CN117063632A - Piezoelectric substrate, sensor, actuator, and biological information acquisition device - Google Patents
Piezoelectric substrate, sensor, actuator, and biological information acquisition device Download PDFInfo
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- CN117063632A CN117063632A CN202280023433.1A CN202280023433A CN117063632A CN 117063632 A CN117063632 A CN 117063632A CN 202280023433 A CN202280023433 A CN 202280023433A CN 117063632 A CN117063632 A CN 117063632A
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- Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
Abstract
The piezoelectric substrate includes an elongated inner conductor and a piezoelectric layer covering an outer peripheral surface of the inner conductor. The piezoelectric layer has a piezoelectric yarn wound around the inner conductor, and an adhesive portion that holds the piezoelectric yarn wound around the outer peripheral surface of the inner conductor. The piezoelectric yarn comprises an optically active polypeptide fiber representing a fiber formed from an optically active polypeptide. The piezoelectric layer has an elastic modulus Y measured by a microhardness meter (according to JIS Z2255) of 1.0GPa to 8.0 GPa.
Description
Technical Field
The present invention relates to a piezoelectric substrate, a sensor, an actuator, and a biological information acquisition device.
Background
In recent years, piezoelectric bodies including polypeptides having optical activity (hereinafter, referred to as "optically active polypeptides") have been studied for use in piezoelectric devices such as sensors and actuators.
Patent document 1 discloses a piezoelectric substrate using a filiform piezoelectric body. The piezoelectric substrate specifically disclosed in patent document 1 includes a nylon yarn, a specific raw yarn, and a copper foil tape. The nylon yarn functions as a core material. Raw silk is an example of a fiber formed from an optically active polypeptide. The raw silk is wound around the nylon silk thread in a spiral shape without gaps in a manner that the nylon silk thread is not exposed. Hereinafter, the raw yarn wound around the nylon yarn is referred to as a "raw yarn layer". The copper foil tape is wound in a spiral shape around the raw yarn wound around the nylon yarn without exposing the raw yarn. Hereinafter, the copper foil tape wound around the raw yarn wound around the nylon yarn will be referred to as "copper foil tape layer". The nylon yarn and the raw yarn layer, and the copper foil tape layer are bonded by a cyanoacrylate adhesive. In other words, the nylon yarn, the raw yarn layer, and the copper foil tape layer are mechanically integrated.
Prior art literature
Patent literature
Patent document 1: international publication No. 2018/092886
Disclosure of Invention
Problems to be solved by the invention
However, a piezoelectric substrate having more excellent piezoelectric sensitivity than the piezoelectric substrate described in patent document 1 is required.
On the other hand, in the case of manufacturing a line sensor of a coaxial line structure using the piezoelectric substrate disclosed in patent document 1 (for example, in the case of using the piezoelectric substrate as a part or all of a wearable product), it is necessary to cut the piezoelectric substrate to a desired length according to the form of use and to mount terminals to the piezoelectric substrate. As a process before the terminal mounting, a terminal mounting preparation is required. In the terminal mounting preparation, the raw silk layer and the copper foil tape layer are peeled off from both end portions of the piezoelectric substrate, and the nylon silk thread is exposed. Specifically, in the preparation for terminal attachment, the copper foil tape layer is peeled from the raw silk layer, and the raw silk layer having a length (usually about several mm) suitable for the extraction of the nylon silk thread is removed, thereby extracting the nylon silk thread.
However, in the piezoelectric substrate disclosed in patent document 1, the nylon yarn, the raw yarn layer, and the copper foil tape layer are mechanically integrated. Therefore, in the preparation for terminal mounting, there is a concern that the copper foil tape layer or the nylon yarn may be broken when the raw yarn layer is removed. Further, the working time for terminal mounting preparation may be long. Therefore, a piezoelectric substrate capable of efficiently performing terminal mounting preparation is demanded. In addition, a piezoelectric substrate having piezoelectric sensitivity superior to that of the conventional one is demanded.
One embodiment of the present disclosure has been made in view of the above.
That is, an object of one embodiment of the present disclosure is to provide a piezoelectric substrate, a sensor, an actuator, and a biological information acquisition device that are excellent in piezoelectric sensitivity.
Another object of another embodiment of the present invention is to provide a piezoelectric substrate, a sensor, an actuator, and a biological information acquisition device, which can efficiently prepare a terminal for attachment and have excellent piezoelectric sensitivity.
Means for solving the problems
Means for solving the above problems include the following embodiments.
<1> a piezoelectric substrate, comprising:
an elongated inner conductor, and
a piezoelectric layer covering an outer peripheral surface of the inner conductor;
the piezoelectric layer has:
a piezoelectric yarn wound around the inner conductor, and
an adhesive part for keeping the state that the piezoelectric yarn is wound around the inner conductor;
the piezoelectric yarn comprises an optically active polypeptide fiber representing a fiber formed from an optically active polypeptide,
the piezoelectric layer has an elastic modulus Y measured by a microhardness meter (according to JIS Z2255) of 1.0GPa to 8.0 GPa.
<2> the piezoelectric substrate according to the above <1>, wherein the longitudinal direction of the piezoelectric yarn is substantially parallel to the main orientation direction of the optically active polypeptide.
<3> the piezoelectric substrate according to the above <1> or <2>, wherein the degree of orientation F of the optically active polypeptide fiber obtained by the following formula (a) by X-ray diffraction measurement is 0.50 or more and less than 1.00.
Degree of orientation f= (180 ° - α)/180 ° … formula (a)
[ in formula (a), α represents a half-width (°) of a peak from orientation. A kind of electronic device
<4> the piezoelectric substrate according to any one of the above <1> to <3>, wherein the piezoelectric yarn is wound in a spiral shape in one direction.
<5> the piezoelectric substrate according to the above <4>, wherein a spiral angle formed between the axial direction of the inner conductor and the longitudinal direction of the piezoelectric yarn is 20 ° to 70 °.
<6> the piezoelectric substrate according to any one of <1> to <5>, wherein the adhesive portion is formed of at least one selected from the group consisting of an epoxy-based adhesive, a urethane-based adhesive, a vinyl acetate resin emulsion-based adhesive, an ethylene vinyl acetate emulsion-based adhesive, an acrylic resin emulsion-based adhesive, a styrene butadiene rubber latex-based adhesive, a silicone resin-based adhesive, an α -olefin-based adhesive, a vinyl chloride resin solvent-based adhesive, a rubber-based adhesive, an elastic adhesive, a chloroprene rubber solvent-based adhesive, a nitrile rubber solvent-based adhesive, and a cyanoacrylate-based adhesive.
<7> the piezoelectric substrate according to any one of <1> to <6>, wherein an external conductor is further provided on the outer peripheral side of the piezoelectric layer,
the inner conductor and the outer conductor are not electrically connected.
<8> the piezoelectric substrate according to any one of the above <1> to <7>, wherein the optically active polypeptide has a β -sheet structure.
<9> the piezoelectric substrate according to any one of the above <1> to <8>, wherein the optically active polypeptide comprises at least one of fibroin and spider silk protein.
<10> the piezoelectric substrate according to any one of <1> to <9>, wherein the optically active polypeptide fiber comprises at least one of silk and spider silk.
<11> the piezoelectric substrate according to the above <10>, wherein the silk is refined silk.
<12> the piezoelectric substrate according to any one of <1> to <11>, wherein each of the piezoelectric yarns comprises a plurality of optically active polypeptide fibers,
the number of turns of the piezoelectric yarn is 500T/m or less.
<13> the piezoelectric substrate according to any one of <1> to <12>, wherein an electrical insulator is further provided at the outermost periphery.
The sensor of <14> comprising the piezoelectric substrate of any one of <1> to <13 >.
An actuator comprising the piezoelectric substrate according to any one of <1> to <13 >.
<16> a biological information acquisition device comprising the piezoelectric substrate according to any one of the above <1> to <13 >.
<17> a piezoelectric substrate, comprising:
an elongated inner conductor, and
a piezoelectric layer covering an outer peripheral surface of the inner conductor;
the piezoelectric layer is formed by winding a long piezoelectric body around the inner conductor, and is not fixed to the inner conductor,
the long piezoelectric body has a plurality of piezoelectric yarns and a bundling body for bundling the plurality of piezoelectric yarns,
at least 1 of the plurality of piezoelectric yarns comprises an optically active polypeptide fiber representing a fiber formed from an optically active polypeptide.
<18> the piezoelectric substrate according to the above <17>, wherein the longitudinal direction of the long piezoelectric body is substantially parallel to the main orientation direction of the optically active polypeptide.
<19> the piezoelectric substrate according to the above <17> or <18>, wherein the degree of orientation F of the optically active polypeptide fiber obtained by the following formula (a) by X-ray diffraction measurement is 0.50 or more and less than 1.00.
Degree of orientation f= (180 ° - α)/180 ° … formula (a)
[ in formula (a), α represents a half-width (°) of a peak from orientation. A kind of electronic device
<20> the piezoelectric substrate according to any one of the preceding claims <17> to 19, wherein the elongated piezoelectric body is wound in a spiral shape in one direction.
<21> the piezoelectric substrate according to the above <20>, wherein a spiral angle formed between the axial direction of the inner conductor and the longitudinal direction of the long piezoelectric body is 20 ° to 70 °.
<22> the piezoelectric substrate according to any one of <17> to <21>, wherein the bundling body bundles the plurality of piezoelectric yarns in a state in which the plurality of piezoelectric yarns are juxtaposed in a direction orthogonal to a longitudinal direction of the plurality of piezoelectric yarns and adjacent ones of the plurality of piezoelectric yarns are brought into contact with each other.
<23> the piezoelectric substrate according to any one of <17> to <22>, wherein the bundling body is formed of at least one selected from the group consisting of epoxy-based adhesives, urethane-based adhesives, vinyl acetate resin emulsion-based adhesives, ethylene-vinyl acetate emulsion-based adhesives, acrylic resin emulsion-based adhesives, styrene butadiene rubber latex-based adhesives, silicone resin-based adhesives, α -olefin-based adhesives, vinyl chloride resin solvent-based adhesives, rubber-based adhesives, elastic adhesives, chloroprene rubber solvent-based adhesives, nitrile rubber solvent-based adhesives, and cyanoacrylate-based adhesives.
<24> the piezoelectric substrate according to any one of <17> to <23>, wherein the thickness of the long piezoelectric body is 0.001mm to 0.4mm,
the width of the long piezoelectric body is 0.1 mm-30 mm,
the ratio of the width of the long piezoelectric body to the thickness of the long piezoelectric body is 2 or more.
<25> the piezoelectric substrate according to any one of <17> to <24>, wherein the elastic modulus Y of the long piezoelectric body measured by a microhardness meter (according to JIS Z2255) is 1GPa to 10 GPa.
<26> the piezoelectric substrate according to any one of <17> to <25>, wherein an external conductor is further provided on the outer peripheral side of the piezoelectric layer,
the inner conductor and the outer conductor are not electrically connected.
<27> the piezoelectric substrate according to any one of <17> to <26>, wherein the optically active polypeptide has a β -sheet structure.
<28> the piezoelectric substrate according to any one of <17> to <27>, wherein the optically active polypeptide comprises at least one of fibroin and spider silk protein.
<29> the piezoelectric substrate according to any one of <17> to <28>, wherein the fiber formed of the optically active polypeptide comprises at least one of silk and spider silk.
<30> the piezoelectric substrate according to the above <29>, wherein the silk is refined silk.
<31> the piezoelectric substrate according to any one of the above <17> to <30>, wherein each of the plurality of piezoelectric yarns comprises a plurality of the optically active polypeptide fibers,
the number of turns of each of the plurality of piezoelectric yarns is 500T/m or less.
<32> the piezoelectric substrate according to any one of <17> to <31>, wherein an electrical insulator is further provided at the outermost periphery.
A <33> sensor comprising the piezoelectric substrate according to any one of the above <17> to <32 >.
An actuator comprising the piezoelectric substrate according to any one of <17> to <32 >.
<35> a biological information acquisition device comprising the piezoelectric substrate according to any one of the above <17> to <32 >.
Effects of the invention
According to the present disclosure, a piezoelectric substrate, a sensor, an actuator, and a biological information acquisition device excellent in piezoelectric sensitivity can be provided.
According to the present disclosure, a piezoelectric substrate, a sensor, an actuator, and a biological information acquisition device, which can efficiently prepare for terminal mounting and are excellent in piezoelectric sensitivity, can be provided.
Drawings
Fig. 1A is a schematic side view showing the appearance of a piezoelectric substrate according to embodiment 1 of the present disclosure.
FIG. 1B is a sectional view taken along line IB-IB of FIG. 1A.
Fig. 2 is a schematic side view showing the appearance of a piezoelectric substrate according to embodiment 2 of embodiment 1 of the present disclosure.
Fig. 3A is a schematic side view showing the appearance of a piezoelectric substrate according to embodiment 1 of embodiment 2 of the present disclosure.
Fig. 3B is a schematic front view showing the appearance of the long piezoelectric body according to embodiment 1 of embodiment 2 of the present disclosure.
FIG. 3C is a cross-sectional view of the IC-IC wire of FIG. 3B.
Fig. 3D is a sectional view of the ID-ID line of fig. 3A.
Fig. 4 is a schematic side view showing the appearance of a piezoelectric substrate according to embodiment 2 of the present disclosure.
Detailed Description
In the present disclosure, a numerical range indicated by "to" is a range including numerical values described before and after "to" as a lower limit value and an upper limit value.
(1) Mode 1
(1.1) piezoelectric substrate
The piezoelectric substrate according to claim 1 of the present disclosure includes an elongated inner conductor and a piezoelectric layer covering an outer peripheral surface of the inner conductor. The piezoelectric layer includes a piezoelectric yarn wound around the inner conductor, and an adhesive portion for maintaining a state in which the piezoelectric yarn is wound around the inner conductor. The piezoelectric yarn comprises an optically active polypeptide fiber representing a fiber formed from an optically active polypeptide. The piezoelectric layer has an elastic modulus Y measured by a microhardness meter (according to JIS Z2255) of 1.0GPa to 8.0 GPa.
Preferably, the length direction of the piezoelectric yarn is substantially parallel to the main orientation direction of the optically active polypeptide.
The degree of orientation F of the optically active polypeptide fiber, as determined by X-ray diffraction using the following formula (a), is preferably 0.50 or more and less than 1.00.
Degree of orientation f= (180 ° - α)/180 ° … formula (a)
[ in formula (a), α represents a half-width (°) of a peak from orientation. A kind of electronic device
In the present disclosure, the term "piezoelectric yarn" means a filament-like piezoelectric body.
In the present disclosure, the term "optically active polypeptide" refers to a polypeptide having asymmetric carbon atoms and having an unbalanced amount of optical isomers.
In the present disclosure, the term "substantially parallel" means: when the angle formed by 2 line segments is represented within a range of 0 ° to 90 °, the angle formed by 2 line segments is 0 ° to less than 30 ° (preferably 0 ° to 22.5 °, more preferably 0 ° to 10 ° and still more preferably 0 ° to 5 °, and particularly preferably 0 ° to 3 °.
