JP2018040689A - Anisotropic strain sensor sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic strain sensor sheet which can be comfortably used on clothes and can selectively detect expansions and contractions in a specific direction.SOLUTION: The anisotropic strain sensor sheet according to the present invention includes a plurality of first directional woven yarns and second directional woven yarns, the first directional yarns having a smaller tensile resistance than the second directional yarns have and the first directional yarns including CNT yarns having a resistance value which varies according to expansions and contractions in a longer direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an anisotropic strain sensor sheet.

  Various attempts have been made to detect the movement of the human body with a sensor and convert it into numerical data. In particular, research on techniques for detecting expansion and contraction of the body surface accompanying the movement of the human body with a strain sensor is in progress.

  As such a strain sensor, a sensor is proposed in which a resistor containing a conductive polymer and a binder resin is laminated on the surface of a substrate such as a cloth, and a change in resistance value due to expansion and contraction of the resistor is measured. (See JP 2014-228507 A). The strain sensor described in this publication is supposed to be incorporated into clothing or the like. However, since a resin resistor is laminated on the surface of the substrate, the initial tensile resistance of the portion having the resistor decreases. Inconveniently, the subject may feel uncomfortable, and the breathability of the portion having the resistor may be reduced, which may cause stuffiness.

  Further, the strain sensor described in the above publication cannot detect only expansion and contraction in a specific direction because the sheet-like resistor is isotropic.

JP 2014-228507 A

  In view of the above disadvantages, an object of the present invention is to provide an anisotropic strain sensor sheet that is less uncomfortable even when applied to clothing and the like and that can selectively detect expansion and contraction in a specific direction.

  The invention made in order to solve the above-mentioned problems comprises a plurality of first direction yarns and a plurality of second direction yarns woven, wherein the plurality of first direction yarns is smaller than the plurality of second direction yarns. The anisotropic strain sensor sheet includes CNT yarns (yarns formed from carbon nanotube fibers) that have a degree of resistance and the resistance values of the plurality of first direction yarns change by stretching in the longitudinal direction.

  The second direction yarn may be a non-twisted yarn.

  The second direction yarn may be a braided yarn.

  The first direction yarn other than the CNT yarn may be a twisted yarn.

  The CNT yarn may have a resin coating layer on the outermost surface.

  The “initial tensile resistance” is a value measured according to JIS-L1013 (2010). Moreover, the “braided thread” means a thread-like body having a configuration (Braided construction) in which a plurality of fibers are knitted without twisting.

  The anisotropic strain sensor sheet of the present invention has a texture almost the same as that of a general woven fabric because the woven yarn includes CNT yarn, and even if used as a fabric constituting at least a part of clothing, It is difficult to give a sense of incongruity. Further, the anisotropic strain sensor sheet can selectively detect only the expansion and contraction in the direction along the first direction yarn by the CNT yarn.

It is a typical top view showing a part of anisotropic strain sensor sheet of one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating the configuration of CNT yarns of the anisotropic strain sensor sheet in FIG. 1.

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

[First embodiment]
The anisotropic strain sensor sheet according to the first embodiment of the present invention shown in FIG. 1 includes a plurality of first direction yarns 1 and a plurality of second direction yarns 2 woven. That is, the anisotropic strain sensor sheet has a woven fabric in which one of the first direction yarn 1 and the plurality of second direction yarns 2 is a warp and the other of the first direction yarn 1 and the plurality of second direction yarns 2 is a weft. Formed from cloth.

  The weaving method of the first direction yarn 1 and the plurality of second direction yarns 2 is not particularly limited, and for example, a plain weave, a twill weave, a satin weave, or the like can be used.

[First direction thread]
The plurality of first direction yarns 1 include CNT yarns 1a whose resistance values change due to expansion and contraction in the longitudinal direction. That is, the one or more first direction yarns 1 are composed of the CNT yarns 1a. Further, the first direction yarn 1 can include a yarn (hereinafter sometimes referred to as a normal yarn) 1b other than the CNT yarn 1a.

  As described above, since the first direction yarn 1 includes the CNT yarn whose strength tends to be small, the first direction yarn 1 may be a weft yarn that is relatively difficult to be loaded when weaving, and the second direction yarn 1 may be a warp yarn. In many cases, it is considered preferable.

