JP2016176875A - Strain sensor and electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strain sensor capable of accurately detecting telescopic strain of a CNT film by sufficiently enhancing conductivity of the CNT film and an electrode.SOLUTION: A strain sensor 1 includes: a CNT film 2 containing a plurality of CNT fibers orientated in one direction, and having elasticity; and a pair of electrodes 3 disposed at both end parts of the CNT film 2. The electrode 3 projects to the side of the CNT film 2, and has a projection part 3b having conductivity. At least a front layer of the plurality of CNT fibers is covered with a material mainly comprising an insulation elastomer, the projection part 3b penetrates the coating mainly comprising the insulation elastomer, and the longitudinal direction of the projection part 3b is substantially parallel with the orientation direction of the CNT fiber. The projection part 3b is formed by penetrating a staple from the outer surface of a planar base body part 3a constituting the electrode 3b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a strain sensor and an electrode.

  There is known a strain sensor that detects strain from a resistance change of a resistor with respect to expansion and contraction. In general, a metal or a semiconductor is used as such a resistor. However, metals and semiconductors have a small amount of deformation that can be reversibly expanded and contracted. For this reason, a strain sensor using a metal or a semiconductor as a resistor has limitations on applications.

  Therefore, a strain sensor using carbon nanotubes (CNT) as the resistor has been proposed (see Japanese Patent Application Laid-Open No. 2011-47702). This strain sensor has a CNT film made of a plurality of CNTs oriented in a predetermined direction. This strain sensor is said to be able to cope with a large strain because the CNT film can expand and contract relatively greatly in the alignment direction of CNT or in a direction perpendicular to the alignment direction.

  This strain sensor has a pair of electrodes on one surface at both ends of the CNT film, and the pair of electrodes can detect a change in resistance of the CNT film. The pair of electrodes can be formed by a pair of conductive paste layers stacked on one surface of both ends of the CNT film and a conductive film stacked on one surface of the pair of conductive paste layers. It is said that.

  However, when the electrode is constituted by the conductive paste layer laminated on one surface of the CNT film and the conductive film laminated on the conductive paste layer in this way, the CNT film and the conductive film are electrically conductive during expansion / contraction of the CNT film. The contact area with the conductive paste layer may change. This also reduces the electrical conductivity between the CNT film and the conductive paste layer, which may cause poor electrical conduction.

2011-47702 gazette

  The present invention has been made based on such circumstances, and an object of the present invention is to provide a strain sensor capable of accurately detecting the expansion / contraction strain of the CNT film by sufficiently increasing the conductivity between the CNT film and the electrode. Another object of the present invention is to provide an electrode capable of sufficiently detecting the stretching strain of the CNT film by sufficiently increasing the conductivity with the CNT film.

  The present invention made in order to solve the above-mentioned problem is a strain comprising a plurality of CNT fibers oriented in one direction and having elasticity, and a pair of electrodes disposed at both ends of the CNT film. The sensor is characterized in that the electrode has a protruding portion of a protruding protrusion that protrudes toward the CNT film and has conductivity.

  In the strain sensor, a pair of electrodes disposed at both ends of the CNT film protrudes toward the CNT film, and has protruding protrusions having conductivity. Therefore, the strain sensor can easily and reliably increase the contact area between the pair of electrodes and the plurality of CNT fibers by bringing the convex protrusions into contact with the CNT fibers. That is, since the protruding portion of the ridge has a ridge line, the surface including the ridge line can be easily brought into contact with the CNT fiber constituting the CNT film, and the contact area between the protruding portion and the CNT film can be easily and reliably increased. . In addition, when the surface including the ridge line is brought into contact with the CNT fiber in this way, the contact area between the protrusion and the CNT fiber hardly changes due to the expansion and contraction of the CNT film. Therefore, the strain sensor can sufficiently detect the stretching strain of the CNT film by sufficiently increasing the conductivity between the CNT film and the electrode.

  It is preferable that at least a surface layer of the plurality of CNT fibers is coated with a material mainly composed of an insulating elastomer, and the protruding portion penetrates the coating mainly composed of the insulating elastomer. In this way, at least the surface layer of the plurality of CNT fibers is coated with a material mainly composed of an insulating elastomer, and the projecting portion penetrates the coating composed mainly of the insulating elastomer, whereby the projecting portion Can be accurately brought into contact with a plurality of CNT fibers, and the adhesive strength between the electrode and the CNT film can be easily and reliably increased.

  The longitudinal direction of the protrusions may be substantially parallel to the orientation direction of the CNT fibers. Thus, when the longitudinal direction of the protrusion is substantially parallel to the orientation direction of the CNT fiber, the surface extending in the longitudinal direction of the protrusion is easily brought into contact with the outer peripheral surface of the CNT fiber. Therefore, the contact area between the CNT fiber and the protrusion can be significantly increased.

  The protrusions may be formed by piercing staples from the outer surface of a flat base portion constituting the electrode. Thus, the protrusion can be easily formed by forming the protrusion by piercing the staple from the outer surface of the flat base portion constituting the electrode. Furthermore, according to this structure, the adhesive strength between the electrode and the CNT film can be increased.

  In addition, the present invention made to solve the above-described problems is an electrode for a strain sensor using a CNT film including a plurality of CNT fibers oriented in one direction, and includes a flat base portion and the base portion. And a protruding portion of a ridge protruding on the side surface of the CNT film.

  Since the electrode includes a flat base portion and a protruding portion of a ridge protruding on the CNT film side surface of the base portion, the contact area with the CNT film can be easily and reliably increased as described above. Can do. Therefore, the electrode can sufficiently detect the stretching distortion of the CNT film by sufficiently increasing the conductivity with the CNT film.

  In the present invention, the phrase “a plurality of CNT fibers are oriented in one direction” does not require that the orientation directions of the plurality of CNT fibers completely coincide with each other. Including a state having a regular deflection. The “longitudinal direction of the protruding portion” refers to the ridge line direction of the protruding portion. Further, “the longitudinal direction of the protrusion and the alignment direction of the CNT fibers are substantially parallel” means that the angle formed by the ridge line of the protrusion and the central axis of the CNT fiber is 0 ° or more and 5 ° or less. “Main component” refers to a component having the largest content, for example, a component having a content of 50% by mass or more.

  As described above, the strain sensor of the present invention can sufficiently detect the expansion / contraction strain of the CNT film by sufficiently increasing the conductivity between the CNT film and the electrode. In addition, the electrode of the present invention can sufficiently enhance the conductivity with the CNT film, and can accurately detect the stretching strain of the CNT film.