In the present disclosure, the degree of orientation F of the piezoelectric yarn is an index indicating the degree of orientation of the optically active polypeptide contained in the piezoelectric yarn.
Since the piezoelectric substrate according to embodiment 1 of the present disclosure includes the above-described configuration, the piezoelectric substrate has excellent piezoelectric sensitivity as compared with the conventional piezoelectric substrate described in patent document 1.
(1.1.1) piezoelectric layer
The piezoelectric substrate according to embodiment 1 of the present disclosure includes a piezoelectric layer.
The piezoelectric layer covers the outer peripheral surface of the inner conductor. The piezoelectric layer preferably covers the entire outer peripheral surface of the inner conductor.
The elastic modulus Y of the piezoelectric layer is 1.0GPa to 8.0 GPa. If the elastic modulus Y of the piezoelectric layer is within the above range, the piezoelectric sensitivity of the piezoelectric substrate is more excellent.
Among them, from the viewpoint of improving the piezoelectric sensitivity of the piezoelectric substrate, the elastic modulus Y of the piezoelectric layer is preferably in the 1 st or 2 nd range, more preferably in the 2 nd range.
The 1 st range is 1.0GPa to 3.6GPa, preferably 1.5GPa to 3.5GPa, more preferably 2.0GPa to 3.4GPa, still more preferably 2.5GPa to 3.3GPa, particularly preferably 2.5GPa to 3.2 GPa.
The 2 nd range is 4.0GPa to 8.0GPa, preferably 4.2GPa to 7.0GPa, more preferably 4.4GPa to 6.5GPa, still more preferably 4.6GPa to 6.0GPa, and particularly preferably 4.9GPa to 5.5 GPa.
The method for measuring the elastic modulus Y of the piezoelectric layer is the same as the measurement method described in the examples.
As a method of adjusting the elastic modulus Y of the piezoelectric layer within the above range, for example, a method of adjusting a material constituting the adhesive portion of the piezoelectric layer and the like can be cited.
The thickness of the piezoelectric layer is not particularly limited, but is preferably 0.02mm to 2.00mm, more preferably 0.05mm to 1.00 mm.
The piezoelectric layer may or may not be fixed to the inner conductor.
In the present disclosure, "fixed to the inner conductor" means that the piezoelectric layer is mechanically integrated with the inner conductor by an adhesive or the like.
In the present disclosure, "not fixed to the internal conductor" means that the piezoelectric layer is mechanically integrated with the internal conductor without using an adhesive or the like.
Wherein the piezoelectric layer is preferably not fixed to the inner conductor. In this way, when the piezoelectric substrate to be described later is prepared for terminal mounting, the piezoelectric layer can be easily removed from the inner conductor, compared with a structure in which the piezoelectric layer and the inner conductor are mechanically integrated. In this case, the internal conductor is not mechanically integrated with the piezoelectric layer, and therefore is not easily broken. As a result, the piezoelectric substrate can be efficiently prepared for terminal mounting of the piezoelectric substrate.
In the case of manufacturing a line sensor of a coaxial line structure using a piezoelectric substrate (for example, in the case of using the piezoelectric substrate as a part or all of a wearable article), it is necessary to cut the piezoelectric substrate to a desired length and mount terminals to the piezoelectric substrate according to the form of use. As a process before the terminal mounting, a terminal mounting preparation is required. In the terminal mounting preparation, the raw silk layer and the copper foil tape layer are peeled off from both end portions of the piezoelectric substrate, and the nylon silk thread is exposed. Specifically, in the preparation for terminal attachment, the copper foil tape layer is peeled from the raw silk layer, and the raw silk layer having a length (usually about several mm) suitable for the extraction of the nylon silk thread is removed, thereby extracting the nylon silk thread.
Furthermore, the piezoelectric layer can be displaced relative to the inner conductor in the axial direction of the inner conductor. Thus, if external stress acts on the piezoelectric substrate, the piezoelectric substrate is more likely to deform than conventional piezoelectric substrates. Therefore, the internal stress of the piezoelectric substrate due to the external stress is not easily concentrated locally. As a result, the piezoelectric substrate is excellent in durability.
The piezoelectric layer has a piezoelectric yarn and an adhesive portion. The piezoelectric yarn is wound around the inner conductor. The adhesive portion holds the piezoelectric yarn in a state of being wound around the inner conductor.
The piezoelectric yarn may be directly wound around the outer peripheral surface of the inner conductor. In the case where an inner insulator described later is disposed on the outer peripheral surface of the inner conductor, the piezoelectric yarn may be wound around the outer peripheral surface of the inner insulator so as to be indirectly wound around the inner conductor.
The winding method of the piezoelectric yarn is not particularly limited, and the piezoelectric yarn may be spirally wound around the inner conductor with respect to the axial direction of the inner conductor, or may not be spirally wound with respect to the axial direction of the inner conductor. Among them, in the winding method of the piezoelectric yarn, from the viewpoint of improving the piezoelectric sensitivity of the piezoelectric substrate, the piezoelectric yarn is preferably spirally wound around the inner conductor with respect to the axial direction of the inner conductor. The piezoelectric yarns may be wound so as to overlap each other or may not overlap each other.
In the piezoelectric substrate according to claim 1 of the present disclosure, the piezoelectric yarn wound in a spiral shape is subjected to a shear stress, whereby electric charges are easily generated. Thus, piezoelectricity is easily exhibited.
The shear stress for the piezoelectric yarn may be applied by, for example, the 1 st non-plastic deformation, the 2 nd non-plastic deformation, the 3 rd non-plastic deformation, or the like.
The 1 st non-plastic deformation means stretching the whole piezoelectric yarn wound in a spiral shape in the direction of the spiral axis.
Non-plastic deformation 2 means twisting a portion of the piezoelectric yarn wound in a spiral (i.e., twisting a portion of the piezoelectric yarn with the spiral shaft as the axis).
The 3 rd non-plastic deformation means bending a part or the whole of the piezoelectric yarn wound in a spiral shape.
The piezoelectric yarn is preferably wound in a spiral shape on the inner conductor in one direction.
The term "spirally wound in one direction" means the 1 st winding method or the 2 nd winding method.
The 1 st winding method represents: the piezoelectric yarn is spirally wound around the inner conductor so as to be left-handed (i.e., counterclockwise) from the proximal side toward the distal side when viewed from one end of the piezoelectric substrate.
The 2 nd winding method represents: the piezoelectric yarn is spirally wound around the inner conductor so as to be rightward (i.e., clockwise) from the proximal side toward the distal side when viewed from one end of the piezoelectric substrate.
When the piezoelectric yarn is wound in a spiral shape in one direction, a phenomenon in which polarities of generated charges cancel each other (that is, a phenomenon in which piezoelectricity is reduced) is suppressed. Thus, the piezoelectricity of the piezoelectric substrate is further improved.
The piezoelectric substrate includes a piezoelectric yarn wound in a spiral shape in one direction, and includes not only a layer including only a layer formed of a piezoelectric yarn but also a layer formed of a piezoelectric yarn stacked in multiple layers.
Examples of the method of stacking layers of piezoelectric yarns include the following methods: the layer of the second layer of the piezoelectric yarn is wound in a spiral shape in the same direction as the one direction so as to be overlapped on the layer of the first layer of the piezoelectric yarn wound in a spiral shape in the one direction.
As a mode of the piezoelectric substrate, the following modes can be mentioned: the piezoelectric yarn includes a 1 st piezoelectric yarn wound in a spiral shape in one direction and a 2 nd piezoelectric yarn wound in a spiral shape in a direction different from the one direction. In this embodiment, the chirality of the optically active polypeptide contained in the 1 st piezoelectric yarn and the chirality of the optically active polypeptide contained in the 2 nd piezoelectric yarn are different from each other.
The helix angle is preferably 20 ° to 70 °, more preferably 25 ° to 65 °, and still more preferably 30 ° to 60 °.
The "helix angle" refers to an angle formed by the axial direction of the inner conductor and the longitudinal direction of the piezoelectric yarn. In the method for measuring the helix angle, in the case where the piezoelectric substrate includes an external conductor described later, the external conductor of the piezoelectric substrate is removed, the piezoelectric layer is placed straight along the axial direction of the internal conductor, a photograph is taken by an optical microscope, the extremely deviated portion is excluded, and the angle of the piezoelectric yarn in the axial direction of the internal conductor is measured at 5 points by image processing, and the angle is calculated from the average value.
(1.1.1.1) piezoelectric yarn
The piezoelectric yarn comprises optically active polypeptide fibers. The term "optically active polypeptide fiber" means a fiber formed from an optically active polypeptide. The inclusion of optically active polypeptides in the piezoelectric yarn contributes to the piezoelectricity of the piezoelectric substrate.
The piezoelectric yarn can be twisted yarn or untwisted yarn. Among them, from the viewpoint of piezoelectricity, the piezoelectric yarn is preferably a twisted yarn. Examples of the untwisted yarn include 1 filament (fiber) and a collection of a plurality of filaments (fibers).
The number of filaments (fibers) constituting the twisted yarn is not particularly limited, but is preferably 3 to 120, more preferably 4 to 30, from the viewpoint of securing the strength of the piezoelectric yarn.
The filaments (fibers) constituting the twisted filaments may contain fibers other than the optically active polypeptide as long as they contain at least 1 optically active polypeptide fiber. Among them, from the viewpoint of improving the piezoelectric sensitivity of the piezoelectric substrate, the filaments (fibers) constituting the twisted filaments are preferably formed only of a plurality of optically active polypeptide fibers.
Each of the plurality of piezoelectric yarns includes a plurality of optically active polypeptide fibers, and the twist number of each of the plurality of piezoelectric yarns is preferably 500T/m or less, more preferably 300T/m or less. When the number of turns of each of the plurality of piezoelectric yarns is within this range, the piezoelectric yarn becomes less likely to break, and the piezoelectric substrate is more excellent in piezoelectric sensitivity.
The thickness of the piezoelectric yarn (in the case where the piezoelectric yarn is an aggregate of a plurality of fibers, the thickness of the aggregate as a whole) is not particularly limited, but is preferably 0.0001mm to 2mm, more preferably 0.001mm to 1mm, and even more preferably 0.005mm to 0.8mm.
In the case where the piezoelectric yarn is 1 filament or an aggregate of a plurality of filaments, the fineness of 1 filament is preferably 0.01 denier to 10000 denier, more preferably 0.1 denier to 1000 denier, still more preferably 1 denier to 100 denier.
(1.1.1.1.1) optically active polypeptide fiber
The optically active polypeptide fibers are preferably long fibers. Thus, the shear stress applied to the piezoelectric substrate becomes easier to transmit to the piezoelectric substrate than in the case where the optically active polypeptide fiber is a short fiber. As a result, the piezoelectric sensitivity of the piezoelectric substrate is improved.
In the present disclosure, "long fiber" refers to a fiber having a length that can be continuously wound from one end to the other end in the longitudinal direction of the piezoelectric substrate.
Silk (silk thread), wool, mohair, cashmere, camel hair, american camel hair, alpaca hair, camel hair, angora, and spider silk are all long fibers. Among the long fibers, silk and spider silk are preferable from the viewpoint of piezoelectricity.
The degree of orientation F of the optically active polypeptide fiber is preferably in the range of 0.50 or more and less than 1.00.
If the degree of orientation F of the optically active polypeptide fiber is 0.50 or more, the piezoelectric property of the piezoelectric substrate is facilitated. If the degree of orientation F of the optically active polypeptide fiber is less than 1.00, productivity of the piezoelectric substrate is facilitated.
The degree of orientation F of the optically active polypeptide fiber is preferably 0.50 to 0.99, more preferably 0.70 to 0.98, and still more preferably 0.80 to 0.97.
The degree of orientation F of the optically active polypeptide fiber is 1.00: the main orientation direction of the optically active polypeptide contained in the optically active polypeptide fiber is parallel to the longitudinal direction of the optically active polypeptide fiber. The degree of orientation F of the optically active polypeptide fiber being 0.80 or more and less than 1.00 represents: the main orientation direction of the optically active polypeptide contained in the optically active polypeptide fiber is substantially parallel to the longitudinal direction of the optically active polypeptide fiber.
The degree of orientation F of the optically active polypeptide fiber is a value obtained by superposing and fixing a piezoelectric yarn on a sample support with respect to a reference axis, measuring the azimuth distribution intensity in the vicinity of a peak from orientation (for example, in the case of silk, in the vicinity of 2θ=20°) by X-ray diffraction measurement, and using the following formula (a), and is referred to as the c-axis orientation.
Degree of orientation f= (180 ° - α)/180 ° … formula (a)
[ in formula (a), α represents a half-width (°) of a peak from orientation. A kind of electronic device
Preferably, the lengthwise direction of the piezoelectric yarn is substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn.
The piezoelectric yarn has a length direction substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn, and contributes to the piezoelectricity of the piezoelectric substrate.
The fact that the longitudinal direction of the piezoelectric yarn is substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn means that the piezoelectric yarn is excellent in tensile strength in the longitudinal direction thereof. Therefore, when the piezoelectric yarn is wound in a spiral shape, the piezoelectric yarn is not easily broken.
In the case where the piezoelectric yarn is silk or spider silk, the longitudinal direction of the piezoelectric yarn (silk or spider silk) is substantially parallel to the main orientation direction of an optically active polypeptide (for example, fibroin or spider silk protein) contained in the piezoelectric yarn during the production of the silk or spider silk.
The length direction of the piezoelectric yarn is substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn, and can be confirmed by comparing the direction in which the sample (piezoelectric yarn) is disposed and the azimuth angle of the crystal peak in the X-ray diffraction measurement.
As a method of making the longitudinal direction of the piezoelectric yarn substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn, for example, a method of using twisted filaments containing a plurality of specific optically active polypeptide fibers as the piezoelectric yarn, and the like can be cited. The specific optically active polypeptide fiber means an optically active polypeptide fiber having an orientation degree F of 0.80 or more and less than 1.00.
From the viewpoints of piezoelectricity of the piezoelectric yarn and strength of the piezoelectric yarn, the optically active polypeptide preferably has a β -sheet structure.
Examples of the optically active polypeptide having a β -sheet structure include an optically active animal protein and an optically active synthetic protein.
Examples of the animal protein having optical activity include fibroin, spider silk protein, sericin, collagen, keratin, and elastin. As the spider silk protein, the spider silk protein described in patent document 1 can be used. As spider silk proteins, artificial spider silk obtained by artificial synthesis methods can be used.
Wherein the optically active polypeptide preferably comprises at least one of a fibroin and a spider silk protein, preferably comprises a fibroin.
Examples of the optically active synthetic Protein include synthetic spider silk (for example, "QMONOS (registered trademark)", synthetic bagworm silk, synthetic Protein (for example, "threaded Protein (registered trademark)") and the like.
As the optically active polypeptide fiber having a β -sheet structure, a fiber formed of an optically active animal protein can be mentioned. Examples of the fiber formed of an optically active animal protein include silk, wool, mohair, cashmere, camel hair, american camel hair, alpaca hair, camel hair, angora, spider silk, and the like.
