JP6161196B2 - Strain sensor - Google Patents

Description

  The present invention relates to a strain sensor.

  A strain sensor that detects strain is configured to detect strain from a resistance change of the resistor with respect to strain (stretching). As this resistor, a metal or a semiconductor is generally used. However, since metals and semiconductors have a small amount of deformation that can be reversibly expanded and contracted, there are limitations on the applications of strain sensors.

  Therefore, devices using carbon nanotubes (CNT) as the resistor have been proposed (see JP 2011-47702 A and JP 2010-281824 A). In these devices, a CNT film made of a plurality of CNTs oriented in a predetermined direction is used. According to the device, the resistance is changed by changing the contact state between the CNTs due to expansion and contraction or cleavage of the CNT film, and the amount of strain can be measured. The CNT film can be expanded and contracted in a direction perpendicular to the alignment direction of the CNTs, so that it can be used as a sensor that can cope with a large strain.

  However, in the above-mentioned conventional device, since the region where expansion and contraction occurs in the CNT film is not limited, different regions may expand and contract for each measurement, and there is a disadvantage that the linearity and reproducibility of sensitivity are low. .

JP 2011-47702 A JP 2010-281824 A

  The present invention has been made based on the above-described circumstances, and an object thereof is to provide a strain sensor having excellent sensitivity linearity and reproducibility.

The invention made to solve the above problems is
A layer structure portion having at least a base layer having flexibility, a CNT layer including a plurality of CNT fibers that are laminated on the surface side of the base layer and oriented in one direction, and a pair connected to the CNT layer A strain sensor comprising a plurality of electrodes,
Between the pair of electrodes, the layer structure portion has a different rigidity region.

  According to the strain sensor, since the layer structure portion including the CNT layer has a different rigidity region, that is, a region having relatively low rigidity exists in the layer structure portion, this low rigidity region has priority over strain. Will stretch or cleave. As described above, since the strain sensor fixes a region that expands or contracts with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, linearity and reproducibility of sensitivity are reduced. improves.

  It is preferable that the different rigidity region is disposed substantially perpendicular to the facing direction of the pair of electrodes. By doing in this way, expansion and contraction or cleavage of the above-mentioned low-rigidity area is effectively generated with respect to expansion and contraction in the direction in which the strain is sensed (opposite direction of the pair of electrodes), and the linearity and reproducibility of the sensitivity are improved. More improved.

  The different rigidity regions are preferably arranged in a direction substantially parallel to or intersecting with the orientation direction of the CNT fibers. Since the CNT layer has a large expansion and contraction in the direction perpendicular to the orientation direction of the CNT fibers, the sensitivity to a relatively large strain amount or its linearity can be obtained by forming the different rigidity regions substantially parallel to the orientation direction of the CNT fibers. Sexuality etc. can be improved. On the other hand, by forming the different rigidity region so as to intersect with the orientation direction of the CNT fibers, it is possible to specify a region to be expanded and contracted. Further, the different rigidity regions may be formed in a plurality of directions. As described above, a region to be further expanded and contracted is specified by arranging different stiffness regions in one direction or two directions (for example, a direction substantially parallel to the opposing direction of the electrodes and the vertical direction thereof) or more. The sensitivity of the sensor and the sensing part can be adjusted.

  It is preferable that the different rigidity region is formed in a line shape or a belt shape. Thus, by providing the linear or belt-like different rigid region, it is possible to make it easier to control and adjust the region to be expanded or contracted or cleaved.

  It is preferable that the different rigidity region has a convex portion or a concave portion formed on at least one surface, back surface, or side surface of the layer structure portion. Since the rigidity of the region where the convex portion is formed is increased and the rigidity of the region where the concave portion is formed is decreased, the different rigidity region can be easily formed by doing in this way.

  The CNT layer may further include an elastomer disposed between the CNT fibers. By doing so, the elastomer can suppress the breakage of the CNT layer and the like, and it becomes easy to form a convex portion and a concave portion in the CNT layer itself. Further, it is desirable that the elastomer is disposed without hindering electrical conduction between the CNT fibers.

  It is also preferable that the layer structure portion further has a protective layer laminated on the surface of the CNT layer. By doing so, the protective layer can protect the CNT layer, and by forming convex portions and concave portions in the protective layer, it is possible to fix a region where expansion and contraction occurs.

  Here, the layer structure portion means that having at least a base material layer and a CNT layer, but a protective layer laminated on the surface side of the base material layer, an assist substrate laminated on the back surface side of the base material layer, etc. The layer structure part may be constituted. In addition, the direction in which the different stiffness regions are arranged is the shape of each different stiffness region, such as a linear shape or a strip shape, in the case of a shape having directionality, the longitudinal direction thereof, and the shape of each different stiffness region is a circular shape, etc. In the case of a shape having no directionality, it refers to the direction when a plurality of different rigidity regions are arranged linearly.

  As described above, according to the strain sensor of the present invention, expansion and contraction and cleavage in different regions for each measurement are suppressed, and as a result, the sensitivity linearity and reproducibility are excellent. Therefore, the strain sensor can be widely used as a pressure sensor, a load cell, a torque sensor, a position sensor, and the like.

Schematic sectional view (a) and schematic plan view (b) of the strain sensor according to the first embodiment of the present invention. Schematic diagram showing the manufacturing process of the strain sensor of FIG. Schematic sectional view (a) and schematic plan view (b) of a strain sensor according to a second embodiment of the present invention. Schematic sectional view of a strain sensor according to a third embodiment of the present invention. Schematic sectional view of a strain sensor according to a fourth embodiment of the present invention. Schematic sectional view (a) and schematic plan view (b) of a strain sensor according to a fifth embodiment of the present invention. Schematic sectional view (a) and schematic bottom view (b) of a strain sensor according to a sixth embodiment of the present invention. Schematic sectional view of a strain sensor according to a seventh embodiment of the present invention. Schematic sectional view of a strain sensor according to an eighth embodiment of the present invention. Schematic sectional view of a strain sensor according to a ninth embodiment of the present invention. Schematic sectional view of a strain sensor according to a tenth embodiment of the present invention. Schematic sectional view of a strain sensor according to the eleventh embodiment of the present invention. Schematic sectional view of a strain sensor according to a twelfth embodiment of the present invention. Schematic plan view of a strain sensor according to another embodiment Schematic plan view of a strain sensor according to another embodiment Schematic plan view of a strain sensor according to another embodiment

  Hereinafter, embodiments of the strain sensor of the present invention will be described in detail as first to twelfth embodiments and other embodiments with reference to the drawings as appropriate.

<First embodiment>
The strain sensor 1 in FIG. 1 is a substantially band-shaped body, and mainly includes a base material layer 10, a CNT layer 11 laminated on the surface of the base material layer 10, and a pair of electrodes 12. In the strain sensor 1, the base layer 10 and the CNT layer 11 form a layer structure portion.

  The base material layer 10 is a substantially strip-like body having flexibility. The size of the base material layer 10 is not particularly limited, and for example, the thickness can be 10 μm to 5 mm, the width can be 1 mm to 5 cm, and the length can be 1 cm to 20 cm.

