JP7370517B2 - Piezoelectric element - Google Patents

Description

The present invention relates to piezoelectric elements .

In recent years, Internet of Everything (IOE) technology, which collects and analyzes motion information obtained by sensing the motions of living organisms via the Internet, has been attracting a lot of attention. In this technology, piezoelectric elements that can convert biological movements into electrical signals play an important role.

As piezoelectric elements, those using ceramic piezoelectric materials such as lead zirconate titanate (hereinafter referred to as "PZT") have become widely used because of their high piezoelectric properties. However, in sensing the motion of a living body such as a human body, a flexible and lightweight piezoelectric element that provides excellent comfort to the living body when attached to the living body is required.

In response, flexible piezoelectric elements using crystalline films of so-called piezoelectric polymers such as ferroelectric polymers and polylactic acid have been developed. Materials for this type of piezoelectric element include, for example, PVDF (poly(vinylidene fluoride)), PVDF-TrFE (PVDF poly(vinylidenefluoride-co-trifluoroethylene)), and PLLA (single optical isomer (L form) of polylactic acid). etc. have been adopted.

However, this type of piezoelectric element has a piezoelectric performance lower than that of a ceramic piezoelectric element. Further, in the manufacturing process of this type of piezoelectric element, it is necessary to perform the above-mentioned stretching, heating, poling treatment, etc. of the crystalline film in order to exhibit piezoelectric performance. For this reason, the manufacturing process of the piezoelectric element becomes complicated.

On the other hand, piezoelectric elements using flexible porous polymer electrets that exhibit higher piezoelectric performance than the above-mentioned crystalline films are also being developed. Polypropylene is often used as the material for this polymer electret. In the production of this polymer electret, a porous polypropylene film is produced by subjecting the polypropylene film to a stretching process, and then the porous polypropylene film is subjected to a poling process using corona discharge. A pair of positive and negative charges is trapped on each side of the hole in one direction. In this way, a polymer electret is produced by forming the aforementioned giant dipole group oriented in one direction in a porous polypropylene film. Moreover, this porous polymer electret is softer than the above-mentioned crystalline film due to its porosity, and is therefore believed to exhibit higher piezoelectric performance than the above-mentioned crystalline film.

However, in the production of a piezoelectric element using a porous polymer electret, it is still necessary to produce a porous polypropylene film and then perform a poling treatment on the produced polypropylene film. Therefore, there is a growing demand for further simplifying the manufacturing process of piezoelectric elements by omitting this poling process.

In contrast, polymer submicron fibers (also referred to as "polymer submicron piezoelectric fibers"), which are fibers made of piezoelectric polymer and having a diameter of less than 1 μm, are being developed. For example, submicron fibers fabricated by electrospinning using piezoelectric polymers such as PVDF, PVDF-TrFE, and PLLA forming chiral polymer crystals have been developed. The reason why these submicron fibers exhibit piezoelectric performance even without the need for poling is that, for example, in the case of ferroelectric polymers such as PVDF and PVDF-TrFE, electrospinning can be used to develop the main properties of the ferroelectric polymer. It is believed that this is due to the orientation of the chains and the induction of polarization by the relatively high voltage used in electrospinning.

An element in which electrodes are formed on both sides of a piezoelectric polymer film made of this type of polymer submicron piezoelectric fiber has been proposed (for example, see Patent Document 1). The element described in Patent Document 1 functions as a pressure-sensitive sensor or an actuator, and is made of continuous fibers of piezoelectric polymer with a fiber diameter of 300 nm or less, and includes a portion formed with the fiber axis direction aligned and a portion thereof. and a piezoelectric polymer film having random fiber axis directions located around the periphery of the piezoelectric polymer film.

Japanese Patent Application Publication No. 2018-133368

By the way, in the case of the element described in Patent Document 1, the piezoelectric polymer film used in the element includes parts that are aligned in the fiber axis direction and parts that are random in the fiber axis direction, so the manufacturing process of the element is complicated. There is a possibility that it will become.

The present invention has been made in view of the above reasons, and an object of the present invention is to provide a piezoelectric element whose manufacturing process can be simplified.

The piezoelectric element according to the present invention is
A polymer fiber body consisting of only random portions in the fiber axis direction, which is made up of three-dimensionally deposited fibers made of a chargeable non-piezoelectric polymer ;
a first conductive member;
a second conductive member disposed opposite to the first conductive member;
a holding member that holds the first conductive member and the second conductive member in a state where the distance between the first conductive member and the second conductive member is changeable;
The polymer fiber body is interposed between the first conductive member and the second conductive member, and when divided by one virtual plane, positive charges are more unevenly distributed than negative charges on one side and the other side is unevenly distributed. More negative charges than positive charges are unevenly distributed on the side ,
The first conductive member is arranged in a region facing one side of the virtual plane,
The second conductive member is arranged in a region facing the other surface of the virtual plane,
The holding member has a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body, and a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body. and a second state in which the first conductive member and the polymer fiber body are in contact with each other, and in the first state, the first conductive member and the polymer fiber body in the opposing direction of the first conductive member and the second conductive member. the first conductive member and the second conductive member such that a distance corresponding to the sum of the distance between the first conductive member and the second conductive member and the polymer fiber body becomes a preset first reference distance. and in the second state, the distance between the first conductive member and the second conductive member in the opposing direction is greater than the thickness of the polymer fibrous body in the opposing direction in the first state. The first conductive member and the second conductive member are held so that they become shorter by a preset second reference distance .

According to the present invention, a polymer fiber body is provided, which is made up of three-dimensionally deposited fibers made of a chargeable non-piezoelectric polymer and is made up of only random portions in the fiber axis direction . When the polymer fiber body is divided by one virtual plane, more positive charges than negative charges are unevenly distributed on one side, and more negative charges than positive charges are unevenly distributed on the other side. Here, the polymer fiber body includes a nozzle that injects a non-piezoelectric polymer solution or a non-piezoelectric polymer melt in which a chargeable non-piezoelectric polymer is dissolved, and a collector that is spaced apart from the nozzle in the injection direction of the nozzle. a voltage applying means for applying a voltage between the nozzle and the collector; and with a preset voltage being applied between the nozzle and the collector by the voltage applying means, a non-piezoelectric voltage is applied from the nozzle to the collector. It is produced by injecting a polymer solution or a non-piezoelectric polymer melt to three-dimensionally deposit non-piezoelectric polymer fibers onto a collector. Thereby, the polymer fiber body can be produced by simply performing an electrospinning process in which non-piezoelectric polymer fibers are three-dimensionally deposited, so that the manufacturing process can be simplified.