Among them, from the viewpoint of piezoelectricity, the optically active polypeptide fiber preferably contains at least one of silk and spider silk, more preferably is formed of at least one of silk and spider silk, and particularly preferably is formed of silk.
Examples of silk include raw silk (raw silk), refined silk, regenerated silk, and fluorescent silk.
As silk, raw silk or refined silk is preferable, and refined silk is particularly preferable.
The term "purified silk" means silk obtained by removing sericin from raw silk having a double structure of sericin and fibroin. By "refining" is meant the removal of sericin from raw silk. The color of the raw silk is matt white, but is changed from matt white to glossy silvery white by removing sericin from the raw silk (i.e., refining). Further, by refining, soft hand is increased.
(1.1.1.2) adhesive portion
The adhesive portion holds the piezoelectric yarn in a state of being wound around the inner conductor.
Thus, when an external stress is applied to the piezoelectric substrate, a shear stress due to the external stress is likely to act on the piezoelectric yarn.
The adhesive portion may cover the entire exposed surface of the piezoelectric yarn or may cover a part of the exposed surface of the piezoelectric yarn. Among them, from the viewpoint of improving the piezoelectric sensitivity of the piezoelectric substrate, the adhesive portion preferably covers a part of the exposed surface of the piezoelectric yarn.
The adhesive portion is preferably formed of at least one selected from the group consisting of an epoxy-based adhesive, a urethane-based adhesive, a vinyl acetate resin emulsion-based adhesive, an ethylene vinyl acetate emulsion-based adhesive, an acrylic resin emulsion-based adhesive, a styrene butadiene rubber latex-based adhesive, a silicone resin-based adhesive, an α -olefin-based adhesive, a vinyl chloride resin solvent-based adhesive, a rubber-based adhesive, an elastic adhesive, a chloroprene rubber solvent-based adhesive, a nitrile rubber solvent-based adhesive, and a cyanoacrylate-based adhesive.
Hereinafter, the material of the adhesive portion may be referred to as "bundling agent".
It is preferable that no irregularities are formed on the surface of the bonded portion. If the surface of the adhesive portion is not formed with irregularities, for example, when an outer conductor is formed by winding a long-shaped conductor described later around the outer peripheral surface of the piezoelectric layer, occurrence of winding disorder of the long-shaped conductor can be suppressed. That is, if no irregularities are formed on the surface of the adhesive portion, the yield in the winding process of the long conductor is improved. In addition, occurrence of a decrease in piezoelectric sensitivity due to winding disorder of the long conductor can be suppressed.
Examples of the method for preventing the surface of the adhesive portion from forming irregularities include: a method of wiping off the excessively supplied bundling agent from the piezoelectric yarn wound around the inner conductor before the bundling agent supplied to the piezoelectric yarn wound around the inner conductor is cured; a method of using an adhesive containing a large amount of solvent as a bundling agent, and the like. The adhesive containing a large amount of solvent means an adhesive having a content of a resin component (solid content) of 60 mass% or less relative to the total amount of the adhesive.
(1.1.2) inner conductor
The piezoelectric substrate according to claim 1 of the present disclosure includes an elongated inner conductor.
The inner conductor functions as a core of the piezoelectric substrate.
The internal conductor is preferably an electrical good conductor, and examples thereof include copper wires, aluminum wires, SUS (Steel Use Stainless) wires, metal wires covered with an insulating film, carbon fibers, resin fibers integrated with carbon fibers, nylon wires, and organic conductive materials. The nylon yarn is formed by spirally winding a copper foil around a fiber. The outer diameter of the fiber can be suitably adjusted according to the desired characteristics of the piezoelectric substrate, and is preferably 0.1mm to 10 mm.
Among them, the internal conductor is preferably a nylon yarn or a carbon fiber from the viewpoint of improving the piezoelectric sensitivity and stability of piezoelectric output and imparting high flexibility, and is preferably a nylon yarn from the viewpoint of low resistivity.
(1.1.3) outer conductor
From the viewpoint of improving the piezoelectric sensitivity and electrostatic shielding property, the piezoelectric substrate according to embodiment 1 of the present disclosure preferably further includes an external conductor.
The outer conductor is disposed on the outer peripheral side of the piezoelectric layer. The inner conductor and the outer conductor are not electrically connected.
The outer conductor functions as a conductor paired with the inner conductor, for example, for detecting an electrical signal from the piezoelectric substrate.
The outer conductor may cover at least a portion of the piezoelectric layer. Specifically, the outer conductor may cover a part of the outer peripheral surface of the piezoelectric layer or may cover the entire outer peripheral surface of the piezoelectric layer.
The external conductor may or may not be fixed to the piezoelectric layer. The term "the external conductor is fixed to the piezoelectric layer" means that the external conductor and the piezoelectric layer are mechanically integrated using a known adhesive.
Wherein the outer conductor is preferably not fixed to the piezoelectric layer. In this way, the external conductor can be easily removed from the piezoelectric layer when the terminal mounting preparation of the piezoelectric substrate is performed. In this case, the piezoelectric layer is not mechanically integrated with the external conductor, and therefore is not easily broken. As a result, the piezoelectric substrate can be more efficiently prepared for terminal mounting of the piezoelectric substrate.
Furthermore, the outer conductor is displaceable relative to the piezoelectric layer in the axial direction of the inner conductor. Thus, if external stress acts on the piezoelectric substrate, the piezoelectric substrate is more likely to deform than conventional piezoelectric substrates. Therefore, the internal stress of the piezoelectric substrate due to the external stress is less likely to locally concentrate. As a result, the piezoelectric substrate is more excellent in durability.
The external conductor is formed by winding a long conductor, for example.
Examples of the cross-sectional shape of the long conductor include a circle, an ellipse, a rectangle, and a special shape. Among them, the cross-sectional shape of the long conductor is preferably rectangular from the viewpoint of improving the piezoelectric sensitivity of the piezoelectric substrate by planar adhesion to the piezoelectric substrate.
The material of the long conductor is not particularly limited, and the following materials are mainly exemplified in terms of the cross-sectional shape.
Examples of the long conductor having a rectangular cross section include a copper foil tape, an aluminum foil tape, and the like obtained by rolling copper wires having a circular cross section and processing the copper wires into a flat plate shape.
Examples of the long conductor having a circular cross section include copper wires, aluminum wires, SUS wires, metal wires covered with an insulating film, carbon fibers, resin fibers obtained by integrating carbon fibers, and nylon wires obtained by spirally winding copper foil around fibers.
As the long-strip conductor, a conductor obtained by coating an organic conductive material with an insulating material may be used.
Examples of the winding method of the long conductor include a method of spirally winding copper foil or the like around the piezoelectric substrate, a method of winding copper wire or the like into a tubular braid and wrapping the piezoelectric substrate, and a method of wrapping the piezoelectric substrate in a tubular shape.
(1.1.4) an electrical insulator
The piezoelectric substrate according to embodiment 1 of the present disclosure may further include an electrical insulator (hereinafter, referred to as "1 st insulator"). The 1 st insulator is disposed on the outermost periphery of the piezoelectric substrate. In other words, at least a part of the outer peripheral surface of the piezoelectric substrate is constituted by the 1 st insulator.
The 1 st insulator preferably covers the entire outermost periphery of the piezoelectric substrate. In other words, the entire outer peripheral surface of the piezoelectric substrate is preferably made of the 1 st insulator. This makes it possible to electrostatically shield the internal conductor. As a result, the change in piezoelectric sensitivity due to external static electricity can be suppressed.
The 1 st insulator is formed by, for example, spirally winding a long material along the outer peripheral surface of the outer conductor.
The material of the 1 st insulator may be an electrically insulating material, and examples thereof include vinyl chloride resin, polyethylene resin, polypropylene resin, ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene hexafluoropropylene copolymer (FEP), tetrafluoroethylene resin (PTFE), tetrafluoroethylene Quan Fu propyl vinyl ether copolymer (PFA), fluororubber, polyester resin, polyimide resin, polyamide resin, polyethylene terephthalate resin (PET), rubber (including elastomer), and the like.
In the case where the piezoelectric substrate according to claim 1 of the present disclosure includes an outer conductor, the 1 st insulator may or may not be fixed to the outer conductor. The term "the 1 st insulator is fixed to the outer conductor" means that the 1 st insulator and the outer conductor are mechanically integrated using a known adhesive.
Among them, the 1 st insulator is preferably not fixed to the outer conductor. Thus, the 1 st insulator can be easily removed from the outer conductor when preparing for terminal mounting of the piezoelectric substrate. In this case, the outer conductor is not mechanically integrated with the 1 st insulator, and therefore is not easily broken. As a result, the piezoelectric substrate can be more efficiently prepared for terminal mounting of the piezoelectric substrate.
Further, the 1 st insulator is displaceable relative to the outer conductor in the axial direction of the inner conductor. Thus, if external stress acts on the piezoelectric substrate, the piezoelectric substrate is more likely to deform than conventional piezoelectric substrates. Therefore, the internal stress of the piezoelectric substrate due to the external stress is less likely to locally concentrate. As a result, the piezoelectric substrate is more excellent in durability.
(1.1.5) inner electrical insulation
In the case where the piezoelectric substrate according to claim 1 of the present disclosure includes an outer conductor, an inner insulator (hereinafter, referred to as "the 2 nd insulator") may be further provided. The 2 nd insulator is disposed between at least one of the piezoelectric layer and the inner conductor and between the piezoelectric layer and the outer conductor, for example.
This can further suppress occurrence of a short circuit between the inner conductor and the outer conductor.
The 2 nd insulator is formed by, for example, spirally winding a long material along the outer peripheral surface of the inner conductor.
The material of the 2 nd insulator is the same as the material exemplified as the material of the 1 st insulator.
The 2 nd insulator may be fixed to at least one of the inner conductor, the piezoelectric layer, and the outer conductor (hereinafter, referred to as "inner conductor, etc.) or may be not fixed. The term "the 2 nd insulator is fixed to the inner conductor or the like" means that the 2 nd insulator and the inner conductor or the like are mechanically integrated using a known adhesive. Among them, the 2 nd insulator is preferably not fixed to the external conductor from the viewpoint of enabling more efficient terminal mounting preparation of the piezoelectric substrate.
(1.1.6) functional layer
The piezoelectric substrate according to embodiment 1 of the present disclosure may further include a functional layer. In the case where the piezoelectric substrate does not include an external conductor, the functional layer is disposed between the piezoelectric layer and the internal conductor. In the case where the piezoelectric substrate according to claim 1 of the present disclosure includes an external conductor, the functional layer is disposed between at least one of the piezoelectric layer and the internal conductor, and between the piezoelectric layer and the external conductor.
Examples of the layer constituting the functional layer (hereinafter referred to as a "constituting layer") include an easy-to-adhere layer, a hard coat layer, a refractive index adjusting layer, an antireflection layer, an antiglare layer, an easy-to-slip layer, an adhesion preventing layer, a protective layer, an antistatic layer, a heat dissipating layer, an ultraviolet absorbing layer, an anti-newton ring layer, a light scattering layer, a polarizing layer, a gas barrier layer, a hue adjusting layer, and an electrode layer.
The functional layer may have a single-layer structure formed of a single layer of constituent layers, or may have a multi-layer structure formed of 2 or more constituent layers. In the case where the functional layer has a multilayer structure, the plurality of constituent layers may be the same constituent layer or may be different constituent layers. In the case where the piezoelectric substrate has a functional layer between the piezoelectric layer and the inner conductor and between the piezoelectric layer and the outer conductor, the functional layer between the piezoelectric layer and the inner conductor may be the same or different from the functional layer between the piezoelectric layer and the outer conductor.
The film thickness of the functional layer is not particularly limited, but is preferably in the range of 0.01 μm to 10 μm.
The material of the functional layer may be appropriately selected according to the function required for the functional layer, and examples thereof include inorganic substances such as metals and metal oxides; organic substances such as resins; a composite composition comprising a resin and microparticles; etc. Examples of the resin include a cured product obtained by curing with temperature and active energy rays.
The functional layer may be fixed to the inner conductor or the like, or may not be fixed. The "functional layer is fixed to the inner conductor or the like" means that the 2 nd insulator and the inner conductor or the like are mechanically integrated using a known adhesive. Among them, the functional layer is preferably not fixed to the external conductor from the viewpoint of enabling more efficient terminal mounting preparation of the piezoelectric substrate.
Hereinafter, a specific example of the piezoelectric substrate according to embodiment 1 will be described with reference to the drawings, but the piezoelectric substrate according to embodiment 1 of the present disclosure is not limited to the following specific example.
In the drawings, substantially the same elements are denoted by the same reference numerals, and description thereof is not repeated.
(1.1.7) the piezoelectric substrate according to embodiment 1 of claim 1
A piezoelectric substrate 10A according to embodiment 1 of embodiment 1 will be described with reference to fig. 1A to 1D. Fig. 1A is a schematic side view showing an appearance of a piezoelectric substrate 10A according to embodiment 1 of the present disclosure. FIG. 1B is a sectional view of line IB-IB of FIG. 1A.
As shown in fig. 1A, a piezoelectric substrate 10A according to embodiment 1 of embodiment 1 includes an elongated inner conductor 12A and a piezoelectric layer 14A. The piezoelectric layer 14A is wound in a spiral shape in one direction with no gap from one end to the other end along the outer peripheral surface of the inner conductor 12A at a spiral angle β1. The piezoelectric layer 14A is not fixed to the inner conductor 12A.
The piezoelectric layer 14A is formed by: the piezoelectric yarn 140A is wound around the outer peripheral surface of the inner conductor 12A in a left-handed manner with respect to the inner conductor 12A, and an adhesive portion (not shown) maintains a state in which the piezoelectric yarn 140A is wound around the inner conductor 12A. Specifically, when the piezoelectric substrate 10A is viewed from one axial end side (right end side in fig. 1A) of the inner conductor 12A, the piezoelectric yarn 140A is wound in a left-handed manner from the near front side to the far side of the inner conductor 12A. The piezoelectric yarn 140A comprises an optically active polypeptide fiber.
The spiral angle β1 is an angle between the direction of the spiral axis G1 (the axial direction of the inner conductor 12A) and the longitudinal direction of the piezoelectric yarn 140A in a side view.
The elastic modulus Y (GPa) of the piezoelectric layer 14A is 1.0GPa to 8.0 GPa.
Thus, the piezoelectric substrate 10A is excellent in piezoelectric sensitivity.
In fig. 1A, a double-headed arrow E1 indicates a main orientation direction of the optically active polypeptide contained in the piezoelectric layer 14A. That is, in embodiment 1 of embodiment 1, the main orientation direction of the optically active polypeptide included in the piezoelectric yarn 140A is substantially parallel to the longitudinal direction of the piezoelectric yarn 140A.
The operational effects of the piezoelectric substrate 10A will be described below.
