JP2017074369A - Electrode for brain wave measurement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for brain wave measurement which secures sufficient conductivity by contact with the scalp without using a conductive paste, reduces a burden on a subject, and measures brain waves accurately even at a hair portion.SOLUTION: An electrode 10 for brain wave measurement is provided with a comb-shaped base member 12, which comprises an elastic body, and a structure formed on the comb-shaped base member 12. The comb-shaped base member 12 comprises a support part 14 and a comb teeth row 17, which comprises multiple comb teeth 16 projecting from the support part 14 in a row. The structure is formed on one side surface of the comb teeth 16 along the comb teeth row 17 and contains multiple nanocarbon members, that form an interconnected network structure and are fixed to the comb-shaped base member 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electroencephalogram measurement electrode.

  As a conventional electroencephalogram measurement electrode, a type in which a conductive paste is interposed between a subject's scalp and an electrode is often used. In addition to reducing the contact impedance between the scalp and the electrode, the conductive paste has the effect of fixing the position of the measurement site, but it requires work removal because it requires removal after measurement. .

  Therefore, in recent years, an electrode (dry electrode) that can ensure low contact impedance without using a conductive paste has been developed. As the dry electrode, for example, a multi-pin type dry electrode (for example, Non-Patent Document 1) used by attaching to a hair band or a multi-pin type dry electrode (for example, Non-Patent Document 2) used by attaching to a head cap has been proposed. ing. In these dry electrodes, the multi-pin is made of a hard metal.

  In addition, in order to reduce the burden on the subject, an electroencephalogram measurement electrode (for example, Patent Document 1) provided with a metal contact portion at the tip of a protruding portion made of rubber, or a metal spring is used. There has been proposed an electroencephalogram measurement electrode in which a spherical tip can be expanded, contracted and swiveled (for example, Patent Document 2).

JP 2013-111361 A JP 2013-240485 A

Manabu Honda, CREST, Strategic Creativity Research Promotion Project, Research Area “Advanced Integrated Sensing Technology”, Research Subject “Wearable Core Functional Integrated Sensing System to Create a Safe Information Environment in the Brain” g-tec Active Dry Electrode “g.SAHARA”, Internet <URL: http://www.gtec.at/Products/Electrodes-and-Sensors/g.SAHARA-Specs-Features>

  However, the electrodes of Non-Patent Documents 1 and 2 have a problem that the test subject feels uncomfortable and the burden on the scalp is large because the multi-pin is made of a hard metal.

  In the electrode of Patent Document 1, a large amount of conductive material is blended in order to impart desired conductivity to the protruding portion made of rubber, so that the inherent flexibility and cushioning properties of the rubber are lowered and become hard. The hard protrusion leads to the pain of the subject when it is brought into contact with the scalp, and the adhesion with the scalp is poor, making it difficult to accurately measure the electroencephalogram. Further, when an expensive conductive material is used, the manufacturing cost cannot be suppressed.

  In the electrode of Patent Document 2, due to the complexity of the structure, poor continuity may occur at the contact point, and electroencephalogram measurement may not be performed well. In addition, since the structure is complicated, the manufacturing cost is high and it is not suitable for mass production.

  In the electroencephalogram measurement, the hair becomes an obstacle and the resistance value rises, so an accurate result cannot be obtained at the hair portion. If the influence of hair can be reduced as much as possible, the accuracy of electroencephalogram measurement can be improved even in the hair portion.

  Accordingly, the present invention provides an electrode for measuring an electroencephalogram that can contact the scalp without using an electrically conductive paste to sufficiently ensure electrical conduction, reduce the burden on the subject, and measure the electroencephalogram with high accuracy even in the hair portion. For the purpose.

  An electroencephalogram measurement electrode according to the present invention is an electroencephalogram measurement electrode comprising a comb-shaped base material made of an elastic body and a structure formed on the comb-shaped base material, wherein the comb-shaped base material includes a support portion, A plurality of comb teeth arranged in a row from the support portion, and the structure is formed on one side surface of the plurality of comb teeth along the comb teeth row, It includes a plurality of nanocarbon materials, wherein the plurality of nanocarbon materials form a network structure connected to each other and are fixed to the comb-shaped base material.

  According to the present invention, the electroencephalogram measurement electrode includes a comb-shaped base material made of an elastic body, and one side surface of the plurality of comb teeth along the comb tooth row in the comb-shaped base material contacts the scalp of the subject. By combing the hair with the plurality of comb teeth, the predetermined one side can contact the scalp while avoiding the hair.

  In the comb-shaped base material, a structure having a network structure in which a plurality of nanocarbon materials are connected is formed on one side surface. When one side where the structure is formed contacts the scalp, the electroencephalogram measurement electrode makes contact with the scalp without using a conductive paste, and ensures sufficient conduction in the hair, thus producing an electroencephalogram with high accuracy. Can be measured. Since the elastic body has flexibility and cushioning properties, even when pressure is applied, it does not give the subject discomfort such as pain, and the burden can be reduced.

