WO2017065196A1

WO2017065196A1 - Electrode for brain wave measurement

Info

Publication number: WO2017065196A1
Application number: PCT/JP2016/080312
Authority: WO
Inventors: 梓森本; 敬造奥井
Original assignee: ニッタ株式会社
Priority date: 2015-10-13
Filing date: 2016-10-13
Publication date: 2017-04-20

Abstract

An electrode (10) for brain wave measurement is provided with a base member (12), which comprises an elastic body, and a structure formed on the base member (12). The electrode (10) for brain wave measurement is characterized in that the base member (12) comprises a support part (14) and an elastically-deformable tilting part (16) formed so as to project from one surface of the support part (14). The electrode (10) for brain wave measurement is further characterized in that the structure is formed on a surface of the tilting part (16) and contains multiple nanocarbon members that form an interconnected network structure and are fixed to the base member (12).

Description

Electroencephalogram measurement electrode

The present invention relates to an electroencephalogram measurement electrode.

As the conventional electroencephalogram measurement electrode, a type in which a conductive paste is interposed between the subject's scalp and the 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 secure a 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

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, since a large amount of conductive material is blended in order to impart desired conductivity to the protruding portion made of rubber, 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, it is possible that the electroencephalogram measurement may not be performed satisfactorily due to the complexity of the structure due to poor conduction at the contact point. 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 resistance value rises due to the hair becoming an obstacle, so the 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 base material made of an elastic body and a structure formed on the base material, wherein the base material includes a support portion and the support portion. A tilting part that protrudes from one surface and is elastically deformable, and the structure is formed on a surface of the tilting part, the structure includes a plurality of nanocarbon materials, and the plurality of nanocarbon materials includes And a network structure connected to each other and fixed to the base material.

According to the present invention, the electroencephalogram measurement electrode includes a base material made of an elastic body, and the surface of the tip of the tilting portion of the base material contacts the scalp of the subject. The tilting part is elastically deformed by pressing the support part and pressing the tilting part against the scalp. The tilting part scrapes the hair by elastically tilting while contacting the scalp on the side. In this manner, the side surface of the tilting portion can contact the scalp while avoiding the hair.

In the base material, a structure having a network structure in which a plurality of nanocarbon materials are connected is formed on the surface of the tilting portion. When the surface of the tilted part where the structure is formed contacts the scalp, the electrode for electroencephalogram measurement contacts the scalp without using a conductive paste and ensures sufficient conduction in the hair part with high accuracy. EEG 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.

Moreover, since the tilting part is elastically deformed along the scalp and the side surface of the elastically deformed tilting part comes into contact with the scalp, the burden on the subject can be further reduced and the contact area with the scalp increases. Since a sufficient contact area can be ensured, an electroencephalogram can be measured with higher sensitivity.

It is a perspective view which shows the structure of the electrode for electroencephalogram measurement which concerns on this embodiment. It is a top view of the electrode for electroencephalogram measurement shown in FIG. FIG. 3 is an X arrow view of the electroencephalogram measurement electrode shown in FIG. 2. It is a figure explaining the state at the time of use of the electrode for electroencephalogram measurement concerning this embodiment, Drawing 4A is a state before pressing, and Drawing 4B is a figure showing the state after pressing. It is a figure explaining the state at the time of use of the conventional multipin type dry electrode, FIG. 5A is a state before a press, FIG. 5B is a figure which shows the state after a press. It is a perspective view which shows the structure of the electrode for electroencephalogram measurement of a modification (1). It is a perspective view which shows the structure of the electrode for electroencephalogram measurement of a modification (2). It is a graph which shows the relationship between CNT density | concentration and volume resistance. It is the schematic which shows the structure of the electrode component for electrode contact resistance measurement.

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

1. Overall Configuration As shown in FIG. 1, the electroencephalogram measurement electrode 10 includes a base material 12 made of an elastic body including a support portion 14 and a tilting portion 16 formed to protrude from one surface of the support portion 14. A structure (not shown) is formed on the surface of the tilting portion 16. In the present embodiment, the structure is formed not on the inside of the tilting portion 16 in the base material 12 but on the surface. Since the structure has conductivity, the surface of the tilting portion 16 is conductive. A conductive path is formed in the base material 12 by the structure. A connection projection 18 for attaching the electroencephalogram measurement electrode 10 to a head cap or the like in use is formed on the other surface of the support portion 14 on the side opposite to the tilting portion 16.