For example, when tension is applied in the longitudinal direction of the piezoelectric substrate 10A, shear stress is applied to the optically active polypeptide contained in the piezoelectric layer 14A, and the optically active polypeptide is polarized. The polarization of the optically active polypeptide is thought to be generated by matching the phase to the radial direction of the piezoelectric substrate 10A as indicated by the arrow in fig. 1B. Thus, the piezoelectric property of the piezoelectric substrate 10A is exhibited. Further, the piezoelectric substrate 10A is excellent in piezoelectric sensitivity.
(1.1.8) the piezoelectric substrate according to embodiment 2 of claim 1
A piezoelectric substrate 20A according to embodiment 2 of claim 1 will be described with reference to fig. 2. Fig. 2 is a schematic side view showing the appearance of the piezoelectric substrate 20A according to embodiment 2 of embodiment 1.
The piezoelectric substrate 20A according to embodiment 2 of claim 1 is different from the piezoelectric substrate 10A according to embodiment 1 of claim 1 in that the piezoelectric substrate is provided with an external conductor 22A.
As shown in fig. 2, the piezoelectric substrate 20A according to embodiment 2 of claim 1 includes an inner conductor 12A, a piezoelectric layer 14A, and an outer conductor 22A. The outer conductor 22A is disposed on the outer peripheral side of the piezoelectric layer 14A. The outer conductor 22A is formed by winding a copper foil coil in a spiral shape around the piezoelectric yarn 140A (on the outer peripheral surface of the piezoelectric layer 14A) wound in a spiral shape around the inner conductor 12A (on the outer peripheral surface). The inner conductor 12A and the outer conductor 22A are not electrically connected.
As shown in fig. 2, embodiment 2 of embodiment 1 is configured such that the end of the piezoelectric layer 14A (i.e., the piezoelectric yarn 140A wound in a spiral shape) is displaced from the end of the external conductor 22A in side view. Thereby, the inner conductor 12A and the outer conductor 22A are reliably insulated. However, the positions of the end portions do not necessarily need to be offset, and the end portions may be overlapped in side view as long as the inner conductor 12A and the outer conductor 22A are electrically insulated.
The piezoelectric substrate 20A achieves the same operational effects as those of the piezoelectric substrate 10A.
Further, since the piezoelectric substrate 20A includes the internal conductor 12A, the electrical signal (voltage signal or charge signal) generated in the piezoelectric layer 14A can be more easily extracted through the internal conductor 12A.
Further, since the piezoelectric substrate 20A includes the outer conductor 22A, the inside of the piezoelectric substrate 20A (the piezoelectric layer 14A and the inner conductor 12A) can be electrostatically shielded by the outer conductor 22A. Therefore, the voltage change of the inner conductor 12A due to the influence of static electricity outside the piezoelectric substrate 20A can be suppressed, and as a result, more stable piezoelectricity can be obtained.
(1.1.9) use of piezoelectric substrate
The application of the piezoelectric substrate according to embodiment 1 of the present disclosure is not particularly limited, and examples thereof include a force sensor, a pressure sensor, a displacement sensor, a deformation sensor, an operation sensor, a vibration sensor, an impact sensor, an ultrasonic sensor, an actuator, and an energy collector.
The application of the piezoelectric substrate according to embodiment 1 of the present disclosure is the same application as that of the piezoelectric substrate described in patent document 1,
(1.2) sensor
The sensor according to claim 1 of the present disclosure includes the piezoelectric substrate according to claim 1 of the present disclosure.
Since the sensor according to claim 1 of the present disclosure includes the piezoelectric substrate according to claim 1 of the present disclosure, the piezoelectric sensitivity is excellent.
The sensor according to embodiment 1 of the present disclosure includes a force sensor, a pressure sensor, a displacement sensor, a deformation sensor, a motion sensor, a vibration sensor, an impact sensor, an ultrasonic sensor, and the like.
(1.3) actuator
The actuator according to claim 1 of the present disclosure includes the piezoelectric substrate according to claim 1 of the present disclosure.
Since the actuator according to claim 1 of the present disclosure includes the piezoelectric substrate according to claim 1 of the present disclosure, the piezoelectric sensitivity is excellent.
(1.4) biological information acquisition apparatus
The biological information acquisition device according to claim 1 of the present disclosure includes the piezoelectric substrate according to claim 1 of the present disclosure.
The biological information acquiring apparatus according to claim 1 of the present disclosure detects a biological signal of a subject or a test animal (hereinafter, these will be collectively referred to as "subject") using the piezoelectric substrate according to claim 1 of the present disclosure, thereby acquiring biological information of the subject.
Examples of the biological signal include a body movement, a pulse signal (heart rate signal), a respiration signal, a body movement signal, a heart shock, and a biological tremor. Organism tremor is a regular involuntary movement of a body part (finger, hand, forearm, upper limb, etc.). The detection of ballistocardiographs also includes the detection of force effects caused by the body's cardiac function. That is, when the heart pumps blood to the aorta and the pulmonary artery, the body is subjected to a reaction force in a direction opposite to the blood flow. The magnitude and direction of this reaction force varies with the functional phase of the heart. The reaction force can be detected by sensing a ballistocardiogram outside the body.
An article to which the biological information acquisition device according to embodiment 1 of the present disclosure is disposed is similar to an article to which the biological information acquisition device described in patent document 1 is disposed.
The biological information acquiring apparatus according to claim 1 of the present disclosure may be used by being embedded in a seat, a steering device, a seat belt, a shift knob, a armrest, a head rest, a steering wheel, or a garment or a hat worn by a driver. The biological information acquiring apparatus according to claim 1 of the present disclosure is suitable for use as a detection unit of an information processing apparatus. The information processing apparatus acquires a biological signal of a subject from the biological information acquisition apparatus according to claim 1 of the present disclosure, and detects abnormality detection, physical condition abnormality, and the like of the subject based on the acquired biological signal by artificial intelligence (AI: artificial Intelligence). The AI includes a learned model.
(2) Mode 2
(2.1) piezoelectric substrate
The piezoelectric substrate according to claim 2 of the present disclosure includes an elongated inner conductor and a piezoelectric layer covering an outer peripheral surface of the inner conductor. The piezoelectric layer is formed by winding a long piezoelectric body around the inner conductor, and is not fixed to the inner conductor. The long piezoelectric body includes a plurality of piezoelectric yarns and a bundling body bundling the plurality of piezoelectric yarns. At least 1 of the plurality of piezoelectric yarns comprises an optically active polypeptide fiber representing a fiber formed from an optically active polypeptide.
Preferably, the longitudinal direction of the long piezoelectric body is substantially parallel to the main orientation direction of the optically active polypeptide.
The degree of orientation F of the optically active polypeptide fiber, as determined by X-ray diffraction using the following formula (a), is preferably 0.50 or more and less than 1.00.
Degree of orientation f= (180 ° - α)/180 ° … formula (a)
[ in formula (a), α represents a half-width (°) of a peak from orientation. A kind of electronic device
In the present disclosure, "not fixed to the internal conductor" means that the piezoelectric layer is mechanically integrated with the internal conductor without using an adhesive or the like.
The terms "piezoelectric yarn", "optically active polypeptide" and "substantially parallel" in embodiment 2 are the same as those in embodiment 1.
In the present disclosure, the degree of orientation F of the optically active polypeptide fiber is an index indicating the degree of orientation of the optically active polypeptide contained in the piezoelectric yarn.
Since the piezoelectric substrate according to claim 2 of the present disclosure includes the above-described configuration, the terminal mounting preparation can be performed more efficiently than the conventional piezoelectric substrate described in patent document 1, and the piezoelectric sensitivity is excellent.
(2.1.1) piezoelectric layer
The piezoelectric substrate according to claim 2 of the present disclosure includes a piezoelectric layer.
The piezoelectric layer covers the outer peripheral surface of the inner conductor. The piezoelectric layer preferably covers the entire outer peripheral surface of the inner conductor.
The thickness of the piezoelectric layer is not particularly limited, but is preferably 0.02mm to 2.00mm, more preferably 0.05mm to 0.50 mm. From the viewpoint of improving the piezoelectric sensitivity of the piezoelectric substrate, the thickness of the piezoelectric layer is preferably the same as that of the elongated piezoelectric body.
The piezoelectric layer is not fixed to the inner conductor. In this way, the piezoelectric layer can be easily removed from the inner conductor when the terminal mounting preparation of the piezoelectric substrate is performed, as compared with a configuration in which the piezoelectric layer and the inner conductor are mechanically integrated. In this case, the internal conductor is not mechanically integrated with the piezoelectric layer, and therefore is not easily broken. As a result, the piezoelectric substrate can be efficiently prepared for terminal mounting of the piezoelectric substrate.
Furthermore, the piezoelectric layer can be displaced relative to the inner conductor in the axial direction of the inner conductor. Thus, if external stress acts on the piezoelectric substrate, the piezoelectric substrate is more likely to deform than conventional piezoelectric substrates. Therefore, the internal stress of the piezoelectric substrate due to the external stress is not easily concentrated locally. As a result, the piezoelectric substrate has durability superior to that of the conventional piezoelectric substrate.
The piezoelectric layer is formed by winding a long piezoelectric body around an inner conductor.
The elongated piezoelectric body may be directly wound around the outer peripheral surface of the inner conductor. In the case where an inner insulator described later is disposed on the outer peripheral surface of the inner conductor, the long piezoelectric body may be wound around the outer peripheral surface of the inner insulator so as to be indirectly wound around the inner conductor.
The long piezoelectric body wound around the outer peripheral surface of the inner conductor may be mechanically integrated as long as the piezoelectric layer is not fixed to the inner conductor. This improves the mechanical strength of the piezoelectric layer. Examples of the method of mechanically integrating the long piezoelectric body wound around the outer peripheral surface of the inner conductor include: a method of applying a known adhesive to a surface of the long piezoelectric body wound around the outer peripheral surface of the inner conductor on the opposite side to the inner conductor, and bonding the long piezoelectric body wound around the outer peripheral surface of the inner conductor by adhesion, and the like.
The winding method of the long piezoelectric body is not particularly limited, and the long piezoelectric body may be spirally wound around the inner conductor with respect to the axial direction of the inner conductor, or may not be spirally wound with respect to the axial direction of the inner conductor. Among them, in the winding method of the long piezoelectric body, from the viewpoint of improving the piezoelectric sensitivity of the piezoelectric substrate, the long piezoelectric body is preferably spirally wound around the inner conductor with respect to the axial direction of the inner conductor. The elongated piezoelectric bodies may be wound so as to overlap each other or may not overlap each other.
In the piezoelectric substrate according to claim 2 of the present disclosure, the charge is easily generated by applying a shear stress to the long piezoelectric body wound in a spiral shape. Thus, piezoelectricity is easily exhibited.
The shear stress for the long-strip-shaped piezoelectric body may be applied by, for example, the 1 st non-plastic deformation, the 2 nd non-plastic deformation, the 3 rd non-plastic deformation, or the like.
The 1 st non-plastic deformation means stretching the whole of the long piezoelectric body wound in a spiral shape in the direction of the spiral axis.
The 2 nd non-plastic deformation means twisting a part of the elongated piezoelectric body wound in a spiral shape (i.e., twisting a part of the elongated piezoelectric body around the spiral axis).
The 3 rd non-plastic deformation means bending a part or the whole of the long piezoelectric body wound in a spiral shape.
The elongated piezoelectric body is preferably wound in a spiral shape on the inner conductor in one direction.
The term "wound in one direction in a spiral shape" in embodiment 2 is the same as that in embodiment 1.
When the long piezoelectric body is wound in a spiral shape in one direction, a phenomenon in which polarities of generated charges cancel each other (that is, a phenomenon in which piezoelectricity is reduced) is suppressed. Thus, the piezoelectricity of the piezoelectric substrate is further improved.
The piezoelectric substrate includes a long piezoelectric body wound in a spiral shape in one direction, and includes not only a layer including a layer formed of a long piezoelectric body but also a layer formed of a long piezoelectric body stacked in multiple layers.
Examples of the method of stacking layers of the long piezoelectric body in multiple layers include the following methods: the layer of the second layer formed of the elongated piezoelectric body is wound in a spiral shape in the same direction as the one direction so as to be overlapped on the layer of the first layer formed of the elongated piezoelectric body wound in the spiral shape in the one direction.
As a mode of the piezoelectric substrate, the following modes can be mentioned: the long piezoelectric body includes a 1 st long piezoelectric body wound in a spiral shape in one direction, and a 2 nd long piezoelectric body wound in a spiral shape in a direction different from the one direction. In this embodiment, the chirality of the optically active polypeptide contained in the 1 st long piezoelectric body and the chirality of the optically active polypeptide contained in the 2 nd long piezoelectric body are different from each other.
The helix angle is preferably 20 ° to 70 °, more preferably 25 ° to 65 °, and still more preferably 30 ° to 60 °.
The term "helix angle" in embodiment 2 is the same as that in embodiment 1.
(2.1.1.1) elongated piezoelectric body
The strip-shaped piezoelectric body is provided with a plurality of piezoelectric yarns and a cluster body. The bundling body bundles a plurality of piezoelectric yarns. The piezoelectric yarns bundled by the bundling body may be aligned or may be random. For example, the plurality of piezoelectric yarns may be intentionally processed and bundled by the bundle so that the longitudinal direction of each of the plurality of piezoelectric yarns is one direction, or may be randomly bundled by the bundle.
The elastic modulus Y of the long piezoelectric body is preferably 1GPa to 10 GPa.
In order for the shear stress to effectively act on the piezoelectric yarn when deforming the piezoelectric layer in the tensile direction, the bundle body needs to have rigidity less likely to deform than the piezoelectric yarn. By setting the elastic modulus Y of the long piezoelectric body to be within the above range, when an external stress is applied to the piezoelectric layer, the stress is easily and effectively transmitted to the piezoelectric yarn. That is, if the elastic modulus of the long piezoelectric body is within the above range, the piezoelectric sensitivity of the piezoelectric substrate is improved. In addition, the durability of the piezoelectric substrate is more excellent, and the piezoelectric substrate can be more efficiently prepared for terminal mounting.
From the viewpoints of the piezoelectric sensitivity of the piezoelectric substrate and the workability of winding the long piezoelectric body, the elastic modulus Y of the long piezoelectric body is more preferably 1GPa to 10GPa, and still more preferably 2GPa to 10 GPa.
The elastic modulus Y of the long piezoelectric body was measured by a microhardness meter (according to JIS Z2255). The measurement environment of the microhardness meter (according to JIS Z2255) was 23.+ -. 2 ℃ and 50.+ -. 5 ℃ in humidity.
The shape of the elongated piezoelectric body may be, for example, a belt shape. "ribbon shape" means a flat and elongated shape.
The size of the long-strip-shaped piezoelectric body is not particularly limited.
Preferably, the thickness of the elongated piezoelectric body is 0.001mm to 0.4mm, the width of the elongated piezoelectric body is 0.1mm to 30mm, and the ratio of the width of the elongated piezoelectric body to the thickness of the elongated piezoelectric body is 2 or more.