1 shows a power generation element according to Embodiment 1 of the present invention, in which (A) is a cross-sectional view in a first state, and (B) is a cross-sectional view in a second state. 1 is a diagram for explaining a method for manufacturing a power generation element according to Embodiment 1. FIG. A power generation element according to Embodiment 2 of the present invention is shown, in which (A) is a cross-sectional view in a second state, and (B) is a cross-sectional view in a first state. A power generation element according to Embodiment 3 of the present invention is shown, in which (A) is a cross-sectional view in a first state, and (B) is a plan view showing a conductive member and a holding member. A power generating element according to Embodiment 4 of the present invention is shown, in which (A) is a plan view in a first state, and (B) is a plan view in a second state. A measuring device for measuring the amount of charge generated in a polymer fiber body is shown, (A) is a schematic diagram showing a state in which an electrode terminal is brought into contact with the polymer fiber body, and (B) is a schematic diagram showing a state in which an electrode terminal is brought into contact with the polymer fiber body. It is a schematic diagram showing a state where it was made to space apart. FIG. 2 shows the results of measuring the amount of charge generated in the polymer fiber body according to the example, and (A) is a diagram showing the measurement results when the electrode terminal is pushed in from a state where the electrode terminal is in contact with the polymer fiber body. , (B) is a diagram showing the measurement results when the electrode terminal was brought into contact with the polymer fiber body from a state in which the electrode terminal was separated from the polymer fiber body, and then the electrode terminal was further pushed in. It is a figure which shows the result of measuring the amount of electric charge generated in the polymer fiber body based on an Example. (A) is a diagram showing how the surface potential of a sample according to an example is measured, (B) is a diagram showing how the surface potential of a sample according to another example is measured, and (C) is a diagram showing how the surface potential of a sample according to another example is measured. FIG. 7 is a diagram showing how the surface potential of a sample is measured according to another example.

(Embodiment 1)
Hereinafter, a power generation element and a method for manufacturing the power generation element according to an embodiment of the present invention will be described in detail with reference to the drawings. The power generation element according to the present embodiment includes a polymer fiber body in which fibers made of a chargeable non-piezoelectric polymer are deposited three-dimensionally, and are produced by an electrospinning method. The fiber diameter (diameter) of the non-piezoelectric polymer constituting the polymer fiber body is 10 nm or more and 100 μm or less, preferably 100 nm or more and 10 μm or less. This polymer fiber body is a so-called charged film in which the distribution of positive and negative charges is biased within the polymer fiber body, and is not a charged film that retains only either positive charge or negative charge. In other words, when the polymer fiber body according to the present embodiment is divided by one virtual plane, more positive charges than negative charges are unevenly distributed on one side, and more negative charges are distributed on the other side than positive charges. They are also widely distributed. Here, the virtual plane may pass through the center of the polymer fiber body, for example. The surface potential of this polymer fiber body is 10V or more and 1×10 ⁵ V or less, preferably 10V or more and 1×10 ⁴ V or less. Note that the surface potential of the polymer fiber body can be measured, for example, with a non-contact type surface potentiometer (for example, KSD-3000 manufactured by Kasuga Denki Co., Ltd.). Here, in measuring the surface potential, the surface potential of the polymer fiber body is measured while the electrode on which the polymer fiber body is placed is maintained at ground potential.

Further, the Young's modulus of the polymer fiber body is 1 Pa or more and 1×10 ⁹ Pa or less, preferably 100 Pa or more and 1×10 ⁵ Pa or less. Furthermore, the thickness of the polymer fiber body is 1 μm or more and 10 mm or less, preferably 1 μm or more and 1 mm or less. In addition, the direction of the thickness of the polymer fiber body, in other words, the alignment direction of the parts where more positive charges are unevenly distributed than negative charges and the parts where more negative charges are unevenly distributed than positive charges in the polymer fiber body. The absolute value of the piezoelectric d constant d1, which corresponds to the amount of charge generated in the thickness direction of the polymer fiber per unit pushing load when pushed in the direction along the d1 is a value within a range where the relational expression (piezoelectric d constant) holds true, preferably a value within a range where the relational expression 150 pC/N≦d1≦1000000 pC/N holds true. Furthermore, when a voltage is applied in the thickness direction of the polymer fiber body, the absolute value of the piezoelectric d constant d2, which corresponds to the amount of change in the thickness of the polymer fiber body per unit voltage, is 10 pm/V≦d2≦1000000 pm/ It is a value within a range where the relational expression of V (d2 is a piezoelectric d constant) holds true, preferably a value within a range where the relational expression of 150 pm/V≦d1≦1000000 pm/V holds true.

Examples of the non-piezoelectric polymer constituting the polymer fiber body include polystyrene, polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, acrylonitrile-styrene copolymer, Polyvinyl chloride, polyacrylonitrile, polyvinylidene chloride-acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, methyl methacrylate-styrene copolymer, polyamide, polyester, aramid, polycarbonate, amorphous fluororesin, non- Ferroelectric fluororesins, non-ferroelectric fluororesin derivatives, non-ferroelectric fluororesin copolymers, polyhydroxybutyrate, polyurethane, polyvinyl acetate, polybutylene succinate, silk, wool, natural Rubber, polyether ketone, polyarylene ether ether ketone, polyacrylonitrile-methacrylate copolymer, polybenzimidazole, polyetherimide, polyethylene sulfide, polyester urethane, polyvinyl alcohol, polyethylene oxide, polyvinyl carbazole, polyvinyl pyrrolidone, collagen, poly Caprolactone, polyhydroxyalkanoic acid, polyglycolic acid, polymethyl methacrylate, amorphous poly-DL-lactic acid (PDLLA), derivatives of polylactic acid, polylactic acid-glycolic acid copolymer, cellulose, cellulose acetate, cellulose derivatives , chitosan, chitin, polypeptides, and proteins. Here, examples of the polyamide include nylon 12 (registered trademark), nylon 4,6 (registered trademark), nylon 6,6 (registered trademark), and nylon 6 (registered trademark). In addition, examples of amorphous fluororesin, non-ferroelectric fluororesin, derivatives of non-dielectric fluororesin, and copolymers of non-ferroelectric fluororesin include Cytop (registered trademark), polytetrafluorocarbon Examples include ethylene (PTFE) and perfluoroalkoxyalkane (PFA). Further, as the non-piezoelectric polymer, a mixture of the plurality of types of non-piezoelectric polymers described above may be employed.