  As a minimum of the number ratio of CNT yarn 1a in a plurality of 1st direction yarns 1, 0.5% is preferred and 1% is more preferred. On the other hand, the upper limit of the ratio of the number of CNT yarns 1a in the plurality of first direction yarns 1 is not particularly limited, but is preferably 50% and more preferably 30%. When the ratio of the number of CNT yarns 1a in the plurality of first direction yarns 1 is less than the lower limit, the strain at a desired position is accurately detected when clothing or the like is formed using the anisotropic strain sensor sheet as a fabric. There is a risk that it will not be possible. Conversely, when the number ratio of the CNT yarns 1a in the plurality of first direction yarns 1 exceeds the upper limit, the strength in the direction along the first direction yarns 1 of the anisotropic strain sensor sheet may be insufficient. .

  The first direction yarn 1 (CNT yarn 1a and normal yarn 1b) has a smaller initial tensile resistance (apparent Young's modulus) than the plurality of second direction yarns 2. The lower limit of the ratio of the average initial tensile resistance of the first direction yarn 1 to the average initial tensile resistance of the second direction yarn 2 is preferably 0.01, and more preferably 0.05. On the other hand, the upper limit of the ratio of the average initial tensile resistance of the first direction yarn 1 to the average initial tensile resistance of the second direction yarn 2 (the overall average value of the first direction yarn 1) is preferably 0.7, 0.5 is more preferable. If the ratio of the first direction yarn 1 to the average initial tensile resistance of the second direction yarn 2 is less than the lower limit, it may not be easy to weave the first direction yarn 1 and the plurality of second direction yarns 2. is there. Conversely, when the ratio of the first direction yarn 1 to the average initial tensile resistance of the second direction yarn 2 exceeds the upper limit, the anisotropy of strain detection of the anisotropic strain sensor sheet may be insufficient. is there.

  The lower limit of the average initial tensile resistance of the first direction yarn 1 is preferably 10 MPa, and more preferably 50 MPa. On the other hand, the upper limit of the average initial tensile resistance of the first direction yarn 1 is preferably 2000 MPa, and more preferably 1000 MPa. When the average initial tensile resistance of the first direction yarn 1 is less than the lower limit, the strain detectable range of the anisotropic strain sensor sheet may be reduced. Conversely, when the average initial tensile resistance of the first directional yarn 1 exceeds the upper limit, the anisotropy of strain detection of the anisotropic strain sensor sheet may be insufficient.

<CNT yarn>
As shown in FIG. 2, the CNT yarn 1 a can have a thread-like conductive portion 12 mainly composed of a bundle of CNTs 11. The CNT yarn 1a preferably has a resin coating layer 13 on the outermost surface.

(Conductive part)
The conductive portion 12 is obtained by aligning a plurality of CNTs 11 in the length direction. The conductive portion 12 may be one obtained by twisting the CNT bundle in which the CNTs 11 are arranged in one direction as described above, or may be one obtained by twisting a plurality of CNT bundles.

  Such a conductive portion 12 is configured to have conductivity by forming a current path by contacting and electrically connecting a plurality of CNTs 11 with each other. The plurality of CNTs 11 constituting the conductive part 12 may be twisted together. The conductive portion 12 having such a configuration exhibits a certain amount of electrical resistance, particularly when the contact area between the CNTs 11 is limited. When the conductive portion 12 expands and contracts in the longitudinal direction, the contact condition between the CNTs 11 changes, and the resistance value of the conductive portion 12 changes.

  The lower limit of the average diameter of the conductive portion 12 is preferably 0.5 μm and more preferably 5 μm. On the other hand, the upper limit of the average diameter of the conductive portion 12 is preferably 1.0 mm, and more preferably 0.5 mm. When the average diameter of the electroconductive part 12 is less than the said minimum, there exists a possibility that continuous contact of CNT11 cannot be ensured but conduction | electrical_connection cannot be obtained. Conversely, if the average diameter of the conductive portion 12 exceeds the upper limit, it may not be easy to form the conductive portion 12, or the CNTs 11 at the center of the conductive portion 12 move irregularly and detection accuracy is insufficient. There is a risk of becoming.