The structure is formed at least on the surface of the tilting portion 16 in the base material 12. In the case where structures are also formed on the remaining surface of the base material 12 such as the surface of the support portion 14 and the surface of the connection protrusion 18, this can ensure electrical continuity with the tilting portion 16.

In the case of this embodiment, the base material 12 is formed of an elastic body having flexibility and cushioning properties, and is formed of, for example, a thermoplastic elastomer. More specifically, examples of the thermoplastic elastomer include urethane-based thermoplastic elastomer (TPU). In the base material 12, the support portion 14 is circular, and the connection protrusion 18 provided on the support portion 14 is also circular.

The base material 12 can have any size suitable for electroencephalogram measurement. Referring to the top view of FIG. 2, for example, the total length L0 of the base material 12 is about 15 to 35 mm, and the length L1 from the other surface of the support portion 14 to the tip 17 of the tilting portion 16 is about 10 to 30 mm. Can do. The diameter D0 of the support portion 14 can be about 8 to 20 mm, and the diameter D1 of the connection projection 18 can be about 3 to 10 mm.

The tilting part 16 protrudingly formed on one surface of the support part 14 is configured to tilt in a specific direction. Since the tilting portion 16 is provided so as to be inclined in a certain direction, it can be tilted in a specific direction by being pressed. In the case of this embodiment, as shown in FIG. 2, the tilting portion 16 is inclined radially from the middle in the length direction toward the outside of the support portion 14.

Since the tilting part 16 is formed of an elastic body, it tilts elastically. Before the tilting portion 16 is elastically deformed, only the surface (end surface) of the tip 17 of the tilting portion 16 becomes a scalp contact surface that contacts the scalp. By tilting the tilting portion 16 elastically along the scalp, the side surface of the tilting portion 16 can also contact the scalp. In the present embodiment, the tilting portion 16 has a cylindrical shape and is integrally formed of the same material as the support portion 14. As shown in FIG. 2, it is preferable that the diameter of the inclined portion 16 is inclined toward the tip 17, and the tip 17 of the tilted portion 16 is rounded. preferable.

The number of tilting portions 16 formed to protrude on one surface of the support portion 14 is not particularly limited, but the scalp contact surface can be increased as the number of tilting portions 16 increases. The plurality of tilting portions 16 are preferably provided on the circumference so that they do not interfere with each other when tilted elastically. The length and diameter of the tilting part 16 are not particularly limited. When the tilting part 16 is pressed in contact with the scalp, the length and diameter of the tilting part 16 can be appropriately set so that a scalp contact surface necessary for electroencephalogram measurement can be secured by elastic deformation along the scalp. Good. The angle of inclination in the tilting portion 16 and the degree of decrease in diameter toward the tip 17 can be appropriately set in consideration of the material of the base material 12, the length of the tilting portion 16, and the like.

In the present embodiment, four tilting portions 16 are formed to protrude from one surface of the support portion 14. As described with reference to FIG. 2, since the tilting portions 16 are inclined radially outward from the middle in the length direction, the tip 17 of each tilting portion 16 is a support portion as shown in FIG. 3. It is located outside the outer edge of 14.

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 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 base material 12, the conductive path is also formed on the surface instead of the inside of the base material 12.

A structure having a CNT network structure can be formed by using van der Waals force of CNT without using an adhesive or the like, and can be fixed to the surface of the tilting portion 16 in the base material 12. Alternatively, the structure having a network structure of CNT is formed by mixing a general adhesive or the like with CNT within a range that does not impair the conductivity of CNT, and is fixed to the surface of tilting portion 16 in base material 12. Also good. In either case, the CNT adheres directly to the surface of the tilting portion 16 in the base material 12.

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

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.

As described above, in this embodiment, the electroencephalogram measurement electrode 10 is composed of the base material 12 having the tilting portion 16 and the structure formed at least on the surface of the tilting portion 16. The base material 12 is made of an elastic body, and the structure is made of a plurality of nanocarbon materials. Since the 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 can be manufactured by preparing a dispersion containing CNTs and forming a structure on at least the surface of the tilting portion 16 in the base material 12 using the dispersion.

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 powdered 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 applied to disperse the CNTs to obtain 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 CNT network structure with a dispersion without adding the above additives and fix the structure to the base material 12.