  The material of the base material layer 10 is not particularly limited as long as it has flexibility, and examples thereof include resins, non-woven fabrics, deformable shapes or materials of metals and metal compounds, and the like. The base material layer 10 needs to be an insulator or a material having a high resistance value. When a material having a low resistance value such as a metal is used, the surface thereof may be coated with an insulating layer or a material having a high resistance value. . Among these, resins are preferable, elastomers such as thermoplastic elastomers and rubbers are more preferable, and rubbers are more preferable. By using such a material, the flexibility of the base material layer 10 can be further increased.

  Examples of the thermoplastic elastomer include styrene elastomer (TPS), olefin elastomer (TPO), vinyl chloride elastomer (TPVC), polyester elastomer (TPEE), polyurethane elastomer (TPU), and nylon elastomer (TPA). 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), Fluoro rubber (FKM), PDMS, etc. can be mentioned. Among these rubbers, natural rubber is preferable from the viewpoint of strength.

  The CNT layer 11 is a substantially strip-like body having flexibility. The CNT layer 11 includes a plurality of CNT fibers 13 and an elastomer 14. The CNT layer 11 has a plurality of recesses 15 formed on the surface.

  The plurality of CNT fibers 13 are oriented in one direction (direction A: the width direction of the strain sensor 1). Due to the orientation of the CNT fibers 13 as described above, when strain is applied in a direction different from the direction A (for example, the direction B: the longitudinal direction of the strain sensor 1), the contact condition between the CNT fibers 13 changes. Happens and resistance change can be obtained.

  Each CNT fiber 13 is composed of a plurality of CNT single fibers. Here, the CNT single fiber means one long CNT. Moreover, the CNT fiber 13 has a connection part which the edge part of CNT single fiber connects, and forms the network structure. The plurality of CNT fibers form a network structure in this manner, so that the CNT fibers 13 are in close contact with each other, and the resistance of the CNT layer 11 can be reduced. In addition, in the said connection part, each CNT single fiber is couple | bonded by the intermolecular force.

  Moreover, the CNT fiber 13 is a state in which each CNT single fiber is substantially oriented in the orientation direction of the CNT fiber 13 and is not twisted. By using such a CNT fiber 13, the uniformity of the CNT layer 11 can be improved and the linearity as the strain sensor 1 can be improved.

  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, a CNT crystal having a desired length can be obtained which is obtained by forming 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 then vertically growing.

  The elastomer 14 is filled between the plurality of CNT fibers 13 forming the CNT layer 11. That is, the elastomer 14 is present so as to be impregnated into a region composed of a plurality of CNT fibers 13.

  Examples of the elastomer include thermoplastic elastomers and rubbers. Specific examples thereof may include those described above as the material of the base material layer 10. Among the elastomers, a thermoplastic elastomer is preferable. By using such a thermoplastic elastomer, the moldability and the like can be improved, for example, the recess 15 can be formed by a stamper as described later.

  As content of the elastomer 14 in the CNT layer 11, 30 mass% or more and 70 mass% or less are preferable with respect to the total mass of the CNT fiber 13 and the elastomer 14. FIG. By setting it as such content, balance, such as the protection function of the CNT fiber 13, a stretching property, the moldability of the recessed part 15 mentioned later, can be aimed at.

  The CNT layer 11 can further contain a conductive additive. Since the CNT layer 11 contains a conductive additive, the electrical resistance of the CNT layer 11 can be lowered. Such conductive additives are not particularly limited, and examples thereof include carbon-based additives such as carbon black and carbon fibers, and metal-based additives such as metal (silver, copper, aluminum, etc.) powder and metal fibers. it can. Among these, a carbon-based additive that is excellent in affinity with CNT and can be uniformly dispersed in the CNT layer 11 is preferable. In addition, as a means for making the CNT layer 11 contain the conductive additive together with the elastomer 14 in this way, there can be mentioned application of a conductive rubber-based adhesive or the like.

  The plurality of recesses 15 are each a recess groove formed linearly in a direction (direction A) substantially perpendicular to the longitudinal direction (direction B) of the strain sensor 1. The plurality of concave portions 15 (concave grooves) are formed at substantially equal intervals. Therefore, the linear recess 15 is formed in a direction substantially parallel to the orientation direction of the CNT fibers 13 oriented in the direction A. Since such a recess 15 is formed in the CNT layer 11, the region where the recess 15 is formed in the layer structure portion (region in plan view) is different in rigidity from other regions (from other regions). It becomes a different rigidity region (low rigidity). Therefore, the expansion and contraction and cleavage of the CNT layer 11 occur preferentially in the region where the recess 15 is formed (different stiffness region). Since the CNT fiber 13 functions as the strain sensor 1 in a direction different from the direction B, it does not have to be oriented in the direction A. In that case, the CNT fiber 13 and the recess 15 intersect each other, and the sensitivity and sensing part of the sensor 1 can be adjusted.

  The cross-sectional shape of the recess 15 is not particularly limited, and may be rectangular, U-shaped, or V-shaped. Among these, in order to concentrate stress more, U shape or V shape is preferable, and V shape is more preferable.

  The depth of the recess 15 is not particularly limited, and can be, for example, 1/10 or more and 99/100 or less of the thickness of the CNT layer 11. By forming the recess 15 having such a depth, a decrease in strength of the CNT layer 11 can be suppressed while causing effective expansion and contraction at this position. In addition, when the strain sensor 1 is expanded and contracted, a portion below the concave portion 15 of the CNT layer 11 is deformed. However, since the space above the portion is a space, when the strain sensor 1 is stretched, the sensor 1 becomes thick. It is possible to prevent the resistance value from decreasing due to contraction in the direction.

  The distance between the recesses 15 is not particularly limited, but may be, for example, 10 μm or more and 5 mm or less, and preferably 50 μm or more and 1 mm or less. By arranging the recesses 15 at such intervals, sensitivity and linearity can be further increased. It is also possible to increase the number of the recesses 15 at a portion where the strain sensor 1 is intentionally expanded and contracted. That is, the concave portions 15 may be arranged at equal intervals or may be arranged at irregular intervals. Further, the degree of expansion and contraction in the strain sensor 1 can be adjusted by partially changing the width of the concave portion 15 in the direction B or changing the depth. In addition, a plurality of recesses 15 are arranged, but when the amount of expansion / contraction may be small, one may be provided.

  As a minimum of the width of CNT layer 11, 1 mm is preferred and 1 cm is more preferred. On the other hand, the upper limit of the width of the CNT layer 11 is preferably 10 cm, and more preferably 5 cm. Thus, by making the width of the CNT layer 11 relatively large, the resistance value of the CNT layer 11 can be lowered, and variations in the resistance value can also be reduced.

  The thickness of the CNT layer 11 is not particularly limited. For example, the lower limit of the average thickness of the CNT layer 11 is preferably 1 μm, and more preferably 10 μm. On the other hand, the upper limit of the average thickness of the CNT layer 11 is preferably 5 mm, and more preferably 1 mm. When the average thickness of the CNT layer 11 is less than the lower limit, it may be difficult to form such a thin film or the resistance may increase excessively. Conversely, when the average thickness of the CNT layer 11 exceeds the upper limit, the sensitivity to strain may be reduced.