The thickness of the long piezoelectric body is more preferably 0.02mm to 0.4mm, and still more preferably 0.05mm to 0.2mm, from the viewpoints of the piezoelectric sensitivity of the piezoelectric substrate and the mechanical strength of the piezoelectric substrate.
The width of the long piezoelectric body is more preferably 0.1mm to 5.0mm, and still more preferably 0.4mm to 1.0mm, from the viewpoints of piezoelectric sensitivity of the piezoelectric substrate and miniaturization of the piezoelectric substrate.
From the viewpoints of piezoelectric sensitivity of the piezoelectric substrate and miniaturization of the piezoelectric substrate, the ratio of the width of the elongated piezoelectric body to the thickness of the elongated piezoelectric body is more preferably 2 to 20, and still more preferably 3 to 10.
In the long piezoelectric body, the arrangement relation between the plurality of piezoelectric yarns and the bundling body is not particularly limited, but the bundling body preferably bundles the plurality of piezoelectric yarns in a state in which the plurality of piezoelectric yarns are juxtaposed in a direction orthogonal to the longitudinal direction of the plurality of piezoelectric yarns and adjacent piezoelectric yarns among the plurality of piezoelectric yarns are brought into contact with each other. In other words, the arrangement state of the plurality of piezoelectric yarns is preferably maintained in a predetermined state by the bundling body. The predetermined state means a state in which the plurality of piezoelectric yarns are aligned in a direction orthogonal to the longitudinal direction of the plurality of piezoelectric yarns and adjacent ones of the plurality of piezoelectric yarns are in contact with each other. This improves the piezoelectric sensitivity of the piezoelectric substrate.
The number of the piezoelectric yarns may be appropriately selected depending on the application of the piezoelectric substrate, etc., and is preferably 2 to 20, more preferably 2 to 8, from the viewpoint of processability.
The long piezoelectric body may be produced by slitting a long piezoelectric body precursor produced in a wide width.
(2.1.1.1.1) piezoelectric yarn
At least 1 of the plurality of piezoelectric yarns comprises an optically active polypeptide fiber. The inclusion of optically active polypeptides in the piezoelectric yarn contributes to the piezoelectricity of the piezoelectric substrate. The piezoelectric yarn according to claim 2 is similar to the piezoelectric yarn exemplified as the piezoelectric yarn according to claim 1.
Each of the plurality of piezoelectric yarns includes a plurality of optically active polypeptide fibers, and the twist number of each of the plurality of piezoelectric yarns is preferably 500T/m or less, more preferably 300T/m or less. When the number of turns of each of the plurality of piezoelectric yarns is within this range, the piezoelectric yarn becomes less likely to break, and the piezoelectric substrate is more excellent in piezoelectric sensitivity.
(2.1.1.1.1.1) optically active polypeptide fiber
The optically active polypeptide fiber of the 2 nd aspect is the same as the optically active polypeptide fiber exemplified as the optically active polypeptide fiber of the 1 st aspect.
The degree of orientation F of the optically active polypeptide fiber is preferably in the range of 0.50 or more and less than 1.00. The technical reason why the degree of orientation F of the 2 nd aspect is within the above-mentioned range, the preferable range of the degree of orientation F, and the method for measuring the degree of orientation F are the same as those of the 1 st aspect.
The longitudinal direction of the elongated piezoelectric body is preferably substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn.
The presence of piezoelectricity of the piezoelectric substrate is facilitated by the fact that the longitudinal direction of the elongated piezoelectric body is substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn.
The fact that the longitudinal direction of the long piezoelectric body is substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn means that the long piezoelectric body is excellent in tensile strength in the longitudinal direction thereof. Therefore, when the long piezoelectric body is wound in a spiral shape, the piezoelectric yarn is not easily broken.
For example, in the case where the piezoelectric yarn is silk or spider silk, the longitudinal direction of the piezoelectric yarn (silk or spider silk) is substantially parallel to the main orientation direction of an optically active polypeptide (for example, fibroin or spider silk protein) contained in the piezoelectric yarn during the production of the silk or spider silk.
The longitudinal direction of the long piezoelectric body is substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn, and can be confirmed by comparing the direction in which the sample (long piezoelectric body) is disposed and the azimuth angle of the crystal peak in the X-ray diffraction measurement.
Examples of the method for making the longitudinal direction of the long piezoelectric body substantially parallel to the main orientation direction of the optically active polypeptide contained in the piezoelectric yarn include: and a method in which a plurality of specific piezoelectric yarns are arranged in parallel in a direction orthogonal to the longitudinal direction of the specific piezoelectric yarns when the elongated piezoelectric body is manufactured. A particular piezoelectric yarn represents a twisted yarn comprising a plurality of particular optically active polypeptide fibers. The specific optically active polypeptide fiber means an optically active polypeptide fiber having an orientation degree F of 0.80 or more and less than 1.00.
From the viewpoints of piezoelectricity of the piezoelectric yarn and strength of the piezoelectric yarn, the optically active polypeptide preferably has a β -sheet structure.
The optically active polypeptide preferably comprises at least one of a fibroin and a spider silk protein, preferably comprises a fibroin.
From the viewpoint of piezoelectricity, the optically active polypeptide fiber preferably comprises at least one of silk and spider silk, more preferably is formed of at least one of silk and spider silk, and particularly preferably is formed of silk.
As silk, raw silk or refined silk is preferable, and refined silk is particularly preferable.
(2.1.1.1.2) bundling body
The bundling body bundles a plurality of piezoelectric yarns. That is, the bundling body is integrated with the plurality of piezoelectric yarns.
Thus, when an external stress is applied to the piezoelectric substrate, a shear stress due to the external stress is likely to act on the piezoelectric yarn.
The bundling body is not particularly limited as long as a plurality of piezoelectric yarns can be bundled, and examples thereof include an adhesive body, a shrink film, and the like.
When a shrink film is used as the bundling body, for example, a plurality of piezoelectric yarns are stored in a bag body formed of the shrink film, and the bag body is heated to shrink the bag body, thereby obtaining a long-shaped piezoelectric body.
When an adhesive is used as the bundling body, for example, an adhesive is impregnated into the plurality of piezoelectric yarns, and the plurality of piezoelectric yarns are adhesively bonded to each other, whereby an elongated piezoelectric body using the adhesive is obtained. In this case, the adhesive may cover the entire outer peripheral surface of each of the plurality of piezoelectric yarns, or may cover a part of the outer peripheral surface of each of the plurality of piezoelectric yarns. The adhesive body may be formed only in a gap portion formed by outer peripheries of adjacent piezoelectric yarns out of the plurality of piezoelectric yarns, the outer peripheries facing each other.
The bundling body (i.e., the adhesive body) is preferably formed of at least one selected from the group consisting of an epoxy-based adhesive, a urethane-based adhesive, a vinyl acetate resin emulsion-based adhesive, an ethylene vinyl acetate emulsion-based adhesive, an acrylic resin emulsion-based adhesive, a styrene butadiene rubber latex-based adhesive, a silicone resin-based adhesive, an α -olefin-based adhesive, a vinyl chloride resin solvent-based adhesive, a rubber-based adhesive, an elastic adhesive, a chloroprene rubber solvent-based adhesive, a nitrile rubber solvent-based adhesive, and a cyanoacrylate-based adhesive. Thus, the piezoelectric yarns are integrated, and the piezoelectric yarns can function as a piezoelectric layer.
(2.1.2) inner conductor
The piezoelectric substrate according to claim 2 of the present disclosure includes an elongated inner conductor.
The piezoelectric substrate according to claim 2 is similar to the piezoelectric substrate exemplified as the piezoelectric substrate according to claim 1.
(2.1.3) outer conductor
From the viewpoint of improving the piezoelectric sensitivity and electrostatic shielding property, the piezoelectric substrate according to claim 2 of the present disclosure may further include an external conductor. The outer conductor is disposed on the outer peripheral side of the piezoelectric layer. The inner conductor and the outer conductor are not electrically connected.
The external conductor of claim 2 is similar to the external conductor exemplified as the external conductor of claim 1.
(2.1.4) an electrical insulator
The piezoelectric substrate according to claim 2 of the present disclosure may further include an electrical insulator (hereinafter, referred to as "1 st insulator"). The 1 st insulator is disposed on the outermost periphery of the piezoelectric substrate. In other words, at least a part of the outer peripheral surface of the piezoelectric substrate is constituted by the 1 st insulator.
The 1 st insulator of claim 2 is the same as the 1 st insulator exemplified as the 1 st insulator of claim 1.
(2.1.5) inner electrical insulation
In the case where the piezoelectric substrate according to claim 2 of the present disclosure includes an outer conductor, an inner insulator (hereinafter, referred to as "the 2 nd insulator") may be further provided. The 2 nd insulator is disposed between at least one of the piezoelectric layer and the inner conductor and between the piezoelectric layer and the outer conductor, for example.
This can further suppress occurrence of a short circuit between the inner conductor and the outer conductor.
The 2 nd insulator of the 2 nd aspect is the same as the 2 nd insulator exemplified as the 2 nd insulator of the 1 st aspect.
(2.1.6) functional layer
The piezoelectric substrate according to claim 2 of the present disclosure may further include a functional layer. In the case where the piezoelectric substrate according to claim 2 of the present disclosure does not include an external conductor, the functional layer is disposed between the piezoelectric layer and the internal conductor. In the case where the piezoelectric substrate according to claim 2 of the present disclosure includes the external conductor, the functional layer is disposed between at least one of the piezoelectric layer and the internal conductor, and between the piezoelectric layer and the external conductor.
The functional layer of the 2 nd aspect is the same as the functional layer exemplified as the functional layer of the 1 st aspect.
Hereinafter, a specific example of the piezoelectric substrate according to embodiment 2 will be described with reference to the drawings, but the piezoelectric substrate according to embodiment 2 of the present disclosure is not limited to the following specific example.
Substantially the same elements are denoted by the same reference numerals throughout the drawings, and the description is not repeated.
(2.1.7) the piezoelectric substrate according to embodiment 1 of claim 2
A piezoelectric substrate 10B according to embodiment 1 of embodiment 2 will be described with reference to fig. 3A to 3D. Fig. 3A is a schematic side view showing an appearance of a piezoelectric substrate 10B according to embodiment 1 of embodiment 2 of the present disclosure. Fig. 3B is a schematic front view showing the appearance of the long piezoelectric body 140B according to embodiment 1 of embodiment 2 of the present disclosure. Fig. 3C is a cross-sectional view of the IC-IC line of fig. 3B. Fig. 3D is a cross-sectional view of the IC-IC line of fig. 3A.
As shown in fig. 3A, the piezoelectric substrate 10B according to embodiment 1 of claim 2 includes an elongated inner conductor 12B and a piezoelectric layer 14B. The piezoelectric layer 14B is wound in a spiral shape in one direction with no gap from one end to the other end along the outer peripheral surface of the inner conductor 12B at a spiral angle β1. The piezoelectric layer 14B is not fixed to the inner conductor 12B.
The piezoelectric layer 14B is formed by winding the elongated piezoelectric body 140B around the outer peripheral surface of the inner conductor 12B in a left-handed manner with respect to the inner conductor 12B. Specifically, when the piezoelectric substrate 10B is viewed from one end side (right end side in fig. 3A) in the axial direction of the inner conductor 12B, the long piezoelectric body 140B is wound in a left-handed manner from the near front side to the far side of the inner conductor 12B.
The spiral angle β1 is an angle between the direction of the spiral axis G1 (the axial direction of the inner conductor 12B) and the longitudinal direction of the long piezoelectric body 140B in a side view.
As shown in fig. 3B, the long piezoelectric body 140B is formed of 4 piezoelectric yarns 141 and a cluster 142. In embodiment 1 of embodiment 2, the piezoelectric yarn 141 is a twisted yarn formed of a plurality of optically active polypeptides. The bundle 142 is formed of a cyanoacrylate-based adhesive. The 4 piezoelectric yarns 141 are juxtaposed in a direction orthogonal to the longitudinal direction of the piezoelectric yarns 141. Adjacent ones 141 of the 4 piezoelectric yarns 141 are in contact with each other. The bundle 142 maintains the above-described arrangement of 4 piezoelectric yarns 141. Specifically, as shown in fig. 3C, the gap portion is formed only in a part of the outer peripheral surface of the adjacent piezoelectric yarns 141 out of the 4 piezoelectric yarns 141 facing each other.
Thus, the piezoelectric substrate 10B can be efficiently prepared for terminal mounting.
In fig. 3A, a double-headed arrow E1 indicates a main orientation direction of the optically active polypeptide contained in the piezoelectric layer 14B. That is, in embodiment 1 of claim 2, the main alignment direction of the optically active polypeptide is substantially parallel to the longitudinal direction of the long piezoelectric body 140B.
The operational effects of the piezoelectric substrate 10B will be described below.
For example, when tension is applied in the longitudinal direction of the piezoelectric substrate 10B, shear stress is applied to the optically active polypeptide contained in the piezoelectric layer 14B, and the optically active polypeptide is polarized. The polarization of the optically active polypeptide is thought to be generated by matching the phase to the radial direction of the piezoelectric substrate 10B as indicated by the arrow in fig. 3D. Thus, the piezoelectric property of the piezoelectric substrate 10B is exhibited. Further, the piezoelectric substrate 10B is excellent in piezoelectric sensitivity.
(2.1.8) the piezoelectric substrate according to embodiment 2 of claim 2
A piezoelectric substrate 20B according to embodiment 2 of claim 2 will be described with reference to fig. 4. Fig. 4 is a schematic side view showing the appearance of a piezoelectric substrate 20B according to embodiment 2 of claim 2.
The piezoelectric substrate 20B according to embodiment 2 of claim 2 is different from the piezoelectric substrate 10B according to embodiment 1 of claim 2 in that the piezoelectric substrate is provided with an external conductor 22B.
As shown in fig. 4, the piezoelectric substrate 20B according to embodiment 2 of claim 2 includes an inner conductor 12B, a piezoelectric layer 14B, and an outer conductor 22B. The outer conductor 22B is disposed on the outer peripheral side of the piezoelectric layer 14B. The outer conductor 22B is formed by winding a copper foil coil in a spiral shape around the long piezoelectric body 140B (on the outer peripheral surface of the piezoelectric layer 14B) spirally wound around the inner conductor 12B (on the outer peripheral surface). The inner conductor 12B and the outer conductor 22B are not electrically connected. The piezoelectric layer 14B is not fixed to the inner conductor 12B. The outer conductor 22B is not fixed to the piezoelectric layer 14B.
As shown in fig. 4, in embodiment 2 of embodiment 2, the end of the piezoelectric layer 14B (i.e., the long piezoelectric body 140B wound in a spiral shape) is displaced from the end of the external conductor 22B in side view. Thereby, the inner conductor 12B and the outer conductor 22B are reliably insulated. However, the positions of the end portions do not necessarily need to be offset, and the end portions may be overlapped in side view as long as the inner conductor 12B and the outer conductor 22B are electrically insulated.
The piezoelectric substrate 20B achieves the same operational effects as those of the piezoelectric substrate 10B.
