Classifications

• • A—HUMAN NECESSITIES
  • A41—WEARING APPAREL
  • A41D—OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
  • A41D13/00—Professional, industrial or sporting protective garments, e.g. surgeons' gowns or garments protecting against blows or punches
• • A—HUMAN NECESSITIES
  • A41—WEARING APPAREL
  • A41D—OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
  • A41D31/00—Materials specially adapted for outerwear
• • A—HUMAN NECESSITIES
  • A41—WEARING APPAREL
  • A41D—OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
  • A41D31/00—Materials specially adapted for outerwear
  • A41D31/04—Materials specially adapted for outerwear characterised by special function or use
  • A41D31/12—Hygroscopic; Water retaining
• • 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
  • A61B5/256—Wearable electrodes, e.g. having straps or bands
• • 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
  • A61B5/265—Bioelectric electrodes therefor characterised by the electrode materials containing silver or silver chloride
• • 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
  • A61B5/27—Conductive fabrics or textiles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
  • B32B5/06—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer characterised by a fibrous or filamentary layer mechanically connected, e.g. by needling to another layer, e.g. of fibres, of paper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/02—Physical, chemical or physicochemical properties
  • B32B7/025—Electric or magnetic properties
• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
  • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
  • D02G3/02—Yarns or threads characterised by the material or by the materials from which they are made
  • D02G3/04—Blended or other yarns or threads containing components made from different materials
• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
  • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
  • D02G3/02—Yarns or threads characterised by the material or by the materials from which they are made
  • D02G3/12—Threads containing metallic filaments or strips
• • D—TEXTILES; PAPER
  • D05—SEWING; EMBROIDERING; TUFTING
  • D05C—EMBROIDERING; TUFTING
  • D05C17/00—Embroidered or tufted products; Base fabrics specially adapted for embroidered work; Inserts for producing surface irregularities in embroidered products

Definitions

• the present invention relates to a base sheet with a fiber electrode, which includes a base sheet and a fiber electrode formed of an embroidered portion containing conductive thread.
• Biosignals are weak electrical signals that are unconsciously emitted from the body.
• Biosignals are generally signals that are emitted from within the body due to biological phenomena such as heart rate, brain waves, pulse, breathing, sweating, and movement. Storing and analyzing such biosignals can be used not only for health management, but also for efficient sports training and in the medical field.
• various research is being conducted on electrodes that input electrical signals to living organisms such as muscles and nerves and provide electrical stimulation. Surface electrode types that are attached directly to the skin are often used in home low-frequency therapy devices.
• An electrode capable of reliably acquiring weak electrical signals and/or inputting electrical signals or imparting electrical stimulation must have low electrical resistance, be able to provide a stable and appropriate sense of electrical stimulation, be comfortable to use over long periods of time as it comes into direct contact with the living body or skin, and be easy to handle.
• electrodes that use thin metal plates, gel electrodes, and rubber electrodes, as well as textile-shaped electrodes in which conductive threads are incorporated into some of the fibers that make up the woven or knitted fabric have been proposed.
• knitted and woven fabrics have been proposed as textile-shaped electrodes.
• the conductive threads used include fibers containing fine particles such as carbon, metal-coated fibers with a fiber surface coated with a metal such as copper, multiple twisted metal threads made of aluminum or tungsten, and composites of these metal threads with organic fibers.
• knitted fabrics are highly elastic, which makes them prone to fluctuations in electrical resistance, and woven fabrics have stable electrical resistance, but there is a problem of high loss of conductive thread during production, which makes them less productive.
• Patent Document 1 proposes an embroidered electrode formed by embroidering conductive thread to make the electrode soft to the touch and highly flexible.
• the conductive thread described in Patent Document 1 is a silver-plated polyamide fiber, which does not have a sufficiently low surface resistance value.
• clothing with embroidered electrodes which is described as "suitable for performing electrocardiogram (ECG) measurements on humans in a walking state.”
• ECG electrocardiogram
• a fiber electrode that has the conductive performance to adequately acquire weak electrical signals, such as biosignals, and to provide electrical stimulation by inputting electrical signals can stably conduct electrical signals when performing various operations, and whose conductive performance is unlikely to deteriorate or change even with repeated use, and a textile product that has such a fiber electrode have not yet been proposed.
• the present invention aims to provide a base sheet with fiber electrodes that has the conductive properties to fully acquire biosignals, which are weak electrical signals that are unconsciously emitted from the body, and to provide electrical stimulation by inputting electrical signals, and whose conductive properties are unlikely to deteriorate or change even with repeated use, and a product that includes the base sheet with fiber electrodes.
• the inventors discovered that the above problems could be solved by using a composite thread containing organic fibers and metal fibers as a conductive thread, forming a fiber electrode having an embroidered portion on a base sheet where the conductive thread is stitched, and adjusting the size of the embroidered portion on the surface of the fiber electrode, the content of metal fibers in the embroidered portion, and the surface resistance value on the surface of the fiber electrode within specific ranges, and thus arrived at the present invention.
• a base sheet with a fiber electrode comprising a base sheet and a fiber electrode constituted by an embroidered portion including conductive thread, the base sheet with a fiber electrode satisfying all of the following characteristics (1) to (4).
• the size of the embroidered portion on the surface of the fiber electrode is 0.1 cm2 or more.
• the conductive yarn is a composite yarn containing organic fibers and metal fibers.
• the content of metal fibers in the embroidery portion is 0.001 to 0.1 g/ cm2 .
• the surface resistance of the fiber electrode surface is 15 ⁇ /cm 2 or less.
• ⁇ 2> The substrate sheet with fiber electrodes according to ⁇ 1>, wherein the metal fibers contained in the conductive yarn have a diameter of 2 to 150 ⁇ m.
• ⁇ 3> The substrate sheet with fiber electrodes according to ⁇ 1> or ⁇ 2>, wherein the absolute value of the change in surface resistance of the fiber electrode surface after 30 friction tests is 1 ⁇ /cm 2 or less.
• ⁇ 4> ⁇ 4> The substrate sheet with a fiber electrode according to any one of ⁇ 1> to ⁇ 3>, wherein the fiber electrode has a dimensional retention rate of 85% or more after 50 washings.
• ⁇ 7> The substrate sheet with a fiber electrode according to any one of ⁇ 1> to ⁇ 6>, wherein the embroidered portion has stitches in which conductive threads are arranged to cross each other.
• ⁇ 8> The substrate sheet with a fiber electrode according to any one of ⁇ 1> to ⁇ 7>, wherein the fiber electrode has a water absorbing agent on a surface thereof.