  The pair of electrodes 12 are stacked at both ends of the surface of the base material layer 10 in the longitudinal direction B (direction substantially perpendicular to the orientation direction (direction A) of the CNT fibers 11A) and are electrically connected to both ends of the CNT layer 11. Has been. At this time, in the CNT layer 11 including the CNT fibers 13, a part of the CNT fibers 13 and the electrode 12 are connected. Thus, when the orientation direction (direction A) of the CNT fibers 13 and the facing direction (direction B) of the pair of electrodes 12 are different, when strain is applied to the facing direction (direction B) of the pair of electrodes 12, A change occurs in the contact state between the CNT fibers 13, and the resistance change can be obtained by using the strain sensor 1. In order to detect strain more efficiently, the opposing direction (direction B) of each recess 15 and the pair of electrodes 12 is preferably substantially vertical (for example, 80 ° or more and 100 ° or less), and is preferably vertical. More preferred. Moreover, it is preferable that each recessed part 15 is arrange | positioned substantially parallel to the orientation direction (direction A) of the CNT fiber 13. FIG.

  Although it does not specifically limit as long as it has electroconductivity as a material which forms the electrode 12, It is preferable to form with a conductive adhesive. By using a conductive adhesive, the adhesion between the base material layer 10 and the CNT layer 11 can be enhanced. Furthermore, by using a conductive adhesive, the conductive adhesive is impregnated when applied to the surface of the CNT layer 11, and the CNT layer 11 and the adhesive (electrode 12) can be easily brought into contact with each other.

  A fixing member 16 is laminated on the surface of the connection portion between the CNT layer 11 and the electrode 12. By providing the strain sensor 1 with the fixing member 16, it is possible to improve the adhesion between the CNT layer 11 and the electrode 12 and to improve the performance sustainability. The material for forming the fixing member 16 is not particularly limited, and a resin, preferably an elastomer such as a thermoplastic elastomer or rubber, can be used.

  According to the strain sensor 1, since the concave portion 15 as described above is formed in the CNT layer 11, the thickness of the CNT layer 11 changes alternately in magnitude along the facing direction (direction B) of the pair of electrodes 12. doing. That is, in the layer structure portion between the pair of electrodes 12 (the layer structure of the base material layer 10 and the CNT layer 11), the region where the concave portion 15 is formed is a different rigidity region having lower rigidity than the other regions. ing. As a result, the rigidity of the layer structure portion changes in a sine curve (alternately in magnitude) along the facing direction (direction B) of the pair of electrodes 12. Accordingly, in the strain sensor 1, in the CNT layer 11, a region having low rigidity with respect to strain (a region where the recess 15 is formed) is preferentially expanded or contracted or cleaved. As described above, since the strain sensor 1 fixes the region that expands or contracts with respect to the strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproducibility of the sensitivity. High nature.

(Production method)
An example of a method for manufacturing the strain sensor 1 will be described with reference to FIG.

(1-1) The slide glass 20 is immersed in latex or a resin solution and then dried. For example, the drying time may be about 8 hours at room temperature. By doing in this way, the resin-made film 21 is formed on both surfaces of the slide glass 20 (refer Fig.2 (a)). This coating 21 becomes the base material layer 10 having a rectangular shape in plan view. A plate material other than the slide glass 20 may be used.

(1-2) Next, the CNT fibers 22 are wound in the width direction of the slide glass 20 on which the coating 21 is formed, and the CNT fiber layer 23 is formed on the coating 21 (see FIG. 2B). The CNT fiber 22 can be obtained by pulling out a crystal of CNT single fiber (CNT) vertically grown on a substrate by a CVD method without twisting. The CNT fibers thus obtained are composed of a plurality of CNT single fibers, and have a structure having a connecting portion for connecting the short CNT fibers in the longitudinal direction.

  After winding the CNT fiber 22, it is preferable to spray or immerse a solvent such as ethanol on the CNT fiber 22 and then dry it. Through this operation, the adhesion between the CNT layer 11 and the coating 21 (base material layer 10) can be enhanced, and the CNT fibers 22 can be densified. By increasing the density of the CNT fibers 22 in this way, the contact area between the CNT fibers 22 can be increased in advance, and the effect of lowering the power consumption by lowering the resistance of the CNT layer 24 (CNT layer 11) described later, An effect of increasing the sensitivity of resistance change when strain is applied can be obtained. In addition, the CNT fibers drawn from the crystals of CNT single fibers are intricately entangled with each other in the micro (observed with a microscope), but the CNT fibers are oriented in one direction in the macro (observed with the naked eye). I can confirm. In the present application, the effect can be obtained by the macro orientation.

(1-3) A diluted conductive elastic adhesive is applied to the surface of the CNT fiber layer 23 and dried to form the CNT layer 24 (see FIG. 2C). As the conductive elastic adhesive, one containing the thermoplastic elastomer 25 and a conductive additive can be used. The solid content concentration of the diluted conductive adhesive is preferably 5% by mass or more and 10% by mass or less. Further, this application may be performed a plurality of times (for example, twice). By doing in this way, the CNT layer 24 in which the thermoplastic elastomer 25 and the conductive additive contained in the conductive adhesive are impregnated in the CNT fiber layer 23 is formed. In order to increase the content of the elastomer or the like to the extent that molding with a stamper 26 described later becomes possible, the number of times of application of the thermoplastic elastomer 25 and the conductive additive can be adjusted.

  The CNT layer 24 may be formed by laminating a separately formed CNT layer 24 on the coating 21 instead of forming the CNT fiber 22 by winding and applying a conductive elastic adhesive.

(1-4) Next, a recess 27 is formed on the surface of the CNT layer 24 using a stamper 26 (see FIG. 2D). The stamper 26 has a plurality of linear convex portions 26A formed in parallel. The stamper 26 is pressed against the surface of the CNT layer 24 so that the direction of the convex portion 26A is the same as the direction substantially perpendicular to the longitudinal direction (direction B) of the strain sensor 1. In this manner, the stamper 26 is heated while pressed against the surface of the CNT layer 24. Since the CNT layer 24 is impregnated with the thermoplastic elastomer 25, the shape of the convex portion 26A of the stamper 26 is transferred, and a concave portion 27 is formed on the surface of the CNT layer 24. The convex portion 26A of the stamper 26 can be formed by etching, for example.

(1-5) Next, the electrode 28 and the fixing member 29 are laminated (see FIG. 2E). Specifically, first, conductive rubber is applied to both ends of the coating film 21 and the CNT layer 24 in the longitudinal direction, and the electrode 28 is formed by drying. This drying may be performed at room temperature for about 1 hour, for example. Next, an elastic adhesive (adhesive containing an elastomer) or latex is applied to the boundary surface between the CNT layer 24 and the electrode 28. Then, the fixing member 29 is formed by hardening or drying these.

  Thereafter, the strain sensor 1 can be obtained by cutting the laminate from the slide glass 20 and removing the peripheral portion and the like. In addition, the manufacturing method of the strain sensor 1 is not limited to the said manufacturing method. For example, in addition to the method of transferring the shape by the plate-like stamper 26 as described above, transfer of the shape using a roller or the like may be used. Alternatively, the shape may be transferred by pressing the stamper 26 in a state before drying after applying the conductive elastic adhesive to the CNT layer 24.