It is a typical sectional view in a field perpendicular to the surface of a distortion sensor concerning a first embodiment of the present invention. FIG. 2 is a schematic plan view of the strain sensor in FIG. 1. FIG. 2 is a cross-sectional view of the strain sensor of FIG. 1 taken along line AA. It is a typical side view which shows the electrode of the distortion sensor of FIG. It is a typical bottom view of the electrode of FIG. It is a typical front view of the electrode of FIG. It is a typical sectional view in a field perpendicular to the surface of a strain sensor concerning a second embodiment of the present invention. FIG. 8 is a cross-sectional view of the strain sensor of FIG. 7 taken along line BB. It is a typical top view which shows the distortion sensor which concerns on 3rd embodiment of this invention. FIG. 10 is a schematic cross-sectional view taken along a plane perpendicular to the surface of the strain sensor of FIG. 9. It is a typical perspective view which shows the electrode of the distortion sensor of FIG. It is a typical top view which shows the distortion sensor which concerns on 4th embodiment of this invention. It is typical sectional drawing in a surface perpendicular | vertical to the surface of the distortion sensor of FIG. It is a typical front view which shows the electrode which concerns on other embodiment of this invention. It is a typical front view which shows the electrode which concerns on other embodiment of this invention.

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

[First embodiment]
<Strain sensor>
1 and 2 includes a CNT film 2 including a plurality of CNT fibers oriented in one direction, a pair of electrodes 3 disposed on both ends and one surface side of the CNT film 2, A pair of sandwiching sheets 4 disposed opposite to the pair of electrodes 3 are provided on both ends of the CNT film 2 and on the other surface side. 1 and 2 includes a protective layer 5a disposed on one surface side of the CNT film 2 and the other surface side of the pair of electrodes 3, the other surface side of the CNT film 2, and And a protective layer 5b disposed on one surface side of the pair of sandwiching sheets 4.

(CNT film)
As shown in FIG. 2, the CNT film 2 is formed in a substantially rectangular shape in plan view with the both end portions in the longitudinal direction. The plurality of CNT fibers constituting the CNT film 2 are oriented in the longitudinal direction. In the CNT film 2, at least the surface layer of a plurality of CNT fibers is coated with a material mainly composed of an insulating elastomer. The CNT film 2 is elastic by the elastic force of the insulating elastomer and is configured to be stretchable at least in the longitudinal direction. The CNT film 2 is configured such that the resistance value can be changed by expanding and contracting at least in the longitudinal direction.

  Each CNT fiber consists of a plurality of CNT single fibers. Here, the CNT single fiber means one long CNT. In addition, the CNT fiber has a connection portion where the ends of the CNT single fibers are connected to each other. The CNT single fibers are connected in the longitudinal direction of these CNT single fibers. In this way, in the CNT film 2, the CNT single fibers are connected in the longitudinal direction, whereby the CNT film 2 having a large orientation length of the CNT fibers can be formed. The sensitivity can be improved by increasing the sensitivity.

  The plurality of CNT fibers constituting the CNT film 2 may form a network structure. Specifically, the plurality of CNT fibers may be connected or contacted in a mesh shape by a connecting portion or the like where the CNT single fibers are connected to each other. At this time, the end portions of three or more CNT single fibers may be coupled to each other at this connection portion, and the end portions of the two CNT single fibers may be coupled to an intermediate portion of another single fiber. When a plurality of CNT fibers form such a network structure, the CNT fibers are in close contact with each other, and the resistance of the CNT film 2 can be reduced.

  Furthermore, the CNT film 2 may have a CNT fiber bundle composed of a plurality of CNT fibers oriented in the longitudinal direction. When the CNT film 2 has a plurality of CNT fiber bundles oriented in the longitudinal direction, when strain is applied so that the CNT film 2 is stretched in the stretching direction, the CNT fiber is cut and separated, and the CNT fiber bundle cutting space (gap) ), The resistance of the CNT film 2 changes more accurately.

  More specifically, the CNT fiber bundle has a bundle structure composed of a plurality of CNT fibers. In an arbitrary cross section of the CNT fiber bundle, the CNT fibers that are not cut and the CNT fibers are cut and separated. Both gaps will exist. When the gap of the CNT fibers widens, the remaining uncut CNT fibers are stretched, which also causes a resistance change. In addition, since the plurality of CNT fibers are coated at least on the surface layer with a material mainly composed of an insulating elastomer, the pressure in the gap is considered to be lower than the atmospheric pressure (negative pressure). When the strain sensor 1 contracts (when strain is released), the contraction force of the gap urges the strain sensor 1 to contract. Furthermore, since the friction between the CNT fibers is reduced in the gap, the movement of the CNT fibers is difficult to be limited.

  The CNT film 2 may have a single-layer structure in which a plurality of CNT fibers or a plurality of CNT fiber bundles are arranged substantially parallel to each other in a planar shape, or may have a multilayer structure. However, in order to ensure a certain degree of conductivity, a multilayer structure is preferable.

  As the CNT single fiber (CNT), both single-wall single-wall nanotubes (SWNT) and multi-wall multi-wall nanotubes (MWNT) can be used. From the viewpoint of conductivity and heat capacity, MWNT is preferable, MWNT having a diameter of 1.5 nm or more and 100 nm or less is more preferable.

  The CNT single fiber (CNT) can be produced by a known method, for example, by a CVD method, an arc method, a laser ablation method, a DIPS method, a CoMoCAT method, or the like. Among these, it is preferable to manufacture by a CVD method using iron as a catalyst and ethylene gas from the viewpoint that CNT (MWNT) having a desired size can be efficiently obtained. In this case, it is possible to obtain a CNT crystal having a desired length which has been grown in a vertical orientation on an iron or nickel thin film serving as a catalyst on a quartz glass substrate or a silicon substrate with an oxide film.

  In the CNT film 2, at least a surface layer of a plurality of CNT fibers is coated with a material mainly composed of an insulating elastomer. Thereby, the plurality of CNT fibers can be expanded and contracted by the elastic force of the insulating elastomer. In addition, by covering a plurality of CNT fibers with an insulating elastomer, the insulating elastomer also functions as a guide member that guides the expansion / contraction direction of the plurality of CNT fibers. As a result, the strain sensor 1 can re-contact the CNT fibers separated at the time of expansion at the same site again at the time of contraction, and can prevent a decrease in the detection accuracy of the stretching strain due to repeated use. Furthermore, according to this configuration, the contact relationship between the plurality of CNT fibers is easily maintained. Moreover, it is easy to adjust the stretchability of a plurality of CNT fibers. Therefore, the stretching strain of the CNT film 2 can be detected with higher accuracy. Further, in order to make it easier to maintain the contact relationship and adjust the stretchability, it is preferable that the back layer of the CNT film 2 is also coated with an insulating elastomer. The “surface layer” refers to the arrangement surface side of the pair of electrodes 3, and the “back layer” refers to the opposite side.