Further, since the piezoelectric substrate 20B includes the internal conductor 12B, the electrical signal (voltage signal or charge signal) generated in the piezoelectric layer 14B can be more easily extracted through the internal conductor 12B.
Further, since the piezoelectric substrate 20B includes the outer conductor 22B, the inside (the piezoelectric layer 14B and the inner conductor 12B) of the piezoelectric substrate 20B can be electrostatically shielded by the outer conductor 22B. Therefore, the voltage change of the inner conductor 12B due to the influence of static electricity outside the piezoelectric substrate 20B can be suppressed, and as a result, more stable piezoelectricity can be obtained.
(2.1.9) use of piezoelectric substrates
The application of the piezoelectric substrate according to claim 2 of the present disclosure is the same as the application exemplified as the application of the piezoelectric substrate according to claim 1.
(2.2) sensor
The sensor according to claim 2 of the present disclosure includes the piezoelectric substrate according to claim 2 of the present disclosure.
Since the sensor according to claim 2 of the present disclosure includes the piezoelectric substrate according to claim 2 of the present disclosure, the piezoelectric sensitivity is excellent.
As the sensor of the 2 nd aspect of the present disclosure, a force sensor, a pressure sensor, a displacement sensor, a deformation sensor, an action sensor, a vibration sensor, an impact sensor, an ultrasonic sensor, and the like are exemplified.
(2.3) actuator
The actuator according to claim 2 of the present disclosure includes the piezoelectric substrate according to claim 2 of the present disclosure.
Since the actuator of claim 2 of the present disclosure includes the piezoelectric substrate of claim 2 of the present disclosure, the piezoelectric sensitivity is excellent.
(2.4) biological information acquisition device
The biological information acquiring apparatus according to claim 2 of the present disclosure includes the piezoelectric substrate according to claim 2 of the present disclosure.
The biological information acquiring apparatus according to claim 2 of the present disclosure detects a biological signal of a subject or a test animal (hereinafter, these will be collectively referred to as "subject") using the piezoelectric substrate according to claim 2 of the present disclosure, thereby acquiring biological information of the subject.
The biological signal, the article on which the biological information acquisition device is disposed, and the use of the biological information acquisition device according to claim 2 are the same as those exemplified in claim 1.
Examples
Hereinafter, embodiments according to the present invention will be described in detail with reference to examples. The present invention is not limited to the description of these examples.
Examples 1 to 4 and comparative examples 1 to 4 correspond to embodiment 1 of the present disclosure, and examples 5 and comparative example 5 correspond to embodiment 2 of the present disclosure.
Example 1
< preparation of optically active polypeptide fiber >
Raw silk is prepared as an optically active polypeptide fiber. Raw silk is a long fiber formed from an optically active polypeptide. The raw silk was 21 denier. The thickness of raw silk is 0.06 mm-0.04 mm.
(measurement of degree of orientation F of optically active polypeptide fiber)
The azimuth distribution intensity of the crystal plane peak [2θ=20° ] was measured by fixing raw silk (optically active polypeptide fiber) on a support table using a wide angle X-ray diffraction device ("RINT 2550" manufactured by Rigaku corporation, accessory device: rotary sample table, X-ray source: cukα, output: 40kv 370ma, detector: scintillation counter).
In the obtained azimuth distribution curve (X-ray interference pattern), the degree of orientation F (c-axis orientation) of raw silk (optically active polypeptide fiber) was calculated from the following formula (a) based on the half-peak width (α) of the peak.
The degree of orientation F of the optically active polypeptide fiber was 0.91.
Degree of orientation (F) = (180 ° - α)/180 ° … (a)
(alpha is the half-width of the peak from orientation)
< preparation of piezoelectric yarn >
The raw silk is refined into 6 filaments with single twist (the number of twists is 150T/m) by a known method to be used as the piezoelectric yarn, thereby manufacturing refined silk. The degree of orientation F of the twisted filaments of the refined silk was 0.86.
Since the degree of orientation F of the optically active polypeptide fiber was 0.86 and 6 filaments (piezoelectric yarns) were produced by single twisting using purified silk, it was estimated that the longitudinal direction of the piezoelectric yarns was substantially parallel to the main orientation direction of the optically active polypeptide contained in the purified silk (optically active polypeptide fiber).
< preparation of double-layer piezoelectric substrate >
As an internal conductor, a "U24-01-00" yarn (yarn diameter: 0.26mm, length: 200 mm) was prepared from Ming's Industrial production, inc.
The piezoelectric yarn is wound around the outer peripheral surface of the inner conductor so that the spiral angle becomes about 45 ° and so that no gap is left-handed as much as possible. Thus, a layer (hereinafter, referred to as "piezoelectric yarn layer") was formed on the outer peripheral surface of the inner conductor, and a piezoelectric substrate precursor was obtained. The piezoelectric yarn layer covers the entire outer peripheral surface of the inner conductor. That is, the outer peripheral surface of the inner conductor is not exposed.
The term "left-handed" means that the piezoelectric yarn is wound in a left-handed manner from the proximal side toward the distal side of the inner conductor (the nylon yarn) when viewed from one end in the axial direction of the inner conductor. The "helix angle" refers to an angle formed by the longitudinal direction of the piezoelectric yarn with respect to the axial direction of the inner conductor.
As a bundling agent, "901H3" (cyanoacrylate-based adhesive) manufactured by Toyama Synthesis Co., ltd.
A bundling agent (cyanoacrylate-based adhesive) is dropped onto the outer peripheral surface of the piezoelectric yarn layer of the piezoelectric substrate precursor so as to permeate into the inside of the piezoelectric yarn. Then, the extra amount of the bundling agent was immediately wiped off the outer peripheral surface of the piezoelectric yarn by a dust-free wiping paper, and the bundling agent was allowed to stand at room temperature to cure. Thus, a piezoelectric yarn layer forms a piezoelectric layer, and a double-layer piezoelectric substrate is obtained.
At this time, a part of the piezoelectric layer is in close contact with the inner conductor, but is not fixed to the inner conductor. That is, the piezoelectric layer and the inner conductor are not mechanically integrated. Therefore, the piezoelectric layer can be easily removed from the inner conductor.
To determine the elastic modulus of the piezoelectric layer, a portion of the double-layer piezoelectric substrate was cut to obtain a measurement sample (double-layer piezoelectric substrate).
The elastic modulus of the piezoelectric layer was measured by the following method using a measurement sample (double-layer piezoelectric substrate). The measurement results are shown in Table 1.
(measurement of elastic modulus Y of piezoelectric layer)
The elastic modulus Y of the piezoelectric layer was measured as the indentation elastic modulus of the piezoelectric layer by a method according to JIS Z2255 using a dynamic microhardness tester.
Specifically, the elastic modulus Y of the piezoelectric layer was evaluated by measurement of the indentation force from the outer peripheral surface of the piezoelectric layer of the measurement sample (double-layer piezoelectric substrate). The outer peripheral surface of the piezoelectric layer of the measurement sample (double-layer piezoelectric substrate) is a surface formed by impregnating and curing a piezoelectric yarn layer obtained by winding a piezoelectric yarn around the outer peripheral surface of the inner conductor with a bundling agent.
The apparatus used herein was a dynamic ultra-microhardness tester "DUH-211R" (manufactured by Shimadzu corporation), and was measured under soft test conditions using a triangular pyramid indenter (inter-prism angle 115 °) made of diamond at a temperature of 23.+ -. 2 ℃ and a humidity of 50.+ -. 5 ℃ as an indenter.
The elastic modulus Y of the piezoelectric layer is evaluated based on the degree of initial elastic recovery during load shedding, and is calculated using the following equations [ equation 1] to [ equation 4 ]. The elastic modulus Y used herein is a value calculated as an elastic modulus assuming 0 irrespective of the poisson's ratio of the measurement sample (double-layer piezoelectric substrate).
[ mathematics 1]
[ math figure 2]
[ math 3]
A＝23.97×h c 2
[ mathematics 4]
h c ＝h max -0.75×(h max -h r )
Each symbol in the following expressions 1 to 4 represents the following.
"Y" represents the elastic modulus (Pa) of the measurement sample including the Poisson's ratio. The calculation result of the elastic modulus includes a deviation from the ideal shape of the indenter as an error.
"E" means the elastic modulus (Pa) of the measurement sample.
“E i "means the elastic modulus of the diamond indenter (1.14X10) 12 Pa)。
“E r "means the composite elastic modulus (Pa) of the measurement sample and indenter.
"v" represents the poisson's ratio of the measured sample.
“v i "represents the poisson's ratio (0.07) of the diamond indenter.
"A" means the projected area of the indentation (m 2 )。
"dP/dh" represents the slope (N/m) at the beginning of the load shedding in the load-indentation depth map.
“h c "means the effective contact depth (m).
“h max "means the maximum press-in depth (m) (hereinafter, referred to as" depth 1 ").
“h r "represents an intersection point (m) of a tangential line at the start of unloading and a depth axis (hereinafter, referred to as" depth 3 ").
“h max- h r "means (depth 1) - (depth 3).
< preparation of three-layer piezoelectric substrate >
A part of the piezoelectric layer at both ends of the measured sample (double-layer piezoelectric substrate) after measurement of the elastic modulus Y of the piezoelectric layer was removed to expose the internal conductor. Crimp terminals are attached to both ends of the measurement sample (piezoelectric substrate) in a state where the internal conductor is exposed. Thus, a double-layer piezoelectric substrate with terminals was obtained. The pressure-bonding terminal is a fixing portion for evaluating the piezoelectric sensitivity of the piezoelectric substrate and a terminal for extracting the internal electrode. Here, the distance between the crimp terminals was adjusted to 150mm.
As the outer conductor, a rolled copper foil tape of rectangular cross section was prepared. The width of the rolled copper foil strip was 0.3mm. The thickness of the rolled copper foil strip was 30 μm.
The rolled copper foil tape is wound on the outer peripheral surface of the piezoelectric layer of the double-layer piezoelectric substrate with the terminal in a right-handed manner without any gap so that the piezoelectric layer is not exposed. Thus, a three-layer piezoelectric substrate was obtained. The outer conductor covers the entire outer peripheral surface of the piezoelectric layer. That is, the outer peripheral surface of the piezoelectric layer is not exposed. The external conductor is not fixed to the piezoelectric layer with an adhesive or the like.
A three-layer piezoelectric substrate was fabricated, operating as described above.
(measurement of the amount of charge generated per unit tensile force (piezoelectric sensitivity))
Using the three-layer piezoelectric substrate, the amount of charge (generated charge) generated when a tensile force is applied to the three-layer piezoelectric substrate was measured by the following method, and the generated charge (piezoelectric sensitivity) per unit tensile force was calculated from the generated charge. The results are shown in Table 1.
Specifically, the three-layer piezoelectric substrate was mounted on a tensile tester (a & D Company, ltd. Manufactured by "Tensilon RTG 1250") having a set distance between chucks of 50 mm.
Next, the charge amount generated on the front and back surfaces of the three-layer piezoelectric substrate at this time was measured by an electrometer (programmable ammeter "617" manufactured by Keithley corporation) using a tensile tester by periodically applying the three-layer piezoelectric substrate in a triangular wave shape at 0.5Hz in a stress range of 1.0N to 2.0N.
The amount of charge generated per unit tensile force is calculated as the piezoelectric sensitivity of the three-layer piezoelectric substrate from the slope of the straight line of the scattergram when the measured amount of charge generated QC is taken as the Y axis and the tensile force FN of the three-layer piezoelectric substrate is taken as the X axis.
The elastic modulus Y of the piezoelectric layer and the measurement result of the piezoelectric sensitivity of the three-layer piezoelectric substrate are shown in table 1.
Example 2
A three-layer piezoelectric substrate was produced and evaluated in the same manner as in example 1, except that a two-layer piezoelectric substrate was obtained by using a bundling agent (urethane-based adhesive a) instead of the bundling agent (cyanoacrylate-based adhesive) in the following manner. The elastic modulus Y of the piezoelectric layer and the measurement result of the piezoelectric sensitivity of the three-layer piezoelectric substrate are shown in table 1.
In example 2, a two-layer piezoelectric substrate was produced as follows.
MEK was added to a polyurethane resin solution (MT-OLESTER M37-50SS: manufactured by Sanjingjingku chemical Co., ltd.), and diluted to prepare a solution having a solid content of 25% by mass, to obtain a bundling agent (polyurethane adhesive A). A piezoelectric substrate precursor was obtained in the same manner as in example 1. Masking tapes are attached to terminal portions of both end portions of the piezoelectric substrate precursor for mounting the crimp terminals. The entire piezoelectric yarn layer of the piezoelectric substrate precursor was immersed in a tank filled with a bundling agent (polyurethane-based adhesive a) for 3 minutes. Then, the piezoelectric substrate precursor was lifted up from the tank filled with the bundling agent (polyurethane-based adhesive a), and the liquid hanging portion of the piezoelectric substrate precursor (bundling agent (polyurethane-based adhesive a) hanging from the piezoelectric substrate precursor) was removed by a dust-free wiping paper. The piezoelectric substrate precursor was then dried for 30 minutes using a dryer at 150 ℃. Thus, a two-layer piezoelectric substrate was obtained.
Example 3
A three-layer piezoelectric substrate was produced and evaluated in the same manner as in example 2, except that a bundling agent (melamine-based adhesive) obtained by diluting a melamine resin solution (manufactured by three-well chemical system) to a solid content of 30 mass% with an n-BuOH solution was used instead of the bundling agent (polyurethane-based adhesive a). The elastic modulus Y of the piezoelectric layer and the measurement result of the piezoelectric sensitivity of the three-layer piezoelectric substrate are shown in table 1.
Example 4
< preparation of optically active polypeptide fiber >
As the optically active polypeptide fiber, a wool yarn containing a synthetic Protein ("brew d Protein (registered trademark)") was prepared. The content of the synthetic protein was 30 mass% relative to the mass of the wool yarn. The thickness of the yarn containing the synthetic protein is about 0.5mm to 0.7 mm.
(measurement of degree of orientation F of optically active polypeptide fiber)
< preparation of piezoelectric yarn >
As for the degree of orientation F of the piezoelectric yarn, which is a yarn containing a synthetic protein, the degree of orientation F was measured by X-ray diffraction from a peak in the vicinity of 2θ=9° as a peak showing orientation, and was found to be 0.58 as in example 1.
A double-layer piezoelectric substrate and a three-layer piezoelectric substrate were produced and evaluated in the same manner as in example 1, except that 1 yarn containing synthetic protein was used instead of 6 yarns obtained by single twisting with refined silk. Table 2 shows the measurement results of the elastic modulus Y of the piezoelectric layer and the piezoelectric sensitivity of the three-layer piezoelectric substrate.
Comparative example 1
A three-layer piezoelectric substrate was produced and evaluated in the same manner as in example 1, except that a cyanoacrylate-based adhesive "201" (manufactured by eastern asia synthesis corporation) was used as the bundling agent (cyanoacrylate-based adhesive) instead of the bundling agent ("901H 3"). The elastic modulus Y of the piezoelectric layer and the measurement result of the piezoelectric sensitivity of the three-layer piezoelectric substrate are shown in table 1.