As shown in FIGS. 1A and 1B, the power generation element 1 according to the present embodiment is in a state where the distances between the polymer fiber body FB, the electrodes 121 and 122, and the electrodes 121 and 122 can be changed. and a holding member 11 that holds the electrodes 121 and 122. The polymer fiber body FB is interposed between the electrodes 121 and 122 in a state in which it is in contact with the electrode 121. Furthermore, when the polymer fiber body FB is divided by one virtual plane VPL passing through the central portion C1, more positive charges than negative charges are unevenly distributed on one side (for example, the upper side in FIG. 1(A)). , more negative charges than positive charges are unevenly distributed on the other side (for example, the lower side of FIG. 1(A)). The electrode 121 is a first conductive member formed in the form of a foil or film from a conductor such as aluminum or copper. The electrode 122 is a second conductive member formed in the shape of a foil or film from a conductive material such as aluminum or copper, and placed opposite the electrode 121 . The electrode 121 is arranged in a region facing one surface of the virtual plane VPL (for example, the lower part of FIG. 1(A)), and the electrode 122 is arranged in the region facing the other surface of the virtual plane VPL (for example, the upper part of FIG. 1(A)). It is located.

The holding member 11 holds the electrodes 121 and 122 in a state where the distance between the electrodes 121 and 122 can be changed, and there are two states: a first state in which the electrode 122 is separated from the polymer fiber body FB, and a first state in which the electrode 122 is separated from the polymer fiber body FB. and a second state of contact. The holding member 11 is formed into an elliptical cylinder shape from an elastic material such as rubber, and an electrode 121 is disposed at a first portion 11a on the inner surface, and the first portion 11a on the inner surface and the cylindrical axis J1 of the holding member 11 are connected to each other. An electrode 122 is disposed on the second portion 11b that is opposed to the second portion 11b. The holding member 11 is urged to be in the first state by its restoring force. When the holding member 11 is pressed so that the electrode 122 approaches the electrode 121 as shown by the arrow AR1 in the first state shown in FIG. There are two states.

Further, as shown in FIG. 1(A), the holding member 11 is held in the first state in which the distance between the electrode 122 and the polymer fiber body FB in the opposing direction of the electrodes 121 and 122 is set in advance. The electrodes 121 and 122 are held at one reference distance W3. Here, the first reference distance W3 is preferably within a range where the relational expression 0≦W3≦500×W0 holds, where W0 is the maximum thickness of the polymer fiber body FB in the direction in which the electrodes 121 and 122 face each other. is within a range where the relational expression 0≦W3≦10×W0 holds true.

Furthermore, the holding member 11 is such that the distance between the electrodes 121 and 122 in the opposing direction of the electrodes 121 and 122 in the above-mentioned second state is equal to the distance between the electrodes 121 and 122 of the polymer fiber body FB in the opposing direction of the polymer fiber body FB in the above-mentioned first state. The electrodes 121 and 122 are held so that they are shorter than the maximum thickness W0 by a preset second reference distance W4. Here, the second reference distance W4 is determined by the relational expression 0≦W4≦0.9×W0, where W0 is the maximum thickness of the polymer fiber body FB in the opposing direction of the electrodes 121 and 122 in the first state. It is within a range where the relational expression 0≦W4≦0.5×W0 holds true.

Next, a method for manufacturing the power generation element 1 according to this embodiment will be explained. The method for manufacturing a power generation element according to the present embodiment includes a step of producing a polymer fiber body FB by an electrospinning method. In the step of producing the polymer fibrous body FB by this electrospinning method, the polymer fibrous body is produced by a method similar to the method for producing a plus tip nanofiber described in, for example, JP-A No. 2016-223055. Specifically, a non-piezoelectric polymer solution is prepared by dissolving a chargeable non-piezoelectric polymer in a solvent such as N,N-dimethylformamide and stirring the solution. Then, a polymer fiber body FB is produced from the produced non-piezoelectric polymer solution by an electrospinning method. In this electrospinning method, for example, as shown in FIG. 2, a syringe 901 for storing a non-piezoelectric polymer, a syringe pump 903, a nozzle 911 provided at the tip of the syringe 901 for injecting a non-piezoelectric polymer solution, and a nozzle 911 for injecting a non-piezoelectric polymer solution are used. An electrospinning apparatus 900 includes a flat collector 902 that is spaced apart from each other in the injection direction of the nozzle 911 and spaced apart from each other, and a voltage applying means E that applies a voltage between the nozzle 911 and the collector 902. use. Voltage application means E applies a preset DC voltage (for example, a voltage of 4.0 kV) between the nozzle 911 and the collector 902, using the nozzle 911 as an anode and the collector 902 as a cathode. Note that the voltage applying means E may apply a voltage between the nozzle 911 and the collector 902, with the nozzle 911 serving as a cathode and the collector 902 serving as an anode. Further, the syringe pump 903 supplies the non-piezoelectric polymer solution stored in the syringe 901 to the nozzle 911 at a preset supply rate (for example, 0.04 ml/hr). This electrospinning apparatus 900 injects a non-piezoelectric polymer solution from the nozzle 911 toward the collector 902 by applying a preset voltage between the nozzle 911 and the collector 902 using the voltage applying means E. Fibers made of non-piezoelectric polymer are deposited three-dimensionally on the surface. Here, the injection of the non-piezoelectric polymer solution is caused by the electrical attraction caused by applying a voltage between the nozzle 911 and the collector 902 exceeding the surface tension of the non-piezoelectric polymer solution. Then, while the non-piezoelectric polymer solution reaches the collector 902 from the nozzle 911, the solvent in the non-piezoelectric polymer solution evaporates and non-piezoelectric polymer fibers are deposited on the collector 902.

As described above, the power generating element 1 according to the present embodiment includes the polymer fiber body FB, which is formed by three-dimensionally depositing fibers made of a chargeable non-piezoelectric polymer produced by an electrospinning method. By producing the polymer fiber body FB by an electrospinning method, positive charges are more concentrated on one side (for example, the upper side of FIG. 1(A)) when divided by one virtual plane VPL than negative charges. On the other side (for example, the lower side of FIG. 1A), more negative charges are unevenly distributed than positive charges. Here, the polymer fiber body FB is spaced from a nozzle 911 that injects a non-piezoelectric polymer solution in which a chargeable non-piezoelectric polymer is dissolved or a non-piezoelectric polymer melt in the injection direction of the nozzle 911. using a collector 902 and a voltage applying means for applying a voltage between the nozzle 911 and the collector 902, and applying a preset voltage between the nozzle and the collector 902 by the voltage applying means, It is produced by injecting a non-piezoelectric polymer solution or a non-piezoelectric polymer melt from a nozzle 911 toward a collector 902 to three-dimensionally deposit non-piezoelectric polymer fibers on the collector. As a result, a high voltage is applied to the non-piezoelectric polymer solution or the non-piezoelectric polymer melt in which the chargeable non-piezoelectric polymer is injected from the nozzle 911, and as a result, the non-piezoelectric polymer is collected in the collector 902. When the polymer fiber body FB is divided by one virtual plane VPL, more positive charges than negative charges are unevenly distributed on one side, and more negative charges than positive charges are unevenly distributed on the other side. . That is, even if the polymer fiber body FB is not subjected to a separate poling treatment, the above-described distribution of positive charges and negative charges occurs inside the polymer fiber body FB.