  As the CNT 11 included in the conductive portion 12, either a single-wall single-wall nanotube (SWNT) or a multi-wall multi-wall nanotube (MWNT) can be used. Among these, MWNT is preferable from the viewpoint of conductivity and heat capacity, and MWNT having a diameter of 1.5 nm to 100 nm is more preferable.

  Such CNT11 can be manufactured by a well-known method, for example, can be manufactured by CVD method, arc method, laser ablation method, DIPS method, CoMoCAT method, etc. 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, a CNT crystal having a desired length can be obtained by growing an iron or nickel thin film serving as a catalyst on a substrate such as a quartz glass substrate or a silicon substrate with an oxide film, and growing vertically. .

  The conductive part 12 may include an insulating fiber in order to adjust the electrical resistivity. That is, by mixing the insulating fibers with the CNTs 11 forming the conductive portion 12, the contact between the CNTs 11 can be suppressed and the electrical resistivity can be increased.

  The blending ratio of the insulating fibers is determined according to the electrical resistance to be obtained. As a general theory, the lower limit of the blending ratio of the insulating fibers in the conductive portion 12 is 0%. On the other hand, the upper limit of the blending ratio of the insulating fibers is preferably 50% by volume. Setting the blending ratio of insulating fibers to 0% means that the conductive portion 12 is formed only from the CNTs 11. Moreover, when the compounding rate of an insulating fiber exceeds the said upper limit, the contact between CNT11 becomes uncertain and there exists a possibility that the detection accuracy of the said anisotropic strain sensor sheet may become inadequate.

  Any chemical fiber can be used as the insulating fiber. The stretchability is not essential for the insulating fiber, but the strength of the conductive portion 12 can be improved by using the stretchable insulating fiber. Examples of stretchable fibers that can be used as insulating fibers include spandex (stretchable urethane fibers).

  As a method of forming the conductive portion 12 by aligning the CNTs 11 in one direction, a catalyst layer is formed on a growth substrate, and a plurality of CNTs 11 oriented in a certain direction are grown by a CVD method, so that natural yarns are grown. As with spinning, a method of continuously pulling out a plurality of CNTs 11 can be mentioned. Insulating fibers can be mixed by, for example, spraying insulating fibers on a growth substrate on which CNTs 11 are formed. That is, by pulling out a part of the CNTs 11 on the growth substrate, the other CNTs 11 and the insulating fibers follow and are drawn in one direction and drawn out into a continuous thread shape. This filamentous body may be used as the conductive part 12 as it is, or a bundle of a plurality of filamentous bodies may be used as the conductive part 12.

(Resin coating layer)
The resin coating layer 13 is mainly composed of a synthetic resin or rubber having insulating properties and stretchability, and covers the peripheral surface of the conductive portion 12, so that the CNT 11 is in contact with a surrounding object and is damaged. It is possible to prevent foreign matter from entering 12 and hindering electrical contact between the CNTs 11. By having such a resin coating layer 13, the strength of the CNT yarn 1a is improved, and it becomes easy to weave a woven fabric using the CNT yarn 1a.

  The resin coating layer 13 is preferably impregnated into at least a part of the surface layer of the conductive portion 12. As described above, the resin coating layer 13 has a function of holding the CNTs 11 on the outer peripheral side of the conductive part 12 by impregnating at least a part of the surface layer of the conductive part 12 and assisting in maintaining the mutual positional relationship of the CNTs 11. Can fulfill. Thereby, the detection sensitivity of the CNT yarn 1a and the linearity of the resistance change can be further improved. Further, by providing a difference in the degree of impregnation of the resin coating layer 13 on the surface layer of the conductive portion 12, a portion that is easily stretched and a portion that is difficult to stretch are formed to induce partial expansion and contraction of the conductive portion 12, and CNT yarn The response of 1a can be further increased. However, since the resin coating layer 13 covers the CNTs 11 and prevents electrical contact between the CNTs 11, the resin coating layer 13 must not be completely impregnated to the central part of the conductive part 12. That is, by having the non-impregnated portion surrounded in the radial direction by the impregnated portion of the resin coating layer 13 inside the conductive portion 12, deformation of the conductive portion 12 in the orientation direction can be prevented from being hindered by the resin.