Next, the base material 12 made of an elastic body is immersed in the dispersion. When an additive such as an adhesive is not contained in the dispersion liquid in which the base material 12 is immersed, the CNT is formed on the surface of the tilting portion 16 by van der Waals force acting between the base material 12 and the CNT. A structure having a network structure is formed and further directly attached to the surface of the tilting portion 16. When an additive such as an adhesive is contained in the dispersion liquid in which the base material 12 is immersed, a force such as an adhesive is added in addition to the above van der Waals force. In this case, CNT adheres to the surface of the tilting portion 16 more strongly.

Prior to immersion in the dispersion, when a predetermined region of the surface of the base material 12 is pretreated, CNTs can be preferentially attached to the surface of the tilting portion 16 of the base material 12. For example, the surface of the tilting portion 16 in the base material 12 can be subjected to a surface treatment to promote CNT adhesion.

After the CNTs are attached to the surface, the base material 12 is pulled up from the dispersion and dried, whereby the CNTs are attached and fixed to the surface of the tilting portion 16 in the base material 12. In this way, a structure having a network structure in which CNTs are connected to each other is formed on the surface of the tilting portion 16 in the base material 12. By repeating the steps of dipping and drying, a structure having a desired thickness can be obtained.

When the base material 12 is immersed in the dispersion as described above, the CNTs directly adhere to at least the surface of the tilting portion 16 of the base material 12 to form a structure. Therefore, the electroencephalogram measurement electrode 10 having a structure formed on the surface of the tilting portion 16 of the base material 12 can be easily formed.

The electroencephalogram measurement electrode 10 of this embodiment can be used as a headset by attaching a plurality of headbands or head caps, for example, so that the tip 17 of the tilting portion 16 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, the tilting portion 16 protrudes from one surface of the support portion 14. The tilting portion 16 can be elastically deformed, and the surface of the tilting portion 16 becomes a scalp contact surface. When the electroencephalogram measurement electrode 10 is used, the tip 17 of the tilting portion 16 is brought into contact with the scalp 20 as shown in FIG. 4A. When the tilting portion 16 is not pressed against the support portion 14, the surface (end surface) of the tip 17 of the tilting portion 16 becomes the scalp contact surface 24.

As shown in FIG. 4B, when a force in the direction of arrow A is applied to the support part 14 of the electroencephalogram measurement electrode 10, the tilt part 16 is pressed by the support part 14 and tilts elastically. Since the tilting portion 16 is inclined outward from the middle in the length direction, the tip 17 spreads in the arrow B direction when pressed. When the tip 17 spreads, the tilting portion 16 is elastically deformed along the scalp and can scrape off unillustrated hair. In the present embodiment, the tilting portion 16 tilts radially outward from the middle of the length, so that the inner portion of the side surface of the tilting portion 16 becomes the scalp contact surface 24. Thereby, it is possible to contact the scalp with a larger area than before the tilting portion 16 is pressed (FIG. 4A).

Thus, in the electroencephalogram measurement electrode 10 of the present embodiment, in addition to the end surface of the tilting portion 16, the side surface also becomes the scalp contact surface. Since the surface of the tilting portion 16 is formed with a conductive path made of a structure including a plurality of CNTs, the scalp is in contact with the conductive path when the electroencephalogram measurement electrode 10 of this embodiment is used. 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.

In addition, the base material 12 including the tilting portion 16 is made of an elastic body and has flexibility and cushioning properties. Since the tilting part 16 is tilted elastically by pressing, even if the tilting part 16 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.

On the other hand, the conventional multi-pin type dry electrode 110 as shown in FIG. 5A is provided with a hard metal multi-pin 116 on the support portion 114. In the multi-pin type dry electrode 110, the end surface of the multi-pin 116 is a scalp contact surface 124 that contacts the scalp 20. Since the multi-pin 116 is made of a hard metal, as shown in FIG. 5B, even if a force in the direction of arrow A is applied to the support portion 114 and pressed, it does not elastically deform. When the multi-pin dry electrode 110 is pressed, the scalp contact surface 124 remains the end surface of the multi-pin 116. Moreover, when the hard metal multi-pin 116 is pressed against the scalp 20, the subject feels pain.

The electroencephalogram measurement electrode 10 of the present embodiment includes the base material 12 made of an elastic body having the tilting portion 16, thereby making it possible to avoid the disadvantages of the conventional multi-pin type dry electrode 110.

Furthermore, the structure is exposed on the surface of the 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 at least on the surface of the tilting portion 16 in the base material 12. By forming the structure in this way, the conductive path is exposed and formed on the surface of the base material 12. Compared with the case where a conductive path exists inside the base material 12, the measured electroencephalogram can be transmitted efficiently.