As explained above, the power generation element 1 according to the present embodiment is made by three-dimensionally depositing chargeable non-piezoelectric polymer fibers produced by electrospinning, and includes one fiber that passes through the central portion C1. The polymer fiber body FB includes a polymer fiber body FB in which more positive charges than negative charges are unevenly distributed on one side when divided by the virtual plane VPL, and more negative charges than positive charges are unevenly distributed on the other side. Here, the polymer fiber body FB is arranged between a nozzle 911 that injects a non-piezoelectric polymer solution containing a chargeable non-piezoelectric polymer, a collector 902 that is arranged apart from the nozzle 911, and a space between the nozzle 911 and the collector 902. A voltage applying means E for applying a voltage is used, and while a preset voltage is applied between the nozzle 911 and the collector 902 by the voltage applying means E, a non-piezoelectric polymer is applied from the nozzle 911 toward the collector 902. It is produced by injecting a solution to three-dimensionally deposit fibers of non-piezoelectric polymer on collector 902. Thereby, the polymer fiber body FB can be produced by simply performing an electrospinning process in which fibers of a non-piezoelectric polymer are three-dimensionally deposited, so that the manufacturing process can be simplified.

Furthermore, the polymer fiber body FB according to the present embodiment is made of a non-piezoelectric polymer, which is cheaper than a piezoelectric polymer. Thereby, the manufacturing cost of the power generation element 1 can be reduced compared to a power generation element using a polymer fiber body produced from a piezoelectric polymer.

Further, in the holding member 11 according to the present embodiment, in the first state, the distance between the polymer fiber body FB and the electrode 122 in the opposing direction of the electrodes 121 and 122 becomes a preset first reference distance W3. The electrodes 121 and 122 are held in this manner. In the second state, the holding member 11 has a preset second reference such that the distance between the electrodes 121 and 122 in the opposing direction is greater than the thickness of the polymer fiber body FB in the first state. Electrodes 121 and 122 are held so that they are shortened by distance W4. Thereby, it is possible to increase the electric power generated when the holding member 11 is deformed from the first state to the second state or when the holding member 11 is deformed from the second state to the first state. Therefore, the range of uses of the power generating element 1 can be expanded.

Further, the holding member 11 according to the present embodiment is formed in a cylindrical shape from an elastic material, and the electrode 121 is disposed at the first portion 11a on the inner surface, and the first portion 11a on the inner surface and the tube of the holding member 11 are arranged in a cylindrical shape. An electrode 122 is disposed at the second portion 11b facing each other with the axis J1 in between. The holding member 11 is urged to the first state by the restoring force of the holding member 11. As described above, since the holding member 11 has a simple configuration, there is an advantage that the power generation element 1 can be manufactured easily.

(Embodiment 2)
Similar to Embodiment 1, the power generation element according to this embodiment includes a polymer fiber body in which fibers made of a chargeable non-piezoelectric polymer are deposited three-dimensionally, and are produced by electrospinning. As shown in FIGS. 3A and 3B, the power generation element 2 according to the present embodiment is in a state where the distances between the polymer fiber body FB, the electrodes 121 and 122, and the electrodes 121 and 122 can be changed. and a holding member 211 that holds the electrodes 121 and 122. Note that in FIGS. 3A and 3B, the same components as in Embodiment 1 are given the same reference numerals as in FIGS. 1A and 1B. The polymer fiber body FB is interposed between the electrodes 121 and 122, in contact with both electrodes 121 and 122. Furthermore, when the polymer fiber body FB is divided by one virtual plane VPL passing through the central portion C1, more positive charges than negative charges are unevenly distributed on one side (for example, the upper side in FIG. 3(A)). , more negative charges than positive charges are unevenly distributed on the other side (for example, the lower side of FIG. 3A). Note that the method for manufacturing the polymer fiber body FB is the same as the method described in Embodiment 1. The electrode 121 is arranged in a region facing one side of the virtual plane VPL (for example, the lower part of FIG. 3(A)), and the electrode 122 is arranged in the region facing the other surface of the virtual plane VPL (for example, the upper part of FIG. 3(A)). It is located.

Similarly to Embodiment 1, the holding member 211 holds the electrodes 121 and 122 in a state where the distance between the electrodes 121 and 122 can be changed, and a first state in which the electrode 122 is separated from the polymer fiber body FB; A second state is possible in which the electrode 122 is in contact with the polymer fiber body FB. The holding member 211 is formed into a plate shape from an elastic material such as rubber, and has two sub-holding members 2111 and 2112 arranged opposite to each other. The sub-holding member 2111 is a first sub-holding member in which the electrode 121 is disposed in a first region A11 on one side in the thickness direction. Further, the sub-holding member 2112 is a second sub-holding member in which the electrode 122 is disposed in the second region A21 on the side facing the sub-holding member 2111 in the thickness direction. Further, the end of the sub-holding member 2111 is fixed to the end of the sub-holding member 2112. Here, the end of the sub-holding member 2111 that is fixed to the sub-holding member 2112 is located in a third area A12 of the sub-holding member 2111 on the sub-holding member 2112 side excluding the first area A11. Furthermore, the end portion of the sub-holding member 2112 that is fixed to the sub-holding member 2111 is located in a fourth area A22 of the sub-holding member 2112 excluding the second area A21 on the sub-holding member 2111 side. Note that the sub-holding member 2111 and the sub-holding member 2112 are not limited to those that are fixed at their respective ends, but may be attached to a portion other than the end in the third area A12 of the sub-holding member 2111, or They may be fixed to each other at a portion other than the end portion of the fourth region A22 of the sub-holding member 2112. The holding member 211 is urged to be in the second state by the restoring force of each of the sub-holding members 2111 and 2112. Then, when the holding member 211 is in the second state shown in FIG. 3(A), the holding member 211 is pressed so that both ends of the holding member 211 approach each other, as shown by arrow AR21 in FIG. 3(B). Then, as shown by the arrow AR22 in FIG. 3(B), the electrodes 121 and 122 are displaced in a direction away from each other, resulting in a first state as shown in FIG. 3(B).

Further, as shown in FIG. 3A, the holding member 211 is arranged such that in the second state, the distance W51 between the electrodes 121 and 122 in the opposing direction is the same as that of the polymer fiber in the first state. The electrodes 121 and 122 are held so that they are shorter by a preset second reference distance W52 than the maximum thickness W50 of the electrodes 121 and 122 in the opposing direction of the body FB. Here, the second reference distance W52 is determined by the relational expression 0≦W52≦0.9×W50, where W50 is the maximum thickness of the polymer fiber body FB in the opposing direction of the electrodes 121 and 122 in the first state. It is within a range where the relational expression 0≦W52≦0.5×W50 holds true.