It is a top view which shows the structure of the electrode for electroencephalogram measurement which concerns on this embodiment. It is a front view which shows the structure of the electrode for electroencephalogram measurement which concerns on this embodiment. It is a schematic diagram explaining the structure of CNT coated paper. FIG. 4A is an SEM image of CNT-coated paper, FIG. 4A is an image at 50 ×, and FIG. 4B is an image at 10000 ×. It is the schematic which shows the structure of the electrode for electroencephalogram measurement of an Example. It is the schematic which shows the structure of the electrode component for electrode contact resistance measurement. It is a graph which shows the relationship between CNT density | concentration and volume resistance.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1. Overall Configuration As shown in FIG. 1, an electroencephalogram measurement electrode 10 includes a comb-shaped base material 12 having a support portion 14 and a comb tooth row 17 including a plurality of comb teeth 16 protruding in a row from the support portion 14. Prepare. In the electroencephalogram measurement electrode 10, one side surface of the plurality of comb teeth 16 along the comb tooth row 17 in the comb-shaped base material 12 serves as a scalp contact surface 18 (see FIG. 2) that contacts the scalp. As shown in FIG. 2, the plurality of comb teeth 16 have a tip 16b thinner than a base end 16a in the thickness direction, and incline toward the opposite side of the scalp contact surface 18 from the middle in the length direction.

  In the present embodiment, the scalp contact surface 18 is configured by providing a structure (not shown) on one side surface of the plurality of comb teeth 16 along the comb tooth row 17. The structure is exposed not on the inside of the comb-shaped base material 12 but on the surface. Since the structure has conductivity, the scalp contact surface 18 is conductive. A conductive path is formed in the comb-shaped base material 12 by the structure.

  The structure is formed on at least one side surface of the plurality of comb teeth 16 along the comb tooth row 17 in the comb-shaped base material 12. In the case where a structure is also formed on the surface of the support portion 14, it is possible to ensure conduction with one side surface of the plurality of comb teeth 16. The structure may be provided on the remaining surface of the comb-shaped base material 12 such as the other side surface of the plurality of comb teeth 16 as long as the interval between the adjacent comb teeth 16 in the comb tooth row 17 can be maintained.

  In the present embodiment, the structure not shown is made of a nanocarbon material. As the nanocarbon material, a carbon nanotube (hereinafter referred to as CNT) is used. The plurality of CNTs are connected to each other to form a structure having a network structure, and are fixed to the comb-shaped base material 12. The connection here includes physical connection (simple contact). Since CNTs themselves have high conductivity, high conductivity can be maintained even after becoming a structure having a network structure of a plurality of CNTs. Such a structure having high conductivity is suitable as a conductive path in the electroencephalogram measurement electrode 10. As described above, since the structure in the present embodiment is formed so as to be exposed on the surface of the comb-shaped base material 12, the conductive path is also formed on the surface instead of the inside of the comb-shaped base material 12.

  A structure having a CNT network structure is formed by using van der Waals force of CNT without using an adhesive or the like, and one side surface of the plurality of comb teeth 16 along the comb teeth row 17 in the comb-shaped base material 12. Can be fixed to. Alternatively, a structure having a network structure of CNTs is formed by mixing a general adhesive or the like with CNTs within a range that does not impair the conductivity of CNTs. It may be fixed to one side of the comb teeth 16. In any case, the CNTs are directly attached to one side surface of the plurality of comb teeth 16 along the comb tooth row 17 in the comb-shaped base material 12.

  In particular, when an adhesive or the like is not used, the surface of the CNT fiber itself is not covered with the adhesive or the like. Therefore, a structure having a network structure is formed by connecting CNTs with no inclusions. Since the high conductivity inherent in CNT is not impaired at all, the electroencephalogram measurement electrode 10 in which such a structure is formed on the comb-shaped base material 12 sufficiently exhibits the high conductivity inherent in CNT.

CNT is manufactured by a general arc discharge method, a vapor phase growth method, a laser evaporation method, or the like. For example, a CNT produced by a vapor phase growth method using a catalyst containing a metal such as Co and Mg and using a gas containing CO (carbon monoxide) and H ₂ as a raw material can be used. Further, CNTs can be used not only in a tube shape but also those whose shape has been changed by heating or the like.

  The comb-shaped base material 12 is formed of an elastic body having flexibility and cushioning properties. In the present embodiment, the comb-shaped base material 12 is formed of, for example, a thermoplastic elastomer. More specifically, examples of the thermoplastic elastomer include urethane-based thermoplastic elastomer (TPU).

  The comb-shaped base material 12 can be of any size suitable for electroencephalogram measurement. For example, the support portion 14 can have a width d1 of about 10 to 15 mm, a length d2 of about 10 to 20 mm, and a thickness d3 shown in FIG. 2 of about 2.0 to 3.0 mm. For example, the comb teeth 16 can have a length d4 of about 15 to 30 mm and a width d5 of about 0.5 to 1.5 mm. In this case, the distance d6 between the adjacent comb teeth 16 can be set to, for example, about 1.0 to 2.0 mm. The tips 16b of the plurality of comb teeth 16 are preferably rounded and have no corners. The number of the comb teeth 16 in the comb-shaped base material 12 is not limited, and may be set as appropriate according to the size of the support portion 14 and the comb teeth 16.

  As described above, in the present embodiment, the electroencephalogram measurement electrode 10 includes the comb-shaped base material 12 having the comb teeth row 17 including the plurality of comb teeth 16, and at least one of the plurality of comb teeth 16 along the comb teeth row 17. And a structure formed on the side surface. The comb-shaped base material 12 is made of an elastic body, and the structure is made of a plurality of nanocarbon materials. Since the comb-shaped base material 12 and the structure are both non-metallic, the electroencephalogram measurement electrode 10 of this embodiment does not include a metal member.

2. Manufacturing Method Next, a manufacturing method of the electroencephalogram measurement electrode 10 will be described. The electroencephalogram measurement electrode 10 produces a dispersion liquid containing CNTs, and uses the dispersion liquid to form one side surface of the plurality of comb teeth 16 along the comb teeth row 17 in the comb-shaped base material 12 (hereinafter referred to as a predetermined one). It can be manufactured by forming a structure on one side).