The structure is fixed to the base material 12 by directly connecting the CNTs without using an adhesive or the like to form a network. Adhesives are not used to form the structure with CNT and to fix the structure to the base material 12, so that the flexibility and cushioning of the 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 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 base material 12 made of an elastic body and a structure made of a nanocarbon material on the surface of the tilting portion 16 of the base material 12. Since no metal member is included, X-ray computed tomography (CT) or nuclear magnetic resonance imaging (MRI) with the electroencephalogram measurement electrode 10 according to this embodiment attached to 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.

In addition, since the metal member is not included, the electroencephalogram measurement electrode 10 can 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. The base material 12 made of an elastic body can integrally form the support portion 14 and the tilting portion 16. Such an electroencephalogram measurement electrode 10 is excellent in mass productivity and can reduce the manufacturing cost.

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.

In the said embodiment, although the case where the base material 12 was formed with the urethane type thermoplastic elastomer (TPU) as a thermoplastic elastomer was demonstrated, this invention is not limited to this, The base material 12 is used using arbitrary elastic bodies. Can be formed. For example, the base material 12 may be formed of other thermoplastic elastomer, resin, rubber or the like.

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), polyhexamethylene sebacamide (nylon 610), polyhexamylene dodecamide (nylon 612), poly Decanamide (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), very low density polyethylene, low density polyethylene (LDPE), medium density polyethylene (MDPE), Density 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), Reethylene 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), fluorinated 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 part 14 and the tilting part 16 in the 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 base material 12 is formed by solidifying a foam material having cushioning properties 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 a material and a nonwoven material. In short, any material that can project and form the tilting portion 16 on one surface of the support portion 14 and exhibits elasticity and can form a structure on the surface of the tilting portion 16 is suitable for the base material 12 without being limited to the above materials. Can be used.

In particular, when a fiber material, a porous material, a foam material, or the like is used as the base material 12, the CNT fibers are easily entangled with the unevenness of the surface. In this case, a structure having a network structure of CNTs can be formed on the surface of the tilting portion 16 of the base material 12 without using an adhesive, and a plurality of CNT fibers are entangled with each other. it can. Thereby, the electroencephalogram measurement electrode 10 having improved conductivity as described above can be obtained.

Various changes can also be made to the tilting portion 16 formed to protrude from one surface of the base material 12. For example, as shown in the electroencephalogram measurement electrode 10A in FIG. 6, a spherical portion 28 can be provided at the tip of the tilting portion 16A (modified example (1)). The spherical portion 28 at the tip can promote the elastic tilting of the tilting portion 16A in addition to relieving the pain of the subject.

By providing the spherical portion 28, the base material 12A of the electroencephalogram measurement electrode 10A has a large surface area at the tip of the tilting portion 16A. In the electroencephalogram measurement electrode 10A, in addition to the side surface of the tilting portion 16A, a conductive structure is also formed on the surface of the spherical portion 28 at the tip. The electroencephalogram measurement electrode 10A has a conductive structure formed in a wider area as compared with the case where the tip portion does not have the spherical portion 28, so that the scalp contact surface when the tilting portion 16A is tilted elastically. It is advantageous in that the area that can be used as the expansion is expanded.

Further, the tilting part may be inclined toward the inside of the support part 14 from the middle in the length direction. For example, as shown in the electroencephalogram measurement electrode 10B in FIG. 7, the tilting portion 16B may be tilted from the middle in the length direction toward the central axis of the support portion 14 (modified example (2)). When the electroencephalogram measurement electrode 10B is used, the tilting portion 16B is elastically deformed by being pressed by the support portion 14 and tilted inward. In this case, the outer part of the side surface of the tilting part 16B comes into contact with the scalp. The electroencephalogram measurement electrode 10B is the same as the modification (1) except that the outer portion of the side surface of the tilting portion 16B becomes the scalp contact surface, and the same effect as the modification (1) is obtained. Furthermore, the configuration may be such that the spherical portion 28 at the tip of the tilting portion 16B is omitted from the electroencephalogram measurement electrode 10B.

The plurality of tilting portions 16 can be elastically tilted without interfering with each other, and can be provided on one surface of the support portion 14 in any arrangement as long as the side surfaces of the respective tilting portions 16 can contact the scalp. You may comprise so that some tilting parts 16 arrange | positioned on the circumference may tilt in a different direction. For example, the plurality of tilting portions 16 can be formed on one surface of the support portion 14 so that the tilting directions of the plurality of tilting portions 16 arranged on the circumference are alternately outside and inside.