Further, as shown in FIG. 3(B), the holding member 211 has a preset distance between the electrode 122 and the polymer fiber body FB in the direction in which the electrodes 121 and 122 face each other in the first state. The electrodes 121 and 122 are held at one reference distance W53. Here, the first reference distance W53 is preferably within a range that satisfies the relational expression 0≦W53≦500×W50, where W50 is the maximum thickness of the polymer fiber body FB in the direction in which the electrodes 121 and 122 face each other. is within a range where the relational expression 0≦W53≦10×W50 holds true.

The power generation element 2 according to the present embodiment can also be produced by simply performing an electrospinning process in which fibers made of non-piezoelectric polymer are three-dimensionally deposited. Simplification can be achieved.

Further, the holding member 211 according to the present embodiment is formed into a plate shape from an elastic material, and has two sub-holding members 2111 and 2112 arranged to face each other. Further, the sub-holding member 2111 is fixed at its end to the end of the sub-holding member 2112. The holding member 211 is urged to the second state by the restoring force of the sub-holding members 2111 and 2112. In this way, since the holding member 211 has a simple configuration in which the two plate-shaped sub-holding members 2111 and 2112 are fixed to each other at their ends, there is an advantage that the power generation element 2 can be easily manufactured.

(Embodiment 3)
Similar to Embodiment 1, the power generation element according to the present embodiment includes a polymer fiber body FB in which chargeable non-ferroelectric polymer fibers are three-dimensionally deposited, which are produced by an electrospinning method. . As shown in FIG. 4(A), the power generation element 3 according to the present embodiment includes a polymer fiber body FB, two conductive members 321 and 322 arranged opposite to each other, and a connection between the two conductive members. A holding member 311 that holds two conductive members so that the distance can be changed is provided. The polymer fiber body is interposed between the two conductive members 321 and 322. Note that the method for manufacturing the polymer fiber body FB is the same as the method described in Embodiment 1.

The conductive member 321 is a first conductive member made of a conductive cloth formed by knitting conductive threads, for example, and the conductive member 322 is made of a conductive cloth similarly to the conductive member 321. This is the second conductive member.

The holding member 311 includes a sheet member 3111 and a sheet member 3112 disposed opposite to one surface of the sheet member 3111. The sheet member 3111 is made of a non-conductive cloth, and is a first sheet member in which a conductive member 321 is disposed in a fifth region A31 on one side in the thickness direction, for example, as shown in FIG. 4(B). be. Further, the sheet member 3112 is a second sheet member that is formed from a non-conductive cloth and has a conductive member 322 disposed in the sixth region A32 on the side facing the sheet member 3111 in the thickness direction. As shown in FIG. 4A, the sheet member 3111 has ends 3111A and 3111B on one side of the sheet member 3111 facing the sheet member 3112, and ends of the sheet member 3112 on the side facing the sheet member 3111. It is fixed to the ends 3112A and 3112B. Here, the ends 3111A and 3111B of the sheet member 3111 are located in the seventh region of the sheet member 3111 excluding the fifth region A31. Furthermore, the ends 3112A and 3112B of the sheet member 3112 are located in the eighth region of the sheet member 3112 excluding the sixth region A32. Note that the sheet members 3111 and 3112 are not limited to those that are fixed at their respective ends; They may be fixed to each other at a portion other than the end portions.

The holding member 311 can take a third state in which two conductive members 321 and 322 are spaced apart from each other, as shown in FIG. 4(A). In the third state, the holding member 311 holds the two conductive members 321 by pulling both ends P31 and P32 of the sheet members 3111 and 3112 away from each other as shown by arrow AR31 in FIG. 4(A). , 322 are displaced toward each other, and the two conductive members 321 and 322 assume a fourth state in which they are in contact with each other.

The power generation element 3 according to the present embodiment includes conductive members 321 and 322 made of conductive cloth, and a holding member 311 formed by fixing sheet members 3111 and 3112 made of cloth to each other at their ends. As a result, flexibility can be increased compared to the power generation elements 1 and 2 described in Embodiments 1 and 2, so the range of application of the power generation element 3 can be expanded.

Furthermore, since the power generation element 3 is mechanically flexible, lightweight, and has excellent breathability, it also has the advantage of being easy to apply to wearable biological movement sensors, which are expected to be in demand as IOE develops in the future.

(Embodiment 4)
Similar to Embodiment 1, the power generation element according to the present embodiment includes a polymer fiber body in which chargeable non-piezoelectric polymer fibers are three-dimensionally deposited, which are produced by electrospinning. As shown in FIGS. 5A and 5B, the power generation element 4 according to the present embodiment includes a polymer fiber body FB, two conductive members 421 and 422 disposed facing each other, and two conductive A holding member 411 that holds two conductive members 421 and 422 such that the distance between the members 421 and 422 can be changed is provided. The polymer fiber body FB is fixed to the conductive member 421.

The conductive member 421 is a third conductive member formed into a cylindrical shape from a conductive cloth formed by, for example, knitting conductive threads, and the conductive member 422, like the conductive member 321, A fourth conductive member made of cloth.

The holding member 411 is formed into an annular shape from an elastic material such as rubber. The holding member 411 is inserted inside each of the two conductive members 421 and 422. The holding member 411 can take a third state in which the two conductive members 421 and 422 are spaced apart from each other, as shown in FIG. 5(A). In the third state, the holding member 411 is pulled in the direction of arrow AR42 in FIG. 5(B) by pulling its ends P31 and P32 away from each other as shown in arrow AR41 in FIG. 5(B). As shown, the two conductive members 421 and 422 are displaced toward each other. Then, the two conductive members 421 and 422 take a fourth state in which they are in contact with each other.

The power generation element 4 according to the present embodiment includes conductive members 421 and 422 formed in a cylindrical shape from conductive cloth, and an annular holding member 411. This has a simpler configuration than the power generation elements 1 and 2 described in Embodiments 1 and 2, so the manufacturing process of the power generation element 3 can be simplified.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments. For example, in the first embodiment, the shape of the holding member 11 may be cylindrical, prismatic, or cylindrical with other cross-sectional shapes. Further, in the second embodiment, the holding member 211 may be one in which the ends of two sub-holding members 2111 and 2112 are connected to each other via a connecting member formed of an elastic material.

In the first embodiment, an example of the power generating element 1 in which the polymer fiber body FB is in contact with the electrode 121 when the holding member 11 is in the first state has been described, but the present invention is not limited to this. For example, when the holding member 11 is in the first state, the polymer fiber body FB may be in contact with the electrode 122. Alternatively, when the holding member 11 is in the first state, the polymer fiber body FB may be in contact with neither of the electrodes 121 and 122. In this case, in the first state, the holding member 11 maintains the sum of the distance between the electrode 121 and the polymer fiber body FB and the distance between the electrode 122 and the polymer fiber body FB in the opposing direction of the electrodes 121 and 122. The electrodes 121 and 122 may be held so that the corresponding distance becomes the first reference distance described above. Also in the second embodiment, when the holding member 211 is in the first state, the polymer fiber body FB may not be in contact with either of the electrodes 121 and 122.