  Prior to preparation of the dispersion, CNTs are pretreated with a mixed acid. As the mixed acid, for example, a 1: 1 mixed solvent of nitric acid and sulfuric acid can be used. After adding CNTs to the mixed solvent, the CNTs are isolated and dispersed by stirring and then irradiating with ultrasonic waves. Thereafter, the CNT is taken out by filtration under reduced pressure, and the CNT surface is neutralized using ammonia water or the like. And after washing | cleaning the surface with a pure water, it is made to dry and powdery CNT is obtained.

  The powdery CNTs that have been pretreated as described above are added to a solvent so as to have a concentration of, for example, 0.01 wt%, and ultrasonic waves are irradiated to disperse the CNTs, thereby obtaining a dispersion. As the solvent, N, N-dimethylformamide (DMF), various alcohols, and the like can be used. Appropriate additives such as a dispersant, a surfactant, and an adhesive may be added to this dispersion. When such an additive is added to the dispersion, the additive coats the fiber surface of the CNT to obtain stronger adhesion, but may impair the original conductivity of the CNT. In order to ensure higher conductivity, it can be said that it is preferable to form a structure having a network structure of CNTs with a dispersion without adding an additive as described above and fix the structure to the comb-shaped base material 12.

  Next, the comb-shaped base material 12 made of an elastic body is immersed in the dispersion. As the comb-shaped base material 12 made of an elastic body, for example, a commercially available resin comb cut into a predetermined size can be used.

  When an additive such as an adhesive is not contained in the dispersion liquid in which the comb-shaped base material 12 is immersed, the CNT is at least applied to the comb teeth row 17 by van der Waals force acting between the comb-shaped base material 12. A structure having a CNT network structure is formed on one side surface of the plurality of comb teeth 16 along the comb teeth 16, and further directly attached to a predetermined one side surface of the comb-shaped base material 12. In the case where an additive such as an adhesive is contained in the dispersion liquid in which the comb-shaped base material 12 is immersed, a force such as an adhesive is taken into consideration in addition to the above van der Waals force. In this case, the CNTs adhere more strongly to the predetermined one side surface of the comb-shaped base material 12.

  Prior to the immersion in the dispersion, when a predetermined region of the surface of the comb-shaped base material 12 is pretreated, CNTs can be preferentially attached to a predetermined one side surface of the comb-shaped base material 12. . For example, surface treatment can be applied to one side surface of the plurality of comb teeth 16 along the comb tooth row 17 in the comb-shaped base material 12 to promote adhesion of CNTs to the one side surface.

  After the CNTs are attached to the surface, the comb base material 12 is pulled up from the dispersion and dried to attach and fix the CNTs on the surface of the comb base material 12. In this way, a structure having a network structure in which CNTs are connected to each other is formed on one side of the plurality of comb teeth 16 along at least the comb teeth row 17 in the comb-shaped base material 12. By repeating the steps of dipping and drying, a structure having a desired thickness can be obtained.

  When the comb-shaped base material 12 is immersed in the dispersion liquid as described above, the CNTs are directly attached to at least one side surface of the plurality of comb teeth 16 along the comb-tooth row 17 in the comb-shaped base material 12 to form a structure. To do. Therefore, the electroencephalogram measurement electrode 10 having a structure formed on one predetermined side surface of the comb-shaped base material 12 can be easily formed.

  The electroencephalogram measurement electrode 10 of the present embodiment can be used as a headset, for example, by attaching a plurality of headbands or head caps so that the scalp contact surface 18 contacts the scalp. The plurality of electroencephalogram measurement electrodes 10 included in the headset do not necessarily have a uniform shape and size, and the shape and size can be arbitrarily changed as necessary.

3. Action and Effect In the electroencephalogram measurement electrode 10 configured as described above, a plurality of comb teeth 16 protrude from the support portion 14 in a row, and a comb tooth row 17 is formed. One side surface of the plurality of comb teeth 16 along the comb tooth row 17 is a scalp contact surface 18. When the electroencephalogram measurement electrode 10 is used, the comb teeth row 17 is inserted into the head hair from the tips 16b of the plurality of comb teeth 16 with the scalp contact surface 18 along the scalp. The scalp contact surface 18 can avoid the scalp and contact the scalp by the plurality of comb teeth 16 scraping the scalp.

  The scalp contact surface 18 of the electroencephalogram measurement electrode 10 is one side surface on which a structure including a plurality of CNTs is formed, and a conductive path is formed on the surface. When the electroencephalogram measurement electrode 10 of this embodiment is used, the scalp is in contact with the conductive path. Thereby, even if it does not use an electrically conductive paste, since conduction | electrical_connection between the electrode 10 for electroencephalogram measurement and a test subject's head is ensured, it becomes possible to reduce a contact impedance to a very low level. As a result, the electroencephalogram measurement electrode 10 can accurately detect a weak electric signal from the head.

  Moreover, the comb-shaped base material 12 including a plurality of comb teeth 16 is made of an elastic body and has flexibility and cushioning properties. Even if one side of the plurality of comb teeth 16 along the comb teeth row 17 contacts the subject's head and pressure is applied, the subject does not feel uncomfortable. The electroencephalogram measurement electrode 10 of the present embodiment can reduce the burden on the subject.