• ⁇ 9> ⁇ 9> A product having, at least in a part thereof, the substrate sheet with a fiber electrode according to any one of ⁇ 1> to ⁇ 8>.
• the base sheet with fiber electrodes of the present invention has an embroidered portion formed on the base sheet and stitched with conductive thread that functions as an electrode, and satisfies all of the above characteristics (1) to (4). Therefore, it has excellent conductive performance for fully acquiring biosignals, which are weak electrical signals that are unconsciously emitted from the body, and for inputting electrical signals to impart electrical stimulation, and can stably conduct electrical signals when performing various actions by making stable contact with the skin. Furthermore, the base sheet with fiber electrodes of the present invention is resistant to deterioration or change in conductive performance even with repeated use.
• the base sheet with fiber electrodes of the present invention is therefore preferably used as a biological electrode, and by providing it on at least a portion of a base, it can be used as a product that can acquire biological signals and/or impart electrical signals or electrical stimuli. Furthermore, when the base sheet with fiber electrodes of the present invention is used as part of clothing, it can be suitably used as clothing that allows health management and wear that allows efficient sports training, and can also be suitably used as a supporter to assist walking.
• FIG. 1 is a photograph in place of a drawing showing one embodiment of a substrate sheet with a fiber electrode of the present invention.
• FIG. 10 is an explanatory diagram showing the image analysis of the substrate sheet with a fiber electrode obtained in Example 2.
• the base sheet with a fiber electrode of the present invention includes a base sheet and a fiber electrode constituted by an embroidered portion including a conductive thread.
• the base sheet with a fiber electrode of the present invention will be described in detail below.
• the substrate sheet in the present invention is not particularly limited as long as it can form a fiber electrode composed of an embroidered portion containing a conductive thread thereon, and examples thereof include woven fabrics, knitted fabrics, nonwoven fabrics, felt, rubber, resin sheets, films, and foam sheets.
• the substrate sheet is preferably one having an excessively large elongation characteristic, for example, a woven fabric, from the viewpoint of maintaining dimensional stability when stitching an embroidered portion thereon, or during use or washing of a product having a substrate sheet with a fiber electrode.
• materials having water retention include materials with low water permeability such as rubber, film, and foam sheets; brushed woven fabrics, knitted fabrics, and nonwoven fabrics.
• the substrate sheet may be a single sheet, or may be a laminate in which one or more materials are layered.
• the type of fabric may be, for example, plain weave, twill weave, satin weave, pile weave, or variations of these weaves.
• the type of knitted fabric may be either warp knit or weft knit. Examples of warp knit fabrics include denbigh knit, cord knit, and atlas knit, and specific examples include tricot half and tricot satin. Examples of weft knit fabrics include plain knit, rib knit, purl knit, and smooth knit, and specific examples include jersey, pique, and smooth.
• the nonwoven fabric may be obtained by any of the following methods: wet laying, chemical bonding, thermal bonding, needle punching, spunlace, stitch bonding, air laying, spun bonding, and melt blowing.
• the base sheet is a felt
• examples of the felt include felts made by fulling.
• the fibers used in weaving or weaving may be filaments or spun yarns using staple fibers.
• Types of filaments and staple fibers include, for example, synthetic fibers such as polyester, nylon, vinylon, polyurethane, and polypropylene; vegetable fibers such as cotton, hemp, and bamboo; regenerated fibers such as viscose rayon, solvent-spun cellulose fibers, and lyocell; animal hair fibers such as sheep, cashmere, camel, angora, mohair, alpaca, mink, and seal; and modal fibers.
• the fiber electrode in the present invention is an electrode formed by embroidering the base sheet with conductive thread.
• the stitches that appear on the surface by embroidery are the stitches.
• the surface of the fiber electrode is the surface on which most of the stitches of the conductive thread are present.
• the surface on which the stitches of the lower thread appear is the back surface of the fiber electrode.
• the fiber electrode in the present invention is an electrode formed by forming an embroidered part with conductive thread on the base sheet, and is not an electrode in an embodiment in which the base sheet itself, such as a knitted fabric or woven fabric, contains conductive thread, that is, an electrode in an embodiment in which at least a part of the thread constituting the base sheet itself uses conductive thread.
• the fiber electrode in the present invention does not stretch excessively itself and shows a stable surface resistance value.
• the fiber electrode in the present invention has conductive threads more densely and exposed on the surface of the fiber electrode compared to the back surface, so that it is possible to conduct electric signals more efficiently than an electrode in an embodiment in which conductive threads are used as threads constituting the base sheet itself, such as a knitted fabric or woven fabric.
• the fiber electrode may be composed of only one embroidered part on a base sheet where conductive thread is stitched, or may be composed of multiple embroidered parts.
• the number is not limited and can be changed appropriately depending on the type of electrical signal to be collected, or the application, such as the acquisition and/or input of electrical signals.
• the aspects and characteristic values of the fiber electrode are described below, but when the fiber electrode has multiple embroidered parts on a base sheet, it is preferable that each embroidered part has the following aspects and characteristics.
• the shape of the embroidered portion is not particularly limited as long as it allows for the acquisition and input of biosignals, and can be appropriately selected depending on the application, such as a circle, ellipse, triangle, square, polygon, or a shape with unevenness.
• the fiber electrode of the present invention is characterized in that the size (area) of the part on the surface of the fiber electrode where stitches are present, i.e., the embroidered part, is 0.1 cm2 or more, and preferably 0.2 cm2 or more.
• the size (area) of the embroidered portion is less than 0.1 cm2 , the ability to acquire biosignals will be poor.
• the upper limit of the size of the embroidered portion is not particularly limited, but is usually 150 cm2 or less, preferably 100 cm2 or less, more preferably 50 cm2 or less, even more preferably 25 cm2 or less, and even more preferably 20 cm2 or less. If the size of the embroidered portion exceeds 150 cm2 , it is undesirable because noise other than biosignals will be easily acquired.
• the size (area) of the embroidery portion is preferably 0.1 to 150 cm 2 , more preferably 0.2 to 100 cm 2 , even more preferably 0.2 to 50 cm 2 , still more preferably 0.2 to 25 cm 2 , and particularly preferably 0.2 to 20 cm 2 .
• the conductive yarn used to form the fiber electrode in the present invention is a composite yarn containing organic fibers and metal fibers.
• the use of the composite yarn containing organic fibers and metal fibers can solve the problem of durability against repeated use that occurs when using metal-plated yarn, that is, the problem of deterioration of conductive performance due to peeling or separation of metal from the fiber electrode due to repeated use.
