location is measured on the cross section of the adhesive electrode 1 for acquiring biosignals, and when measurements are taken at multiple arbitrary locations, the thickness may be the average value of the thicknesses at these measurement locations.
  • the adhesive electrode 1 for acquiring biosignals is an electrode with adhesive properties (adhesive electrode) and contains a conductive polymer, a water-based emulsion adhesive, a moisturizer, and a neutralizing agent.
  • the inventors of the present application have noticed that when using an adhesive electrode 1 for acquiring biosignals that contains a water-based emulsion adhesive as a binder resin, the neutralizing agent used in the adhesive electrode 1 for acquiring biosignals affects the irritation and flexibility of the adhesive electrode 1 for acquiring biosignals on the surface of the skin 2.
  • the inventors have discovered that by including a neutralizing agent in the adhesive electrode 1 for acquiring biosignals, it is possible to reduce irritation to the surface of the skin 2 and increase flexibility while maintaining adhesion with low resistance.
  • the conductive polymer contained in the adhesive electrode 1 for acquiring biological signals may be, for example, a polythiophene-based conductive polymer, a polyaniline-based conductive polymer, a polypyrrole-based conductive polymer, a polyacetylene-based conductive polymer, a polyphenylene-based conductive polymer, or a derivative thereof, or a complex thereof. These may be used alone or in combination of two or more. Of these, it is preferable to use a complex in which polythiophene is doped with polyaniline as a dopant.
  • PEDOT/PSS poly3,4-ethylenedioxythiophene (PEDOT) is doped with polystyrene sulfonic acid (poly4-styrenesulfonate; PSS), because it has a lower contact impedance with the living body and a high conductivity.
  • PEDOT poly3,4-ethylenedioxythiophene
  • PSS polystyrene sulfonic acid
  • the aqueous emulsion adhesive contained in the adhesive electrode 1 for acquiring a biological signal is used as a binder resin for the adhesive electrode 1 for acquiring a biological signal.
  • the aqueous emulsion adhesive has the function of improving the adhesiveness and flexibility of the adhesive electrode 1 for acquiring a biological signal. Therefore, by including the aqueous emulsion adhesive in the adhesive electrode 1 for acquiring a biological signal, the adhesive electrode 1 for acquiring a biological signal can have low elasticity and can improve its ability to conform to the unevenness of the surface of the skin 2.
  • a water-based emulsion adhesive it is preferable to use an acrylic emulsion adhesive.
  • the acrylic emulsion adhesive preferably uses a silane emulsion adhesive that contains a water-dispersible copolymer and an organic liquid component that is compatible with the water-dispersible copolymer.
  • a water-dispersible copolymer is a polymer obtained by copolymerizing a monomer mixture containing an alkyl (meth)acrylate with a silane monomer that is copolymerizable with the alkyl (meth)acrylate.
  • a monomer mixture containing an alkyl (meth)acrylate ester is a monomer mixture that contains an alkyl (meth)acrylate ester as the main component, preferably at 50 wt% to 100 wt%.
  • (meth)acrylic acid alkyl ester a straight-chain or branched alkyl ester having an alkyl group with 1 to 15 carbon atoms, preferably 1 to 9 carbon atoms, is used.
  • Specific examples include (meth)acrylic acid alkyl esters having straight-chain or branched alkyl groups, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (
  • the monomer mixture containing the (meth)acrylic acid alkyl ester may also contain a carboxyl group-containing monomer copolymerizable with the (meth)acrylic acid alkyl ester.
  • Carboxyl group-containing monomers copolymerizable with (meth)acrylic acid alkyl esters are not particularly limited as long as they are polymerizable compounds containing a carboxyl group in their structure and are copolymerizable with (meth)acrylic acid alkyl esters, but examples include (meth)acrylic acid, itaconic acid, maleic acid, maleic anhydride, and 2-methacryloyloxyethyl succinic acid. Acrylic acid is particularly preferred.
  • the carboxyl group-containing monomer is contained in an amount of 0.1 wt% to 10 wt% relative to 100 wt% of the monomer mixture containing the (meth)acrylic acid alkyl ester.