  Examples of the insulating elastomer include synthetic resin and rubber. Among these, rubber is preferable. By using rubber, a sufficient protective function of the CNT fiber can be exhibited even against a large strain.

  Examples of the synthetic resin include phenol resin (PF), epoxy resin (EP), melamine resin (MF), urea resin (urea resin, UF), unsaturated polyester (UP), alkyd resin, polyurethane (PUR), heat Curable polyimide (PI), polyethylene (PE), high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate (PVAc), acrylonitrile butadiene styrene resin (ABS), acrylonitrile styrene resin (AS), polymethyl methacrylate (PMMA), polyamide (PA), polyacetal (POM), polycarbonate (PC), modified Polyphe Ether (m-PPE), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and cyclic polyolefin (COP) and the like.

  Examples of the rubber include natural rubber (NR), butyl rubber (IIR), isoprene rubber (IR), ethylene / propylene rubber (EPDM), butadiene rubber (BR), urethane rubber (U), and styrene / butadiene rubber (SBR). , Silicone rubber (Q), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), acrylonitrile butadiene rubber (NBR), chlorinated polyethylene (CM), acrylic rubber (ACM), epichlorohydrin rubber (CO, ECO), Examples thereof include fluororubber (FKM) and polydimethylsiloxane (PDMS).

  The material mainly composed of the insulating elastomer may be coated on at least the surface layer of the plurality of CNT fibers by applying an aqueous emulsion. The aqueous emulsion refers to an emulsion in which the main component of the dispersion medium is water. Since CNT has high hydrophobicity, when the insulating elastomer is coated by application using an aqueous emulsion, the insulating elastomer does not completely enter between the plurality of CNT fibers. That is, the insulating elastomer is partially impregnated between the plurality of CNT fibers, but this insulating elastomer does not adhere to the entire region in the radial cross section of each CNT fiber. As a result, it is suppressed that the insulating elastomer completely penetrates between the plurality of CNT fibers and affects the resistance change of the CNT film 2, and the sensitivity to the distortion of the CNT film 2 due to the presence of the insulating elastomer is reduced. Can be suppressed.

  The main component of the dispersion medium of the aqueous emulsion is water, but other hydrophilic dispersion medium such as alcohol may be contained.

  Preferred emulsions include so-called latexes in which the dispersion medium is water and rubber is a dispersoid, and natural rubber latex is preferred. By using natural rubber latex, a thin and strong film can be formed.

  Moreover, the material which has the said insulating elastomer as a main component is good to contain the coupling agent. When the material containing the insulating elastomer as a main component contains a coupling agent, the insulating elastomer and the CNT fiber can be cross-linked and the bonding strength between the insulating elastomer and the CNT fiber can be improved.

  As said coupling agent, amino coupling agents, such as an aminosilane coupling agent, an amino titanium coupling agent, and an amino aluminum coupling agent, a silane coupling agent, etc. can be used, for example.

  Moreover, it is preferable that the material which has an insulating elastomer as a main component contains the dispersing agent which has the adsorptivity with respect to CNT fiber. Examples of such a dispersing agent having an adsorptive property include an adsorbing group having a salt structure (for example, an alkylammonium salt) and a hydrophobic group (for example, an alkyl chain or an aromatic ring) of a CNT fiber. The thing etc. which have the hydrophilic group (for example, polyether etc.) which can interact in a molecule | numerator etc. can be used.

  The lower limit of the resistance value of the CNT film 2 under no load (value measured between the pair of electrodes 3) is preferably 10Ω, and more preferably 100Ω. On the other hand, the upper limit of the resistance value of the CNT film 2 under no load is preferably 100 kΩ, and more preferably 10 kΩ. If the resistance value of the CNT film 2 at the no-load range is less than the lower limit, the current for detecting elongation increases and the power consumption of the strain sensor 1 may increase. Conversely, when the resistance value of the CNT film 2 under no load exceeds the upper limit, the voltage of the detection circuit increases, and it becomes difficult to reduce the size and power consumption of the device that processes the output of the strain sensor 1. There is a fear.

  The average length in the longitudinal direction of the CNT film 2 is not particularly limited, and can be freely selected according to the measurement target using the strain sensor 1, and can be, for example, 1 cm or more and 20 cm or less.

  The average length in the longitudinal direction (the average length of As in FIG. 1) in the region sandwiched between the pair of electrodes 3 in plan view of the CNT film 2 is freely selected according to the measurement object using the strain sensor 1. be able to. As said average length, it is 2 mm or more and 18 cm or less, for example.

  The average length in the longitudinal direction (the average length of An in FIG. 1) in the region overlapping with the pair of electrodes 3 in plan view of the CNT film 2 depends on the method of fixing to the measurement object, the method of wiring to the electrodes 3, etc. For example, it can be 3 mm or more and 5 cm or less.

  The average width of the CNT film 2 can be freely selected according to the measurement object using the strain sensor 1. The lower limit of the average width of the CNT film 2 is preferably 1 mm, and more preferably 1 cm. On the other hand, the upper limit of the average width of the CNT film 2 is preferably 10 cm, and more preferably 5 cm. If the average width of the CNT film 2 is less than the lower limit, the resistance value of the CNT film 2 may become excessively large or may vary. On the contrary, when the average width of the CNT film 2 exceeds the upper limit, the strain sensor 1 becomes large, and the applicable measurement target may be excessively limited.

  The lower limit of the average thickness of the CNT film 2 is preferably 1 μm and more preferably 10 μm. On the other hand, the upper limit of the average thickness of the CNT film 2 is preferably 5 mm, and more preferably 1 mm. If the average thickness of the CNT film 2 is less than the lower limit, it may be difficult to form the CNT film 2 or the resistance may increase excessively. Conversely, when the average thickness of the CNT film 2 exceeds the upper limit, the sensitivity to strain may be reduced.

(Protective layer)
The protective layers 5a and 5b are directly laminated on both surfaces of the CNT film 2. The protective layers 5 a and 5 b cover both surfaces of the CNT film 2 and protect the CNT film 2.

  The laminated structure of the protective layers 5a, 5b and the CNT film 2 may be formed by applying a material for forming another layer (or film) to any one of the layers (or films). The film may be formed by fusing or welding, or may be formed by bonding each layer (or film) using an elastic adhesive.

  The material of the protective layers 5a and 5b is not particularly limited as long as it has flexibility, and examples thereof include synthetic resins, rubbers, nonwoven fabrics, deformable shapes or materials of metals and metal compounds, and the like. The front and back protective layers 5a and 5b may be formed of different materials.