  The lower limit of the average thickness of the resin coating layer 13 on the outer peripheral surface of the conductive portion 12 is preferably 0.1 μm, and more preferably 0.2 μm. On the other hand, the upper limit of the average thickness of the resin coating layer 13 on the outer peripheral surface of the conductive portion 12 is preferably 0.5 mm, and more preferably 0.2 mm. When the average thickness of the resin coating layer 13 on the outer peripheral surface of the conductive part 12 is less than the lower limit, the protection of the conductive part 12 may be insufficient. On the contrary, when the average thickness of the resin coating layer 13 on the outer peripheral surface of the conductive portion 12 exceeds the upper limit, the expansion and contraction of the CNT yarn 1a may be hindered.

  Examples of the synthetic resin as the main component of the resin coating layer 13 include phenol resin (PF), epoxy resin (EP), melamine resin (MF), urea resin (urea resin, UF), unsaturated polyester (UP), Alkyd resin, polyurethane (PUR), thermosetting 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), polymethylmethacryl (PMMA), polyamide (PA), polyacetal ( POM), polycarbonate Preparative (PC), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and cyclic polyolefin (COP) and the like.

  Examples of the rubber as the main component of the resin coating layer 13 include natural rubber (NR), butyl rubber (IIR), isoprene rubber (IR), ethylene / propylene rubber (EPDM), butadiene rubber (BR), and urethane rubber (U ), 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), fluorine rubber (FKM), PDMS and the like. Among these rubbers, natural rubber is preferable from the viewpoint of strength.

  The resin coating layer 13 is preferably formed from an aqueous emulsion. An aqueous emulsion refers to an emulsion in which the main component of the dispersion medium is water. Since the CNT 11 is highly hydrophobic, when the resin coating layer 13 is formed from an aqueous emulsion, the resin coating layer 13 does not impregnate the entire inside of the conductive portion 12 by providing the resin coating layer 13 by, for example, coating or dipping. It is possible to fill the periphery of the conductive portion 12 or a part of the surface layer. By doing in this way, it can suppress that resin which forms the resin coating layer 13 permeates the whole inside of the electroconductive part 12, and affects the resistance change of the said thread-like distortion sensor element. In addition, the water-based emulsion can form the more stable resin coating layer 13 by passing through a drying process.

  The main component of the dispersion medium of the aqueous emulsion is water, but other hydrophilic dispersion medium such as alcohol may be contained. The dispersoid of the emulsion is usually a resin, and the above-described rubber, particularly natural rubber is preferable. Further, polyurethane may be used as the dispersoid. Preferred emulsions include so-called latexes in which the dispersion medium is water and rubber is a dispersoid, and natural rubber latex is more preferable. By using natural rubber latex, a thin and strong resin coating layer 13 can be formed.

  Moreover, the resin coating layer 13 is good to contain the coupling agent. When the resin coating layer 13 contains a coupling agent, the resin coating layer 13 and the conductive portion 12 can be cross-linked, and the bonding force between the resin coating layer 13 and the conductive portion 12 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.

  As a minimum of content with respect to 100 mass parts of resin components of resin coating layer 13 of a coupling agent, 0.1 mass part is preferred and 0.5 mass part is more preferred. On the other hand, as an upper limit of content with respect to 100 mass parts of resin components of the resin coating layer 13 of a coupling agent, 10 mass parts is preferable and 5 mass parts is more preferable. When content of a coupling agent is less than the said minimum, there exists a possibility that formation of the crosslinked structure of the electroconductive part 12 and the resin coating layer 13 may become inadequate. On the other hand, when the content of the coupling agent exceeds the above upper limit, residual amine or the like that does not form a crosslinked structure increases, and the quality of the CNT yarn 1a and the anisotropic strain sensor sheet may be reduced.

  Moreover, it is preferable that the resin coating layer 13 contains the dispersing agent which has the adsorptivity with respect to the electroconductive part 12. FIG. Examples of such a dispersing agent having an adsorptive property include an adsorbing group portion having a salt structure (for example, an alkylammonium salt), or a hydrophobic group of the conductive portion 12 (for example, an alkyl chain or an aromatic ring). Those having a hydrophilic group (for example, polyether etc.) in the molecule that can interact with the molecule can be used.