  In the case of this embodiment, the structure is exposed on the surface of the comb-shaped base material 12 to form a network structure in which a plurality of CNTs are connected to each other. Thereby, the structure in the electroencephalogram measurement electrode 10 can exhibit conductivity that is a function derived from CNT. When a plurality of CNTs are directly connected to each other without an adhesive or the like to form a structure having a network structure, the original conductivity of the CNTs is not impaired. For this reason, it becomes more preferable as the electrode 10 for electroencephalogram measurement.

  The structure is formed on one side surface of the plurality of comb teeth 16 along at least the comb tooth row 17 in the comb-shaped base material 12. By forming the structure in this way, the conductive path is exposed and formed on the surface of the comb-shaped base material 12. Compared with the case where a conductive path exists inside the comb-shaped base material 12, the measured electroencephalogram can be efficiently transmitted.

  The structure is directly connected to the CNTs without using an adhesive or the like to form a network, and is fixed to the comb-shaped base material 12. Adhesives are not used to form the structure with CNT and to fix the structure to the comb-shaped base material 12, so that the flexibility and cushioning properties of the comb-shaped base material 12 are maintained in addition to good conductivity. can do. Therefore, the electroencephalogram measurement electrode 10 can reduce the burden on the subject by having flexibility and cushioning properties as a whole. Since the structure exists on the surface of the comb-shaped base material 12, the amount of CNT used can be minimized, leading to a reduction in manufacturing cost.

  The electroencephalogram measurement electrode 10 according to the present embodiment includes a comb-shaped base material 12 made of an elastic body and a structure made of a nanocarbon material on one predetermined side of the comb-shaped base material 12. Since a metal member is not included, X-ray computed tomography (CT) or nuclear magnetic resonance imaging (MRI) is performed with the electroencephalogram measurement electrode 10 according to the present embodiment mounted on the head. Thus, even if image information is acquired, the occurrence of artifacts can be prevented. Therefore, the electroencephalogram measurement electrode 10 can simultaneously acquire image information obtained by X-ray CT, MRI, or the like and an electroencephalogram by the electroencephalogram electrode.

  Moreover, since the metal member is not contained, the electroencephalogram measurement electrode 10 can also be used for a subject having metal allergy. The electroencephalogram measurement electrode 10 according to the present embodiment can be disposable, and is excellent in terms of hygiene. When a commercially available resin comb is cut into an appropriate size and used as the comb-shaped base material 12 made of an elastic body, the electroencephalogram measurement electrode 10 is excellent in mass productivity, and the manufacturing cost can be reduced.

4). The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the gist of the present invention.

  As the comb-shaped base material 12, you may use the molded object shape | molded using the arbitrary elastic bodies which have a softness | flexibility and cushioning properties. In this case, for example, another thermoplastic elastomer, resin, rubber, or other elastic body can be used as a raw material. Using any elastic body as a raw material, the comb-shaped base material 12 having any size and any shape can be produced by, for example, injection molding.

  Other thermoplastic elastomers include, for example, olefin-based thermoplastic elastomers (TPO), styrene-based thermoplastic elastomers, ester-based thermoplastic elastomers (TPC), polyamide-based thermoplastic elastomers (TPAE), and polyvinyl chloride-based thermoplastics. An elastomer (TPVC) etc. are mentioned.

  Examples of the resin include acrylonitrile styrene (AS) resin, acrylonitrile butadiene (ABS) resin, epoxy resin, tetrafluoroethylene / ethylene copolymer (ETFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), hexafluoro Propylene / ethylene copolymer (EFEP), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene / ethylene copolymer (ECTFE), polycaproamide (nylon 6), polyhexa Methylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polyhexamylene sebacamide (nylon 610), polyhexamylene dedecanide (nylon 612), polydo Canamide (nylon 12), polyundecanamide (nylon 11), polyhexamethylene terephthalamide (nylon 6T), polyxylylene adipamide (nylon XD6), polynonamethylene terephthalamide (nylon 9T), polyundecane methylene terephthalamide (Nylon 11T), polydecane methylene decanamide (nylon 1010), polydecamethylene dodecanamide (nylon 1012) amide elastomer (TPA), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polyethylene naphthalate ( PEN) polycarbonate (PC), linear low density polyethylene (LLDPE), ultra low density polyethylene, low density polyethylene (LDPE), medium density polyethylene (MDPE), high Polyethylene (HDPE), crosslinked polyethylene, ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl alcohol copolymer (EVOH), butenediol / vinyl alcohol copolymer (BVOH), polyvinyl alcohol (PVA), polybutene (PB), urethane elastomer (TPU), ester elastomer (TPC), olefin elastomer (TPO), styrene elastomer (TPS), modified polyphenylene ether (modified PPE), liquid crystal polymer (LCP), cycloolefin copolymer ( COC), polyether ketone (PEK), polyglycolic acid (PGA), polyarylate (PAR), polymethylpentene (PMP), polyether ether ketone (PEEK), polyether sulfone (PES), poly Ethylene terephthalate (PET), phenol resin (PF), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polyimide (PI), polyetherimide (PEI), acrylic resin (PMMA), polyacetal (POM), Examples include polypropylene (PP), polyphenylene sulfide (PPS), polystyrene (PS), polysulfone (PSU), polytetrafluoroethylene (PTFE), and polyvinyl chloride (PVC).

  Examples of rubber include natural rubber (NR), ethylene / propylene rubber (EPM, EPDM), chloroprene rubber (CR), butyl rubber (IIR), polyurethane rubber (U), silicone rubber (VMQ, FVMQ), and acrylic rubber (ACM). ), Epichlorohydrin rubber (ECO), fluorine-based rubber (FKM, FEPM, FFKM), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), chlorinated polyethylene (CPE), chlorosulfonated polyethylene (CSM), Examples thereof include butadiene rubber (BR) and styrene-butadiene rubber (SBR).