• the conductive yarn is a composite yarn containing organic fibers and metal fibers, and is preferably a twisted yarn made by twisting together the above-mentioned two fibers, and more preferably a twisted yarn made by covering a core yarn with a sheath yarn (hereinafter sometimes referred to as a "core-sheath composite twisted yarn").
• organic fibers used in the conductive yarn of the present invention include natural fibers such as cotton, hemp, wool, and silk; synthetic fibers such as polyester, nylon, acrylic, polyolefin, para-aramid, meta-aramid, polyarylate, and polybenzoxazole; and regenerated fibers such as rayon.
• synthetic fibers such as polyester, nylon, acrylic, polyolefin, para-aramid, meta-aramid, polyarylate, and polybenzoxazole
• regenerated fibers such as rayon.
• water-soluble fibers such as water-soluble vinylon and alkali-soluble fibers that can be dissolved in an alkaline solution can also be used as organic fibers.
• alkali-soluble fibers include fibers made of polycaprolactone resin, polylactic acid resin, polyhydroxybutyrate resin, polyglycolic acid resin, polyethylene adipate resin, and copolymerized polyester resin using a specific copolymerization component. Of these, fibers made of copolymerized polyester resin and/or polylactic acid resin are preferred.
• copolymerized polyester resins include those in which an aromatic dicarboxylic acid having a metal sulfonate group is included as a copolymerization component in the acid components that make up the polyester.
• aromatic dicarboxylic acids having a metal sulfonate group include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, sodium sulfonaphthalenedicarboxylic acid, sodium sulfophenyldicarboxylic acid, and 5-sodium sulfoterephthalic acid.
• the aromatic dicarboxylic acid is included in an amount of 0.5 to 5 mol %.
• the organic fiber may be in the form of any of spun yarn, filament yarn, composite yarn, and a combination of these yarns, but among these, it is preferable to use multifilament yarn as described above.
• the organic fiber may be raw yarn that has not been false-twisted, or may be false-twisted yarn.
• the organic fiber may be made by twisting raw yarn or false-twisted yarn.
• the cross-sectional shape of the organic fiber is not particularly limited, and may be any of a circular cross section, irregular cross section, hollow cross section, etc.
• the organic fiber may contain titanium dioxide, silicon dioxide, pigments, etc., depending on the characteristics to be imparted.
• the organic fiber is preferably a spun yarn or a multifilament. If it is a spun yarn, the thickness is preferably 10 to 100, more preferably 15 to 80, and even more preferably 20 to 70. If it is a multifilament, the single fiber fineness is preferably 0.3 to 10 dtex, the number of single fibers is preferably 5 to 150, and the total fineness is preferably 8 to 330 dtex. The total fineness is more preferably 10 to 170 dtex, and even more preferably 20 to 100 dtex.
• metal fibers used in the conductive thread of the present invention include metal-coated fibers obtained by coating, plating, metal vapor deposition, or sputtering a metal such as copper, nickel, or silver on the fiber surface; metal fibers made of metals (simple elements) such as aluminum and tungsten; and conductive fibers such as fibers containing fine particles of carbon, conductive ceramic, metal, etc.
• metal fibers made of simple metals from the viewpoint of increasing conductivity, it is preferable to use metal fibers made of simple metals, and it is more preferable to use metal yarns, which are metal fibers made of simple metals and are continuous metal wires.
• Examples of materials for metal fibers made of simple metals include gold, silver, copper, brass, platinum, iron, steel, zinc, tin, nickel, stainless steel, aluminum, tungsten, and molybdenum. Of these, at least one filament selected from tungsten, molybdenum, and stainless steel is preferable because of its excellent corrosion resistance and strength, and it is more preferable to use tungsten, with tungsten metal yarn being even more preferable. These metals may be used alone or in combination of two or more kinds.
• the material for the metal fibers may also be an alloy made of two or more kinds of metals.
• the metal fibers used in the conductive yarn of the present invention may be monofilament yarns of the metal fibers mentioned above (for example, monofilament yarns (metal yarns) of metal fibers made of simple metal or monofilament yarns of metal-coated fibers, etc.), or multifilament yarns in which multiple types of metal fibers are twisted or aligned may be used.
• the monofilament thread is not twisted (single twist).
• the monofilament thread is not twisted (single twist).
• the diameter of the metal fibers is preferably 2 to 150 ⁇ m, more preferably 2 to 100 ⁇ m, even more preferably 5 to 50 ⁇ m, and even more preferably 10 to 20 ⁇ m. If the diameter is less than 2 ⁇ m, the composite thread will have poor conductivity and strength. If the diameter exceeds 150 ⁇ m, defects are likely to occur when forming the embroidered portion using the composite thread, and the metal fibers on the surface of the obtained fiber electrode will be more noticeable in appearance, resulting in poor flexibility and texture.
• the electrical resistance of the metal fiber (metal thread) is preferably 1 ⁇ 10 -4 to 1 ⁇ 10 10 ⁇ /m, more preferably 1 ⁇ 10 -4 to 1 ⁇ 10 5 ⁇ /m, and even more preferably 1 ⁇ 10 -4 to 1 ⁇ 10 3 ⁇ /m.
• the electrical resistance of the metal fiber (metal thread) is measured in an environment of 23° C. using a 1 m sample of the metal fiber, and the average electrical resistance of five samples is used.
• the conductive yarn in the present invention is preferably a core-sheath composite twisted yarn formed by covering a core yarn with a sheath yarn, as described above.
• the core-sheath composite twisted yarn is a twisted yarn made of a core yarn and a sheath yarn that is wound around the outer periphery of the core yarn and covers it, and it is preferable that both the core yarn and the sheath yarn are twisted yarns containing organic fibers.
• Form 1 Two types of sheath yarns, a metal fiber and an organic fiber B, are wound around a core yarn made of an organic fiber A in the S or Z twist direction.
• Form 2 A sheath yarn of organic fiber B is wound around a core yarn made of organic fiber A and metal fiber in the S or Z twist direction.
• the fiber electrode can easily follow the movements of various actions and can stably contact the skin, thereby stably acquiring biosignals and inputting electrical signals to provide electrical stimulation.
• the durability against repeated use, shape stability after washing, and operability during embroidery are also excellent.
• the organic fiber A used for the core yarn and the organic fiber B used for the sheath yarn may be of the same type or different types.
• the conductive yarn is preferably a twisted yarn N obtained by twisting two or more core-sheath composite twisted yarns (twisted yarns M) of form 1 or form 2.