  • silane monomer copolymerizable with (meth)acrylic acid alkyl ester is not particularly limited as long as it is a polymerizable compound having a silicon atom and is copolymerizable with (meth)acrylic acid alkyl ester, but silane compounds having a (meth)acryloyl group such as (meth)acryloyloxyalkylsilane derivatives are preferred because of their excellent copolymerizability with (meth)acrylic acid alkyl esters.
  • silane monomers include 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, and 3-(meth)acryloyloxypropylmethyldiethoxysilane. These silane monomers can be used alone or in combination of two or more.
  • silane monomers that can be used include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.
  • silane monomer with the monomer mixture containing the (meth)acrylic acid alkyl ester in an amount of 0.005 wt% to 2 wt% per 100 wt% of the monomer mixture containing the (meth)acrylic acid alkyl ester.
  • the silane compounds that act as crosslinking points are evenly distributed within the molecules of the resulting copolymer.
  • the aqueous emulsion adhesive is a water-dispersed type, the inside and outside of the aqueous emulsion adhesive particles are evenly crosslinked, giving it excellent cohesive strength, and the addition of organic liquid components makes it less irritating to the skin, while also providing excellent fixation and sweat-resistant fixation.
  • the aqueous dispersion type copolymer may be a copolymer of a monomer copolymerizable with the (meth)acrylic acid alkyl ester other than the above-mentioned silane-based monomer and carboxyl group-containing monomer, if necessary.
  • the monomer copolymerizable with the (meth)acrylic acid alkyl ester other than the silane-based monomer and the carboxyl group-containing monomer can be used for the purpose of adjusting the cohesive force of the adhesive electrode 1 for acquiring biological signals when the aqueous emulsion adhesive is formed into a sheet or the like, or improving compatibility with organic liquid components, and the amount used can be set arbitrarily according to the purpose by replacing a part of the content of the (meth)acrylic acid alkyl ester.
  • Examples of monomers copolymerizable with (meth)acrylic acid alkyl esters other than silane monomers and carboxyl group-containing monomers include sulfoxyl group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalene sulfonic acid, and acrylamidomethylpropane sulfonic acid; hydroxyl group-containing monomers such as (meth)acrylic acid hydroxyethyl ester and (meth)acrylic acid hydroxypropyl ester; amide group-containing monomers such as (meth)acrylamide, dimethyl (meth)acrylamide, N-butylacrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide; (meth)acrylic acid alkylamino alkyl esters such as (meth)acryl
  • the water-dispersed polymer can be prepared as a water dispersion of a (meth)acrylic acid alkyl ester copolymer, for example, by subjecting a mixture of a monomer mixture containing a (meth)acrylic acid alkyl ester and a silane-based monomer to conventional emulsion polymerization.
  • the polymerization method may be a general batch polymerization, continuous dropwise polymerization, or divided dropwise polymerization, and the polymerization temperature is, for example, 20°C to 100°C.
  • the polymerization initiator used in the polymerization is not particularly limited, and any general component used as a polymerization initiator can be used.
  • a chain transfer agent may be used in the polymerization.
  • the chain transfer agent There are no particular limitations on the chain transfer agent, and any of the general components used as chain transfer agents can be used.
  • the water-dispersible copolymer may be prepared by obtaining a copolymer of a monomer mixture containing a (meth)acrylic acid ester and a silane-based monomer by a method other than emulsion polymerization, and then dispersing the copolymer in water with an emulsifier.
  • the organic liquid components contained in the acrylic emulsion adhesive are blended with the water-dispersible copolymer to maintain good adhesion to the surface of the skin 2, while reducing damage to the keratin when peeled off from the surface of the skin 2, and reducing pain when peeled off.
  • the organic liquid component is liquid at room temperature and has good compatibility with the water-dispersible copolymer. "Compatibility” means that the organic liquid component is uniformly dissolved and incorporated into the water-dispersible copolymer, and that no separation can be confirmed by visual inspection.
  • organic liquid components examples include esters of monobasic or polybasic acids having 8 to 18 carbon atoms and branched alcohols having 14 to 18 carbon atoms, and esters of unsaturated fatty acids or branched acids having 14 to 18 carbon atoms and alcohols with tetrahydric or less.