In the fourth embodiment, the example in which the polymer fiber body FB is fixed only to the conductive member 421 has been described, but the invention is not limited to this. For example, the polymer fiber body FB is fixed to both of the two conductive members 421 and 422. It may be fixed.

In Embodiment 4, an example has been described in which the conductive members 421 and 422 are formed into a cylindrical shape from a conductive cloth formed by knitting conductive threads, but the present invention is not limited to this, for example. The conductive members 421 and 422 may be formed into a cylindrical shape from a nonwoven fabric containing conductive fibers. Alternatively, the conductive members 421 and 422 may be in the form of a mesh made of metal wire, for example. Furthermore, in the fourth embodiment, an example in which the holding member 411 is formed of an elastic material in an annular shape has been described, but the present invention is not limited thereto. For example, it may be a cylindrical member made of the elastic material described in Embodiment 1.

In each embodiment, the polymer fiber body FB may be a charged body with a porous structure whose Young's modulus is 1 Pa or more and 1×10 ⁹ Pa or less, preferably 100 Pa or more and 1×10 ⁵ Pa or less. . Further, the non-piezoelectric polymer fibers constituting the polymer fiber body FB may have an elliptical cross section, a rectangular cross section, a star shape, or other shapes.

In Embodiments 1 and 2, when the polymer fiber body FB is divided by one virtual plane passing through the center of the polymer fiber body FB, more positive charges than negative charges are unevenly distributed on one side and the other side is unevenly distributed. I explained that there are more negative charges unevenly distributed than positive charges. However, the virtual plane is not necessarily limited to one that passes through the center of the polymer fiber body FB, and may, for example, pass through a position offset from the center within the polymer fiber body FB.

Although the embodiments and modifications of the present invention (including those described in the notes; the same applies hereinafter) have been described above, the present invention is not limited to these. The present invention includes combinations of the embodiments and modifications as appropriate, and modifications as appropriate.

A polymer fiber body that constitutes a part of the power generation element according to the present invention and a method for manufacturing the polymer fiber body will be described based on Examples.

(Example 1)
A polymer fiber body was produced by electrospinning using polystyrene as a non-piezoelectric polymer, and the properties of the produced polymer fiber body were evaluated. The polystyrene used in the electrospinning method had a weight average molecular weight of about 280,000, and N,N-dimethylformamide was used as the solvent. First, 2.0269 g of polystyrene was dissolved in 4.7280 g of N,N-dimethylformamide. Polystyrene was dissolved in the solvent by stirring using a magnetic stirrer at room temperature and atmospheric pressure.

As the electrospinning device, one similar to that described in JP-A-2016-223055 was used. Specifically, a metal nozzle (inner diameter 0.18 mm) was attached to the syringe. In addition, KD-100 (manufactured by KD Scientific Inc.) was used as a syringe pump. A glass substrate coated with an ITO (Indium Tin Oxide) thin film electrode was used as the collector. The distance between the metal nozzle and the collector was 12 cm, and HARb-30R1 (manufactured by Matsusada Precision Co., Ltd.) was used as the voltage application means. In addition, the discharge rate of the non-piezoelectric polymer solution from the metal nozzle by the syringe pump when producing the polymer fiber body was 0.25 ml/hr, and the voltage applied between the metal nozzle and the collector was such that the metal nozzle side was at a high potential. The voltage was set to 5.0kV. Further, the deposition time of the polystyrene fibers was 8 min. In this way, a polymer fiber body composed of polystyrene fibers having an average fiber diameter of 3.88 μm could be obtained.

Regarding the produced polymer fiber body, the electric charge generated in the polymer fiber body FB was measured using the measuring device shown in FIGS. 6(A) and (B). The measuring device includes a glass substrate 201, an electrode 202 formed from ITO (Indium Tin Oxide) provided on the glass substrate 201, an electrode terminal 101, and a generated charge measuring section 100. The generated charge measurement unit 100 outputs the amount of charge generated in the polymer fiber body FB and input via the electrode 202 or the electrode terminal 101. FIG. 7(A) shows the result when the electrode terminal 101 is pushed toward the electrode 202 by a distance W1 from the state in which it is in contact with the polymer fiber body FB as shown in FIG. 6(A). In FIG. 7A, S11 is when the pressing load is set to 0.05N, S12 is when the pressing load is set to 0.14N, S13 is when the pressing load is set to 0.21N, and S14 is when the pressing load is set to 0.21N. shows a profile when the pressing load is set to 0.28N. Further, times T11, T12, T13, and T14 are the timings when the electrode terminal 101 is pushed in, and times T21, T22, T23, and T24 are the timings when the electrode terminal 101 is removed from the polymer fiber body FB. As shown in FIG. 7(A), it was found that the greater the pressing force when pushing the electrode terminal 101 toward the electrode 202, the greater the amount of charge generated in the polymer fiber body FB.

Next, as shown in FIG. 6(B), the electrode terminal 101 is brought close to the polymer fiber body FB from a distance of 87 μm from the surface of the polymer fiber body FB to a preset position, and then returned to the original position. FIG. 7B shows the results of measuring the amount of charge generated in the polymer fiber body FB when the polymer fiber body FB was returned to a state separated from the surface by 87 μm. In S21, when the electrode terminal 101 is brought closer to the polymer fiber body FB by a distance W2 of 21 μm as shown in FIG. 6(B), in S22, when the distance W2 shown in FIG. When the fibrous body is not pushed into contact with the fibrous body, S23 shows the profile when the fibrous body FB is pushed in to a distance W1 of 6 μm, and S24 shows the profile when the fibrous body FB is pushed down to a distance W1 of 14 μm. Further, times T31, T32, T33, and T34 are the timings when the electrode terminal 101 is brought close to or pushed into the polymer fiber body FB, and times T41, T42, T43, and T44 are the timings when the electrode terminal 101 is separated from the polymer fiber body FB. This is the timing at which they were let go or left. As shown in FIG. 7(B), when the electrode terminal 101 approaches the polymer fiber body FB and further contacts it and then pushes it in, the larger the total pushing distance of the electrode terminal 101 (87 μm−W2+W1), the more the polymer fiber body FB It was found that the amount of charge generated increases.