• the metal fibers contained in each twisted yarn M come into contact with each other in the twisted yarn N, resulting in a twisted yarn with better conductive performance. Therefore, by using the twisted yarn N, the number of contact points between the metal fibers in the fiber electrode increases, and a fiber electrode with better conductive performance can be obtained.
• the number of twisted yarns is preferably 2 to 9, and more preferably 4 to 8. If the number of twisted yarns is within the above range, the number of contact points between the metal fibers can be increased, and since the twisted yarn N does not become too thick, the surface of the fiber electrode does not become thick or hard when used in the fiber electrode, and the fiber electrode can easily follow the movements of various operations.
• the fiber electrode comes into contact with the object for receiving or transmitting an electric signal, that is, the surface of a living body that emits or receives an electric signal
• Methods for exposing more metal fibers on the surface of the conductive yarn include, for example, arranging metal fibers in the sheath yarn of the core-sheath composite twisted yarn (above form 1), or performing twisting processing so that the metal fibers appear on the yarn surface.
• Methods for exposing more metal fibers on the surface of the fiber electrode include, for example, using water-soluble fibers such as water-soluble vinylon or alkali-soluble fibers that can be dissolved in an alkaline solution as at least a part of the organic fibers in the core-sheath composite twisted yarn, embroidering the core-sheath composite twisted yarn on a base sheet, and then dissolving the water-soluble fibers or alkali-soluble fibers using hot water or an alkaline solution.
• water-soluble fibers or alkali-soluble fibers as the organic fibers of the sheath yarn of the core-sheath composite twisted yarn.
• the embroidered portion in which the conductive thread is stitched must have a certain density of conductive threads and a specific amount of metal fibers. That is, the fiber electrode according to the present invention must have a metal fiber content of 0.001 to 0.1 g/cm 2 in the embroidered portion, and preferably 0.003 to 0.08 g/cm 2.
• the metal fiber content is less than 0.001 g/cm 2 , the metal fiber content is too low to sufficiently acquire a biosignal, while if it exceeds 0.1 g/cm 2 , the metal fiber content is too high, making the surface of the embroidered electrode hard, making it difficult to follow the movements of various actions, and causing a poor texture when in contact with the skin.
• the content of the metal fibers in the embroidery portion is preferably 0.003 to 0.05 g/ cm2 , more preferably 0.003 to 0.03 g/ cm2 , even more preferably 0.004 to 0.02 g/ cm2 , and particularly preferably 0.004 to 0.01 g/ cm2 .
• the content of the organic fibers in the embroidered portion will vary depending on the type of organic fiber, but when multifilaments (e.g., polyester multifilaments) are used, the content is preferably 0.001 to 0.5 g/ cm2 , more preferably 0.003 to 0.1 g/ cm2 , and even more preferably 0.003 to 0.05 g/ cm2 .
• multifilaments e.g., polyester multifilaments
• the length (total length) of the metal fibers in the conductive thread contained in the embroidered portion is preferably 100 to 900 cm/ cm2 , more preferably 120 to 500 cm/ cm2 , and even more preferably 150 to 400 cm/ cm2 .
• the fiber electrode of the present invention must have a surface resistance of 15 ⁇ /cm2 or less on the fiber electrode surface, preferably 13 ⁇ /cm2 or less , more preferably 10 ⁇ /cm2 or less , even more preferably 5 ⁇ /cm2 or less , even more preferably 3 ⁇ /cm2 or less , and particularly preferably 2 ⁇ / cm2 or less.
• the surface resistance of the fiber electrode surface is an index showing the conductive performance of the fiber electrode. If the surface resistance of the fiber electrode surface exceeds 15 ⁇ / cm2 , it becomes difficult to sufficiently acquire a biosignal, which is a weak electrical signal, or to input an electrical signal to a living body and apply an electrical stimulus.
• the surface resistance value on the surface of the fiber electrode is a value obtained by the following measurement method.
• Method for measuring surface resistance The surface resistance was measured using a digital tester at the two longest points between any two points on the surface of the fiber electrode, and the measured value was converted from the electrode size (area) to a unit area value, which was taken as the surface resistance per cm2 .
• the surface resistance was measured six times for each of eight fiber electrodes, and the average of the 48 measurements was taken as the surface resistance. The measurement was performed in an environment with a temperature of 20°C and a humidity of 65%.
• the fiber electrode of the present invention is often used as a product attached to a base material such as a woven fabric, knitted fabric, nonwoven fabric, felt, rubber, resin sheet, film, etc., and such products are often worn on a living body and are often used repeatedly. Therefore, the fiber electrode of the present invention has an absolute value of the change in surface resistance after 30 friction tests on the fiber electrode surface of preferably 1 ⁇ /cm2 or less, more preferably 0.5 ⁇ /cm2 or less , and even more preferably 0.3 ⁇ / cm2 or less. By satisfying this value, it is possible to maintain the conductive performance even after repeated use (excellent durability of conductive performance).
• the change in surface resistance of the fiber electrode surface after 30 friction tests is a value obtained by the following measurement method.
• the surface resistance of the fiber electrode before the friction test is measured using the method described above.
• the fiber electrode is attached to the friction element side of the friction tester type II (Gakushin type) and the white cotton cloth for friction is attached to the test piece base side, based on the case of the dry test of the friction tester type II (Gakushin type), specifically, the fiber electrode is rubbed back and forth against the white cotton cloth for friction 30 times under the conditions of a load of 2N, a speed of 30 reciprocations per minute, and a reciprocation distance of 100 mm.
• the fiber electrode is removed from the friction element, and the surface resistance of the fiber electrode is measured using the method described above. Then, the absolute value of the difference in the surface resistance of the fiber electrode before and after the friction test is taken as the change.
• the fiber electrode of the present invention is washed frequently. Therefore, the fiber electrode of the present invention preferably has a dimensional retention of 85% or more, more preferably 90% or more, after 50 washes. If the dimensional retention is less than 85% after 50 washes, the conductive performance is likely to be reduced or changed due to dimensional changes caused by repeated washing.
• the dimensional retention after 50 washes is a value obtained by the following measurement method and calculation formula.
• the fiber electrode in the present invention is formed by embroidering conductive threads on a base sheet, and therefore has flexibility.
• the flexibility of the base sheet with fiber electrodes is evaluated using a thickness index T calculated by the following formula. The closer the value of the thickness index T is to 1, the easier it is to bend the electrode part on which the fiber electrodes are formed, and the higher the flexibility, and the larger the value of the thickness index T is, the harder it is to bend the electrode part on which the fiber electrodes are formed, and the lower the flexibility.