  • esters of monobasic or polybasic acids having 8 to 18 carbon atoms with branched alcohols having 14 to 18 carbon atoms include isostearyl laurate, isocetyl myristate, octyldodecyl myristate, isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimellitate, and triisocetyl trimellitate.
  • Examples of unsaturated fatty acids or branched acids with 14 to 18 carbon atoms include myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, isostearic acid, etc.
  • tetrahydric or lower alcohols examples include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitan.
  • the content of the organic liquid component can be set as appropriate depending on the type of water-dispersible copolymer and the organic liquid component, and may be, for example, 20 wt% to 80 wt% relative to 100 wt% of the water-dispersible copolymer.
  • the acrylic emulsion adhesive is a silane emulsion adhesive
  • the acrylic emulsion adhesive may be a silane emulsion adhesive containing 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, and 3-methacryloxypropyltrimethoxysilane.
  • the acrylic emulsion adhesive may be a two-component or three-component acrylic emulsion adhesive that contains a monomer mixture containing an alkyl (meth)acrylate ester and a carboxyl group-containing monomer. These may contain solvents and other components in appropriate amounts within the range in which performance can be achieved.
  • the monomer mixture containing the (meth)acrylic acid alkyl ester contained in the two-component or three-component acrylic emulsion adhesive is similar to the monomer mixture containing the (meth)acrylic acid alkyl ester contained in the above-mentioned silane-based emulsion adhesive, so details are omitted.
  • the carboxyl group-containing monomer is preferably a carboxyl group-containing monomer copolymerizable with an alkyl (meth)acrylate ester.
  • the carboxyl group-containing monomer copolymerizable with an alkyl (meth)acrylate ester is the same as the carboxyl group-containing monomer contained in the monomer mixture containing an alkyl (meth)acrylate described above, and so details will be omitted.
  • two-component acrylic emulsion adhesives that can be used include adhesives that contain 2-ethylhexyl acrylate, which is a monomer mixture that contains an alkyl (meth)acrylate ester, and acrylic acid, which is a carboxyl group-containing monomer mixture.
  • three-component acrylic emulsion adhesives that can be used include an adhesive that contains 2-ethylhexyl acrylate and methyl methacrylate, which are monomer mixtures that contain (meth)acrylic acid alkyl esters, and acrylic acid, which is a carboxyl group-containing monomer mixture.
  • the average particle size of the aqueous emulsion adhesive is preferably 100 nm to 1.0 ⁇ m, more preferably 100 nm to 500 nm, and even more preferably 100 nm to 300 nm. If the average particle size is within the above preferred range, the adhesive electrode 1 for acquiring biological signals can be provided with adhesive strength and water resistance.
  • the shape of the aqueous emulsion adhesive is not particularly limited, and may be, for example, spherical, ellipsoidal, spindle-shaped, crushed, plate-shaped, columnar, etc.
  • the average particle size refers to the volume average particle size based on the effective diameter.
  • the average particle size is the particle size (median diameter) when the cumulative amount of particles, starting from the smallest, accounts for 50% by volume on a particle size distribution curve obtained by measuring the particle size distribution of an emulsion adhesive or an acrylic emulsion adhesive using, for example, a laser diffraction/scattering method or a dynamic light scattering method.
  • the content of the aqueous emulsion adhesive is preferably 35 wt% to 90 wt%, more preferably 40 wt% to 85 wt%, and even more preferably 50 wt% to 80 wt%, relative to 100 wt% of the adhesive electrode for acquiring biological signals.
  • the content of the aqueous emulsion adhesive is within the above preferred range, adhesive strength and softness can be imparted to the adhesive electrode for acquiring biological signals 1, and a decrease in conductivity can be suppressed.
  • the neutralizing agent contained in the adhesive electrode 1 for acquiring biological signals exerts a neutralizing effect on the conductive polymer, neutralizing the conductive polymer and improving its flexibility. If the conductive polymer is, for example, PEDOT-PSS, the neutralizing effect can be effectively exerted on PEDOT-PSS, even if PEDOT-PSS has acidic properties, so that PEDOT-PSS can be effectively neutralized.