<Second embodiment>
The strain sensor 3 in FIG. 3 is a substantially band-shaped body, and includes a base material layer 10, a CNT layer 31 laminated on the surface of the base material layer 10, a protective layer 36 laminated on the surface of the CNT layer 31, and a pair of The electrode 32 is mainly provided. In the strain sensor 3, the base layer 10, the CNT layer 31, and the protective layer 36 form a layer structure portion.

  The base material layer 10 is the same as the strain sensor 1 of FIG.

  The CNT layer 31 is a substantially strip-like body having flexibility. The CNT layer 31 is formed from a plurality of CNT fibers 13. The plurality of CNT fibers 13 are oriented in one direction (direction A: the width direction of the strain sensor 3). The CNT fiber 13 is the same as the strain sensor 1 of FIG.

  The front and back surfaces of the CNT layer 31 are substantially flat and have a substantially uniform thickness. The thickness of the CNT layer 31 is not particularly limited. For example, the lower limit of the average thickness of the CNT layer 31 is preferably 1 μm, and more preferably 10 μm. On the other hand, the upper limit of the average thickness of the CNT layer 31 is preferably 5 mm, and more preferably 1 mm. The width of the CNT layer 31 is approximately the same as that of the CNT layer 11 in FIG.

  The protective layer 36 covers a part of the CNT layer 31 and the electrode 32. A part of the pair of electrodes 32 has an exposed portion that is not covered with the protective layer 36. By laminating the protective layer 36 in this way, the protective layer 36 protects the CNT layer 31.

  The material of the protective layer 36 is not particularly limited as long as it has flexibility, and the same material as that of the base material layer 10 can be exemplified. However, the material of the protective layer 36 is preferably a resin, and more preferably an elastomer (such as a thermoplastic elastomer or rubber).

  The protective layer 36 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. CNT is highly hydrophobic. Therefore, when the protective layer 36 is formed from an aqueous emulsion, for example, when the protective layer 36 is provided by coating or dipping, the protective layer 36 is not impregnated in the CNT layer 31 and is laminated on the surface of the CNT layer 31. can do. By doing in this way, it can suppress that resin which forms the protective layer 36 penetrates into the CNT layer 31 and affects the resistance change of the CNT layer 31, and the strain sensitivity of the CNT layer 31 due to the presence of the protective layer 36 is suppressed. The decrease 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. Further, the dispersoid of the emulsion is usually a resin, and the above-described rubber and thermoplastic elastomer, particularly natural rubber are preferable. Examples of the preferable emulsion include so-called latex in which the dispersion medium is water and the rubber is a dispersoid, and natural rubber latex is preferable. By using natural rubber latex, a thin and strong protective film can be formed.

  The protective layer 36 has a plurality of recesses 37 formed on the surface. Each concave portion 37 is a concave groove formed linearly in a direction substantially perpendicular to the longitudinal direction (direction B) of the strain sensor 3. The plurality of concave portions 37 (concave grooves) are formed at substantially equal intervals in the longitudinal direction (direction B) of the strain sensor 3. By forming such a concave portion 37 in the protective layer 36, the region where the concave portion 37 is formed in the layer structure portion (region in plan view) is different in rigidity (reduced) from the other regions. ) It becomes a region with different rigidity. Therefore, the rigidity of the region where the concave portion 37 is formed (different stiffness region) is reduced, and expansion and contraction and cleavage occur preferentially in this region. In addition, the protective layer 36 and the CNT layer 31 are fixed, and along with the preferential expansion and contraction of the specific region (concave portion 37) of the protective layer 36, the region of the CNT layer 31 located in the region expands or contracts. Become.

  The cross-sectional shape, depth, and interval of the concave portion 37 are the same as those of the concave portion 15 of the strain sensor 1 of FIG.

  It does not specifically limit as average thickness of the protective layer 36, For example, they are 10 micrometers or more and 3 mm or less.

  The pair of electrodes 32 are disposed at both end portions in the longitudinal direction B on the surface side of the base material layer 10 and are connected to both ends of the CNT layer 31. Specifically, each electrode 32 is disposed on the surface of a pair of first conductive layers 38 disposed at both ends in the longitudinal direction B of the surface of the base material layer 10.

  Each first conductive layer 38 enhances electrical connectivity between the CNT layer 31 and the electrode 32. The material for forming the first conductive layer 38 is not particularly limited as long as it has conductivity, and for example, a conductive rubber adhesive can be used. By using an adhesive in this way as the first conductive layer 38, it is possible to improve the adhesion of the both ends of the base material layer 10, the electrode 32, and the CNT layer 31.

  The electrode 32 has a strip shape. The pair of electrodes 32 are disposed in parallel to each other in the width direction of the base material layer 10. The material for forming the electrode 32 is not particularly limited, and for example, a metal such as copper, silver, or aluminum can be used.

  The shape of the electrode 32 is not particularly limited and may be, for example, a film shape, a plate shape, or a mesh shape, but a mesh shape is preferable. By using the mesh-like electrode 32 as described above, adhesion and adhesion to the first conductive layer 38 and the second conductive layer 39 described later can be improved. As such a mesh-like electrode 32, a metal mesh or a nonwoven fabric obtained by vapor deposition or sputtering of metal can be used. The electrode 32 may be formed by applying a conductive adhesive or the like.

  A second conductive layer 39 is laminated on the surface of the boundary portion between the both ends of the CNT layer 31 and the pair of electrodes 32. The pair of second conductive layers 39 sandwiches both ends of the electrode 32 and the CNT layer 31 together with the pair of first conductive layers 38. Each second conductive layer 39 enhances the electrical connectivity between the electrode 32 and the CNT layer 31 as in the first conductive layer 38. The material for forming the second conductive layer 39 is not particularly limited as long as it has conductivity, and for example, a conductive rubber adhesive can be used. By using an adhesive in this way as the second conductive layer 39, the adhesiveness of both ends of the electrode 32 and the CNT layer 31 can be enhanced.

  According to the strain sensor 3, since the concave portion 37 as described above is formed in the protective layer 36 laminated on the surface of the CNT layer 31, the thickness of the protective layer 36 is the opposite direction of the pair of electrodes 32 (direction B). ) Are alternating in magnitude. That is, in the layer structure portion between the pair of electrodes 32 (layer structure including the base material layer 10, the CNT layer 31, and the protective layer 36), the region where the concave portion 37 is formed is less rigid than the other regions. It is a different rigidity region. As a result, the rigidity of the layer structure portion changes in a sine curve (alternately in magnitude) along the opposing direction (direction B) of the pair of electrodes 32. Therefore, according to the strain sensor 3, the specific portion of the CNT layer 31 corresponding to the region having low rigidity against the strain (the region where the concave portion 37 is formed) is preferentially expanded or contracted or cleaved. In this way, since the strain sensor 3 fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature.

(Production method)
Although it does not specifically limit as a manufacturing method of the distortion sensor 3, For example, it can manufacture with the following manufacturing processes.