• T2 cannot be measured, and it can be said that it has no flexibility.
• Thickness index T (T2-T1)/T1 (T1: thickness of the base sheet with fiber electrodes, T2: maximum thickness of the base sheet with fiber electrodes when folded in half in a direction perpendicular to the embroidery direction of the conductive thread on which the fiber electrodes are embroidered and so that the fiber electrodes face each other)
• the thickness index T is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.8 or less. If the thickness index T is 4.0 or less, the electrode part on which the fiber electrodes are formed has sufficient flexibility, so that the electrode part can stably contact the skin and easily conduct electrical signals stably when performing various operations.
• a surface embroidered with thread has a certain degree of hardness, and the hardness varies depending on the thickness and number of threads, the density of the embroidered part, etc. Therefore, the lower limit of the thickness index T is not particularly limited, but is usually 1.0 or more, and may be 1.2 or more.
• the thickness index T is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, and even more preferably 1.0 to 2.8.
• the thickness index T may be preferably 1.2 to 4.0, 1.2 to 3.0, or 1.2 to 2.8.
• the conductive thread is present at a certain density in the embroidered portion where the conductive thread is stitched, but depending on the thickness of the conductive thread and the embroidery conditions, there may be a void portion where the conductive thread is not stitched in the embroidered portion, i.e., where the conductive thread does not exist.
• the ratio of the void portion in the embroidered portion of the fiber electrode is preferably 18% or less, more preferably 14% or less, even more preferably 10% or less, even more preferably 8% or less, and particularly preferably 6% or less.
• the conductive thread is present at a high density in the embroidered portion, and the number of contact points between the metal fibers increases, thereby obtaining a fiber electrode with better conductive performance.
• the lower limit of the porosity is not particularly limited as long as the effects of the above-mentioned conductive performance and flexibility are not impaired.
• the porosity of the embroidered portion of the fiber electrode can be determined by image analysis, for example, using "ImageJ" (Wayne Rasband, National Institutes of Health) as image analysis software.
• the image analysis method involves setting a threshold value at the brightness boundary between the void portion in the embroidered portion and the portion where the conductive thread is present for the captured image of the base sheet with the fiber electrode, and binarizing the brightness.
• the portion where the conductive thread is present becomes white, and the void portion becomes black, so that the white portion can be identified as the portion where the conductive thread is present, and the black portion can be identified as the void portion.
• the porosity is obtained by calculating the ratio of the total area of the void portions identified as voids to the total area of the embroidered portion.
• the fiber electrode of the present invention preferably has an impedance of a specific value or less as an index showing that an electrical signal can be easily acquired and input on the surface of a living body.
• the impedance is evaluated by a test in accordance with ANSI/AAMI EC12:2000.
• the AC impedance of the fiber electrode of the present invention is preferably 2 k ⁇ (2000 ⁇ ) or less, more preferably 1000 ⁇ or less, even more preferably 100 ⁇ or less, even more preferably 50 ⁇ or less, even more preferably 30 ⁇ or less, and particularly preferably 10 ⁇ or less.
• the above standard requires that the impedance of a biological electrode at 10 Hz and not exceeding 100 ⁇ A p-p (A p-p: difference between the maximum current value and the minimum current value measured with an alternating current) must be 2 k ⁇ or less. If the fiber electrode of the present invention has an AC impedance of 2 k ⁇ or less, the impedance between the surface of a living body and the fiber electrode is small, making it easier to acquire and input an electrical signal.
• the AC impedance of the fiber electrode is a value obtained by the following measurement method.
• Method for measuring fiber electrode AC impedance Measurements are made in accordance with ANSI/AAMI EC12:2000. Specifically, the procedure is as follows: Two substrate sheets with fiber electrodes are stacked so that the embroidered parts are joined to obtain a pair of samples. Then, a 100g weight is placed on top of the samples to apply pressure, and the AC impedance at 10 Hz is measured under conditions of 23°C and 40% humidity. The AC impedance is measured for five samples, and the average value is used.
• the fiber electrode of the present invention has a small effect on impedance characteristics even when exposed to the atmosphere for a long time. That is, when conventionally used gel electrodes are exposed to the atmosphere for a long time, the gel evaporates, and the impedance tends to increase, resulting in poor impedance characteristics. On the other hand, the fiber electrode of the present invention has the above-mentioned configuration, and the impedance does not change significantly even when exposed to the atmosphere for a long time, so the effect on impedance characteristics is small.
• the fiber electrode of the present invention has an AC impedance of preferably 2 k ⁇ (2000 ⁇ ) or less, more preferably 1000 ⁇ or less, even more preferably 100 ⁇ or less, even more preferably 50 ⁇ or less, even more preferably 30 ⁇ or less, and particularly preferably 10 ⁇ or less after being left at 23°C x 55% RH for 24 hours.
• the AC impedance of the fiber electrode after being left for 24 hours at 23°C x 55% RH is a value obtained by the following measurement method.
• the base sheet with the fiber electrode is left in an environment of 23°C x 55% RH for 24 hours, and then the AC impedance is measured by the same method as above.
• the AC impedance is measured for four samples, and the average value is used.
• the base sheet with fiber electrodes of the present invention is often used by being attached to a living body as a product attached to a part of a substrate, and when used for such purposes, it is washed frequently. Therefore, in order to minimize the effect on impedance characteristics even after repeated washing and to enable stable acquisition and input of electrical signals, the fiber electrodes of the present invention, after 50 washes, have an AC impedance measured by the same method as above of preferably 2 k ⁇ (2000 ⁇ ) or less, more preferably 1000 ⁇ or less, even more preferably 100 ⁇ or less, even more preferably 50 ⁇ or less, even more preferably 40 ⁇ or less, and particularly preferably 10 ⁇ or less.
• the AC impedance of the fiber electrode after 50 washes is a value obtained by the following measurement method.
• the base sheet with the fiber electrode is washed 50 times based on the C4M method of JIS L 1930:2014 (Home washing test method for textile products).
• Method A line drying
• the AC impedance is then measured using the same method as above.
• the AC impedance is measured for four samples, and the average value is used.
• the fiber electrode in the present invention may have water absorption properties due to water absorption processing.
• the water absorption processing method is not particularly limited, but examples include a method of attaching a compound (water absorbent) having a hydrophilic group to the surface of the fiber electrode by coating, adsorption, or exhaustion.