  • Preferred examples of neutralizing agents include imidazole compounds.
  • Imidazole compounds are organic structures that have an imidazole group.
  • the imidazole group of an imidazole compound acts as a neutralizing agent, for example, in the pH range of 3.5 to 6.5.
  • Examples of imidazole compounds include heterocyclic amines.
  • Heterocyclic amines include, for example, imidazole, 2-methylimidazole, 2-propylimidazole, 2-undecylimidazole, 2-phenylimidazole, N-methylimidazole, 1-(2-hydroxyethyl)imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl
  • the neutralizing agent include 2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, 4,5-imidazoledicarboxylic acid, dimethyl 4,5-imidazoledicarboxylate, benzimidazole, 2-aminobenzimidazole, 2-aminobenzimidazole-2-sulfonic
  • the content of the neutralizing agent is preferably 0.5 wt% to 2.4 wt%, more preferably 0.7 wt% to 2.2 wt%, and even more preferably 1.0 wt% to 2.0 wt%, relative to 100 wt% of the adhesive electrode for acquiring biosignals.
  • the moisturizing agent contained in the adhesive electrode 1 for acquiring biological signals has the function of improving the conductivity of the adhesive electrode 1 for acquiring biological signals, as well as improving the adhesive strength and flexibility.
  • Humectants include polyol compounds such as glycerin, ethylene glycol, propylene glycol, sorbitol, and polymers thereof; aprotic compounds such as N-methylpyrrolidone (NMP), dimethylformaldehyde (DMF), N-N'-dimethylacetamide (DMAc), and dimethylsulfoxide (DMSO). These may be used alone or in combination of two or more. Of these, glycerin is preferred from the standpoint of compatibility with other components.
  • NMP N-methylpyrrolidone
  • DMF dimethylformaldehyde
  • DMAc N-N'-dimethylacetamide
  • DMSO dimethylsulfoxide
  • the content of the moisturizer is preferably 2 wt% to 60 wt%, more preferably 3 wt% to 50 wt%, and even more preferably 5 wt% to 35 wt%, relative to 100 wt% of the adhesive electrode for acquiring biosignals. If the content of the moisturizer is within the above preferred range, the adhesive strength of the adhesive electrode for acquiring biosignals 1 can be improved and high adhesion to the surface of the skin 2 can be maintained, while the storage modulus can be reduced and the viscoelasticity can be increased, thereby suppressing the amount of noise generated during use. In addition, the adhesive electrode for acquiring biosignals 1 can be prevented from absorbing water from the outside, thereby suppressing swelling.
  • the pH of the adhesive electrode 1 for acquiring biological signals at 25°C is preferably 3.5 to 7.5, more preferably 3.7 to 7.2, and even more preferably 4.0 to 7.5.
  • the pH of the adhesive electrode 1 for acquiring a biological signal can be measured by a known method.
  • the pH can be measured by contacting litmus paper with the adhesive electrode 1 for acquiring a biological signal, or by contacting litmus paper with a solvent (e.g., water) dropped onto the adhesive electrode 1 for acquiring a biological signal, measuring the pH of the solvent, and using the pH of the solvent as the pH of the adhesive electrode 1 for acquiring a biological signal.
  • a solvent e.g., water
  • the method for manufacturing the adhesive electrode 1 for acquiring a biological signal is not particularly limited. An example of the method for manufacturing the adhesive electrode 1 for acquiring a biological signal will be described below. For example, first, a conductive polymer and a solution containing a neutralizer (neutralizer-containing solution) are mixed to prepare a first mixed solution (conductive polymer neutralization step). The conductive polymer is neutralized by being contained in the neutralizer-containing solution.
  • the mixing ratio of the conductive polymer to the neutralizing agent-containing solution, mixing conditions such as mixing time, and the temperature of the neutralizing agent-containing solution are not particularly limited, and may be set to any appropriate size as long as the conductive polymer can be sufficiently mixed into the neutralizing agent-containing solution.
  • the first mixed solution is mixed with an aqueous emulsion adhesive and a moisturizer to prepare a second mixed solution (mixing process).