  As a minimum of content with respect to 100 mass parts of resin components of the resin coating layer 13 of the said dispersing agent, 0.1 mass part is preferable and 1 mass part is more preferable. On the other hand, as an upper limit of content with respect to 100 mass parts of resin components of the resin coating layer 13 of a dispersing agent, 5 mass parts is preferable and 3 mass parts is more preferable. When content of a dispersing agent is less than the said minimum, there exists a possibility that the joining force of the electroconductive part 12 and the resin coating layer 13 may become inadequate. On the other hand, when the content of the dispersant exceeds the upper limit, the amount of the dispersant that does not contribute to the bonding with the conductive portion 12 increases, and the quality of the CNT yarn 1a and thus the anisotropic strain sensor sheet may be deteriorated.

<Normal thread>
As the normal yarn 1b, one used as a woven yarn for a general woven fabric can be adopted, but it is preferable that the normal yarn 1b has an initial tensile resistance smaller than that of the second direction yarn 2. As the normal yarn 1b, a monofilament formed from a single fiber or a multifilament formed from a large number of fibers may be used. Among these, as the normal yarn 1b, a twisted yarn formed by twisting a large number of fibers is particularly preferable in terms of relatively high stretchability.

  Thus, since the normal yarn 1b has a relatively small initial tensile resistance, the expansion and contraction of the anisotropic strain sensor sheet in the direction along the first direction yarn 1 is not hindered, and the electric power generated by the expansion and contraction of the CNT yarn 1a. A change in resistance can be efficiently generated.

  The material of the normal yarn 1b may be natural fiber, synthetic fiber, or a mixture of natural fiber and synthetic fiber. Examples of the natural fiber include cotton, silk, hemp and the like. On the other hand, examples of the main component of the synthetic fiber include polyamide, polyester, acrylic resin, polyvinyl alcohol, polyolefin, and polyurethane.

  The lower limit of the average diameter of the normal yarn 1b is preferably 10 μm, and more preferably 100 μm. On the other hand, the upper limit of the average diameter of the normal yarn 1b is preferably 2 mm, and more preferably 1 mm. When the average diameter of the normal yarn 1b is less than the lower limit, it is difficult to weave the first direction yarn 1 and the second direction yarn 2 because the strength of the first direction yarn 1 including the normal yarn 1b is insufficient. There is a risk of becoming. On the contrary, when the average diameter of the normal yarn 1b exceeds the upper limit, the first direction yarn 1 and the second direction yarn 2 may be woven because the rigidity of the first direction yarn 1 including the normal yarn 1b becomes too large. May be difficult.

[Second direction thread]
The second direction yarn 2 can be one that is used as a woven yarn for a general woven fabric, and preferably has an initial tensile resistance greater than that of the first direction yarn 1 (both the CNT yarn 1a and the ordinary yarn 1b). . As this 2nd direction thread | yarn 2, the monofilament formed from one fiber may be used, and the multifilament formed from many fibers may be used. Among these, as the second directional yarn 2, a non-twisted yarn formed by bundling a large number of fibers without twisting them is preferable because it has excellent flexibility and particularly low stretchability. Further, as the second direction yarn 2, a braided yarn knitted without twisting a large number of fibers is also preferable in that it has excellent flexibility and strength but has relatively low stretchability.

  Thus, the second direction yarn 2 has a relatively large initial tensile resistance, thereby suppressing expansion and contraction in the direction along the second direction yarn 2 of the anisotropic strain sensor sheet. Thereby, it is possible to suppress the CNT yarn 1a from expanding and contracting in the direction along the second direction yarn 2, and to reduce measurement errors caused by the expansion and contraction of the anisotropic strain sensor sheet in a direction different from the direction to be measured. Can do.

  As a material of the 2nd direction thread | yarn 2, a natural fiber, a synthetic fiber, an inorganic fiber, etc. can be used, for example, The thing which mixed multiple types may be used. Examples of the natural fiber include cotton, silk, hemp and the like. Examples of the main component of the synthetic fiber include polyamide, polyester, acrylic resin, polyvinyl alcohol, polyolefin, and polyurethane. Examples of the inorganic fiber include glass fiber and carbon fiber.