(2-1) As in the first embodiment, the slide glass is immersed in latex or a resin solution and then dried. By doing in this way, the resin-made rectangular-view film (base material layer 10) can be formed on both surfaces of the slide glass.

(2-2) A conductive rubber adhesive is applied to both ends of the base material layer 10 in the longitudinal direction to form a pair of first conductive layers 38. Next, the electrode 32 is laminated on the surface of each first conductive layer 38.

(2-3) Next, as in the first embodiment, the CNT fiber 13 is wound between the electrodes 32 on the slide glass (base material layer 10) to form the CNT layer 31. By doing so, it is possible to obtain a CNT layer 31 composed of a plurality of CNT fibers 13 oriented in one direction (substantially perpendicular to the opposing direction of the pair of electrodes 32). As in the first embodiment, after winding the CNT fibers 13, it is preferable to spray a solvent such as isopropyl alcohol or ethanol on the CNT layer 31 or immerse it in this solvent and then dry it.

(2-4) A conductive rubber adhesive is applied to both ends of the CNT layer 31 in the longitudinal direction so as to expose a part of the electrode 32, thereby forming a pair of second conductive layers 39.

(2-5) Next, the protective layer 36 is formed by applying latex on the surface of the CNT layer 31. Thus, the protective layer 36 can be laminated on the surface of the CNT layer 31 by using latex. At this time, the protective layer 36 is formed so that a part of the electrode 32 is exposed. As described above, the latex is an aqueous emulsion and has hydrophilicity.

(2-6) Next, similarly to the first embodiment (1-4), the concave portion 37 is formed on the surface of the protective layer 36 using a stamper or the like. After doing in this way, the distortion sensor 3 can be obtained by cutting out from a slide glass and removing a peripheral part etc.

<Third embodiment>
The strain sensor 4 in FIG. 4 mainly includes a base material layer 10, a CNT layer 41 laminated on the surface of the base material layer 10, and a pair of electrodes 12. In the strain sensor 4, the base layer 10 and the CNT layer 41 form a layer structure portion. The base material layer 10 and the electrode 12 are the same as those of the strain sensor 1 of FIG. In the strain sensor 4, as in the strain sensor 1 of FIG. 1, the fixing member 16 is laminated on the surface of the connection portion between the CNT layer 41 and the electrode 12.

  The CNT layer 41 is a substantially strip-like body having flexibility. The CNT layer 41 includes a plurality of CNT fibers 13 and an elastomer 14. The CNT layer 41 has a plurality of convex portions 45 formed on the surface. The CNT layer 41 is the same as the CNT layer 11 of the strain sensor 1 of FIG. 1 except that it has a plurality of convex portions 45 instead of the concave portions 15, and thus other explanations are omitted.

  Each convex part 45 is a convex line formed in a straight line. Each protrusion 45 (protrusion) is formed in parallel with the orientation direction of the CNT fiber 13 and at substantially equal intervals. Since such a convex portion 45 is formed on the surface of the CNT layer 41, the region where the convex portion 45 is formed in the layer structure portion (region in plan view) is different in rigidity from the other regions (others). This is a different rigidity region. Therefore, expansion and contraction preferentially occurs in a region (between the convex portions 45) other than the region where the convex portion 45 is formed (different stiffness region). Moreover, this convex part 45 also has a protection function of the CNT layer 41 main body (CNT fiber 13).

  The material of the convex portion 45 is not particularly limited, but a resin is preferable from the viewpoint of moldability and the like. Examples of the resin include phenol resin, epoxy resin, polyethylene, polystyrene, polyamide and the like.

  The convex portion 45 may have conductivity. When the convex part 45 has electroconductivity, in the part in which the convex part 45 is formed, an electric current flows through this convex part 45 preferentially. For this reason, the resistance value of a portion with a small deformation (portion where the convex portion 45 is formed) can be lowered, and the sensitivity of the strain sensor 4 can be raised as a whole. In addition, for example, the convex portion 45 can be made conductive by forming the convex portion 45 with a resin to which a conductive additive is added.

  Although it does not restrict | limit especially as an interval between the said convex parts 45, For example, they can be 10 micrometers or more and 5 mm or less, and 50 micrometers or more and 1 mm or less are preferable. By arranging the convex portions 45 at such intervals, the sensitivity and linearity thereof can be further increased.

  According to the strain sensor 4, since the convex portions 45 as described above are formed on the CNT layer 41, the thickness of the CNT layer 41 changes alternately in magnitude along the facing direction of the pair of electrodes 12. . That is, in the layer structure portion between the pair of electrodes 12 (layer structure of the base material layer 10 and the CNT layer 41), the region where the convex portion 45 is formed is a different rigidity region having higher rigidity than other regions. It has become. As a result, the rigidity of the layer structure portion changes in a sine curve (alternatively in magnitude) along the opposing direction of the pair of electrodes 12. Therefore, in the strain sensor 4, in the CNT layer 41, a region having low rigidity against strain (a region between the convex portions 45) is preferentially expanded or contracted or cleaved. In this way, since the strain sensor 4 fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature.

  The strain sensor 4 can be manufactured with reference to the manufacturing method of the strain sensor 1 of FIG. As a method of forming the convex portion 45 instead of the concave portion 15, after forming the CNT layer 41, for example, a resin convex portion may be formed. A dispenser or the like can be used to form the convex portion 45.

<Fourth embodiment>
The strain sensor 5 of FIG. 5 mainly includes a base material layer 10, a CNT layer 31 laminated on the surface of the base material layer 10, a protective layer 57 laminated on the surface of the CNT layer 31, and a pair of electrodes 32. Prepare. In the strain sensor 5, the base layer 10, the CNT layer 31, and the protective layer 57 form a layer structure portion. Except for the protective layer 57, it is the same as the strain sensor 3 of FIG.

  The protective layer 57 has a plurality of convex portions 58 formed on the surface. Each convex portion 58 is a ridge formed in a straight line. The plurality of protrusions 58 (projections) are formed in parallel with the orientation direction of the CNT fibers 13 and at substantially equal intervals. Since such a convex portion 58 is formed in the protective layer 57, the region where the convex portion 58 is formed in the layer structure portion (region in plan view) is different in rigidity from other regions (other regions). This is a different stiffness region (which is more rigid than the region). Therefore, expansion and contraction preferentially occurs in a region (between convex portions) other than the region where the convex portion 58 is formed (different stiffness region). In addition, the protective layer 57 and the CNT layer 31 are fixed, and the region of the CNT layer 31 located in the specific region (between the protrusions 58) of the protective layer 57 expands or contracts along with the expansion and contraction of the specific region. .

  Since the protective layer 57 is the same as the protective layer 36 of the strain sensor 3 of FIG. 3 except that the protective layer 57 has a convex portion 58 instead of the concave portion 37, other description is omitted.