  • the second mixed solution is used as a composition for forming an adhesive electrode.
  • the mixing ratio of the first mixed solution to the aqueous emulsion adhesive and moisturizer, the mixing conditions such as the mixing time, the temperature of the second mixed solution, etc. are not particularly limited, and may be set to any appropriate value as long as the aqueous emulsion adhesive and moisturizer can be sufficiently mixed into the first mixed solution.
  • the second mixed solution is applied to the surface (coating surface) of the release substrate, and then dried to evaporate the water contained in the second mixed solution (coating and drying process). Because the aqueous emulsion adhesive has a particulate shape, by applying the second mixed solution to the coating surface of the release substrate, the aqueous emulsion adhesive bonds and fuses to itself, forming a coating film that is a cured product of the adhesive electrode forming composition.
  • a release liner or a core material can be used as the release substrate.
  • a resin film such as a polyethylene terephthalate (PET) film, a polyethylene (PE) film, a polypropylene (PP) film, a polyamide (PA) film, a polyimide (PI) film, or a fluororesin film can be used.
  • a resin film such as a PET film or a PI film; a ceramic sheet; a metal film such as an aluminum foil; a resin substrate reinforced with glass fiber or plastic nonwoven fiber; a silicone substrate or a glass substrate can be used.
  • the method of applying the second mixed solution to the coating surface of the release substrate is not particularly limited as long as the second mixed solution can be applied to the release substrate, and any general application method may be used.
  • Application methods that can be used include roll coating, screen coating, gravure coating, spin coating, reverse coating, bar coating, blade coating, spray coating, air knife coating, dipping, dispensing, and the like, as well as a method in which a small amount of the second mixed solution is dropped onto the coating surface of the substrate and spread with a doctor blade. By using these application methods, the second mixed solution is evenly applied onto the coating surface.
  • the drying conditions for the second mixed solution applied to the coating surface of the release substrate are not particularly limited as long as they allow the second mixed solution applied to the release substrate to be dried, and general drying conditions may be used.
  • the solution When drying, the solution may be dried at room temperature or may be heated using a dryer.
  • a general dryer such as a drying oven, a vacuum oven, an air circulation type oven, a hot air dryer, a far-infrared dryer, a microwave reduced pressure dryer, or a high-frequency dryer may be used.
  • the second mixed solution applied to the coating surface of the substrate may be dried by a method of heating the inside of the dryer to a high temperature, a method of heating the substrate, a method of blowing hot air onto the second mixed solution, or a method of irradiating the second mixed solution with far-infrared rays, microwaves, or high frequencies, etc.
  • the heating temperature and heating time when the second mixed solution is heated using a dryer are set to a temperature and time that can evaporate the moisture contained in the second mixed solution.
  • the heating temperature may be, for example, 100°C to 200°C. If the conductive composition contains a crosslinking agent, a heating temperature within the range of 100°C to 200°C can promote the evaporation of the moisture contained in the second mixed solution.
  • the heating time of the second mixed solution may be, for example, 0.5 minutes to 300 minutes. A heating time of 0.5 minutes to 300 minutes can sufficiently evaporate the moisture contained in the second mixed solution.
  • the obtained cured product is punched (pressed) using a press or the like as necessary to form one or more through holes in the surface of the cured product and mold the outer shape of the cured product into a predetermined shape (molding process).
  • the obtained cured product may have only through holes 11 formed in its surface, or only the outer shape may be molded into a predetermined shape. Furthermore, if the cured product can be used as it is as an adhesive electrode for acquiring biosignals, the cured product may be used as such without being molded or otherwise processed.
  • the adhesive electrode 1 for acquiring biosignals contains a conductive polymer, an aqueous emulsion adhesive, a moisturizer, and a neutralizer.
  • the adhesive electrode 1 for acquiring biosignals exhibits conductivity, and is softened while exhibiting adhesive strength to the skin 2, thereby improving conformability to the surface of the skin 2.
  • the adhesive electrode 1 for acquiring biosignals keeps resistance low.