Next, the electrode terminal 101 is brought close to the polymer fiber body FB from a distance of 335.1 μm from the surface of the polymer fiber body FB to a preset position, and then again 335.1 μm from the surface of the polymer fiber body FB. FIG. 8 shows the results of measuring the amount of charge generated in the polymer fiber body FB when the polymer fiber body FB was returned to the state separated by .1 μm. In FIG. 8, when the distance W2 is greater than 0, the electrode terminal 101 and the polymer fiber body FB are in a non-contact state, and when the distance W2 is less than 0, the electrode terminal 101 is in contact with the polymer fiber body FB. state. As shown in FIG. 8, when the electrode terminal 101 is pushed in after contacting the polymer fiber body FB, the rate of increase in the amount of charge generated in the polymer fiber body FB per unit displacement of the electrode terminal 101 increases. It turned out that there was.

(Example 2)
A sample 500A according to Example 2 in which a polymer fiber body FB was deposited on an aluminum foil 501 as shown in FIG. 9(A) was prepared by using an aluminum foil as a collector and using the same method as in Example 1. Then, regarding the sample 500A according to Example 2, the surface potential of the sample 500A was measured using a non-contact surface potentiometer. At this time, as shown in FIG. 9(A), the measurement probe 591 of the surface electrometer was placed at a position facing the polymer fiber body FB of the sample 500A. Further, the aluminum foil 501 was maintained at ground potential. As the surface electrometer, KSD-3000 manufactured by Kasuga Denki Co., Ltd. was used. As a result of measuring the surface potential, the surface potential of the polymer fiber body FB was 439V.

(Example 3)
Samples 500B1 and 500B2 were prepared in which polymer fiber bodies FB1 and FB2 were deposited on aluminum foils 521 and 522, respectively, as shown in FIG. 9(B), using aluminum foil as the collector and using the same method as in Example 1. did. Then, as shown in FIG. 9(B), samples 500B1 and 500B2 were stacked on top of each other so that the aluminum foils 521, 522 and the polymer fiber bodies FB1, FB2 were lined up in the same direction. did. Regarding the sample according to Example 3, the surface potential on the polymer fiber body FB side of sample 500B was measured using a non-contact type surface electrometer. At this time, as shown in FIG. 9(B), the measurement probe 591 of the surface electrometer was placed at a position facing the polymer fiber body FB2 of the sample 500B2. Further, the aluminum foil 521 was maintained at ground potential. The same surface electrometer as in Example 2 was used. As a result of measuring the surface potential, the surface potential of the polymer fiber body FB2 was 536V. In other words, in the case of the sample 500B according to Example 3, which has a so-called two-layer structure in which the samples 500B1 and 500B2 are stacked so that the aluminum foils 521 and 522 and the polymer fiber bodies FB1 and FB2 are aligned in the same direction, the sample 500B has a so-called single layer structure. It was found that the surface potential was increased compared to sample 500A according to Structure Example 2.

(Example 4)
Samples 500B1 and 500B2 were prepared in which polymer fiber bodies FB1 and FB2 were deposited on aluminum foils 521 and 522, respectively, as shown in FIG. 9(C), using aluminum foil as the collector and using the same method as in Example 1. did. Then, as shown in FIG. 9C for the samples 500B1 and 500B2, the alignment directions of the aluminum foils 521 and 522 and the polymer fiber bodies FB1 and FB2 are opposite to each other, so that the polymer fiber bodies FB1 and FB2 face each other. A sample 500C was prepared by superimposing the above. Regarding sample 500C according to Example 4, the surface potential of sample 500C was measured using a non-contact type surface potentiometer. At this time, as shown in FIG. 9C, the measurement probe 591 of the surface electrometer was placed at a position facing the aluminum foil 522 of the sample 500B2. Further, the aluminum foil 521 was maintained at ground potential. The same surface electrometer as in Example 2 was used. As a result of measuring the surface potential, the surface potential of sample 500C was 21V. In other words, this is an example of a two-layer structure in which samples 500B1 and 500B2 are stacked so that the aluminum foils 521 and 522 and the polymer fiber bodies FB1 and FB2 are arranged in opposite directions, and the polymer fiber bodies FB1 and FB2 face each other. In the case of sample 500C according to Example 4, it was found that the surface potential was significantly lower than that of sample 500A according to Example 2, which had a so-called single layer structure.

From the above results, it was considered that the polymer fiber body FB is a unique supporting model that carries positive and negative charges in a state where the distribution of positive and negative charges is biased. In particular, the surface potential of sample 500B according to Example 3 is higher than that of sample 500A according to Example 2, while the surface potential of sample 500C according to Example 4 is higher than that of sample 500C according to Example 2. As shown in FIGS. 9(A) to 9(C), the charge distribution within the polymer fiber bodies FB, FB1, and FB2 is extremely small. It was found that this can be explained by a charge charging model in which more positive charges than negative charges are unevenly distributed on one side of the thickness direction of 501, 521, and 522, and more negative charges than positive charges are unevenly distributed on the other side.

INDUSTRIAL APPLICATION This invention is suitable as a sensor for sensing the movement of a living body, or a power generation element which generates electricity from the movement of a living body.

1, 2, 3, 4: power generation element, 11,211,311,411: holding member, 11a: first part, 11b: second part, 100: generated charge measuring section, 101: electrode terminal, 121, 122: Electrode, 201: Glass substrate, 202: Electrode, 321, 322, 421, 422: Conductive member, 500A, 500B, 500C, 500B1, 500B2: Sample, 501, 521, 522: Aluminum foil, 591: Measurement probe, 900: Electrospinning device, 901: Syringe, 902: Collector, 903: Syringe pump, 911: Nozzle, 2111, 2112: Sub-holding member, 3111, 3112: Sheet member, 3111A, 3111B, 3112A, 3112B, P31, P32: End part , A11: first region, A12: third region, A21: second region, A22: fourth region, A31: fifth region, A32: sixth region, C1: central portion, E: voltage application means, FB, FB1, FB2: Polymer fiber body, J1: Cylindrical axis, VPL: Virtual plane, W3, W53: First reference distance, W4, W52: Second reference distance

Claims (10)