• any of padding method, exhaustion method, spray method, kiss roll coater method, slit coater method, etc. may be adopted to apply an aqueous solution containing a water absorbent to the surface of the fiber electrode, and the treatment may be performed under normal temperature and normal pressure conditions, or a dry heat treatment may be performed at 105 to 190 ° C for 30 to 150 seconds.
• a conductive thread having water absorption properties may be used to form the fiber electrode.
• the water absorption processing may be performed on at least the surface of the fiber electrode, and may be performed on both the front and back sides of the fiber electrode.
• the fiber product of the present invention by imparting water absorbency to the surface of the fiber electrode, it is possible to obtain the effect of further improving the conductive performance and reducing the impedance.
• the fiber product of the present invention when the fiber product of the present invention is worn on the human body, it is possible to prevent the surface of the fiber electrode from easily separating from the wearer's skin due to sweat, and to reduce the discomfort caused by sweat remaining on the skin surface without being absorbed by the fiber electrode.
• the method for producing the base sheet with the fiber electrode of the present invention is not particularly limited, and examples thereof include a method of forming a fiber electrode composed of an embroidered portion by embroidering the base sheet with the conductive thread.
• Methods for forming a fiber electrode having the above characteristics include using the conductive thread in the embroidered portion, forming the embroidered portion by machine embroidery, forming the types of stitches (stitches that appear on the surface by embroidery) shown below, or forming the stitch lengths, row intervals, and offset values shown below.
• Types of stitches include running stitch, cross stitch, tatami stitch, and chain stitch. Of these, running stitch and tatami stitch are preferred.
• the stitch length is preferably 1 to 10 mm, and more preferably 2 to 8 mm.
• the row spacing is preferably 0.1 to 1.5 mm, and more preferably 0.3 to 1.3 mm. Note that row spacing refers to the spacing between stitch lines when forming stitches, but in the case of a backstitch line such as tatami stitch, it refers to the spacing between stitch line 1 and stitch line 2 when stitch line 1, backstitch line, and stitch line 2 are formed in that order.
• the offset value refers to the absolute value of the length of the shift between the needle drop points on adjacent stitch lines, but in the case of a backstitch line as described above, it refers to the absolute value of the length of the shift between the needle drop points on a stitch line and the backstitch line adjacent to it.
• the offset value is preferably 0.5 to 1.0 mm, and more preferably 0.6 to 0.9 mm.
• the embroidered portion where the conductive thread is stitched onto the base sheet preferably has stitches arranged so that the conductive thread crosses in two different directions.
• a running stitch can be performed by understitching the running stitch in the weft direction, and then by lockstitching the running stitch in the warp direction.
• the two threads cross at 90 degrees, but the angle at which the two threads cross is preferably 20 to 160 degrees, and more preferably 30 to 150 degrees.
• the stitch type, stitch length, row spacing, and offset value of the understitching may be the same as those of the main stitching described above, but it is preferable that the row spacing of the understitching is 2 to 6 times that of the main stitching.
• the base sheet with fiber electrodes of the present invention can be used as a biological electrode.
• Preferred usage modes of the base sheet with fiber electrodes used for a biological electrode include a mode in which the base sheet can directly contact a living body to obtain a biological signal and/or provide an electric signal or electric stimulation, such as an electrode for obtaining a biological signal such as a cardiac potential, a myoelectric potential, or an electroencephalogram, and an electrode for providing an electric stimulation to a living body, such as a low-frequency, high-frequency, or EMS electrode.
• a biological electrode using the base sheet with fiber electrodes of the present invention can be attached to at least a part of a base and used as a product that can acquire biological signals and/or provide electrical signals or electrical stimulation.
• the product of the present invention has a base sheet with a fiber electrode.
• Examples of the product having a base sheet with a fiber electrode include a product having a base (woven fabric, knitted fabric, nonwoven fabric, felt, rubber, resin sheet, film, etc.) on which a fiber electrode is directly formed at least partially, and a product having a base sheet with a fiber electrode fixed to the base.
• the base sheet with a fiber electrode may be detachable from the base.
• An example of a substrate having fiber electrodes formed directly on it is one in which embroidery is formed on the substrate itself by stitching conductive thread directly onto the substrate.
• the substrate corresponds to the substrate sheet of the substrate sheet with fiber electrodes.
• the method of fixing the base sheet with fiber electrodes to the base is not particularly limited, but examples of the method include adhesion, sewing using conductive thread, and soldering.
• the method of making it detachable is also not particularly limited, but examples of the method include providing magnets, buttons, hooks, snap buttons, and hook-and-loop fasteners on the base and the base sheet with fiber electrodes.
• Products that allow the base sheet with fiber electrodes to be detached have the advantage that the base sheet with fiber electrodes can be installed so that an electrical signal can be acquired or input at a desired location, or the base sheet with fiber electrodes can be installed and used on another base.
• the base sheet with fiber electrodes of the present invention is washable, but by removing the base sheet with fiber electrodes and washing only the base when washing, the load on the base sheet with fiber electrodes can be reduced and the durability of the base sheet with fiber electrodes can be improved.
• the base sheet with fiber electrodes may be fixed entirely to the substrate, or at least partially. If only a portion of the base sheet with fiber electrodes is fixed to the substrate, expansion and contraction of the product is less likely to be hindered by the base sheet with fiber electrodes when the product is stretched or contracted due to bodily movements after being attached to a living body, and the base sheet with fiber electrodes can flexibly follow the movements of the body, achieving a high degree of fit of the fiber electrodes to the surface of the living body.
• Products having a base sheet with fiber electrodes are not particularly limited, but examples thereof include textile products.
• the textile product is clothing
• the clothing may be either upper or lower clothing, and specific examples include innerwear, sportswear, hospital clothing, nightwear, various uniforms, etc.
• the base sheet with fiber electrodes can also be attached to various types of clothing that come into contact with a part of the living body, and can be used for, for example, wristbands, gloves, socks, supporters, corsets, belly wraps, hats, and belt-like items such as belts and bands.
• two fiber electrodes can be attached to one belt-like item to form a product in which the two fiber electrodes are integrated, and the product can be easily set by attaching it to the part where it is desired to obtain a biosignal or input an electrical signal.
• Specific examples include chest belts, abdominal belts, and leg belts.
• the base sheet with fiber electrodes can also be used for products that come into contact with a part of the living body, and can also be used for products such as watches, chairs, beds, carpets, handlebars, and various covers. Products having such fiber electrodes can be used as products that can acquire biosignals and/or impart electrical signals or electrical stimuli by using the fiber electrodes as bioelectrodes as described above.