  The support portion 14 and the plurality of comb teeth 16 in the comb-shaped base material 12 may use different materials by multicolor molding, insert molding, or the like, as long as flexibility and cushioning properties are not impaired.

  Further, the comb-shaped base material 12 is formed by solidifying a foam material having a cushioning property such as urethane foam, a porous material such as wood or cork, a material made into a thread shape based on various fibers, or a material in which fibers are woven or knitted. You may form with the material and non-woven material which were made. In short, any material can be suitably used without being limited to the above materials as long as it can form a plurality of comb teeth 16 projecting in a row and exhibits elasticity and can form a structure on a predetermined side surface.

  In particular, when a fiber material, a porous material, a foamed material, or the like is used as the comb-shaped base material 12, the CNT fibers are easily entangled with the irregularities on the surface. In this case, a structure having a CNT network structure in which a plurality of CNT fibers are intertwined on at least one side surface of the plurality of comb teeth 16 along the comb tooth row 17 in the comb-shaped base material 12 without using an adhesive. The body can be formed and can be directly fixed to the comb-shaped base material 12 at the same time. Thereby, the electroencephalogram measurement electrode 10 with improved conductivity as described above can be obtained.

  The plurality of comb teeth 16 protruding in a row from the comb-shaped base material 12 do not necessarily have to be inclined to the side opposite to the scalp contact surface 18 from the middle in the length direction. Unlike the shape shown in FIG. 2, the base end 14 a of the support portion 14 to the tip end 16 b of the comb teeth 16 may be in a straight line. The plurality of comb teeth 16 may have a uniform thickness from the proximal end 16a to the distal end 16b. The length d4, the width d5, and the interval d6 of the comb teeth 16 may be appropriately set according to the type of elastic body to be used, the width d1 and the length d2 of the support portion 14, and the like.

  The support part 14 in the comb-shaped base material 12 does not necessarily have a rectangular shape defined by the width d1 and the length d2. As long as the original elasticity can be maintained and the scalp contact surface 18 is not prevented from contacting the scalp, the support portion 14 and the plurality of comb teeth 16 can have any shape.

  When consideration about the artifact is not required, a part of the electroencephalogram measurement electrode 10 may include a metal member such as a metal plate as long as the flexibility and cushioning property of the comb-shaped base material 12 are not impaired. . For example, when a structure is not formed on the surface of the support portion 14, a metal plate may be disposed on the surface of the support portion 14 while ensuring conduction with the scalp contact surface 18 by a conductive wire. By providing a metal plate, it is easy to transmit an electric signal, and the accuracy of measurement can be further increased.

  In the above embodiment, the CNTs are fixed directly to at least one side surface of the plurality of comb teeth 16 along the comb tooth row 17 in the comb base material 12, thereby fixing the CNTs to the comb base material 12. Although the structure was formed by being exposed on the surface of CNT, the CNTs may be fixed to the comb-shaped base material 12 through a fiber base material. The fixing of the CNTs to the comb-shaped base material 12 through the fiber base material can be achieved, for example, by attaching a CNT-coated paper 20 as shown in FIG. The CNT coated paper 20 includes a fiber base material 22 and a structure 24 formed by attaching CNTs to the surface of the fiber base material 22.

  Examples of the fiber base material 22 include semi-paper, Japanese paper, Kara paper, knitted fabric, woven fabric, and non-woven fabric having a low fiber density. The type and dimensions (diameter, length, density, etc.) of the fibers constituting the fiber base material 22 are appropriately selected according to the material and size of the comb-shaped base material 12 to which the CNT coated paper 20 is attached. be able to.

  The CNT-coated paper 20 can be produced by immersing the fiber substrate 22 in a dispersion containing CNT as described above and drying it. The structure 24 having a predetermined thickness is formed on the surface of the fiber base 22 by repeating the dipping and drying steps, and the CNT-coated paper 20 is obtained. The electroencephalogram measurement electrode 10 having the conductive scalp contact surface 18 is obtained by attaching one surface of the CNT-coated paper 20 to one side surface of the plurality of comb teeth 16 along the comb teeth row 17 in the comb-shaped base material 12. Thus, it can be more easily produced.

  As described above, in the electroencephalogram measurement electrode 10, a conductive path is formed in the comb-shaped base material 12 by a structure including a plurality of CNTs. The conductive path by such a structure is not limited to the surface of the comb-shaped base material 12 but may be formed inside the comb-shaped base material 12. Even in this case, the structure is formed on one side surface of the plurality of comb teeth 16 along the comb tooth row 17.

  The electroencephalogram measurement electrode having a conductive path inside the comb-shaped base material 12 can be produced by molding a conductive elastic body into a predetermined shape. The conductive elastic body can be prepared, for example, by blending CNT as a nanocarbon material with an elastic body serving as a base material. As the base material, any elastic body as described above can be used. When the blending amount (concentration) of CNT is about 1 to 15 wt% of the elastic body, a conductive path required for the electroencephalogram measurement electrode can be formed without impairing the elasticity of the elastic body.

  When CNT is blended at a concentration exceeding 15 wt%, the original characteristics of the elastic body as the base material may be impaired. The concentration of CNT is preferably 3 wt% or more of the elastic body, more preferably 7 wt% or more, and most preferably 10 wt% or more.