  • the adhesive electrode 1 for acquiring biosignals increases flexibility, and by setting the pH at 25°C to 3.5 to 7.5, irritation to the skin 2 can be reduced.
  • the adhesive electrode 1 for acquiring biosignals reduces irritation to the skin 2, has excellent flexibility, and can maintain adhesion to the skin 2 with low resistance.
  • the resistance of the adhesive electrode 1 for acquiring a biosignal can be evaluated by measuring the sheet resistance of the adhesive electrode 1 for acquiring a biosignal.
  • the sheet resistance is the surface resistance of the adhesive electrode 1 for acquiring a biosignal.
  • the sheet resistance can be measured using a general resistance measurement method, for example, using a non-contact resistance measuring device by an eddy current measurement method in accordance with JIS Z 2316-1:2014.
  • the measurement range may be a predetermined range on the main surface of the adhesive electrode 1 for acquiring a biosignal.
  • the flexibility of the adhesive electrode 1 for acquiring a biosignal can be evaluated by measuring the breaking elongation (also called the breaking elongation rate) of the adhesive electrode 1 for acquiring a biosignal.
  • the breaking elongation of the adhesive electrode 1 for acquiring a biosignal is preferably 1700% to 5000%, more preferably 2000% to 4500%, and even more preferably 2500% to 4000%. If the breaking elongation of the adhesive electrode 1 for acquiring a biosignal is within the above preferred range, the adhesive electrode 1 for acquiring a biosignal can easily stretch in a state of contact with the surface of the skin 2 and can maintain a state of contact with the surface of the skin 2.
  • the adhesive electrode 1 for acquiring a biosignal can reduce noise generated during measurement of bioinformation and reduce discomfort to the subject. In addition, it is possible to prevent the adhesive electrode 1 for acquiring a biosignal from becoming too soft and causing the shape of the adhesive electrode 1 for acquiring a biosignal to become unstable.
  • the breaking elongation of the adhesive electrode 1 for acquiring a biosignal is a value expressed as a percentage obtained by dividing the elongation of the gauge length when the adhesive electrode 1 for acquiring a biosignal breaks in a tensile test by the gauge length of the adhesive electrode 1 for acquiring a biosignal before the tensile test.
  • the breaking elongation of the adhesive electrode 1 for acquiring a biosignal is calculated by dividing the amount of elongation (L-Lo) of the gauge length of the broken adhesive electrode 1 for acquiring a biosignal by the gauge length Lo of the adhesive electrode 1 for acquiring a biosignal before the tensile test, as shown in the following formula (1), and expressing the value as a percentage.
  • Breaking elongation [%] (L - Lo) / Lo ⁇ 100 ... (1) (In the formula, Lo is the gauge length of the adhesive electrode for acquiring a biological signal before the tensile test, and L is the gauge length of the adhesive electrode for acquiring a biological signal after the breakage.)
  • the distance between the reference points of the adhesive electrode for acquiring a biosignal is preferably the length in the longitudinal direction of the adhesive electrode for acquiring a biosignal 1, since the adhesive electrode for acquiring a biosignal 1 has a shape in which one side in the longitudinal direction is formed into an approximately rectangular shape and the other side is formed into an approximately arc shape in a plan view.
  • the breaking elongation of the adhesive electrode 1 for acquiring biosignals can be measured by performing a tensile test using a tensile tester in accordance with JIS Z 2241.
  • the distance between the chucks of a pair of jigs that grip both ends of the adhesive electrode 1 for acquiring biosignals in the longitudinal direction is taken as the gauge distance, and a tensile test is performed at a predetermined tensile speed.
  • the point at which the adhesive electrode 1 for acquiring biosignals breaks is taken as the elongation of the adhesive electrode 1 for acquiring biosignals.
  • a rectangular electrode sheet having a predetermined size may be used as a test specimen.
  • both ends of the short sides of the rectangular sheet may be gripped and fixed with a tensile test jig, and one or both of the pair of jigs may be moved in the longitudinal direction of the electrode sheet with a predetermined tensile strength to pull the rectangular electrode sheet.
  • Both ends of the short sides of the rectangular electrode sheet may be within a predetermined range from the surface of the short side, depending on the size of the rectangular electrode sheet, etc.