A polymer fiber body consisting of only random portions in the fiber axis direction, which is made up of three-dimensionally deposited fibers made of a chargeable non-piezoelectric polymer ;
a first conductive member;
a second conductive member disposed opposite to the first conductive member;
a holding member that holds the first conductive member and the second conductive member in a state where the distance between the first conductive member and the second conductive member is changeable;
The polymer fiber body is interposed between the first conductive member and the second conductive member, and when divided by one virtual plane, positive charges are more unevenly distributed than negative charges on one side and the other side is unevenly distributed. More negative charges than positive charges are unevenly distributed on the side ,
The first conductive member is arranged in a region facing one side of the virtual plane,
The second conductive member is arranged in a region facing the other surface of the virtual plane,
The holding member has a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body, and a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body. and a second state in which the first conductive member and the polymer fiber body are in contact with each other, and in the first state, the first conductive member and the polymer fiber body in the opposing direction of the first conductive member and the second conductive member. the first conductive member and the second conductive member such that a distance corresponding to the sum of the distance between the first conductive member and the second conductive member and the polymer fiber body becomes a preset first reference distance. and in the second state, the distance between the first conductive member and the second conductive member in the opposing direction is greater than the thickness of the polymer fibrous body in the opposing direction in the first state. holding the first conductive member and the second conductive member so that they are shorter by a preset second reference distance;
Piezoelectric element. the holding member is biased to the first state;
The piezoelectric element according to claim 1 . A polymer fiber body consisting of only random portions in the fiber axis direction, which is made up of three-dimensionally deposited fibers made of a chargeable non-piezoelectric polymer;
a first conductive member;
a second conductive member disposed opposite to the first conductive member;
a holding member that holds the first conductive member and the second conductive member in a state where the distance between the first conductive member and the second conductive member is changeable;
When the polymer fiber body is divided by one virtual plane, more positive charges than negative charges are unevenly distributed on one side, and more negative charges than positive charges are unevenly distributed on the other side,
The polymer fiber body is interposed between the first conductive member and the second conductive member,
The first conductive member is arranged in a region facing one side of the virtual plane,
The second conductive member is arranged in a region facing the other surface of the virtual plane,
The holding member has a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body, and a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body. and a second state in which it is in contact with
the holding member is biased to the first state;
Piezoelectric element. The holding member is formed into a cylindrical shape from an elastic material, the first conductive member is disposed at a first portion on the inner surface, and the first portion on the inner surface faces the holding member across the cylinder axis thereof. the second conductive member is disposed at a second portion;
A piezoelectric element according to claim 2 or 3 . the holding member is biased to the second state;
The piezoelectric element according to claim 1 . A polymer fiber body consisting of only random portions in the fiber axis direction, which is made up of three-dimensionally deposited fibers made of a chargeable non-piezoelectric polymer;
a first conductive member;
a second conductive member disposed opposite to the first conductive member;
a holding member that holds the first conductive member and the second conductive member in a state where the distance between the first conductive member and the second conductive member is changeable;
When the polymer fiber body is divided by one virtual plane, more positive charges than negative charges are unevenly distributed on one side, and more negative charges than positive charges are unevenly distributed on the other side,
The polymer fiber body is interposed between the first conductive member and the second conductive member,
The first conductive member is arranged in a region facing one side of the virtual plane,
The second conductive member is arranged in a region facing the other surface of the virtual plane,
The holding member has a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body, and a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body. and a second state in which it is in contact with
the holding member is biased to the second state;
Piezoelectric element. The holding member includes a first sub-holding member formed in a plate shape made of an elastic material and having the first conductive member disposed in a first region on one side in the thickness direction; a second sub-holding member disposed opposite to the first sub-holding member, and in which the second conductive member is disposed in a second region on the first sub-holding member side in the thickness direction; ,
The first sub-holding member has a third area other than the first area on one side of the first sub-holding member, and a third area on a side of the second sub-holding member opposite to the one side of the first sub-holding member. is fixed to a fourth area excluding the second area in
A piezoelectric element according to claim 5 or 6. A polymer fiber body consisting of only random portions in the fiber axis direction, which is made up of three-dimensionally deposited fibers made of a chargeable non-piezoelectric polymer;
a first conductive member;
a second conductive member disposed opposite to the first conductive member;
a holding member that holds the first conductive member and the second conductive member in a state where the distance between the first conductive member and the second conductive member is changeable;
When the polymer fiber body is divided by one virtual plane, more positive charges than negative charges are unevenly distributed on one side, and more negative charges than positive charges are unevenly distributed on the other side,
The polymer fiber body is interposed between the first conductive member and the second conductive member,
The first conductive member is arranged in a region facing one side of the virtual plane,
The second conductive member is arranged in a region facing the other surface of the virtual plane,
The holding member has a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body, and a first state in which at least one of the first conductive member and the second conductive member is separated from the polymer fiber body. and a second state in which it is in contact with
The first conductive member and the second conductive member are formed from conductive cloth,
The holding member includes a first sheet member made of cloth and having the first conductive member disposed in a fifth region on one surface side in the thickness direction, and a first sheet member made of cloth and facing the one surface of the first sheet member. and a second sheet member in which the second conductive member is arranged in a sixth region on the first sheet member side in the thickness direction,
The first sheet member is fixed to a seventh region of the first sheet member excluding the fifth region and an eighth region of the second sheet member on the first sheet member side excluding the sixth region. There is,
Piezoelectric element. A polymer fiber body consisting of only random portions in the fiber axis direction, which is made up of three-dimensionally deposited fibers made of a chargeable non-piezoelectric polymer;
a third conductive member;
a fourth conductive member disposed opposite to the third conductive member;
a holding member that holds the third conductive member and the fourth conductive member so that the distance between the third conductive member and the fourth conductive member can be changed ;
When the polymer fiber body is divided by one virtual plane, more positive charges than negative charges are unevenly distributed on one side, and more negative charges than positive charges are unevenly distributed on the other side, and the third fixed to at least one of the conductive member and the fourth conductive member,
The holding member has a third state in which the third conductive member and the fourth conductive member are spaced apart from each other, and a state in which the polymer fiber is fixed to the one of the third conductive member and the fourth conductive member. a fourth state in which the other of the third conductive member and the fourth conductive member is in contact with the body;
The third conductive member and the fourth conductive member are formed in a cylindrical shape from conductive cloth,
The holding member is formed in an annular shape from an elastic material, and is inserted into the inside of the third conductive member and the inside of the fourth conductive member.
Piezoelectric element. The non-piezoelectric polymers include polystyrene, polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, acrylonitrile-styrene copolymer, polyvinyl chloride, polyacrylonitrile. , polyvinylidene chloride-acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, methyl methacrylate-styrene copolymer, polyamide, polyester, aramid, polycarbonate, amorphous fluororesin, non-ferroelectric fluororesin , nonferroelectric fluororesin derivatives, nonferroelectric fluororesin copolymers, polyhydroxybutyrate, polyurethane, polyvinyl acetate, polybutylene succinate, silk, wool, natural rubber, polyetherketone, Polyarylene ether ether ketone, polyacrylonitrile-methacrylate copolymer, polybenzimidazole, polyetherimide, polyethylene sulfide, polyester urethane, polyvinyl alcohol, polyethylene oxide, polyvinyl carbazole, polyvinyl pyrrolidone, collagen, polycaprolactone, polyhydroxyalkanoic acid , polyglycolic acid, polymethyl methacrylate, amorphous poly-DL-lactic acid (PDLLA), derivatives of polylactic acid, polylactic acid-glycolic acid copolymer, cellulose, cellulose acetate, cellulose derivatives, chitosan, chitin, poly at least one polymer selected from peptides and proteins;
A piezoelectric element according to any one of claims 1 to 9 .

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