  Examples of the synthetic resin include phenol resin (PF), epoxy resin (EP), melamine resin (MF), urea resin (urea resin, UF), unsaturated polyester (UP), alkyd resin, polyurethane (PUR), heat Curable polyimide (PI), polyethylene (PE), high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate (PVAc), acrylonitrile butadiene styrene resin (ABS), acrylonitrile styrene resin (AS), polymethyl methacrylate (PMMA), polyamide (PA), polyacetal (POM), polycarbonate (PC), modified Polyphe Ether (m-PPE), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and cyclic polyolefin (COP) and the like.

  Examples of the rubber include natural rubber (NR), butyl rubber (IIR), isoprene rubber (IR), ethylene / propylene rubber (EPDM), butadiene rubber (BR), urethane rubber (U), and styrene / butadiene rubber (SBR). , Silicone rubber (Q), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), acrylonitrile butadiene rubber (NBR), chlorinated polyethylene (CM), acrylic rubber (ACM), epichlorohydrin rubber (CO, ECO), Examples thereof include fluororubber (FKM) and polydimethylsiloxane (PDMS). Among these, natural rubber is preferable from the viewpoint of strength and the like.

  As a minimum of average thickness of protective layers 5a and 5b, 10 micrometers is preferred and 15 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the protective layers 5a and 5b is preferably 5 mm, and more preferably 2 m. If the average thickness of the protective layers 5a and 5b is less than the lower limit, the CNT film 2 may not be sufficiently protected. On the other hand, if the average thickness of the protective layers 5a and 5b exceeds the upper limit, the strain sensor 1 may be unnecessarily thick, or the elastic modulus of the CNT film 2 may increase and hinder the deformation of the measurement target. . In addition, the average thickness of the protective layers 5a and 5b on the front and back sides may be different from each other.

(electrode)
The electrode 3 includes a flat base portion 3a and a protruding portion 3b having a protrusion protruding from the surface of the base portion 3a on the CNT film 2 side. Both the base 3a and the protrusion 3b have conductivity. The protrusion part 3b raises the contact area of the electrode 3 and CNT fiber by contact | abutting with CNT fiber. The electrode 3 is pressed against one surface of the protective layer 5a with the protruding portion 3b facing the CNT film 2, so that the protruding portion 3b breaks through the protective layer 5a. Invade inside. In addition, the protrusion 3b penetrates a coating mainly composed of an insulating elastomer of a plurality of CNT fibers. That is, the protrusion 3b has the effect of breaking through the protective layer 5a, the effect of penetrating a coating mainly composed of an insulating elastomer that covers a plurality of CNT fibers, and the effect of contacting the CNT film 2 over a wide area. As a result, the strain sensor 1 can accurately bring the protrusions 3b into contact with the plurality of CNT fibers, and can easily and reliably increase the adhesive strength between the electrode 3 and the CNT film 2. The electrode 3 itself constitutes the present invention.

  The electrode 3 is used as a terminal for electrically taking out a detection signal of the strain sensor 1. Further, the electrode 3 does not substantially expand and contract during use of the strain sensor 1. Note that “substantially does not expand and contract” means expansion and contraction of a region (hereinafter also referred to as “expandable region As”) disposed between the pair of electrodes 3 in plan view during measurement using the strain sensor 1. It means that the ratio of the expansion / contraction ratio of the electrode 3 to the ratio is 1/100 or less, preferably 1/1000 or less.

  Further, the number of digits of the ratio of the expansion / contraction ratio of the expansion / contraction region As to the expansion / contraction ratio of the electrode 3 during measurement using the strain sensor 1 is preferably larger than the number of effective numerical values in the measurement, and larger by two or more digits. Is more preferable.

  The base portion 3a is not particularly limited as long as it has sufficient non-stretchability (tensile strength) and conductivity. For example, a metal foil, a conductive woven fabric, or the like is used. The base portion 3a may be a laminate having at least a conductive layer disposed on the outer surface and a reinforcing material layer that imparts non-stretchability. Examples of the material of the metal foil include copper, aluminum, nickel, and stainless steel. In addition, as the conductive woven fabric, one containing conductive metal or carbon fibers can be used. Furthermore, you may coat | cover the surface of the base | substrate part 3a with the material which does not corrode easily, such as gold | metal | money. Moreover, you may comprise the base | substrate part 3a by coat | covering the surface of ceramics with gold | metal | money etc.

  As a minimum of average thickness of base part 3a, 10 micrometers is preferred and 50 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the base portion 3a is preferably 1 mm, and more preferably 0.5 mm. If the average thickness of the base part 3a is less than the lower limit, the base part 3a may be broken by bending or the like. Conversely, if the average thickness of the base portion 3a exceeds the upper limit, the strain sensor 1 may be unnecessarily thick, or the non-stretchable region An may be insufficiently flexible and cannot be properly attached to the measurement target. There is.

  A plurality of protruding portions 3b are formed on the surface of the base portion 3a on the CNT film 2 side. The longitudinal directions of the plurality of protrusions 3b are parallel. Moreover, as shown in FIG. 3, the plurality of protrusions 3b have a longitudinal direction substantially parallel to the orientation direction of the CNT fibers. That is, the plurality of protrusions 3 b have a longitudinal direction substantially parallel to the expansion / contraction direction of the strain sensor 1. As described above, the longitudinal direction of the plurality of protrusions 3b is substantially parallel to the orientation direction of the CNT fibers, so that the plurality of protrusions 3b are infiltrated into the CNT film 2 composed of the plurality of CNT fibers. The surface extending in the longitudinal direction of the protrusion 3b is likely to come into contact with the outer peripheral surface of the CNT fiber. Therefore, the contact area between the CNT fiber and the protrusion 3b can be remarkably increased.

  The electrode 3 does not necessarily have a plurality of the protrusions 3b, and the number of the protrusions 3b may be one. The lower limit of the number of the protrusions 3b is one, and more preferably two. On the other hand, the upper limit of the number of the protrusions 3b is preferably 8, and more preferably 6. When the number of the protrusions 3b is within the above range, the contact area between the protrusions 3b and the CNT fibers can be increased. Moreover, it can suppress that a CNT fiber is cut | disconnected by this projection part 3b, and can suppress that the intensity | strength of the CNT film | membrane 2 falls.