The plurality of tilting portions 16 arranged on the circumference may be tilted from the middle in the length direction so as to tilt toward the tilting portion 16 adjacent in a certain direction (for example, clockwise).

Furthermore, the tilting part 16 may be provided on one surface of the support part 14 on the circumference of two concentric circles. Thereby, a scalp contact surface can be increased. Also in this case, the tilting portion 16 on the inner circumference and the tilting portion 16 on the outer circumference are tilted elastically without interfering with each other, and the side surfaces of the respective tilting portions 16 contact the scalp. If possible, it can be set as an arbitrary configuration. The tilting portion 16 on the inner circumference and the tilting portion 16 on the outer circumference can be configured to tilt in the same direction (inner side or outer side).

Alternatively, the tilting portion 16 on the inner circumference may be configured to tilt in a different direction from the tilting portion 16 on the outer circumference. For example, the tilting portion 16 on the inner circumference can be configured to tilt toward the inside, and the tilting portion 16 on the outer circumference can be configured to tilt toward the outside. On the contrary, the tilting portion 16 on the inner circumference may be configured to tilt toward the outside, and the tilting portion 16 on the outer circumference may be configured to tilt toward the inside. .

The support part 14 in the base material 12 does not need to be circular, and may be a polygon such as a quadrangle. For example, when a rectangular support portion is used, four tilting portions can be provided at the four corners of one surface. The four tilting portions may be configured to tilt in a certain direction (for example, clockwise) toward the adjacent tilting portions. As long as the tilting part can be pressed and thereby the tilting part can tilt elastically without interfering with each other, and the side surface of the tilting part can contact the scalp, the support part and the tilting part can have any shape. .

When consideration about the artifact is not required, a metal member such as a metal plate may be included in a part of the electroencephalogram measurement electrode 10 as long as the flexibility and cushioning properties of the 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 surface of the tilting portion 16 by a conducting wire. By providing a metal plate, it is easy to transmit an electric signal, and the accuracy of measurement can be further increased.

As described above, in the electroencephalogram measurement electrode 10, a conductive path is formed in the base material 12 by a structure including a plurality of CNTs. The conductive path formed by such a structure is not limited to the surface of the base material 12 and may be formed inside the base material 12. Even in this case, the structure is formed on the surface of the tilting portion 16.

The electroencephalogram measurement electrode having a conductive path inside the 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. If 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 CNT 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 shape by an injection molding machine to obtain an electroencephalogram measurement electrode. The thus produced electroencephalogram measurement electrode can be said to be a 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 base material, and the like.

In the electroencephalogram measurement electrode composed of a base material made of a conductive elastic body, a conductive path by the structure is also formed inside. Thereby, the surface of the tilting part can be made into 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, but 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 to the surface or inside of the base material 12 by the same method as described above, and a conductive scalp contact surface is provided on the surface of the tilting portion 16. be able to.

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

In this embodiment, an electroencephalogram measurement electrode made of a conductive base material is produced, and its electrical characteristics are examined. The conductive base material is a CNT kneaded product, and is obtained by molding a mixed raw material obtained by kneading CNT into an elastic body serving as a base material into a predetermined shape. Therefore, the electroencephalogram measurement electrode of this example 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 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. First, CNTs were produced by a general thermal CVD method using iron as a catalyst.

CNT and base material were melt-kneaded with a twin-screw extruder to produce a CNT kneaded strand having a diameter of 0.3 cm. 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. CNT kneaded resin pellets were injection-molded into a shape having a support portion and a tilting portion as shown in FIGS. In this way, three electroencephalogram measurement electrodes of this example made of a conductive base material were produced.

The electroencephalogram measurement electrode of this example has flexibility and cushioning properties by using a nylon resin as a base material. The electroencephalogram measurement electrode according to the present embodiment is a base material 12 in which a tilting portion 16 protrudes from one surface of a support portion 14. The total length L0 of the base material 12 is 23.5 mm, the length L1 from the other surface of the support portion 14 to the tip of the tilting portion 16 is 20 mm, the diameter D0 of the support portion 14 and the diameter D1 of the connecting projection 18 are 10 mm and It was 5 mm.

<Measurement of impedance>
Using an LCR meter, the impedance of the electroencephalogram measurement electrode of the example was measured. 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 20 mm. The average value of the measured values for the three samples was 468Ω. 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 the example has an impedance suitable as an electroencephalogram measurement electrode.