• Products having a base sheet with fiber electrodes may be equipped with wiring, connectors, electronic control units such as biosignal detection devices and electrical stimulation devices, and electronic control units that can be attached and detached via connectors, as necessary, to ensure electrical continuity.
• the type of connector attached to the fiber electrode of the base sheet with fiber electrode of the present invention is not particularly limited, but when used in products such as the above-mentioned clothing, supporters, covers, etc., small and lightweight connectors are preferred to prevent discomfort to the user caused by contact with the body, and examples of such connectors include snap buttons and conductive sticker-shaped connectors, as well as soldering, adhesion with conductive paste, sewing with conductive thread, magnets, hooks, etc.
• these connectors are insulated, and for example, insulated buttons made of stainless steel are preferably used from the viewpoint of excellent washing durability.
• the number of fiber electrodes attached to the base may be multiple and can be changed as appropriate depending on the type of biosignal to be collected, or the application, such as obtaining a biosignal and/or electrical stimulation by inputting an electrical signal, but 1 to 50 is preferable, and 1 to 25 is even more preferable.
• the fiber electrode of the present invention is used as a biological electrode, for example, by providing two or more fiber electrodes on the skin side of the product, it is possible to measure cardiac potential, muscle potential, etc. It is also possible to measure pulse, breathing, movement state, etc. by providing fiber electrodes on the skin side or surface of the product and measuring changes in impedance of the body.
• the location of the fiber electrode can be changed as appropriate depending on the type of biosignal to be collected, or the application, such as obtaining a biosignal and/or electrical stimulation by inputting an electrical signal. For example, when measuring electrocardiograms, it is preferable to place the electrode near the left chest, and when measuring electromyograms or electroencephalograms, it is preferable to place the electrode near the muscle or brain to be measured.
• the biosignals collected by the fiber electrodes of the present invention are measured over a long period of time using various devices depending on the purpose, and are analyzed as various types of data for use in health management, sports training, the medical field, etc.
• various devices depending on the purpose, and are analyzed as various types of data for use in health management, sports training, the medical field, etc.
• by inputting an electrical signal to muscles or nerves using the fiber electrodes of the present invention they can be used as a device for applying electrical stimulation in the medical field and training applications, games and toys, etc., or as an electrode for measuring the impedance of a living body.
• the amount of metallic fibers and organic fibers contained in the embroidery part and the length (total length) of the metallic fibers The fiber electrode was separated into organic fibers and metal fibers, and the weight of each and the length (total length) of the metal fibers were measured.
• the content (g/ cm2) of the metal fibers or organic fibers in the embroidered part was calculated from the area of the embroidered part and the weight of the metal fibers or organic fibers.
• the length (total length) (cm/cm2 ) of the metal fibers in the embroidered part was also calculated from the area of the embroidered part and the length (total length) of the metal fibers.
• (c) Surface resistance value on the surface of the fiber electrode The surface resistance value was measured at the two points with the longest distance when any two points were connected on the surface of the fiber electrode using a digital tester (OHM Digital Multi Tester TDB-401, manufactured by Ohm Electric Co., Ltd.), and the measured value was converted from the electrode size (area) to a unit area value, which was defined as the surface resistance value per cm2 .
• the surface resistance value was measured six times for each of eight fiber electrodes, and the average value of a total of 48 measured values was defined as the surface resistance value. The measurement was performed in an environment of 20°C and humidity of 65%.
• Thickness index T (T2-T1)/T1 (T1: thickness of the base sheet with fiber electrodes, T2: maximum thickness of the base sheet with fiber electrodes when folded in half in a direction perpendicular to the embroidery direction of the conductive thread on which the fiber electrodes are embroidered and so that the fiber electrodes face each other)
• the ratio of the total area of the void parts where no conductive thread exists per any 2 cm x 2 cm area (total area 4 cm 2 ) of the embroidered part was calculated to obtain the void ratio (%).
• the void ratio (%) was calculated by binarizing the brightness of an image taken from directly above the center of the embroidered part of the base sheet with fiber electrodes using the image analysis software "ImageJ" (Wayne Rasband, National Institutes of Health), setting the threshold value of the brightness boundary between the void parts in the embroidered part and the part where the conductive thread exists to 80.
• FIG. 2 is an explanatory diagram showing the image analysis of the base sheet with fiber electrodes obtained in Example 2.
• FIG. 2(a) is an image obtained by converting a photograph taken from directly above the center of the embroidered portion of a base sheet with a fiber electrode into an 8-bit image
• FIG. 2(b) is an image showing the result of extracting void portions in order to calculate the porosity by image analysis, in which the portions 4 where the conductive threads exist are shown in white and the void portions 3 are shown in black.
• the impedance of the fiber electrode in the initial state was measured in accordance with ANSI/AAMI EC12:2000. Specifically, the measurement was performed by the following method. Two sheets of base material sheets with fiber electrodes prepared in the examples, comparative examples, and reference examples were prepared. A stainless steel one-sided rivet (terminal) with a diameter of 10 mm was attached to the embroidered part of a square of 1 cm x 1 cm (the small square part at the top of the convex electrode shown in Figure 1). At that time, the metal fittings on the surface side of the fiber electrode were protected with an insulating material. Then, two base material sheets with fiber electrodes were stacked so that the embroidered parts were joined to obtain a pair of samples.
• a crocodile clip-type measurement probe terminal was connected to the rivet of each fiber electrode under pressure with a 100 g weight placed on top of the sample, and the AC impedance at 10 Hz was measured under conditions of 23 ° C. and 40% humidity.
• An impedance analyzer (HIOKI ELECTRIC CO., LTD., IM3570) was used to measure the AC impedance. The AC impedance was measured for the five samples, and the average value was taken as the impedance of the fiber electrode in its initial state.
• Example 1 The following core yarn and sheath yarn were prepared as conductive yarns, and twisted at 300 turns/m (S twist) using a covering twisting machine to obtain a core-sheath composite twisted yarn in which one core yarn was covered with two sheath yarns. Seven of the obtained core-sheath composite twisted yarns were then twisted together to obtain a conductive yarn.
• S twist 300 turns/m
• Core yarn Organic fiber A, polyester multifilament (55 dtex/144 f) x 1 Sheath yarn: Metal fiber, tungsten metal yarn (diameter 13 ⁇ m) x 1 Sheath yarn: Organic fiber B, nylon 6 multifilament (13 dtex/7 f) x 1
• Base sheet Needle-punched nonwoven fabric made of polyester staple fibers (thickness 1.19 mm, basis weight 240 g/ m2 )
• the conductive thread was used for the main stitching and understitching, and the polyester multifilament (organic fiber A) used for the core thread was used for the lower thread (the thread appearing on the back surface of the fiber electrode).