Comparative example 2
A three-layer piezoelectric substrate was produced and evaluated in the same manner as in example 2, except that the bundling agent (urethane-based adhesive B) prepared as described below was used instead of the bundling agent (urethane-based adhesive a). The elastic modulus Y of the piezoelectric layer and the measurement result of the piezoelectric sensitivity of the three-layer piezoelectric substrate are shown in table 1.
The bundling agent (polyurethane-based adhesive B) of comparative example 2 was prepared as follows.
"TAKELAC A-3210" (manufactured by Mitsui chemical Co., ltd.) and "TAK ENATE A-3070" (manufactured by Mitsui chemical Co., ltd.) were combined at 1:1, and mixing the mixture to obtain a mixed solution. Then, the mixed solution was diluted with ethyl acetate to prepare a solution having a solid content of 20 mass%, thereby obtaining a bundling agent (polyurethane-based adhesive B).
Comparative example 3
A three-layer piezoelectric substrate was produced and evaluated in the same manner as in example 2, except that the urethane adhesive C "take 6335" was used instead of the bundling agent (urethane adhesive a). The elastic modulus Y of the piezoelectric layer and the measurement result of the piezoelectric sensitivity of the three-layer piezoelectric substrate are shown in table 1.
Comparative example 4
A three-layer piezoelectric substrate was produced and evaluated in the same manner as in example 4, except that cyanoacrylate-based adhesive "201" (manufactured by eastern asia synthetic corporation) was used instead of the bundling agent ("901H 3"). Table 2 shows the measurement results of the elastic modulus Y of the piezoelectric layer and the piezoelectric sensitivity of the three-layer piezoelectric substrate.
< evaluation of deterioration when load is applied >
The three-layer piezoelectric substrate having a total length of 150mm in example 1 was set in a tensile testing machine for measuring piezoelectric sensitivity, and deterioration was evaluated when a load was applied to the three-layer piezoelectric substrate. Specifically, in a tensile testing machine provided with a three-layer piezoelectric substrate, the crosshead was gradually moved manually in the tensile direction and fixed at a position where the tensile load was 0.2N. The position was set to zero as the displacement reference point, and the operation of stretching 2mm from this position to the position of zero was repeated 100 times. At this time, the crosshead speed was set to 30mm/sec.
Before and after the test, sensitivity evaluation was performed in the same manner as in example 1, in which the applied load was applied to 1N to 2N, and the sensitivity after the test was divided by the sensitivity before the test to calculate the sensitivity change.
The same test was performed using the three-layer piezoelectric substrate of example 2 and the three-layer piezoelectric substrate of comparative example 1, and the respective sensitivity changes were calculated.
The sensitivity change of the three-layer piezoelectric substrate of example 1 was 1.00. The sensitivity of the three-layer piezoelectric substrate of example 2 was changed to 0.98. The sensitivity change of the three-layer piezoelectric substrate of comparative example 1 was 0.80.
From these results, it is clear that the three-layer piezoelectric substrates of example 1 and example 2 have small sensitivity variations, whereas the sensitivity variations of the three-layer piezoelectric substrate of comparative example 1 are significantly reduced.
TABLE 1
TABLE 2
The piezoelectric substrates of comparative examples 1 to 3 include an elongated inner conductor and a piezoelectric layer covering the outer peripheral surface of the inner conductor. The piezoelectric layer has a piezoelectric yarn wound around the outer peripheral surface of the inner conductor, and an adhesive portion that holds the piezoelectric yarn wound around the outer peripheral surface of the inner conductor. The piezoelectric yarn comprises refined silk as optically active polypeptide fiber. However, the elastic modulus Y of the piezoelectric layer is not in the range of 1.0GPa to 8.0 GPa.
Therefore, the piezoelectric substrate of each of comparative examples 1 to 3 had a piezoelectric sensitivity of 2.3pC/N/mm or less. As a result, it was found that the piezoelectric substrates of comparative examples 1 to 3 were not excellent in piezoelectric sensitivity.
On the other hand, the piezoelectric substrates of examples 1 to 3 include an elongated inner conductor and a piezoelectric layer covering the outer peripheral surface of the inner conductor. The piezoelectric layer has a piezoelectric yarn wound around the outer peripheral surface of the inner conductor, and an adhesive portion that holds the piezoelectric yarn wound around the outer peripheral surface of the inner conductor. The piezoelectric yarn comprises refined silk as optically active polypeptide fiber. The elastic modulus Y of the piezoelectric layer is in the range of 1.0GPa to 8.0 GPa.
Therefore, the piezoelectric sensitivity of the piezoelectric substrates of examples 1 to 3 was 2.6pC/N/mm or more higher than that of comparative examples 1 to 3. As a result, the piezoelectric substrates of examples 1 to 3 were found to have excellent piezoelectric sensitivity.
When comparing the piezoelectric substrate of example 1 with the piezoelectric substrate of example 2, the elastic modulus Y of the piezoelectric layer of example 1 is in the range of 4.0GPa to 8.0GPa, and thus the piezoelectric sensitivity of example 1 is 5.0pC/N/mm higher than that of example 2.
On the other hand, when comparing the piezoelectric substrate of example 3 with the piezoelectric substrate of example 2, the elastic modulus Y of the piezoelectric layer of example 3 is in the range of 1.0GPa to 3.6GPa, and thus the piezoelectric sensitivity of example 3 is 4.2pC/N/mm higher than that of example 2.
The piezoelectric substrate of comparative example 4 includes an elongated inner conductor and a piezoelectric layer covering the outer peripheral surface of the inner conductor. The piezoelectric layer has a piezoelectric yarn wound around the outer peripheral surface of the inner conductor, and an adhesive portion that holds the piezoelectric yarn wound around the outer peripheral surface of the inner conductor. The piezoelectric yarn contains a wool yarn containing a synthetic protein as an optically active polypeptide fiber. However, the elastic modulus Y of the piezoelectric layer is not in the range of 1.0GPa to 8.0 GPa.
Therefore, the piezoelectric substrate of comparative example 4 had a piezoelectric sensitivity of 0.14pC/N/mm or less. As a result, it was found that the piezoelectric substrate of comparative example 4 was not excellent in piezoelectric sensitivity.
On the other hand, the piezoelectric substrate of example 4 includes an elongated inner conductor and a piezoelectric layer covering the outer peripheral surface of the inner conductor. The piezoelectric layer has a piezoelectric yarn wound around the outer peripheral surface of the inner conductor, and an adhesive portion that holds the piezoelectric yarn wound around the outer peripheral surface of the inner conductor. The piezoelectric yarn contains a wool yarn containing a synthetic protein as an optically active polypeptide fiber. The elastic modulus Y of the piezoelectric layer is in the range of 1.0GPa to 8.0 GPa.
Therefore, the piezoelectric substrate of example 4 had a piezoelectric sensitivity of 0.32pC/N/mm or more than that of comparative example 4. As a result, the piezoelectric substrate of example 4 was found to have excellent piezoelectric sensitivity.
Example 5
< preparation of optically active polypeptide fiber >
Raw silk is prepared as an optically active polypeptide fiber. Raw silk is a long fiber formed from an optically active polypeptide. The raw silk was 21 denier. The thickness of raw silk is 0.06 mm-0.04 mm.
(measurement of degree of orientation F of optically active polypeptide fiber)
The azimuth distribution intensity of the crystal plane peak [2θ=20° ] was measured by fixing raw silk (optically active polypeptide fiber) on a support table using a wide angle X-ray diffraction device ("RINT 2550" manufactured by Rigaku corporation, accessory device: rotary sample table, X-ray source: cukα, output: 40kv 370ma, detector: scintillation counter).
In the obtained azimuth distribution curve (X-ray interference pattern), the degree of orientation F (c-axis orientation) of raw silk (optically active polypeptide fiber) was calculated from the following formula (a) based on the half-peak width (α) of the peak.
The degree of orientation F of the optically active polypeptide fiber was 0.91.
Degree of orientation (F) = (180 ° - α)/180 ° … (a)
(alpha is the half-width of the peak from orientation)
< preparation of piezoelectric yarn >
The raw silk is refined into 6 filaments with single twist (the number of twists is 150T/m) by a known method to be used as the piezoelectric yarn, thereby manufacturing refined silk. The degree of orientation F of the twisted filaments of the refined silk was 0.86.
Degree of orientation (F) = (180 ° - α)/180 ° … (a)
(alpha is the half-width of the peak from orientation)
< production of elongated piezoelectric body >
As an adhesive, "ARON ALPHA 901H3" (cyanoacrylate-based adhesive) manufactured by Toyo Kagaku Co., ltd.
The 4 piezoelectric yarns were pulled in alignment so that they did not overlap each other, making lateral contact. Specifically, 4 piezoelectric yarns are arranged so that 4 piezoelectric yarns are aligned in a direction perpendicular to the longitudinal direction of the piezoelectric yarns and adjacent ones of the 4 piezoelectric yarns are in contact with each other. In this state, the adhesive was dropped onto 4 piezoelectric yarns, and the adhesive was impregnated into the 4 piezoelectric yarns. The 4 piezoelectric yarns were adhesively bonded with an adhesive. Thus, a long piezoelectric body was obtained. The long piezoelectric body is formed of 4 piezoelectric yarns and an adhesive body that bundles the 4 piezoelectric yarns. The adhesive covers the entire outer peripheral surfaces of the 4 piezoelectric yarns.
The long piezoelectric body was heat-treated at 120℃for 6 hours. The thickness of the resulting long piezoelectric body was 0.08mm. The width of the long piezoelectric body was 0.65mm. The ratio of the width of the elongated piezoelectric body to the thickness of the elongated piezoelectric body was 8.1.
Since the degree of orientation F of the optically active polypeptide fiber was 0.91, the degree of orientation of the yarn (piezoelectric yarn) obtained by subjecting the purified silk to 6 single twists was 0.86, and 4 piezoelectric yarns were juxtaposed in a direction orthogonal to the longitudinal direction of the piezoelectric yarn to produce a long piezoelectric body, it was evaluated that the longitudinal direction of the long piezoelectric body was substantially parallel to the main orientation direction of the optically active polypeptide contained in the purified silk (optically active polypeptide fiber).
< preparation of double-layer piezoelectric substrate >
As an internal conductor, a "U24-01-00" (wire diameter: 0.26mm, length: 200 mm) of a nylon wire manufactured by Ming and Qing industries, inc. was prepared.
The long piezoelectric body is wound around the outer peripheral surface of the inner conductor so that the spiral angle is about 45 ° and so that no gap is left-handed as much as possible. Thus, a piezoelectric layer covering the outer peripheral surface of the inner conductor is formed, and a two-layer piezoelectric substrate is obtained. The piezoelectric layer covers the entire outer peripheral surface of the inner conductor. That is, the outer peripheral surface of the inner conductor is not exposed. The piezoelectric layer is not fixed to the inner conductor by an adhesive or the like.
The term "left-handed" means that the long piezoelectric body is wound in a left-handed manner from the proximal side toward the distal side of the inner conductor (nylon yarn) when viewed from one end in the axial direction of the inner conductor. The "helix angle" refers to an angle formed by the longitudinal direction of the elongated piezoelectric body with respect to the axial direction of the inner conductor.
The elastic modulus Y of the long piezoelectric body was measured by the following method using the long piezoelectric body. The elastic modulus Y of the long piezoelectric body was measured by a microhardness meter (according to JIS Z2255). The elastic modulus Y of the long piezoelectric body was measured and found to be 3.9GPa.
(measurement of elastic modulus Y of elongated piezoelectric body)
The elastic modulus Y of the long piezoelectric body was measured as the indentation elastic modulus of the long piezoelectric body by a method in accordance with JIS Z2255 using a dynamic ultra-microhardness meter.
Specifically, regarding the elastic modulus Y of the long piezoelectric body, the long piezoelectric body is unwound from the piezoelectric layer of the measurement sample (double-layer piezoelectric substrate), and the measurement sample is obtained. When the rolled piezoelectric body has a winding mark, the rolled piezoelectric body is cut to about several mm to obtain a measurement sample. The measurement sample was fixed to the substrate, and the measurement was performed by pressing the indenter from the flat portion of the measurement sample.
The apparatus used herein was a dynamic ultra-microhardness tester "DUH-211R" (manufactured by Shimadzu corporation), and was measured under soft test conditions using a triangular pyramid indenter (inter-prism angle 115 °) made of diamond at a temperature of 23.+ -. 2 ℃ and a humidity of 50.+ -. 5 ℃ as an indenter.
The elastic modulus Y of the elongated piezoelectric body was evaluated based on the degree of initial elastic recovery during the load shedding, and was calculated using the formulas [ formula 1] to [ formula 4] of example 1. The elastic modulus Y used herein is a value calculated as an elastic modulus assuming 0 irrespective of the poisson's ratio of the measurement sample.
< preparation of three-layer piezoelectric substrate >
As the outer conductor, a rolled copper foil tape of rectangular cross section was prepared. The width of the rolled copper foil strip was 0.3mm. The thickness of the rolled copper foil strip was 30 μm.
The rolled copper foil tape was wound on the outer peripheral surface of the piezoelectric layer used for measuring the elastic modulus Y of the long piezoelectric body in a right-handed manner without any gap so that the piezoelectric layer was not exposed. The outer conductor covers the entire outer peripheral surface of the piezoelectric layer. That is, the outer peripheral surface of the piezoelectric layer is not exposed. The external conductor is not fixed to the piezoelectric layer with an adhesive or the like.
A three-layer piezoelectric substrate was fabricated, operating as described above.
Next, as a process before terminal mounting, terminal mounting preparation is performed. In the terminal mounting preparation, the piezoelectric layer and the external conductor are peeled off from both end portions of the three-layer piezoelectric substrate, and the nylon yarn is exposed. Specifically, in preparation for terminal mounting, a portion of a length required for a terminal is unwound, and outer conductors at both ends of the three-layer piezoelectric substrate are peeled off from the piezoelectric layer. Then, a portion of the terminal having a desired length was unwound, and the 5mm piezoelectric layer was removed for removal of the inner conductor, thereby exposing the nylon wire.
In example 5, the inner conductor, the piezoelectric layer, and the outer conductor are not mechanically integrated with each other by an adhesive or the like. Therefore, when the piezoelectric layer is removed, the inner conductor and the outer conductor are not broken. The time required for the terminal mounting preparation is 2 minutes or less. The time required for terminal mounting preparation means a time from a time point when the operation for exposing the silk thread is started to a time point when the silk thread is exposed.
< measurement of piezoelectric sensitivity of three-layer piezoelectric substrate (electrometer) >)
The piezoelectric sensitivity (pC/N.multidot.mm) of the three-layer piezoelectric substrate was measured by the following method using an electrometer.
As a result, the piezoelectric sensitivity of the three-layer piezoelectric substrate was 3.3 pC/N.multidot.mm.