  According to the strain sensor 5, since the convex portion 58 as described above is formed on the protective layer 57 laminated on the surface of the CNT layer 31, the thickness of the protective layer 57 is along the facing direction of the pair of electrodes 32. The size changes alternately. That is, in the layer structure portion between the pair of electrodes 32 (layer structure including the base material layer 10, the CNT layer 31, and the protective layer 57), the region where the convex portion 58 is formed is more rigid than the other regions. It is a high different rigidity region. As a result, the rigidity of the layer structure portion changes in a sine curve (alternately in magnitude) along the opposing direction of the pair of electrodes 32. Therefore, according to the strain sensor 5, the specific portion of the CNT layer 31 corresponding to the region having low rigidity against strain (the region between the convex portions 58) is preferentially expanded or contracted or cleaved. As described above, since the strain sensor 5 fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature.

  The strain sensor 5 can be manufactured with reference to the manufacturing method of the strain sensor 3 of FIG. The formation of the convex portion 58 instead of the concave portion 37 can be performed by a dispenser or the like as in the strain sensor 4 of FIG.

<Fifth embodiment>
The strain sensor 6 in FIG. 6 mainly includes a base material layer 60, a CNT layer 61 laminated on the surface of the base material layer 60, and a pair of electrodes 12. In the strain sensor 6, the base layer 60 and the CNT layer 61 form a layer structure portion. Except for the base material layer 60 and the CNT layer 61, they are the same as the strain sensor 1 of FIG.

  The base material layer 60 has a plurality of recesses 65 formed on the back surface. The recess 65 is a groove formed linearly in a direction (direction A) substantially perpendicular to the longitudinal direction (direction B) of the strain sensor 6, similarly to the recess 15 of the strain sensor 1 of FIG. 1. The recess 65 is formed in a direction substantially parallel to the orientation direction of the CNT fibers 13.

  The CNT layer 61 is a substantially strip-like body having flexibility. The CNT layer 61 includes a plurality of CNT fibers 13 and an elastomer 14. Since the CNT layer 61 is the same as the CNT layer 11 of the strain sensor 1 of FIG. 1 except that the recess 15 is not formed, other description is omitted.

  According to the strain sensor 6, since the recess 65 as described above is formed in the base material layer 60, the thickness of the CNT layer 61 is alternately increased and decreased along the opposing direction (direction B) of the pair of electrodes 12. It has changed. That is, in the layer structure portion between the pair of electrodes 12 (the layer structure of the base material layer 60 and the CNT layer 61), the region where the recess 65 is formed becomes a different rigidity region that is less rigid than the other regions. Yes. As a result, the rigidity of the layer structure portion changes in a sine curve (alternately in magnitude) along the facing direction (direction B) of the pair of electrodes 12. Therefore, in the strain sensor 6, in the CNT layer 61, a region having low rigidity with respect to strain (a region where the recess 65 is formed) is preferentially expanded or contracted or cleaved. In this way, since the strain sensor 6 fixes the region that expands or contracts with respect to the strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of the sensitivity. High nature.

  The strain sensor 6 can be manufactured with reference to the manufacturing method of the strain sensor 1 of FIG. The concave portion 65 can be formed by providing a convex portion on the surface of the ride glass 20 (FIG. 2) on which the coating film 21 used when forming the strain sensor 6 is formed.

<Sixth embodiment>
7 mainly includes a base material layer 60, a CNT layer 61 laminated on the surface of the base material layer 60, an assist substrate 60A laminated on the back surface of the base material layer 60, and a pair of electrodes 12. Prepare. In the strain sensor 6A, the base layer 60, the CNT layer 61, and the assist substrate 60A form a layer structure portion. Except for the provision of the assist substrate 60A, it is the same as the strain sensor 6 of FIG.

  The assist substrate 60 </ b> A is formed on the back surface of the base material layer 60 so as to cover the recess 65. The material of the assist substrate 60A is not particularly limited as long as it has flexibility, and the same material as that of the base material layer 60 can be used. However, the material of the assist substrate 60A is preferably a resin, and more preferably an elastomer (such as a thermoplastic elastomer or rubber).

  The assist substrate 60A is preferably formed from an aqueous emulsion for the same reason as the protective layer 36 of the strain sensor 3 of FIG.

  The assist substrate 60A may be formed as a member having a Young's modulus different from that of the base material layer 60. The material of the assist substrate 60A in this case can be appropriately selected according to the Young's modulus design conditions, and in addition to synthetic resin and rubber, woven fabric, non-woven fabric, knit, and the like can be used. In particular, when a knit is used as the assist substrate 60A, the base material layer 60 can be entirely or partially impregnated into the knit fiber layer. By doing so, the bonding strength between the knit and the base material layer 60 is increased, and the knit also serves to suppress the extension of the strain sensor 6A.

  When the Young's modulus of the assist substrate 60A is set lower than the base material layer 60, the upper limit of the ratio of the Young's modulus of the assist substrate 60A to the Young's modulus of the base material layer 60 is preferably 0.9, and more preferably 0.7. . When the ratio of the Young's modulus exceeds the upper limit, there is a possibility that the effect of increasing the followability to the movement of the strain sensor 6A by the assist substrate 60A cannot be obtained sufficiently. On the other hand, the lower limit of the ratio of the Young's modulus of the assist substrate 60A to the Young's modulus of the base material layer 60 is preferably 0.4, and more preferably 0.5. When the ratio of the Young's modulus is less than the lower limit, the assist substrate 60A and the base material layer 60 may be easily peeled off due to expansion and contraction.

  When the Young's modulus of the assist substrate 60A is higher than that of the base layer 60, the upper limit of the ratio of the Young's modulus of the assist substrate 60A to the Young's modulus of the base layer 60 is preferably 2.5, and more preferably 2.0. . When the ratio of the Young's modulus exceeds the upper limit, the strain sensor 6A is not easily deformed, and the sensor sensitivity may be reduced. On the other hand, the lower limit of the ratio of the Young's modulus of the assist substrate 60A to the Young's modulus of the base material layer 60 is preferably 1.1, and more preferably 1.5. When the ratio of the Young's modulus is less than the lower limit, the effect of adjusting the expansion / contraction rate of the strain sensor 6A by the assist substrate 60A may not be sufficiently obtained.

  The average thickness of the assist substrate 60A is not particularly limited, but may be, for example, 10 μm or more and 1000 μm or less.

  According to the strain sensor 6A, the same effect as the strain sensor 6 of FIG. The strain sensor 6 </ b> A can further prevent the base material layer 60 from tearing due to the recess 65 by providing the assist substrate 60 </ b> A so as to cover the recess 65 on the back surface of the base material layer 60.

<Seventh embodiment>
The strain sensor 7A of FIG. 8 mainly includes a base material layer 10, a CNT layer 71A laminated on the surface of the base material layer 10, and a pair of electrodes 12. In the strain sensor 7A, the base layer 10 and the CNT layer 71A form a layer structure portion. Except for the CNT layer 71A, it is the same as the strain sensor 1 of FIG.

  The CNT layer 71A is a substantially strip-like body having flexibility. The CNT layer 71A includes a plurality of CNT fibers 73A and an elastomer 74A. The CNT layer 71A has a plurality of recesses 75A formed on the surface.

  The plurality of CNT fibers 73A are oriented in one direction (direction B: longitudinal direction of the strain sensor 7A). Since the CNT fibers 73A are oriented in this way, when strain is applied in the direction A (the width direction of the strain sensor 7A), the contact condition between the CNT fibers 73A changes, and a resistance change can be obtained. . In addition, in the CNT layer 71A including the CNT fibers 73A, a part of the CNT fibers 73A and the electrode 12 are connected.