The material of the plurality of protrusions 3b is not particularly limited as long as it has conductivity and has certain heat resistance and hardness, and includes, for example, metals such as copper, aluminum, nickel, stainless steel, and these metals. An alloy is mentioned. The method for producing the plurality of protrusions 3b is not particularly limited, and examples thereof include production by integral molding with the base 3a by press molding, nanoimprinting, etching, sandblasting, and the like. In addition, the electrode 3 may be manufactured by separately manufacturing the base portion 3a and the plurality of protrusions 3b and attaching the plurality of protrusions 3b to the surface of the base portion 3a with an adhesive or the like.
Furthermore, the surfaces of the plurality of protrusions 3a may be covered with a material that is not easily corroded, such as gold. Moreover, you may comprise the projection part 3b by coat | covering the surface of ceramics with gold | metal | money etc.

  As shown in FIGS. 4 and 5, each protrusion 3b has a substantially rectangular parallelepiped shape in which the ridge line direction is the longitudinal direction, the direction perpendicular to the ridge line direction in plan view is the width direction, and the protruding direction is the height direction. Is formed. Moreover, as shown in FIG. 6, each protrusion part 3b has the front-end | tip part gradually contracted toward the front-end | tip. In this manner, the tip portion of each protrusion 3b is gradually reduced in width toward the tip, so that the electrode 3 is easily brought into contact with the CNT fiber by pressing. Specifically, when the tip of each projection 3b is gradually reduced toward the tip, each projection 3b is protected when the electrode 3 is pressed against one surface of the CNT film 2. It is easy to enter the gap between the CNT fibers constituting the CNT film 2 through the layer 5a. Further, at this time, each protrusion 3 b has a certain height or more, so that the tip of the protrusion 3 b can reach the other surface side of the CNT film 2. Thereby, the contact area of the surface extended in the longitudinal direction of each projection part 3b and the outer peripheral surface of CNT fiber is fully raised. Furthermore, since the longitudinal direction of each protrusion 3b and the orientation direction of the CNT fiber are substantially parallel, even if the longitudinal direction of each protrusion 3b and the orientation direction of the CNT fiber are slightly deviated due to the expansion and contraction of the strain sensor 1, It is difficult for the fibers to be stressed and the contact area is easily maintained.

  The lower limit of the average length in the longitudinal direction of the protrusion 3b is preferably 0.2 mm, and more preferably 2 mm. On the other hand, the upper limit of the average length in the longitudinal direction of the protrusion 3b is preferably 1 cm, and more preferably 5 mm. If the average length in the longitudinal direction of the protrusion 3b is less than the lower limit, the contact area with the CNT fiber may not be sufficiently increased. Conversely, if the average length in the longitudinal direction of the protrusion 3b exceeds the upper limit, the protective layer 5a, the protective layer 5b, and the CNT film 2 may be broken in the longitudinal direction (the orientation direction of the CNT fibers).

  As a minimum of average length of the width direction of projection part 3b, 0.05 mm is preferred and 0.5 mm is more preferred. On the other hand, the upper limit of the average length in the width direction of the protrusion 3b is preferably 2 mm, and more preferably 1 mm. If the average length in the width direction of the protrusion 3b is less than the lower limit, the strength of the protrusion 3b is not sufficiently high, and it may be difficult to insert the protrusion 3b into the CNT film 2 side.

  As a minimum of average height of projection part 3b, 10 micrometers is preferred, 15 micrometers is more preferred, and 18 micrometers is still more preferred. On the other hand, the upper limit of the average height of the protrusions 3b is preferably 1 cm, more preferably 5 mm, and even more preferably 2 mm. If the average height of the protrusion 3b is less than the lower limit, the protrusion 3b may not be able to contact the CNT fiber accurately. Conversely, if the average height of the protrusion 3b exceeds the upper limit, the protrusion 3b becomes unnecessarily high and may protrude from the back side of the strain sensor 1.

  In addition, the protrusion 3b penetrates the CNT film 2 in the front and back direction, so that the adhesive strength between the electrode 3 and the CNT film 2 can be easily and reliably increased, and the non-stretchable region An extends irregularly. Can be accurately suppressed. Therefore, the protrusion 3b preferably has a height that can penetrate the CNT film 2 in the front-back direction. Accordingly, the lower limit of the average height of the protrusions 23b in consideration of this point can be set to 20 μm, for example. Further, in order to more accurately prevent the non-stretchable region An from extending irregularly, the protrusion 3b is penetrated to the inside of the sandwich sheet 4 facing the base portion 3a on which the protrusion 3b is disposed. May be. In consideration of this point, the lower limit of the average height of the protrusions 23b can be set to 30 μm, for example.

  The lower limit of the inclination angle of the tip of the protrusion 3b with respect to the protruding direction of the protrusion 3b is preferably 10 °, more preferably 20 °. On the other hand, the upper limit of the inclination angle is preferably 60 °, and more preferably 45 °. If the tilt angle is less than the lower limit, the strength on the tip side of the tip portion may be reduced. On the other hand, if the tilt angle exceeds the upper limit, it may be difficult to insert the protrusion 3b into the CNT film 2 side.

  The electrode 3 can be laminated using, for example, an adhesive. As this adhesive, for example, a pressure-sensitive adhesive, a curable adhesive, a thermoplastic adhesive, or the like can be used. As said adhesive, an acrylic adhesive etc. are mentioned, for example. Examples of the curable adhesive include an epoxy adhesive. As the adhesive, a conductive adhesive containing a conductive filler in a synthetic resin can also be used.

  When the electrode 3 is laminated on one surface side of the CNT film 2, the adhesive is attached only to the other surface side of the base portion 3b in order to make the plurality of protrusions 3b contact the CNT fiber accurately. Is preferred. That is, it is preferable that the adhesive is not attached to the plurality of protrusions 3b. Therefore, for example, an adhesive accommodating recess for arranging an adhesive may be provided on the other surface side of the base portion 3a. According to such a configuration, it is possible to easily prevent the adhesive from adhering to the plurality of protrusions 3b.

(Nipping sheet)
The sandwich sheet 4 is laminated on the other surface of the protective layer 5b so as to cover the other surface of the non-stretchable region An. The sandwiching sheet 4 can be laminated using, for example, an adhesive. As this adhesive, the same adhesive used for laminating the electrodes 3 can be used.

  Like the electrode 3, the sandwich sheet 4 does not substantially expand and contract during use of the strain sensor 1, and prevents the non-expandable region An from expanding and contracting. That is, the sandwich sheet 4 sandwiches the non-stretchable region An of the CNT film 2 and the pair of protective layers 5a and 5b between the electrode 3 and thereby more reliably prevents the stretch of the non-stretchable region An. For this reason, by providing the sandwich sheet 4, the strain sensor 1 more clearly separates the non-stretchable region An and the stretchable region As of the CNT film 2 and the pair of protective layers 5a and 5b. Therefore, the strain sensor 1 has a high correlation between the amount of expansion and contraction and the electrical resistance value of the CNT film 2, and is excellent in strain detection accuracy.