Method for measuring the piezoelectric sensitivity (pC/N.mm) of a three-layer piezoelectric substrate (electrometer)
The three-layer piezoelectric substrate was mounted on a tensile tester (A & D Company, ltd. "Tensilon RTG 1250") having a set distance between chucks of 150 mm. Specifically, the crimp terminal (electrical and mechanical connection portion) on one end side of the three-layer piezoelectric substrate is clamped by one chuck member, and the crimp terminal (electrical and mechanical connection portion) on the other end side of the three-layer piezoelectric substrate is clamped by the other chuck member. Further, an electrode for measuring the charge amount of an electrometer (programmable meter "617" manufactured by Kei thley corporation) was connected to the pressure contact terminal of the three-layer piezoelectric substrate, and an electrode of an electrometer (programmable meter "617" manufactured by Keithley corporation) was connected to the external conductor (rolled copper foil tape) of the three-layer piezoelectric substrate.
Next, tension was repeatedly applied to the three-layer piezoelectric substrate by a tensile tester at a constant moving speed of 5 mm/min in a stress range of 1N to 2N, and the amount of charge generated on the inner conductor side of the three-layer piezoelectric substrate at this time was measured by an electrometer (programmable ammeter "617" manufactured by Keithley corporation).
Based on the slope of the straight line of the scattergram when the measured generated charge amount QC is taken as the Y axis and the tensile force FN of the three-layer piezoelectric substrate is taken as the X axis, the generated charge amount per unit tensile force is calculated, and the calculated value is divided by the distance between the press-contact terminals to obtain the piezoelectric sensitivity (pC/N.mm).
Comparative example 5 ]
Refined silk and an inner conductor were prepared in the same manner as in example 5.
In comparative example 5, instead of winding the long piezoelectric body of example 5 around the outer peripheral surface of the inner conductor, 4 pieces of refined silk were pulled out around the outer peripheral surface of the inner conductor, and the inner conductor was wound spirally around the inner conductor without any gap so that the inner conductor was not exposed, and further, 4 pieces of refined silk were pulled out and wound in the same manner.
The spiral angle of the refined silk is set to about 45 degrees, and the winding direction of the refined silk is set to be left-handed. Thereby, a refined silk layer covering the outer peripheral surface of the inner conductor is formed. The refined silk layer covers the whole outer peripheral surface of the inner conductor. That is, the outer peripheral surface of the inner conductor is not exposed.
The helix angle of the refined silk represents the angle of the length direction of the refined silk relative to the long axis direction of the inner conductor.
Next, "ARON AL PHA 901H3" (cyanoacrylate-based adhesive) manufactured by Toyo Synthesis Co., ltd was prepared as an adhesive.
The adhesive was dropped onto the outer peripheral surface of the refined silk layer to impregnate it into the refined silk layer, and then heat-treatment was performed at 120℃for 6 hours. Thereby, the refined silk layer is adhesively bonded to the inner conductor, and they are mechanically integrated. Thus, a piezoelectric layer covering the outer peripheral surface of the inner conductor is formed, and a two-layer piezoelectric substrate is obtained. The piezoelectric layer is fixed to the inner conductor by an adhesive.
Next, as an external conductor, a rolled copper foil tape having a rectangular cross section was prepared. The width of the rolled copper foil strip was 0.3mm. The thickness of the rolled copper foil strip was 30 μm.
The rolled copper foil tape was wound on the outer peripheral surface of the piezoelectric layer used for measuring the elastic modulus Y of the long piezoelectric body in a right-handed manner without any gap so that the piezoelectric layer was not exposed. The outer conductor covers the entire outer peripheral surface of the piezoelectric layer. That is, the outer peripheral surface of the piezoelectric layer is not exposed. The external conductor is not fixed to the piezoelectric layer with an adhesive or the like.
A three-layer piezoelectric substrate was fabricated, operating as described above.
Next, as a process before terminal mounting, terminal mounting preparation is performed. In the terminal mounting preparation, the piezoelectric layer and the external conductor are peeled off from both end portions of the three-layer piezoelectric substrate, and the nylon yarn is exposed. Specifically, in preparation for terminal mounting, a portion of a length required for a terminal is unwound, and outer conductors at both ends of the three-layer piezoelectric substrate are peeled off from the piezoelectric layer. Then, a portion of the terminal having a desired length was unwound, and the 5mm piezoelectric layer was removed for removal of the inner conductor, thereby exposing the nylon wire.
In comparative example 5, the inner conductor and the piezoelectric layer are mechanically integrated with each other by an adhesive. Therefore, the time required for terminal mounting preparation takes more than 5 times of embodiment 5. The time required for terminal installation preparation represents the time required from the time point when the operation for exposing the silk thread is started to the time point when the silk thread is exposed.
The piezoelectric sensitivity (pC/N.multidot.mm) of the three-layer piezoelectric substrate was measured in the same manner as in example 5. As a result, the piezoelectric sensitivity of the three-layer piezoelectric substrate was 2.8 pC/N.multidot.mm.
The three-layer piezoelectric substrate of comparative example 5 includes an elongated inner conductor and a piezoelectric layer covering the outer peripheral surface of the inner conductor. The piezoelectric layer is formed by winding a long piezoelectric body around the outer peripheral surface of the inner conductor. The long piezoelectric body has 4 piezoelectric yarns and an adhesive body that holds the state in which the 4 piezoelectric yarns are wound around the outer peripheral surface of the inner conductor. However, the piezoelectric layer is fixed to the inner conductor with an adhesive.
Therefore, the piezoelectric sensitivity of the three-layer piezoelectric substrate was 2.8 pC/N.multidot.mm. The time required for the end mounting preparation was 5 times or more that of example 5. As a result, it was found that the three-layer piezoelectric substrate of comparative example 5 was not able to efficiently prepare for terminal mounting, nor was the piezoelectric sensitivity excellent.
On the other hand, the three-layer piezoelectric substrate of example 5 includes an elongated inner conductor and a piezoelectric layer covering the outer peripheral surface of the inner conductor. The piezoelectric layer is formed by winding a long piezoelectric body around the inner conductor, and is not fixed to the inner conductor. The long piezoelectric body has 4 piezoelectric yarns and an adhesive body that bundles the 4 piezoelectric yarns.
Therefore, the piezoelectric sensitivity of the three-layer piezoelectric substrate was 3.3 pC/N.multidot.mm higher than that of comparative example 5. The time required for the end fitting was less than 2 minutes shorter than that of comparative example 5. As a result, it was found that the three-layer piezoelectric substrate of example 5 was capable of efficiently performing terminal mounting preparation, and was excellent in piezoelectric sensitivity.
The disclosures of japanese patent applications 2021-061998 filed on 3/31 of 2021 and the disclosures of japanese patent applications 2021-061999 filed on 3/31 of 2021 are incorporated herein by reference in their entirety.
All documents, patent applications and technical standards described in the present specification are incorporated in the present specification by reference, and the degree to which each document, patent application and technical standard is incorporated by reference is the same as in the case of specific and individual descriptions.
Claims (35)
1. A piezoelectric substrate is provided with:
an elongated inner conductor, and
a piezoelectric layer covering an outer peripheral surface of the inner conductor;
the piezoelectric layer has:
a piezoelectric yarn wound around the inner conductor, and
an adhesive portion that holds the state in which the piezoelectric yarn is wound around the inner conductor;
the piezoelectric yarn comprises an optically active polypeptide fiber representing a fiber formed from an optically active polypeptide,
the piezoelectric layer has an elastic modulus Y measured by a microhardness meter (according to JIS Z2255) of 1.0GPa to 8.0 GPa.
2. The piezoelectric substrate of claim 1, wherein the length direction of the piezoelectric yarn is substantially parallel to the main orientation direction of the optically active polypeptide.
3. The piezoelectric substrate according to claim 1 or claim 2, wherein the degree of orientation F of the optically active polypeptide fiber, as determined by X-ray diffraction using the following formula (a), is 0.50 or more and less than 1.00,
degree of orientation f= (180 ° - α)/180 ° … formula (a)
In the formula (a), α represents a half-width (°) of a peak from orientation.
4. A piezoelectric substrate according to any one of claims 1 to 3, wherein the piezoelectric yarn is wound in a spiral in one direction.
5. The piezoelectric substrate according to claim 4, wherein a spiral angle between an axial direction of the inner conductor and a longitudinal direction of the piezoelectric yarn is 20 ° to 70 °.
6. The piezoelectric substrate according to any one of claims 1 to 5, wherein the adhesive portion is formed of at least one selected from the group consisting of an epoxy-based adhesive, a urethane-based adhesive, a vinyl acetate resin emulsion-based adhesive, an ethylene vinyl acetate emulsion-based adhesive, an acrylic resin emulsion-based adhesive, a styrene butadiene rubber latex-based adhesive, a silicone resin-based adhesive, an α -olefin-based adhesive, a vinyl chloride resin solvent-based adhesive, a rubber-based adhesive, an elastic adhesive, a chloroprene rubber solvent-based adhesive, a nitrile rubber solvent-based adhesive, and a cyanoacrylate-based adhesive.
7. The piezoelectric substrate according to any one of claim 1 to claim 6, wherein an external conductor is further provided on an outer peripheral side of the piezoelectric layer,
the inner conductor and the outer conductor are not electrically connected.
8. The piezoelectric substrate of any one of claims 1-7, wherein the optically active polypeptide has a β -sheet structure.
9. The piezoelectric substrate of any one of claims 1-8, wherein the optically active polypeptide comprises at least one of a silk fibroin and a spider silk protein.
10. A piezoelectric substrate according to any one of claims 1 to 9 wherein the optically active polypeptide fibre comprises at least one of silk and spider silk.
11. The piezoelectric substrate of claim 10, wherein the silk is refined silk.
12. The piezoelectric substrate according to any one of claim 1 to claim 11, wherein the piezoelectric yarns each comprise a plurality of optically active polypeptide fibers,
the number of turns of the piezoelectric yarn is 500T/m or less.
13. The piezoelectric substrate according to any one of claims 1 to 12, further comprising an electrical insulator at the outermost periphery.
14. A sensor comprising the piezoelectric substrate according to any one of claims 1 to 13.
15. An actuator comprising the piezoelectric substrate according to any one of claims 1 to 13.
16. A biological information acquisition device comprising the piezoelectric substrate according to any one of claims 1 to 13.
17. A piezoelectric substrate is provided with:
An elongated inner conductor, and
a piezoelectric layer covering an outer peripheral surface of the inner conductor;
the piezoelectric layer is formed by winding an elongated piezoelectric body around the inner conductor, and is not fixed to the inner conductor,
the long piezoelectric body comprises a plurality of piezoelectric yarns and a bundling body for bundling the plurality of piezoelectric yarns,
at least 1 of the plurality of piezoelectric yarns comprises an optically active polypeptide fiber representing a fiber formed from an optically active polypeptide.
18. The piezoelectric substrate according to claim 17, wherein a longitudinal direction of the elongated piezoelectric body is substantially parallel to a main orientation direction of the optically active polypeptide.
19. The piezoelectric substrate according to claim 17 or claim 18, wherein the degree of orientation F of the optically active polypeptide fiber, as determined by X-ray diffraction using the following formula (a), is 0.50 or more and less than 1.00,
degree of orientation f= (180 ° - α)/180 ° … formula (a)
In the formula (a), α represents a half-width (°) of a peak from orientation.
20. The piezoelectric substrate according to any one of claims 17 to 19, wherein the elongated piezoelectric body is wound in a spiral shape in one direction.
21. The piezoelectric substrate according to claim 20, wherein a spiral angle formed between an axial direction of the inner conductor and a longitudinal direction of the elongated piezoelectric body is 20 ° to 70 °.
22. The piezoelectric substrate according to any one of claims 17 to 21, wherein the bundling body bundles the plurality of piezoelectric yarns in a state in which the plurality of piezoelectric yarns are juxtaposed in a direction orthogonal to a longitudinal direction of the plurality of piezoelectric yarns and adjacent ones of the plurality of piezoelectric yarns are brought into contact with each other.
23. The piezoelectric substrate according to any one of claims 17 to 22, wherein the bundling body is formed of at least one selected from the group consisting of an epoxy-based adhesive, a urethane-based adhesive, a vinyl acetate resin emulsion-based adhesive, an ethylene vinyl acetate emulsion-based adhesive, an acrylic resin emulsion-based adhesive, a styrene butadiene rubber latex-based adhesive, a silicone resin-based adhesive, an α -olefin-based adhesive, a vinyl chloride resin solvent-based adhesive, a rubber-based adhesive, an elastic adhesive, a chloroprene rubber solvent-based adhesive, a nitrile rubber solvent-based adhesive, and a cyanoacrylate-based adhesive.
24. The piezoelectric substrate according to any one of claim 17 to claim 23, wherein the thickness of the elongated piezoelectric body is 0.001mm to 0.4mm,
The width of the strip-shaped piezoelectric body is 0.1 mm-30 mm,
the ratio of the width of the elongated piezoelectric body to the thickness of the elongated piezoelectric body is 2 or more.
25. The piezoelectric substrate according to any one of claims 17 to 24, wherein the elastic modulus Y of the elongated piezoelectric body measured by a microhardness meter (according to JIS Z2255) is 1GPa to 10 GPa.
26. The piezoelectric substrate according to any one of claim 17 to claim 25, wherein an external conductor is further provided on an outer peripheral side of the piezoelectric layer,
the inner conductor and the outer conductor are not electrically connected.
27. The piezoelectric substrate of any one of claims 17-26, wherein the optically active polypeptide has a β -sheet structure.
28. The piezoelectric substrate of any one of claims 17-27, wherein the optically active polypeptide comprises at least one of a silk fibroin and a spider silk protein.
29. A piezoelectric substrate according to any one of claims 17 to 28 wherein the fibre formed from the optically active polypeptide comprises at least one of silk and spider silk.
30. The piezoelectric substrate of claim 29, wherein the silk is refined silk.
31. The piezoelectric substrate according to any one of claim 17 to claim 30, wherein each of the plurality of piezoelectric yarns comprises a plurality of the optically active polypeptide fibers,
the number of turns of each of the plurality of piezoelectric yarns is 500T/m or less.
32. The piezoelectric substrate according to any one of claims 17 to 31, further comprising an electrical insulator at the outermost periphery.
33. A sensor comprising the piezoelectric substrate according to any one of claims 17 to 32.
34. An actuator comprising the piezoelectric substrate according to any one of claims 17 to 32.
35. A biological information acquisition device comprising the piezoelectric substrate according to any one of claims 17 to 32.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2021-061998 | 2021-03-31 | ||
| JP2021061999 | 2021-03-31 | ||
| JP2021-061999 | 2021-03-31 | ||
| PCT/JP2022/016136 WO2022210922A1 (en) | 2021-03-31 | 2022-03-30 | Piezoelectric base material, sensor, actuator, and biometric information acquisition device |
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| CN117063632A true CN117063632A (en) | 2023-11-14 |
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| CN202280023433.1A Pending CN117063632A (en) | 2021-03-31 | 2022-03-30 | Piezoelectric substrate, sensor, actuator, and biological information acquisition device |
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| CN (1) | CN117063632A (en) |
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