  For example, a mixed raw material is prepared by melt-kneading an elastic body and CNTs with a twin screw extruder or the like. The conditions for melt kneading can be appropriately selected according to the type of elastic body. The mixed raw material after melt-kneading is made to pass through a pelletizer to produce pellets. The pellets can be made in a general size. For example, the diameter of the pellet is about 2 to 3 mm, and the length is about 2 to 3 mm.

  The obtained pellets are molded into a predetermined comb shape by an injection molding machine to obtain an electroencephalogram measurement electrode. The thus produced electroencephalogram measurement electrode can be said to be a comb-shaped base material made of a conductive elastic body. The conditions for injection molding can be appropriately selected according to the type of the elastic body, the size of the target comb-shaped base material, and the like.

  In the electroencephalogram measurement electrode formed of a comb-shaped base material made of a conductive elastic body, a conductive path by the structure is also formed inside. Accordingly, at least one side surface of the plurality of comb teeth along the comb tooth row can be used as a conductive scalp contact surface. Since the electroencephalogram measurement electrode also has the elasticity inherent in the elastic body, the same effect as described above can be obtained.

  In the above embodiment, CNT is used as the nanocarbon material forming the structure. However, the present invention is not limited to CNT, and graphene can also be used. Graphene is a nanocarbon material having high conductivity like CNT. Except for changing CNT to graphene, a structure is formed by fixing graphene on the surface or inside of the comb-shaped base material 12 in the same manner as described above, and the conductive scalp contact surface is formed along the comb teeth row 17. The plurality of comb teeth 16 can be provided on one side surface.

5). EXAMPLES Examples of the electroencephalogram measurement electrode will be described below, but the present invention is not limited to the following examples.

[Example 1]
In this embodiment, an electroencephalogram measurement electrode is prepared by attaching CNT-coated paper to a comb-shaped base material, and its electrical characteristics are examined. The CNT-coated paper is composed of a fiber base material and a structure formed by attaching CNTs to the surface of the fiber base material. Therefore, in the electroencephalogram measurement electrode of Example 1, a structure having a network structure in which a plurality of CNTs are connected to each other is exposed on the surface of the comb-shaped base material.

<Preparation of CNT dispersion>
CNTs were produced by a general thermal CVD method using iron as a catalyst. The CNTs isolated and dispersed using a mixed acid and ultrasonic waves were taken out, neutralized with ammonia water, and washed with pure water. Finally, it was dried in an oven to obtain powdered CNTs.

  Powdered CNTs were dispersed in DMF to prepare a CNT dispersion. The concentration of CNT in the dispersion is 0.01 wt%. Here, CNTs were dispersed by ultrasonic irradiation without using an adhesive.

<Production of CNT-coated paper>
A commercially available half paper as a fiber base was cut into a predetermined size, dipped in the CNT dispersion prepared above, and dried. The distance between the inspection terminals was set to about 1 cm and pressed against the surface of the dried half paper, and the resistance value was measured. When the measured resistance value did not reach the predetermined value, the resistance value was measured in the same manner after repeating dipping and drying again. The CNT-coated paper 20 as shown in FIG. 3 was produced by repeating immersion and drying until the resistance value on the surface of the half paper after drying reached a predetermined value.

  An SEM photograph of the surface of the obtained CNT-coated paper 20 is shown in FIG. In FIG. 4A (magnification: 50 times), it is confirmed that the fibers constituting the half paper as the fiber base material 22 are entangled with each other. In FIG. 4B (magnification: 10000 times), it can be confirmed that a plurality of fine CNTs adhere to the fiber surface of the fiber substrate 22. The plurality of CNTs form a structure 24 having a network structure connected to each other.

  In this embodiment, since no additive such as an adhesive is used, the CNTs are in direct contact with each other by van der Waals force, and the original high conductivity of the CNTs can be maintained. In the CNT coated paper 20, the original flexibility of the fiber base material 22 is not impaired by the additive. Since the CNT-coated paper 20 maintains the original softness of the half paper as the fiber base material 22, the CNT-coated paper 20 can be attached to a predetermined side surface of the comb teeth 16 in the comb-shaped base material 12.

<Preparation of electroencephalogram measurement electrode>
The comb-shaped base material 12 was prepared by cutting a commercially available plastic comb so that the number of comb teeth was five.

  The CNT coated paper 20 produced above is cut according to the surface along the comb tooth row 17 in the comb-shaped base material 12, and is pasted on one side surface of the plurality of comb teeth 16 along the comb tooth row 17 with a commercially available double-sided tape. I attached. Between adjacent comb teeth 16, the CNT-coated paper 20 was cut using scissors and separated to obtain the electroencephalogram measurement electrode 10 of Example 1.

  FIG. 5 shows a side view of the electroencephalogram measurement electrode 10 of the first embodiment. In the electroencephalogram measurement electrode 10, a plurality of comb teeth 16 project from the support portion 14 and are arranged in a row in a direction perpendicular to the paper surface to form a comb tooth row 17. A CNT-coated paper 20 is attached to one side surface of the plurality of comb teeth 16 along the comb tooth row 17. The surface of the CNT coated paper 20 attached to one side surface of the plurality of comb teeth 16 along the comb tooth row 17 becomes a scalp contact surface 18.

<Measurement of electrode contact resistance>
Electrode parts for measurement were prepared using the electroencephalogram measurement electrode 10 of Example 1, and electrode contact resistance was measured for the forehead and the hair. For measurement, a wireless bioelectric signal measuring device (Polymate Mini) manufactured by Miyuki Giken and an active electrode (dish electrode) were used.