  The material of the sandwiching sheet 4 may be any material that has sufficient non-stretchability, and may be conductive or insulating. Specifically, as the sandwich sheet 4, for example, a resin sheet mainly composed of polyimide, polyethylene terephthalate, or the like, a woven cloth such as a glass cloth, or the like can be used, and the same one as the electrode 3 is used. You can also. Moreover, you may use the commercially available adhesive tape by which the adhesive was previously laminated | stacked as the clamping sheet 4. FIG.

  As a minimum of average thickness of pinching sheet 4, 20 micrometers is preferred and 50 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the sandwich sheet 4 is preferably 1 mm, and more preferably 0.5 mm. If the average thickness of the sandwiching sheet 4 is less than the lower limit, the sandwiching sheet 4 may be broken by bending or the like. Conversely, if the average thickness of the sandwich sheet 4 exceeds the upper limit, the strain sensor 1 may be unnecessarily thick, or the flexibility of the non-stretchable region An may be insufficient and cannot be appropriately attached to the measurement target. There is.

  The opposing electrode 3 and the sandwiching sheet 4 may be sandwiched by fastening members (not shown) such as bolts, rivets, and clamps. This fastening member may penetrate through the electrode 3, the protective layers 5 a and 5 b, the CNT film 2, and the sandwich sheet 4. The fastening member may also be used as a member for fixing the strain sensor 1 to the measurement target.

<Manufacturing method>
The strain sensor 1 includes, for example, a step of forming a sheet body having a CNT film 2 and a pair of protective layers 5a and 5b, a step of cutting the sheet body into a desired planar shape, and one of the protective layers 5a. It can be manufactured by a method comprising a step of laminating a pair of electrodes 3 on the surface and a step of laminating a pair of sandwich sheets 4 on the other surface of the protective layer 5b.

<Advantages>
In the strain sensor 1, a pair of electrodes 3 disposed on one surface side of both ends of the CNT film 2 protrude toward the CNT film 2, and have protruding protrusions 3 b having conductivity. Therefore, the strain sensor 1 can easily and reliably increase the contact area between the pair of electrodes 3 and the plurality of CNT fibers by bringing the convex protrusions 3b into contact with the CNT fibers. That is, since the protruding portion 3b of the ridge has a ridgeline, the surface including the ridgeline can be easily brought into contact with the CNT fiber constituting the CNT film 2, and the contact area between the protruding portion 3b and the CNT film 2 can be easily and reliably obtained. Can be increased. In addition, when the surface including the ridge line is brought into contact with the CNT fiber in this way, the contact area between the protrusion 3b and the CNT fiber hardly changes due to the expansion and contraction of the CNT film 2. Accordingly, the strain sensor 1 can sufficiently detect the expansion / contraction strain of the CNT film 2 by sufficiently increasing the conductivity between the CNT film 2 and the electrode 3.

  Since the electrode 3 includes the flat base portion 3a and the protruding protrusions 3b protruding from the side surfaces of the CNT film 2 of the base portion 3a, the contact area with the CNT film 2 is easy as described above. And it can surely be enlarged. Accordingly, the electrode 3 can sufficiently detect the stretching distortion of the CNT film 2 by sufficiently increasing the conductivity with the CNT film 2.

[Second Embodiment]
<Strain sensor>
The strain sensor 11 of FIG. 7 includes a CNT film 12 including a plurality of CNT fibers oriented in one direction, a pair of electrodes 13 disposed on both ends and one surface side of the CNT film 12, and the CNT film. 12 is provided with a pair of sandwiching sheets 4 disposed opposite to the pair of electrodes 13 on both ends and the other surface side. 7 includes a protective layer 5a disposed on one surface side of the CNT film 12 and the other surface side of the pair of electrodes 13, and the other surface side of the CNT film 12 and a pair of sandwiches. And a protective layer 5 b disposed on one surface side of the sheet 4. The pair of sandwiching sheets 4 and the protective layers 5a and 5b of the strain sensor 11 of FIG. 7 are the same as the pair of sandwiching sheets 4 and the protective layers 5a and 5b of the strain sensor 1 of FIGS. Therefore, the description is omitted.

(CNT film)
In the CNT film 12, as shown in FIG. 8, the orientation direction of the plurality of CNT fibers is the width direction of the CNT film 12. Except for the orientation direction of the CNT fibers, the strain sensor 1 of FIGS. It can be the same as the CNT film 12.

(electrode)
The electrode 13 includes a flat base portion 13a and a protruding portion 13b that protrudes from the surface of the base portion 13a on the CNT film 12 side. The electrode 13 is configured in the same manner as the electrode 3 of FIGS. 1 and 2 except that the longitudinal direction of the plurality of protrusions 13 b is parallel to the width direction of the CNT film 2.

<Advantages>
Similar to the strain sensor 1 in FIGS. 1 and 2, the strain sensor 11 allows the protruding protrusion 13 b to enter the CNT film 12 made of CNT fibers, and the protrusion 13 b contacts the CNT fibers. By making contact, the contact area between the pair of electrodes 13 and the plurality of CNT fibers can be easily and reliably increased. Therefore, the strain sensor 11 can sufficiently detect the expansion / contraction strain of the CNT film 12 by sufficiently increasing the conductivity between the CNT film 12 and the pair of electrodes 13.

[Third embodiment]
The strain sensor 21 of FIGS. 9 and 10 includes a CNT film 2 including a plurality of CNT fibers oriented in one direction, a pair of electrodes 23 disposed on both ends and one surface side of the CNT film 2, A pair of sandwiching sheets 4 disposed opposite to the pair of electrodes 23 are provided on both ends of the CNT film 2 and on the other surface side. 9 and 10 includes a protective layer 5a disposed on one surface side of the CNT film 2 and the other surface side of the pair of electrodes 23, the other surface side of the CNT film 2, and And a protective layer 5b disposed on one surface side of the pair of sandwiching sheets 4. The CNT film 2, the pair of sandwich sheets 4 and the protective layers 5a and 5b of the strain sensor 21 of FIGS. 9 and 10 are the CNT film 2, the pair of sandwich sheets 4 and the protective layer 5a of the strain sensor 1 of FIGS. , 5b, the same reference numerals are given and description thereof is omitted.