  • the breaking elongation of the adhesive electrode 1 for acquiring biosignals may be the average value of the measured values of multiple adhesive electrodes 1 for acquiring biosignals.
  • the pulling direction of the adhesive electrode 1 for acquiring a biosignal when measuring the breaking elongation of the adhesive electrode 1 for acquiring a biosignal may be changed as appropriate according to the shape of the adhesive electrode 1 for acquiring a biosignal in a planar view.
  • the breaking elongation of the adhesive electrode 1 for acquiring a biosignal is preferably the breaking elongation in the long axis direction of the adhesive electrode 1 for acquiring a biosignal.
  • the breaking elongation of the adhesive electrode 1 for acquiring a biosignal is preferably the breaking elongation in the longitudinal direction of the adhesive electrode 1 for acquiring a biosignal.
  • the breaking elongation of the adhesive electrode 1 for acquiring a biosignal may be the breaking elongation in the direction of one side of the adhesive electrode 1 for acquiring a biosignal.
  • the breaking elongation of the adhesive electrode 1 for acquiring a biological signal may be the breaking elongation of the diameter of the adhesive electrode 1 for acquiring a biological signal.
  • the adhesive electrode 1 for acquiring biological signals can contain an imidazole compound as a neutralizing agent. This ensures that the adhesive electrode 1 for acquiring biological signals is flexible and neutralized, so that irritation to the skin 2 can be reliably reduced and flexibility can be increased.
  • the adhesive electrode 1 for acquiring biological signals can have a neutralizing agent content of 0.5 wt% to 2.4 wt%. This increases the flexibility of the adhesive electrode 1 for acquiring biological signals and allows neutralization to be more reliably achieved, thereby reliably reducing irritation to the skin 2 and further increasing its flexibility.
  • the adhesive electrode 1 for acquiring biosignals can use an acrylic emulsion adhesive instead of a water-based emulsion adhesive. This allows the adhesive electrode 1 for acquiring biosignals to suppress a decrease in adhesive strength while maintaining resistance, and reliably improves conformability to the surface of the skin 2. Therefore, the adhesive electrode 1 for acquiring biosignals can have high adhesive strength and conformability to the surface of the skin 2.
  • the adhesive electrode 1 for acquiring biosignals can use a silane-based emulsion adhesive containing a water-dispersible copolymer and an organic liquid component as an acrylic emulsion adhesive. This allows the adhesive electrode 1 for acquiring biosignals to reliably keep the viscoelasticity low, thereby increasing the adhesive strength and further improving the conformability to the surface of the skin 2. Therefore, the adhesive electrode 1 for acquiring biosignals can further increase its flexibility and more reliably maintain its adhesiveness.
  • the adhesive electrode 1 for acquiring biosignals exhibits high flexibility while reducing irritation to the skin, and can maintain adhesion with low resistance, so it can be effectively used as an electrode (bioelectrode) for biosensors, particularly for adhesive biosensors that require good adhesion to human skin, high flexibility, and safety for the skin.
  • Example 1 1.0 g of PEDOT/PSS pellets (Orgacon DRY, manufactured by Agfa Materials Japan) as a conductive polymer and 23 g of an imidazole solution with an imidazole concentration of 30 mM were added to a plastic container, and the mixture was mixed while stirring and defoaming using a planetary stirring and defoaming device to prepare a first mixed solution.
  • PEDOT/PSS pellets Orgacon DRY, manufactured by Agfa Materials Japan
  • a silane-based emulsion adhesive manufactured by Nitto Denko Corporation
  • 2.0 g of glycerin manufactured by Wako Pure Chemical Industries, Ltd.
  • a moisturizing agent was added to the plastic container and mixed with the first mixed solution to prepare a second mixed solution that is a composition for forming an adhesive electrode that is uniformly mixed.
  • a coating film that is a cured product of the composition for forming an adhesive electrode having adhesive properties was prepared.
  • the coating film was punched (pressed) into a desired approximately rectangular shape as shown in FIG. 1 in a plan view and formed into a sheet, to prepare an electrode sheet (bioelectrode) having adhesive properties.