  Specifically, as shown in FIG. 6, the active electrode 26 to which the conducting wire 32 is connected is attached to the scalp contact surface 18 side of the electroencephalogram measurement electrode 10 using the terminal retainer 28, and the measurement electrode component 30. Was made. The electrode contact resistance was measured by bringing the scalp contact surface 18 into contact with the forehead or the hair portion. The forehead was measured by applying a polishing gel before measurement to lower the contact resistance. The electrode contact resistance at the forehead portion was 40-60 kΩ, while the electrode contact resistance at the hair portion was similarly 40 kΩ-60 kΩ, and the electrode contact resistance was low even at the hair portion with a disability.

  For comparison, the electrode contact resistance was measured for the forehead portion and the hair portion in the same manner using only the active electrode 26 (Comparative Example 1). For the forehead part, 40-60 kΩ, the same result as in Example 1 was obtained. However, the hair portion was a large value of 300 kΩ or more. Since the comparative example 1 is only the active electrode 26, hair cannot be avoided. It has been found that the active electrode 26 has a problem that the hair becomes an obstacle and the electrode contact resistance becomes high, and the electroencephalogram cannot be accurately measured for the hair portion.

  In the electroencephalogram measurement electrode 10 of the first embodiment, the plurality of comb teeth 16 reach the scalp while scraping the head hair, and the scalp contact surface 18 contacts the scalp avoiding the hair. The scalp contact surface 18 has a structure having a network structure in which a plurality of CNTs are connected to each other, so that sufficient conductivity can be ensured without a conductive paste. When the electroencephalogram measurement electrode 10 of Example 1 is used, a low resistance value can be obtained even in the hair portion, and it becomes possible to measure the electroencephalogram with high accuracy.

[Example 2]
In this embodiment, an electroencephalogram measurement electrode made of a conductive comb-shaped base material is produced, and its electrical characteristics are examined. The conductive comb-shaped base material is a CNT kneaded product, and is obtained by forming a mixed raw material obtained by kneading CNT into an elastic body serving as a base material into a comb shape. Therefore, the electroencephalogram measurement electrode of Example 2 has a structure having a network structure in which a plurality of CNTs are connected to each other in addition to the surface of the comb-shaped base material.

<Relationship between CNT concentration and volume resistance>
Samples of CNT kneaded products containing CNTs at different concentrations were prepared, and the relationship between CNT concentration and volume resistance was examined. In preparation of the sample, first, CNT and a base material were melt-kneaded with a twin-screw extruder to prepare a CNT kneaded strand having a diameter of 0.3 cm. As CNTs, those obtained by a general thermal CVD method using iron as a catalyst were used as in Example 1 described above. CNT may be subjected to pretreatment using a mixed acid, but pretreatment is not always necessary. As the base material, a polyamide-based thermoplastic elastomer (Pebax 2533, manufactured by Arkema Co., Ltd.) was used. The CNT concentration was 1.9 wt%, 3.3 wt%, 3.9 wt%, and 11.6 wt%.

The obtained CNT kneaded strand was cut into a length of 10 cm to prepare a sample. Both ends of the sample were sandwiched between four terminal probes, and the electrical resistance Rs was measured using an LCR meter (IM3590, manufactured by Hioki Electric Co., Ltd.). For each sample, using the measured electrical resistance Rs (Ω), cross-sectional area A (0.15 ² πcm ² ), and length L (10 cm), the volume resistance ρ (Ω Cm) was calculated.
ρ = (Rs · A) / L Formula (1)

  For each CNT concentration, the average value of the volume resistance ρ of three samples was determined, and the result is shown in the graph of FIG. The volume resistance ρ of the sample of the CNT kneaded product decreases as the CNT concentration increases. If the volume resistance ρ is about 100 Ω · cm or less, it can be suitably used as an electrode for electroencephalogram measurement. In the case of producing an electroencephalogram measurement electrode using the above-mentioned CNT and a polyamide-based thermoplastic elastomer as a base material, the CNT concentration is preferably 7 wt% or more, more preferably 10 wt% or more. It was confirmed. The appropriate CNT concentration range can vary depending on the type of CNT or base material.

<Preparation of electroencephalogram measurement electrode>
Using the same CNT and base material as described above, a CNT kneaded strand was produced by the same method as described above. The concentration of CNT was 12 wt%. The diameter of the CNT kneaded strand was 0.3 cm. The obtained CNT kneaded strand was made into a CNT kneaded resin pellet having a length of about 2 mm by passing through a pelletizer. The CNT kneaded resin pellets were injection molded into a comb shape as shown in FIGS. In this way, three electroencephalogram measurement electrodes of Example 2 made of a conductive comb-shaped base material were produced.

  The electroencephalogram measurement electrode of Example 2 has flexibility and cushioning properties by using a polyamide-based thermoplastic elastomer as a base material. In the electroencephalogram measurement electrode of Example 2, the width d1, the length d2, and the thickness d3 of the support portion 14 are 11 mm, 13.8 mm, and 2.5 mm, respectively, the length d4, the width d5 of the comb teeth 16, And the distance d6 were 17.3 mm, 0.7 mm, and 1.2 mm, respectively.

<Measurement of impedance>
The impedance of the electroencephalogram measurement electrode of Example 2 was measured using an LCR meter. Specifically, both ends of the electroencephalogram measurement electrode were sandwiched between four terminal probes, and the impedance at 10 Hz was measured. The distance between the probes is 35 mm. The average value of the measured values for the three samples was 170Ω. The electroencephalogram measurement electrode preferably has an impedance of about 10 KΩ or less, more preferably about 1 KΩ or less. The electroencephalogram measurement electrode of Example 2 has an impedance suitable as an electroencephalogram measurement electrode.