  According to the strain sensor 7A, the orientation direction of the CNT fiber 73A is different from that of the strain sensor 1 of FIG. 1, but the concave portion 75A is formed in the CNT layer 71A, so that the strain sensor 1 of FIG. In the CNT layer 71A, a region having low rigidity against strain (a region in which the recess 75A is formed) preferentially expands or contracts. In this way, since the strain sensor 7A fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature. In FIG. 8, there are CNT fibers 73A that are divided in the longitudinal direction by the recesses 75A, but the CNT fibers 73A may not be divided by the recesses 75A. The same effect can be obtained by forming the recess 75A only in the elastomer 74A located on the surface side of the strain sensor 7A with respect to the CNT fiber 73A. Further, the CNT film 71A in the lower part of the recess 75A may be thinned by the pressure when forming the recess 75A. Thus, even if the recess 75A is formed deeply, the CNT fibers 73A are not divided, so that a large rigidity distribution can be formed in the longitudinal direction of the strain sensor 7A without lowering the resistance value of the CNT film 71A.

<Eighth embodiment>
The strain sensor 7B of FIG. 9 is a substantially band-shaped body, and includes a base material layer 10, a CNT layer 71B laminated on the surface of the base material layer 10, a protective layer 36 laminated on the surface of the CNT layer 71B, and a pair of The electrode 32 is mainly provided. In the strain sensor 7B, the base layer 10, the CNT layer 71B, and the protective layer 36 form a layer structure portion. Other than the CNT layer 71B is the same as the strain sensor 3 in FIG.

  The CNT layer 71B is a substantially strip-like body having flexibility. The CNT layer 71B includes a plurality of CNT fibers 73B and an elastomer 74B.

  The plurality of CNT fibers 73B are oriented in one direction (direction B: the longitudinal direction of the strain sensor 7B). When the CNT fibers 73B are oriented in this way, when the strain is applied in the direction A (the width direction of the strain sensor 7B), the contact state between the CNT fibers 73B changes, and a resistance change can be obtained. it can.

  According to the strain sensor 7B, the orientation direction of the CNT fibers 73B is different from that of the strain sensor 3 of FIG. 3, but the concave portion 37 is formed in the protective layer 36, so that the strain sensor 3 of FIG. In the CNT layer 71B, a region having low rigidity (region in which the concave portion 37 is formed) with respect to strain preferentially expands or contracts. In this way, since the strain sensor 7B fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature.

<Ninth embodiment>
The strain sensor 7 </ b> C in FIG. 10 is a substantially band-shaped body, and mainly includes a base material layer 10, a CNT layer 71 </ b> C laminated on the surface of the base material layer 10, and a pair of electrodes 12. In the strain sensor 7C, the base layer 10 and the CNT layer 71C form a layer structure portion. Except for the CNT layer 71C, it is the same as the strain sensor 4 of FIG.

  The CNT layer 71C is a substantially strip-like body having flexibility. The CNT layer 71C includes a plurality of CNT fibers 73C and an elastomer 74C. The CNT layer 71C has a plurality of convex portions 45 formed on the surface.

  The plurality of CNT fibers 73C are oriented in one direction (direction B: longitudinal direction of the strain sensor 7C). When the CNT fibers 73C are oriented in this way, when strain is applied in the direction A (the width direction of the strain sensor 7C), the contact condition between the CNT fibers 73C changes, and a resistance change can be obtained. it can.

  According to the strain sensor 7C, the orientation direction of the CNT fibers 73C is different from that of the strain sensor 4 of FIG. 4, but the convex portion 45 is formed on the CNT layer 71C, so that the strain sensor 4 of FIG. In addition, in the CNT layer 71C, a region having low rigidity (region between the convex portions 45) with respect to strain preferentially expands or contracts. In this way, since the strain sensor 7C fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature.

<Tenth embodiment>
The strain sensor 7D of FIG. 11 mainly includes a base material layer 10, a CNT layer 71D laminated on the surface of the base material layer 10, a protective layer 57 laminated on the surface of the CNT layer 71D, and a pair of electrodes 32. Prepare. In the strain sensor 7D, the base layer 10, the CNT layer 71D, and the protective layer 57 form a layer structure portion. Except for the CNT layer 71D, it is the same as the strain sensor 5 of FIG.

  The CNT layer 71D is a substantially strip-like body having flexibility. The CNT layer 71D includes a plurality of CNT fibers 73D.

  The plurality of CNT fibers 73D are oriented in one direction (direction B: longitudinal direction of the strain sensor 7D). When the CNT fibers 73D are oriented in this way, when strain is applied in the direction A (the width direction of the strain sensor 7D), a change occurs in the contact state between the CNT fibers 73D, thereby obtaining a resistance change. it can.

  According to the strain sensor 7D, the orientation direction of the CNT fibers 73D is different from that of the strain sensor 5 of FIG. 5, but the convex portion 58 is formed on the protective layer 57, so that the strain sensor 5 of FIG. In addition, in the CNT layer 71D, a region having low rigidity against strain (region between the convex portions 45) preferentially expands or contracts. In this way, since the strain sensor 7D fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature.

<Eleventh embodiment>
The strain sensor 7E of FIG. 12 mainly includes a base material layer 60, a CNT layer 71E laminated on the surface of the base material layer 60, and a pair of electrodes 12. The strain sensor 7E forms a layer structure portion with the base material layer 60 and the CNT layer 71E. Except for the CNT layer 71E, it is the same as the strain sensor 6 of FIG.

  The CNT layer 71E is a substantially strip-like body having flexibility. The CNT layer 71E includes a plurality of CNT fibers 73E and an elastomer 74E.

  The plurality of CNT fibers 73E are oriented in one direction (direction B: longitudinal direction of the strain sensor 7E). When the CNT fibers 73E are oriented in this way, when strain is applied in the direction A (the width direction of the strain sensor 7E), the contact condition between the CNT fibers 73E changes, and a resistance change can be obtained. it can.

  According to the strain sensor 7E, the orientation direction of the CNT fibers 73E is different from that of the strain sensor 6 of FIG. 6, but the concave portion 65 is formed in the base material layer 60, so that the strain sensor 6 of FIG. In addition, in the CNT layer 71E, a region having low rigidity (a region where the recess 65 is formed) with respect to strain preferentially expands or contracts. In this way, since the strain sensor 7E fixes a region that expands or contracts or cleaves with respect to strain, it is suppressed that a different region expands or contracts for each measurement, and as a result, the linearity and reproduction of sensitivity. High nature.

<Twelfth embodiment>
The strain sensor 7F in FIG. 13 mainly includes a base material layer 60, a CNT layer 71E laminated on the surface of the base material layer 60, a pair of electrodes 12, and an assist substrate 60A. In the strain sensor 7F, the base layer 60, the CNT layer 71E, and the assist substrate 60A form a layer structure portion. Since it is the same as the strain sensor 7E of FIG. 12 except that the assist substrate 60A is provided, the same reference numerals are given and description thereof is omitted.