(electrode)
The electrode 23 includes a flat base portion 23a and a protruding portion 23b that protrudes from the surface of the base portion 23a on the CNT film 2 side. Both the base portion 23a and the protruding portion 23b have conductivity. The base portion 23a can have the same configuration as the base portion 3a of the electrode 3 shown in FIGS. As shown in FIG. 11, the protrusion 23b is formed by piercing staples from the outer surface (one surface) of the base portion 23a. Specifically, a pair of opposing leg portions of the staple are each configured as a protrusion 23b. The staple is not particularly limited as long as it can form ridges, and a commercially available staple, for example, can be used. Further, it is preferable that the staple penetrates the sandwiching sheet 4 and the leading end protrudes from the other surface of the sandwiching sheet 4. Furthermore, it is preferable that the leading end of the staple protruding from the other surface of the sandwiching sheet 4 is bent and fixed so as to contact the other surface of the sandwiching sheet 4. Moreover, the facing direction is preferable as the bending direction. When the leading end of the staple is protruded from the other surface of the sandwiching sheet 4 as described above, the average height of the protrusion 23b can be set to 2 mm or more and 8 mm or less, for example.

  The material of the projecting portion 23b is not particularly limited as long as it has conductivity and has a certain heat resistance and hardness. For example, the same material as the projecting portion 3b of the electrode 3 in FIGS. . Each protrusion 23b is formed in a substantially rectangular parallelepiped shape with the ridgeline direction as the longitudinal direction, the direction perpendicular to the ridgeline direction in plan view as the width direction, and the protruding direction as the height direction. Moreover, each protrusion 23b is gradually reduced in width toward the tip. Further, the protrusion 23b has a longitudinal direction substantially parallel to the orientation direction of the CNT fibers.

  The average length in the longitudinal direction, the average length in the width direction, the average height, and the inclination angle of the tip of the protrusion 23b can be the same as those of the protrusion 3b of the electrode 3 in FIGS.

<Advantages>
The distortion sensor 21 is formed by the protruding portion 23b being pierced with staples from the outer surface of the base portion 23a. Therefore, the protruding portion 23b can be easily formed. Furthermore, according to this configuration, the adhesive strength between the electrode 23 and the CNT film 2 can be increased.

[Fourth embodiment]
12 and 13 includes a CNT film 32 including a plurality of CNT fibers oriented in one direction, and a pair of electrodes 33 disposed on both ends and one surface side of the CNT film 32. Prepare. 12 and 13 includes a protective layer 34 disposed on the other surface side of the CNT film 32.

(CNT film)
The CNT film 32 includes a plurality of thread-like strain sensor elements 32a having a core material including a plurality of CNT fibers oriented in the longitudinal direction and a protective film covering the outer peripheral surface of the core material. The plurality of strain sensor elements 32a are arranged substantially parallel to each other in a planar shape. These strain sensor elements 32 a are laminated in a single layer on one surface of the protective layer 34. The core material is configured as a fiber bundle in which a plurality of fibers including CNT fibers and insulating fibers are oriented in one direction.

  The protective film is made of a material whose main component is an insulating elastomer. That is, the outer periphery of a plurality of CNT fibers is coated with a material mainly composed of an insulating elastomer. The CNT film 32 is elastic by the elastic force of the insulating elastomer and is configured to be stretchable at least in the longitudinal direction. The protective film covers the outer periphery with a material mainly composed of an insulating elastomer to prevent CNT fibers from being damaged and foreign matters from being mixed into the core material. As this insulating elastomer, for example, an insulating elastomer similar to that covering the CNT fiber of the strain sensor 1 of FIGS.

(electrode)
The electrode 33 includes a flat base portion 33a and one protruding portion 33b protruding from the surface of the base portion 33a on the CNT film 32 side. Both the base portion 33a and the protruding portion 33b have conductivity. The base portion 33a can have the same configuration as the base portion 3a of the electrode 3 in FIGS.

  The material of the protrusion 33b is not particularly limited as long as it has conductivity and has a certain heat resistance and hardness. For example, the same material as the protrusion 3b of the electrode 3 in FIGS. . The protrusion 33b is formed in a substantially rectangular parallelepiped shape with the ridgeline direction as the longitudinal direction, the direction perpendicular to the ridgeline direction in plan view as the width direction, and the protruding direction as the height direction. Further, the protrusion 33b is gradually reduced in width toward the tip. Furthermore, as for the projection part 33b, the longitudinal direction cross | intersects the orientation direction of CNT fiber. Specifically, the longitudinal direction of the protrusion 33b is substantially orthogonal to the orientation direction of the CNT fibers.

  The protrusion 33b is in contact with the plurality of thread-like strain sensor elements 32a, and preferably in contact with all the thread-like strain sensor elements 32a. The protrusion 33b is in contact with one surface side of these thread-like strain sensor elements 32a. The protrusion 33b is in contact with the plurality of CNT fibers by penetrating the protective film covered by the surface layer of the core material constituting the plurality of thread-like strain sensor elements 32a. Is conducting.

  The lower limit of the average length in the longitudinal direction of the protrusion 33b is preferably 1 mm, and more preferably 1 cm. On the other hand, the upper limit of the average length in the longitudinal direction of the protrusion 33b is preferably 10 cm, and more preferably 5 cm. If the length of the protrusion 33b in the longitudinal direction is less than the lower limit, it may be difficult to make contact with the plurality of thread-like strain sensor elements 32a. Conversely, if the average length in the longitudinal direction of the protrusion 33b exceeds the upper limit, the protrusion 33b may protrude outward from both ends of the CNT film 32 in the width direction. Note that it is preferable that both ends in the longitudinal direction of the protrusion 33 b reach both ends in the width direction of the CNT film 32. When both ends in the longitudinal direction of the protrusion 33b reach both ends in the width direction of the CNT film 32, the contact area with the plurality of strain sensor elements 32a is obtained by bringing one protrusion 33b into contact with the plurality of strain sensor elements 32a. Can be easily and reliably increased. Further, according to such a configuration, when a plurality of strain sensor elements 32a are laminated in a single layer on one surface of the protective layer 34 as in the present embodiment, all the strain sensors are formed by one protrusion 33b. The contact area with the element 32a can be increased.

  As a minimum of average height of projection part 33b, 10 micrometers is preferred and 15 micrometers is still more preferred. On the other hand, the upper limit of the average height of the protrusion 33b is preferably 4 mm, and more preferably 2 mm. If the average height of the protrusion 33b is less than the lower limit, the protrusion 33b may not be able to contact the CNT fiber accurately. Conversely, if the average height of the protrusions 33b exceeds the upper limit, the longitudinal direction of the protrusions 33b intersects the orientation direction of the CNT fibers, which may cause the CNT fibers to be cut.

  The average length in the width direction of the protrusion 33b and the inclination angle of the tip can be the same as those of the protrusion 3b of the electrode 3 in FIGS.