  For comparison, a molded body was produced using conductive nylon, and the impedance was measured by the same method (Comparative Example 2). As the conductive nylon, a polyamide thermoplastic elastomer, Pebax 5533 SN 70 (manufactured by Arkema Co., Ltd.) was used, and a molded body having the same size and shape as the electroencephalogram measurement electrode of Example 2 was obtained by injection molding. Individually produced. The conductive nylon molded body of Comparative Example 2 had an average impedance value of 100 kΩ.

  Since the electroencephalogram measurement electrode of Example 2 is made of a conductive comb base material in which CNTs are kneaded with an elastic body as a base material, a structure having a network structure in which a plurality of CNTs are connected to each other is a comb base. In addition to the surface of the material, it is also formed inside. A comb-shaped base material in which such a structure is formed not only on the surface but also on the inside has a conductive path throughout, and thus has excellent conductivity.

  When the electroencephalogram measurement electrode of Example 2 made of such a conductive comb base material is used, the scalp is in contact with the conductive path. Since the electroencephalogram measurement electrode of Example 2 ensures electrical continuity between the electroencephalogram measurement electrode and the subject without using a conductive paste, like the electroencephalogram measurement electrode of Example 1, the contact impedance is extremely low. It can be lowered to a lower level. As a result, the electroencephalogram measurement electrode of Example 2 can accurately detect a weak electrical signal from the head.

<Measurement of electrode contact resistance>
Measurement electrode parts were prepared using the electroencephalogram measurement electrodes of Example 2, and the electrode contact resistance was measured for the forehead and the hair by the same method as in Example 1. The electrode for electroencephalogram measurement of Example 2 had an electrode contact resistance of the forehead part of 20 kΩ and an electrode contact resistance of the hair part of 50 to 150 kΩ.

  For comparison, the electrode contact resistance was measured for the forehead portion and the hair portion in the same manner using only the active electrode 26 (Comparative Example 3). As for the forehead part, 20 kΩ, the same result as in Example 2 was obtained. However, the hair portion was a large value of 300 kΩ or more. Since Comparative Example 3 includes only the active electrode 26, the hair becomes an obstacle and becomes high, and the electroencephalogram cannot be accurately measured for the hair portion.

  Furthermore, the conductive nylon molded body similar to the above-mentioned comparative example 2 was combined with the active electrode to produce an electrode component (Comparative Example 4). When the electrode contact resistance of Comparative Example 4 was measured for the forehead portion and the hair portion in the same manner as described above, the electrode contact resistances of the forehead portion and the hair portion were both the same as those of Comparative Example 3 with only the active electrode. .

  It has been confirmed that the impedance of the conductive nylon molded body is about three orders of magnitude greater than the electroencephalogram measurement electrode of Example 2 made of a CNT kneaded product (Comparative Example 2). The conductive nylon molded body cannot ensure sufficient conductivity. For this reason, even when the conductive nylon molded body and the active electrode are combined, it is extremely difficult to accurately measure the electroencephalogram as in the case of only the active electrode.

  In the electroencephalogram measurement electrode of Example 2, since CNTs are kneaded with an elastic body as a base material, sufficient conductivity can be ensured not only on the surface but also inside. The electrode component using the electroencephalogram measurement electrode of Example 2 can obtain a lower resistance value than that in the past in the hair portion, and can measure the electroencephalogram with higher accuracy. Moreover, since the electroencephalogram measurement electrode of Example 2 has flexibility and cushioning properties, an effect of reducing the burden on the subject can be obtained.

DESCRIPTION OF SYMBOLS 10 Electroencephalogram measurement electrode 12 Comb-shaped base material 14 Support part 14a Base end 16 Comb tooth 16a Base end 16b Tip 17 Comb row 18 Scalp contact surface

Claims (9)

An electroencephalogram measurement electrode comprising a comb-shaped base material made of an elastic body and a structure formed on the comb-shaped base material,
The comb-shaped base material includes a support portion and a comb tooth row including a plurality of comb teeth protruding in a row from the support portion, and the structure is provided on one side surface of the plurality of comb teeth along the comb tooth row. The body is formed,
The structure includes a plurality of nanocarbon materials, and the plurality of nanocarbon materials form a network structure connected to each other and are fixed to the comb-shaped base material. electrode.   2. The electroencephalogram measurement electrode according to claim 1, wherein the plurality of comb teeth are inclined in the length direction in the opposite direction to the one side surface.   3. The electroencephalogram measurement electrode according to claim 1, wherein the plurality of nanocarbon materials are fixed to the comb-shaped base material by being directly fixed to the one side surface of the plurality of comb teeth. .   The plurality of nanocarbon materials are fixed to the comb-shaped base material by being fixed to a fiber base material affixed to the one side surface of the plurality of comb teeth. The electrode for electroencephalogram measurement as described.   The comb-shaped base material is a conductive comb-shaped base material including the plurality of nanocarbon materials, and the structure is formed inside the comb-shaped base material. Electrode for measuring brain waves.   6. The electrode for electroencephalogram measurement according to claim 5, wherein the comb-shaped base material has a volume resistance of 100 Ω · cm or less.   The electroencephalogram measurement electrode according to claim 1, wherein the plurality of nanocarbon materials are selected from carbon nanotubes and graphene.   The electrode for electroencephalogram measurement according to claim 1, wherein the elastic body is selected from a resin, a thermoplastic elastomer, and rubber. The electrode for electroencephalogram measurement according to any one of claims 1 to 8, wherein a metal member is not included.

Images