• a single-head embroidery machine (TMEZ-SC, manufactured by Tajima Industries Co., Ltd.) was used to embroider the base sheet in the following configuration to form the fiber electrode shown in Figure 1 (having an embroidered portion consisting of a 2 cm x 2 cm square and a 1 cm x 1 cm square), thereby producing a base sheet with a fiber electrode.
• the conductive threads cross at right angles (90 degree intersecting angle) in the warp and weft directions.
• Example 2 The following core yarn and sheath yarn were prepared as conductive yarns, and a core-sheath composite twisted yarn was obtained in the same manner as in Example 1. Next, five of the obtained core-sheath composite twisted yarns were plyed together to obtain a conductive yarn.
• Core yarn Organic fiber A, polyester multifilament (55 dtex/144 f) x 1 Sheath yarn: Metal fiber, tungsten metal yarn (diameter 13 ⁇ m) x 1 Sheath yarn: Organic fiber B, nylon 6 multifilament (13 dtex/7 f) x 1
• Base sheet Needle-punched nonwoven fabric made of polyester staple fibers (thickness 1.19 mm, basis weight 240 g/ m2 )
• a base sheet with a fiber electrode was produced in the same manner as in Example 1, except that the base sheet was embroidered in the following manner using the conductive thread in the main stitching and understitching.
• the conductive threads cross at right angles (90 degree intersecting angle) in the warp and weft directions.
• Example 3 The base sheet with the fiber electrode prepared in Example 2 was impregnated in an aqueous solution obtained by adding a polyester-based SR agent "Parasorb PET2" (manufactured by Ohara Palladium Co., Ltd.) as a water absorbing agent to water (5 g per 100 ml), and the water absorbing agent was adhered to the front and back surfaces of the fiber electrode. Then, the base sheet with the fiber electrode that had been subjected to water absorption processing was prepared by drying for 20 minutes in a dryer at 100°C.
• a polyester-based SR agent "Parasorb PET2" manufactured by Ohara Palladium Co., Ltd.
• Example 4 The following core yarn and sheath yarn were prepared as conductive yarns, and twisted at 300 turns/m (S twist) using a covering twisting machine to obtain a core-sheath composite twisted yarn in which one core yarn was covered with two sheath yarns. Five of the obtained core-sheath composite twisted yarns were then twisted together to obtain a conductive yarn.
• S twist 300 turns/m
• Core yarn Organic fiber A, polyester multifilament (55 dtex/144 f) x 1 Sheath yarn: Metal fiber, tungsten metal yarn (diameter 13 ⁇ m) x 1 Sheath yarn: Organic fiber B, polylactic acid filament (33 dtex/18 f) x 1
• Base sheet Needle-punched nonwoven fabric made of polyester staple fibers (thickness 1.19 mm, basis weight 240 g/ m2 )
• the conductive thread was used for the main stitching and understitching, and the polyester multifilament (organic fiber A) used for the core thread was used for the lower thread (thread appearing on the back surface of the fiber electrode), and embroidery was performed on the base sheet using a single-head embroidery machine (TMEZ-SC, manufactured by Tajima Industries Co., Ltd.) in the following configuration.
• TMEZ-SC single-head embroidery machine
• the polylactic acid filaments in the conductive thread were alkaline-eluted using a known device, and the fiber electrode shown in FIG. 1 (having an embroidered portion consisting of a 2 cm x 2 cm square and a 1 cm x 1 cm square) was formed, thereby producing a base sheet with a fiber electrode.
• the surface of the fiber electrode of the obtained base sheet with a fiber electrode had a large amount of exposed metal fibers due to the elution of the polylactic acid filaments.
• the conductive threads cross at right angles (90 degree intersecting angle) in the warp and weft directions.
• Example 5 A base sheet with a fiber electrode was produced in the same manner as in Example 4, except that a laminate having the following configuration was used as the base sheet.
• Surface knit Warp knit made of polyethylene terephthalate yarn (75 dtex 72 fil)
• Film Film made of polycarbonate-based polyurethane resin
• Back knit Warp knit made of polyethylene terephthalate yarn (56 dtex 36 fil)
• Example 1 Instead of the conductive yarn, a ply-twisted yarn made by plying five polyester multifilaments (55 dtex/144f) was prepared. Then, the ply-twisted yarn was used in the main stitching and understitching, and the laminate used in Example 5 was used as the base sheet. In the same manner as in Example 2, except that, embroidery was performed on the base sheet with the following configuration, to produce a base sheet with a fiber electrode.
• the conductive threads cross at right angles (90 degree intersecting angle) in the warp and weft directions.
• the base sheet with fiber electrode obtained in Examples 1 to 5 satisfies all of the above characteristics (1) to (4), and therefore has excellent conductive performance capable of acquiring biosignals, which are weak electrical signals, and is also unlikely to deteriorate or change in conductive performance even with repeated use.
• the base sheet with fiber electrode obtained in Examples 1 to 5 has excellent initial impedance, and the impedance characteristics are less affected even after long exposure to the atmosphere and repeated washing.
• the fiber electrodes of the base sheet with fiber electrode obtained in Examples 1 to 5 have excellent electrical properties and are practically usable as bioelectrodes.
• the base sheet with fiber electrode obtained in Examples 1 to 5 also had a thickness index T that was not significantly different from that of Reference Example 1, in which the embroidery part was formed with thread that did not contain metal fibers, and was smaller than the gel electrode of Reference Example 2, and had excellent flexibility.
• the fiber electrodes of the base sheet with fiber electrode obtained in Examples 1 to 5 had a small porosity and the embroidery part was densely formed with conductive thread.
• the substrate sheet with fiber electrodes obtained in Comparative Example 1 had a high surface resistance value on the surface of the fiber electrodes, poor electrical conductivity, and impedance was also poorer than that of the substrate sheets with fiber electrodes obtained in Examples 1 to 5. Furthermore, when the substrate sheet with fiber electrodes obtained in Comparative Example 1 was used repeatedly, the surface resistance value of the metal-plated thread surface was high, the electrical conductivity was poor, and the electrical conductivity was reduced due to partial peeling of the metal, resulting in poor durability.
• Base sheet 2 Fiber electrode (embroidery part) 3: Void area (black) 4: Part where conductive thread is present (white)

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