  • the imidazole concentration in the imidazole solution is 30 mM, so the imidazole content is 0.047 g.
  • the silane-based emulsion adhesive aqueous solution contains approximately 52% of the silane-based emulsion adhesive, so the silane-based emulsion adhesive content is 6.5 g.
  • Example 2 the imidazole concentration of the imidazole solution used to prepare the electrode sheet was changed from 30 mM to 60 mM, 90 mM, 102 mM, or 150 mM, as shown in Table 1, in the same manner as in Example 1, to prepare the electrode sheet.
  • the tensile test conditions were as follows. Table 2 shows the measurement results of the breaking elongation of the electrode sheets of each Example and Comparative Example. The relationship between the imidazole concentration of the electrode sheets of each Example and Comparative Example 1 and the breaking elongation in the longitudinal direction is shown in FIG. 3. (Tensile test conditions) Distance between chucks of tensile test fixtures: 50 mm Tensile strength: 300 mm/min
  • the electrode sheets of the above examples have excellent flexibility, low resistance, and maintain adhesiveness while reducing the burden on the skin, if the imidazole concentration of the imidazole used as the neutralizing agent is set to a specified value. Therefore, even if the adhesive electrode for acquiring biosignals according to this embodiment is attached to the skin of a subject for a long period of time (e.g., 24 hours), it can be said that it can be effectively used to stably measure bioinformation without continuously placing a burden on the subject for a long period of time.
  • a conductive polymer an aqueous emulsion adhesive, a moisturizer, and a neutralizer
  • An adhesive electrode for acquiring biological signals having a pH at 25°C of 3.5 to 7.5.
  • ⁇ 4> The adhesive electrode for acquiring a biological signal according to any one of ⁇ 1> to ⁇ 3>, wherein the aqueous emulsion adhesive is an acrylic emulsion adhesive.
  • ⁇ 5> The adhesive electrode for acquiring a biological signal according to ⁇ 4>, wherein the acrylic emulsion adhesive is a silane emulsion adhesive containing a water-dispersible copolymer and an organic liquid component compatible with the water-dispersible copolymer.
  • a biosensor comprising the adhesive electrode for acquiring a biosignal according to any one of ⁇ 1> to ⁇ 5>.

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Abstract

Électrode adhésive pour acquérir un biosignal, selon la présente invention, comprenant un polymère électroconducteur, un agent adhésif en émulsion à base d'eau, un agent hydratant, ainsi qu'un agent neutralisant et ayant une valeur de pH de 3,5 à 7,5 à 25°C.
PCT/JP2023/034379 2022-09-27 2023-09-21 Électrode adhésive pour acquérir un biosignal et biocapteur WO2024070906A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017042300A (ja) * 2015-08-25 2017-03-02 国立大学法人山梨大学 導電性組成物、導電性部材及び生体センシング用デバイス
JP2019008911A (ja) * 2017-06-21 2019-01-17 信越ポリマー株式会社 導電性高分子分散液及びその製造方法、導電性フィルム及びその製造方法、並びに導電性ガラス基材及びその製造方法
JP2020037670A (ja) * 2018-06-28 2020-03-12 積水化成品工業株式会社 生体用粘着シート及びウェアラブル型の生体情報計測用デバイス
JP2022114676A (ja) * 2021-01-27 2022-08-08 東ソー株式会社 導電性高分子水溶液、及び導電性高分子膜

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017042300A (ja) * 2015-08-25 2017-03-02 国立大学法人山梨大学 導電性組成物、導電性部材及び生体センシング用デバイス
JP2019008911A (ja) * 2017-06-21 2019-01-17 信越ポリマー株式会社 導電性高分子分散液及びその製造方法、導電性フィルム及びその製造方法、並びに導電性ガラス基材及びその製造方法
JP2020037670A (ja) * 2018-06-28 2020-03-12 積水化成品工業株式会社 生体用粘着シート及びウェアラブル型の生体情報計測用デバイス
JP2022114676A (ja) * 2021-01-27 2022-08-08 東ソー株式会社 導電性高分子水溶液、及び導電性高分子膜

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