  As a minimum of the average diameter of the 2nd direction thread 2, 10 micrometers is preferred and 100 micrometers is more preferred. On the other hand, the upper limit of the average diameter of the second direction yarn 2 is preferably 2 mm, and more preferably 1 mm. If the average diameter of the second direction yarns 2 is less than the lower limit, the strength of the second direction yarns 2 may be insufficient, and it may not be easy to weave the first direction yarns 1 and the second direction yarns 2. There is. On the other hand, when the average diameter of the second direction yarn 2 exceeds the upper limit, it is difficult to weave the first direction yarn 1 and the second direction yarn 2 because the rigidity of the second direction yarn 2 becomes too large. There is a fear.

〔how to use〕
Since the anisotropic strain sensor sheet is formed of a woven fabric containing the CNT yarn 1a capable of detecting strain as a woven yarn, for example, at least one piece of clothing worn in close contact with a human body such as a shirt, gloves, and a supporter. It can be used as a material constituting the part.

  In the anisotropic strain sensor sheet, the clothing using the anisotropic strain sensor sheet is wired to two points of the CNT yarn 1a corresponding to a joint or the like for which movement is to be detected. By measuring the electrical resistance, it can be used as a strain sensor for detecting the movement of the human body.

<Advantages>
In the anisotropic strain sensor sheet, since the CNT yarn 1a for detecting strain is a part of the woven fabric, the texture is substantially the same as that of a general woven fabric, and it is difficult for the wearer to feel uncomfortable.

  Moreover, since the first direction yarn 1 including the CNT yarn 1a has a smaller initial tensile resistance than the second direction yarn 2, the anisotropic strain sensor sheet only expands and contracts in the direction along the first direction yarn 1. It can be detected selectively.

  In addition, the anisotropic strain sensor sheet easily separates the CNTs 11 constituting the conductive portion 12 of the CNT yarn 1a at the crossing position with the second direction yarn 2, so that each portion in the length direction of the CNT yarn 1a The electrical resistance varies locally according to the amount of expansion / contraction of the portion. For this reason, the anisotropic strain sensor sheet is relatively excellent in detection sensitivity and linearity.

[Other Embodiments]
The said embodiment does not limit the structure of this invention. Therefore, in the above-described embodiment, components of each part of the above-described embodiment can be omitted, replaced, or added based on the description and common general knowledge of the present specification, and they are all interpreted as belonging to the scope of the present invention. Should.

  The anisotropic strain sensor sheet may be coated on the surface with resin, or may be entirely impregnated with resin. In particular, when the CNT yarn does not have a resin coating layer, the CNT yarn may be reinforced by resin coating or impregnation.

  In addition, the CNT yarn of the anisotropic strain sensor sheet may be a bundle or a twist of a plurality of single yarns formed by coating a conductive portion comprising a CNT bundle with a resin coating layer. It is also possible to include a single yarn having no electrical conductivity.

  The anisotropic strain sensor sheet according to the present invention can be particularly suitably used to construct a wearable device that detects the movement of a human body.

1 First direction thread 1a CNT thread 1b Normal thread 2 Second direction thread 11CNT
12 conductive part 13 resin coating layer

Claims (5)

A plurality of first direction yarns and a plurality of second direction yarns woven,
The plurality of first direction yarns has a lower initial tensile resistance than the plurality of second direction yarns;
An anisotropic strain sensor sheet, wherein the plurality of first-direction yarns include CNT yarns whose resistance value changes by stretching in the longitudinal direction.   The anisotropic strain sensor sheet according to claim 1, wherein the second direction yarn is a non-twisted yarn.   The anisotropic strain sensor sheet according to claim 1, wherein the second direction yarn is a braided yarn.   The anisotropic strain sensor sheet according to claim 1, wherein the first direction yarn other than the CNT yarn is a twisted yarn.   The anisotropic strain sensor sheet according to any one of claims 1 to 4, wherein the CNT yarn has a resin coating layer on an outermost surface.

Images