(Protective layer)
The protective layer 34 is directly laminated on the other surface of the CNT film 32. The protective layer 34 covers the other surface of the CNT film 32 and protects the CNT film 32. As the protective layer 34, it can be set as the structure similar to the protective layer 5b of the distortion sensor 1 of FIG.1 and FIG.2, for example. Further, as the protective layer 32, it is also possible to use a fabric that can expand and contract in the longitudinal direction of the CNT film 32.

<Advantages>
Similar to the strain sensor 1 in FIGS. 1 and 2, the strain sensor 31 makes the contact area between the pair of electrodes 33 and the plurality of CNT fibers easy by bringing the convex protrusions 33 b into contact with the CNT fibers. And it can surely be enlarged. Therefore, the strain sensor 31 can sufficiently enhance the electrical continuity between the CNT film 32 and the pair of electrodes 33 and can detect the expansion / contraction strain of the CNT film 32 with high accuracy.

  Furthermore, since the longitudinal direction of the protrusion 33b is substantially orthogonal to the orientation direction of the CNT fibers, the strain sensor 31 is brought into contact with the plurality of CNT fibers by bringing one protrusion 33b into contact with the plurality of CNT fibers. The area can be easily and reliably increased.

[Other Embodiments]
In addition, the strain sensor and electrode which concern on this invention can be implemented in the aspect which gave the various change and modification other than the said aspect. For example, the strain sensor is not necessarily required to have a protective layer laminated on both surfaces of the CNT film and a pair of sandwich sheets disposed to face the pair of electrodes. Further, in the strain sensor, the protrusion does not necessarily have to penetrate the coating of the CNT fiber whose main component is an insulating elastomer. For example, even when the surface layer of a plurality of CNT fibers is coated with a material mainly composed of an insulating elastomer, the strain sensor has an insulating property in a region where the CNT film and the electrode face each other in a plan view. The electrode and a plurality of CNT fibers may be laminated after removing the coating containing the elastomer as a main component.

  The strain sensor and the electrode can be configured by appropriately combining the configurations of the respective embodiments. For example, in the case of the fourth embodiment in which the CNT film is a filament having a core material including a plurality of CNT fibers oriented in the longitudinal direction and a protective film covering the outer peripheral surface of the core material, The longitudinal direction of the protrusions and the orientation direction of the CNT fibers may be substantially parallel. Further, when the CNT film does not have such a filamentous body, the longitudinal direction of the protruding portion of the electrode and the orientation direction of the CNT fiber may be substantially orthogonal. Further, the strain sensor has, for example, the longitudinal direction of the protruding portion of one electrode and the orientation direction of the CNT fiber substantially parallel, and the longitudinal direction of the protruding portion of the other electrode is substantially orthogonal to the orientation direction of the CNT fiber. Also good. In addition, in the strain sensor, when each electrode has two or more protrusions, the longitudinal directions of these protrusions do not need to be parallel. Even when the longitudinal direction of the protrusion and the orientation direction of the CNT fiber are substantially parallel, the tip of the protrusion does not need to reach the other surface side of the CNT film, for example, it is positioned on the surface layer side of the CNT film. May be.

  The shape of the protrusion is not limited to the shape of the above embodiment. For example, the protrusion may not have a tip portion that gradually decreases toward the tip. Moreover, even when it has a front-end | tip part, this front-end | tip part may be connected with the front-end | tip of the base end part which has substantially the same width, for example, and a projection part may be comprised only from a front-end | tip part. Furthermore, the tip of the tip may be a V-shaped protrusion or a trapezoid. When the tip of the tip is trapezoidal, the average width of the tip can be, for example, 1 μm or more and 2 mm or less.

  The protrusion may be formed, for example, by piercing a flat conductive thread through the CNT film from the outer surface of the base body. Furthermore, as the electrode, for example, a shape as shown in FIGS. 14 and 15 can be adopted. Hereinafter, the electrodes of FIGS. 14 and 15 will be described.

  The electrode 41 of FIG. 14 has a flat base portion 41a and a plurality of protruding portions 41b protruding from the surface of the base portion 41a on the CNT film side. In the electrode 41, one side surface of the protruding portion 41b is curved to the other side surface side. Thereby, the contact area of this projection part 41b and CNT fiber can be enlarged further by contact | abutting so that this curved surface may be along the outer peripheral surface of CNT fiber. Moreover, according to this structure, it is easy to hold | maintain the contact state of the projection part 41b and CNT fiber stably.

  The electrode 51 in FIG. 15 includes a flat base portion 51a and a plurality of protruding protrusion portions 51b protruding from the surface of the base portion 51a on the CNT film side. The electrode 51 has a plurality of protrusions 51b arranged in a stripe pattern on the surface of the base 51a. Thereby, the protrusion part 51b can be arrange | positioned densely and the contact area of the electrode 51 and CNT fiber can be enlarged.

  The pair of electrodes do not necessarily need to be disposed on one surface side of the CNT film. For example, one electrode of the pair of electrodes may be disposed on one surface side of the CNT film, and the other electrode may be disposed on the other surface side of the CNT film.

  As described above, since the strain sensor of the present invention can sufficiently detect the stretching strain of the CNT film by sufficiently increasing the conductivity between the CNT film and the electrode, it measures the stretching strain having a large stretching rate. Suitable as a sensor for Moreover, the electrode of the present invention is suitable as an electrode for a sensor for measuring elongation strain having a large expansion / contraction rate.

1, 11, 21, 31 Strain sensor 2, 12, 32 CNT film 32a Strain sensor element 3, 13, 23, 33, 41, 51 Electrodes 3a, 13a, 23a, 33a, 41a, 51a Base portions 3b, 13b, 23b , 33b, 41b, 51b Projection part 4 Nipping sheets 5a, 5b, 34 Protective layer As Stretchable region An Non-stretchable region

Claims (5)

A CNT film including a plurality of CNT fibers oriented in one direction and having elasticity;
A strain sensor comprising a pair of electrodes disposed at both ends of the CNT film,
The strain sensor characterized in that the electrode has a protruding portion of a protruding protrusion that protrudes toward the CNT film and has conductivity.   2. The strain sensor according to claim 1, wherein at least a surface layer of the plurality of CNT fibers is coated with a material having an insulating elastomer as a main component, and the protruding portion penetrates the coating having the insulating elastomer as a main component. .   The strain sensor according to claim 1 or 2, wherein a longitudinal direction of the protruding portion is substantially parallel to an orientation direction of the CNT fiber.   4. The strain sensor according to claim 1, wherein the protrusion is formed by piercing a staple from an outer surface of a flat base portion constituting the electrode. An electrode for a strain sensor that includes a plurality of CNT fibers oriented in one direction and uses an elastic CNT film,
A flat substrate portion;
An electrode comprising: a protruding portion protruding from a CNT film side surface of the base portion.

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