  According to the strain sensor 7F, the same effect as the strain sensor 7E of FIG. Furthermore, the strain sensor 7F can suppress the base material layer 60 from being split by the recess 65 as a trigger by providing the assist substrate 60A so as to cover the recess 65 on the back surface of the base material layer 60.

<Other embodiments>
The strain sensor of the present invention is not limited to the above embodiment. For example, as in the strain sensors 8A, 8B, and 8C in FIGS. 14A to 14C, linear protrusions or recesses 85A, 85B, and 85C are formed perpendicular to the orientation direction of the CNT fibers 83A, 83B, and 83C. Further, it may be formed. For example, it is possible to improve the stability of the shape when stretched by forming the straight convex portions 85A at both end portions (see FIG. 14A). In addition, the recess 85B disposed substantially parallel to the expansion / contraction direction (B direction) of the strain sensor 8B can absorb the contraction in the width direction as the strain sensor 8B extends. (See FIG. 14 (b)). Furthermore, by regularly forming the vertical and horizontal linear convex portions or concave portions 85C, the layer structure portion as a whole can be expanded and contracted evenly and uniformly (see FIG. 14C). Furthermore, a linear convex portion or concave portion 85D may be formed so as to intersect the orientation direction of the CNT fiber 83D as in the strain sensor 8D of FIG. A convex portion or concave portion 85E having a circular shape or the like may be formed in a plan view like the strain sensor 8E. Each strain sensor in FIG. 14 schematically shows the relationship between the orientation direction of the CNT fibers and the projections or depressions, and other configurations such as electrodes are omitted. In addition, a convex part can be formed densely near the center which is easily deformed, or a concave part can be formed densely in a part to be sensed, or a curved convex part or a concave part may be used. As described above, the arrangement position, direction, shape, and the like of the convex portion or the concave portion can be appropriately set in consideration of the portion that is desired to be expanded or contracted (deformed) or the portion that is desired to be expanded or contracted (deformed). Further, the convex portion or the concave portion may be a line or a band, and may be a curve, a wave shape or a zigzag shape, or may be a discrete one such as a dotted line, and their width varies depending on the place. It may be a thing. In the case of a concave portion in FIG. 14E or a discrete concave portion such as a linear or strip-like concave portion such as a dotted line, the layer structure portion having the concave portion may be penetrated. In that case, it will deform | transform in the part which did not penetrate. You may use both the recessed part which has not penetrated, and the recessed part which penetrated as a recessed part.

  15A to 15E, the orientation directions of the CNT fibers 83F, 83G, 83H, 83I, and 83J are the same as those of the strain sensors 8F to 8J. Even in the case of being substantially parallel to the longitudinal direction B, convex portions or concave portions 85F to 85J similar to the convex portions or concave portions 85A to 85E of the strain sensors 8A to 8E in FIGS. 14 (a) to 14 (e) are provided. Also good.

  Also, a plurality of recesses 95 (cuts) may be formed on the side surface of the band-shaped layer structure portion 99 as in the strain sensor 9 of FIG. The layer structure portion 99 has a base material layer, a CNT layer, and other layers as required, like the strain sensor 1 of FIG. The CNT layer includes CNT fibers oriented in the width direction A or the longitudinal direction B of the layer structure portion 99. A pair of electrodes 92 are formed at both ends in the longitudinal direction of the layer structure portion 99 so as to be connected to the CNT layer. By making the shape like this strain sensor 9, the width of the layer structure portion 99 changes, the rigidity of the region provided with the recess 95 is lowered, and a different rigidity region is obtained. In addition, if the recessed part 95 is formed in the side surface of at least 1 layer of the strip | belt-shaped layer structure part 99, the rigidity of one area | region of the layer structure part 99 can be changed as a different rigidity area | region.

  Furthermore, a convex part or a concave part may be formed on another layer forming the layer structure part, for example, a base material layer, or a convex part or a concave part may be formed on the back surface or both surfaces of one layer (for example, a CNT layer). Also good. When forming a convex part or a recessed part on both surfaces, these may be provided in the position which opposes, may be shifted, and may be provided in a different direction. Furthermore, a hollow portion may be formed between the respective layers. Further, instead of changing the thickness or width of the layer, for example, a change in rigidity can be formed by regularly including materials having different elastic moduli in the base material layer. In either method, the region that expands or contracts with respect to strain is fixed by causing a layer structure portion to have a different rigidity region (region having higher or lower rigidity than other regions) between the pair of electrodes. Therefore, a strain sensor with high sensitivity linearity and reproducibility can be obtained.

  Moreover, you may form a linear convex part and a recessed part in parallel so that it may cross | intersect the orientation direction of CNT fiber. The orientation direction of the CNT fibers and the facing direction of the electrodes are not limited to the same direction or orthogonal directions, and may be intersecting directions (excluding the orthogonal directions). The relationship between these directions may be set as appropriate according to the application of the strain sensor. Furthermore, the layer structure portion can be used by being deformed. For example, the use of the strain sensor can be expanded by using a cylindrical shape or a wave shape.

  As described above, the strain sensor of the present invention has excellent sensitivity linearity and reproducibility, and can be widely used as a pressure sensor, load cell, torque sensor, position sensor, and the like.

1, 3-6, 6A, 7A-7F, 8A-8J, 9 Strain sensor 10, 60 Base material layer 11, 31, 41, 61, 71A-71E CNT layer 12, 32, 92 Electrode 13, 73A-73E, 83A to 83J CNT fiber 14, 74A, 74C, 74E Elastomer 15, 37, 65, 75A Recess 16 Fixing member 20 Slide glass 21 Coating 22 CNT fiber 23 CNT fiber layer 24 CNT layer 25 Elastomer 26 Stamper 26A Protrusion 27 Recess 28 Electrode 29 Fixing member 36, 57 Protective layer 38 First conductive layer 39 Second conductive layer 45, 58 Convex part 60A Assist substrate 85A-85J Convex part or concave part 95 Concave part (cut)
99 layer structure

Claims (5)

A layer structure portion having at least a base layer having flexibility, a CNT layer including a plurality of CNT fibers that are laminated on the surface side of the base layer and oriented in one direction, and a pair connected to the CNT layer A strain sensor comprising:
Between the pair of electrodes, wherein the layer structure portion have a different rigidity region,
The strain sensor , wherein the different rigidity region has a convex portion or a concave portion formed on at least one surface, back surface, or side surface of the layer structure portion .   The strain sensor according to claim 1, wherein the different rigidity region is disposed substantially perpendicular to a facing direction of the pair of electrodes.   The strain sensor according to claim 1, wherein the different rigidity region is arranged in a direction substantially parallel to or intersecting with an orientation direction of the CNT fibers.   The strain sensor according to claim 1, 2, or 3, wherein the different rigidity region is formed in a line shape or a belt shape. A layer structure portion having at least a base material layer having flexibility and a CNT layer including a plurality of CNT fibers which are laminated on the surface side of the base material layer and oriented in one direction; and
A pair of electrodes connected to the CNT layer
A strain sensor comprising:
Between the pair of electrodes, the layer structure portion has a different rigidity region,
The strain sensor , wherein the different rigidity region has a through hole penetrating at least one layer of the layer structure portion .

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