As a comparative example, a molded body using conductive nylon (Comparative Example 1) and a molded body using conductive urethane (Comparative Example 2) were produced, and impedance was measured by the same method. As the conductive nylon, Pebax 5533 SN 70 (manufactured by Arkema Co., Ltd.), which is a polyamide-based thermoplastic elastomer, was used, and as the conductive urethane, a conductive urethane-based thermoplastic elastomer (manufactured by Tosoh Corp.) was used. Using these conductive resins, three molded bodies having the same size and shape as the electroencephalogram measurement electrodes of Examples were produced by injection molding. The conductive nylon molded body of Comparative Example 1 had an average impedance value of 253 kΩ, and the conductive urethane molded body of Comparative Example 2 had an average impedance value of 34 kΩ.

Since the electroencephalogram measurement electrode of the embodiment is made of a conductive 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 has In addition, it is also formed inside. Since the base material in which such a structure is formed not only on the surface but also on the inside has a conductive path throughout, the conductivity is excellent.

When using the electroencephalogram measurement electrode of the embodiment made of such a conductive base material, the scalp is in contact with the conductive path. Since the electroencephalogram measurement electrode of the embodiment ensures electrical continuity between the electroencephalogram measurement electrode and the subject without using a conductive paste, the contact impedance can be lowered to a very low level. As a result, the electroencephalogram measurement electrode of the embodiment can accurately detect a weak electric signal from the head.

<Measurement of electrode contact resistance>
Electrode parts for measurement were produced using the electroencephalogram measurement electrodes of the example, 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. 9, the active electrode 26 to which the conducting wire 32 is connected is attached to the connection projection 18 of the electroencephalogram measurement electrode 10 using a clip 28, thereby producing a measurement electrode component 30. did. The tip 17 and the side surface of the tilting part 16 protruding from the support part 14 were brought into contact with the forehead part or the hair part, and the electrode contact resistance was measured. The forehead was measured by applying a polishing gel before measurement to lower the contact resistance. As a result, the electrode contact resistance at the forehead portion was 20 kΩ, and the electrode contact resistance at the hair portion was 100 to 200 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 the example was obtained. However, the hair portion was a large value of 300 kΩ or more. Since the comparative example 3 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.

Furthermore, an electrode part (Comparative Example 4) in which the same conductive nylon molded body as that in Comparative Example 1 described above is combined with an active electrode, and a molded body in which the same conductive urethane molded body as in the above Comparative Example 2 is combined with an active electrode ( Comparative Example 5) was prepared. When the electrode contact resistance of Comparative Examples 4 and 5 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 almost the same as those of Comparative Example 3 with only the active electrode. there were.

It has been confirmed that the impedance of the conductive nylon molded body and the conductive urethane molded body is significantly larger than that of the electroencephalogram measurement electrode of the example made of the CNT kneaded product (Comparative Examples 1 and 2). Neither the conductive nylon molded body nor the conductive urethane molded body can ensure sufficient electrical conductivity, so it is extremely difficult to accurately measure the brain waves when combined with the active electrode, as with the active electrode alone. It is.

In the electroencephalogram measurement electrode of the example, 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 such an example can obtain a lower resistance value than that in the past even in the hair portion, and can measure the electroencephalogram with higher accuracy. In addition, since the electroencephalogram measurement electrode of the example 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 Base material 14 Support part 16 Tilt part

Claims

An electroencephalogram measurement electrode comprising a base material made of an elastic body and a structure formed on the base material,
The base material includes a support part, and a tilting part that protrudes and elastically deforms on one surface of the support part, and the structure is formed on a surface of the tilting part,
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 base material. .
2. The electroencephalogram measurement electrode according to claim 1, wherein a plurality of the tilting portions are provided on the circumference.
3. The electroencephalogram measurement electrode according to claim 1, wherein the tilting portion has a spherical portion at the tip.
The electroencephalogram measurement electrode according to any one of claims 1 to 3, wherein the plurality of nanocarbon materials are fixed to the base material by being fixed to the surface of the tilting portion. .
4. The method according to claim 1, wherein the base material is a conductive base material including the plurality of nanocarbon materials, and the structure is formed inside the base material. The electrode for electroencephalogram measurement according to Item.
6. The electroencephalogram measurement electrode according to claim 5, wherein the conductive base material has a volume resistance of 100 Ω · cm or less.
7. The electroencephalogram measurement electrode according to claim 1, wherein the plurality of nanocarbon materials are selected from carbon nanotubes and graphene.
The electroencephalogram measurement electrode according to any one of claims 1 to 7, 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 the electrode does not contain a metal member.