Mechanical stimulation response element

Abstract

The main purpose of the present invention is to provide a mechanical stimulation response element which is capable of more precisely and efficiently stimulating a functional material in a polymer base material. A mechanical stimulation response element according to the present invention comprises a high-frequency mechanical vibration element, and a composite material part that is provided on the surface of a vibrator in the high-frequency mechanical vibration element. The composite material part comprises a composite material of a polymer base material and a functional material the physical properties of which are changed by a distortion. The high-frequency mechanical vibration element is for applying high-frequency minute vibration exceeding the upper limit of frequencies at which deformation of the polymer base material can follow a stress, and changes the physical properties of the functional material by means of the high-frequency minute vibration applied by the high-frequency mechanical vibration element.

Description

Mechanically responsive elements

[0001] The present invention relates to a mechanical stimulus responsive element.

[0002] Composite materials, which use a polymer network as a base material and either bond functional materials to the polymer matrix or disperse functional materials in the polymer matrix, have attracted attention in recent years because they combine the elastic properties of polymers with the properties of functional materials.

[0003] For example, Non-Patent Document 1 discloses a stimuli-responsive material in which a mechanochromic material, a functional material that changes color or emits light due to changes in its molecular structure caused by mechanical stimuli such as pressure or vibration, is bonded to a polymer matrix. The optical properties of the stimuli-responsive material can be controlled by applying a mechanical stimulus to the mechanochromic material through the polymer matrix. Therefore, various applications are expected, such as strain sensing that visualizes strain generated in a polymer matrix, imaging that detects minute forces, and memory devices that enable the writing and reading of complex information using mechanical stimuli.

[0004] Non-Patent Document 2 discloses a stimuli-responsive material that can control the electrical resistivity according to the amount of deformation of a polymer matrix by dispersing and compounding a conductive material, such as a carbon material or a metal nanomaterial, in the polymer matrix. The stimuli-responsive material is expected to be used in the field of soft electronics, taking advantage of the compounding of a soft, stretchable polymer matrix with a conductive material, and in strain sensors that detect the amount of deformation by reading the change in electrical resistivity due to stretching.

[0005] MA Ghanem, A. Basu, R. Behrou, N. Boechler, AJ Boydston, SL Craig, Y. Lin, BE Lynde, A. Nelson, H. Shen and DW Storti, Nat. Review. Mater., 6, 84 (2021). A. Larmagnac, S. Eggenberger, H. Janossy and J. Voros, Sci. Rep., 4, 7254 (2014).

[0006] Although stimuli-responsive materials, which can control various physical properties in response to mechanical stimuli, are attractive, precise control is difficult due to the non-uniformity of strain generated in the functional material. Furthermore, there are several challenges, such as the need to generate large strains of several percent or more throughout the stimuli-responsive material to express or adjust its function, and in some cases the response of stimuli-responsive materials to strain is irreversible.

[0007] In view of the above circumstances, a main object of the present invention is to provide a mechanical stimulus responsive element that can stimulate a functional material in a polymer matrix more precisely and efficiently.

[0008] One aspect of the present invention is a mechanical stimulus responsive element comprising a high-frequency mechanical vibration element and a composite material part provided on the surface of a vibrator of the high-frequency mechanical vibration element, wherein the composite material part includes a composite material of a polymer matrix and a functional material whose physical properties change with strain, and the high-frequency mechanical vibration element is a mechanical vibration element that applies high-frequency micro-vibrations that exceed the upper frequency limit at which deformation of the polymer matrix can follow stress, and the high-frequency micro-vibrations caused by the high-frequency mechanical vibration element change the physical properties of the functional material, thereby forming a mechanical stimulus responsive element.

[0009] According to the present invention, a mechanical stimulus responsive element is provided that can stimulate a functional material in a polymer matrix more precisely and efficiently.

[0010] FIG. 1 is a schematic diagram showing a schematic configuration of a mechanical stimulus responsive element according to an example of an embodiment; FIG. 2 is a schematic diagram showing how a functional material in a composite material is stimulated in a conventional technology; FIG. 3 is a graph showing the relationship between the strain generated in the composite material when the functional material in the composite material is stimulated and the luminescence intensity in the conventional technology; FIG. 4 is a schematic diagram showing how a functional material in a composite material is stimulated in the present invention; FIG. 5 is a graph showing the relationship between the strain generated in the composite material when the functional material in the composite material is stimulated and the luminescence intensity in the present invention; FIG. 6 is a schematic diagram showing a schematic configuration of a mechanical stimulus responsive element of Example 1; FIG. 7 is a schematic diagram showing a schematic configuration of a mechanical stimulus responsive element of Example 2.

[0011] An embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment described below. The drawings used in the following description may show essential parts enlarged for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional proportions of each component may not necessarily be the same as in reality.

[0012] Fig. 1 is a schematic diagram showing the general configuration of a mechanostimulus-responsive element 1 according to an embodiment. As shown in Fig. 1, the mechanostimulus-responsive element 1 includes a high-frequency mechanical vibration element 10 and a composite material section 20 provided on the surface of a vibrator 12 in the high-frequency mechanical vibration element 10. The composite material section 20 includes a composite material of a polymer matrix 22 and a functional material 24 whose physical properties change with strain. The high-frequency mechanical vibration element 10 is a mechanical vibration element that applies high-frequency micro-vibrations that exceed the upper limit of the frequency at which deformation of the polymer matrix 22 can follow stress.

[0013] In the mechanostimulus responsive element 1, the physical properties of the functional material 24 can be changed by high-frequency microvibrations caused by the high-frequency mechanical vibration element 10. More specifically, the high-frequency microvibrations applied by the high-frequency mechanical vibration element 10 are transmitted to the functional material 24 through the polymer matrix 22, causing microstrains in the functional material 24, which change the physical properties of the functional material 24. Therefore, in the mechanostimulus responsive element 1, the physical properties of the functional material 24 can be controlled by the high-frequency microvibrations applied by the high-frequency mechanical vibration element 10.

[0014] (High-Frequency Mechanical Vibration Element) The high-frequency mechanical vibration element 10 can be any mechanical vibration element capable of applying high-frequency microvibrations to the composite material portion 20 that exceed the upper limit of the frequency at which the deformation of the polymer matrix 22 can follow the stress. The deformation of a polymer in response to stress generally involves a certain delay. While polymers easily deform in response to low-frequency stress, the movement of the molecular chains cannot keep up with high-frequency stress, and the polymer behaves essentially like a hard material. The "upper limit of the frequency at which the deformation of the polymer matrix can follow the stress" refers to the upper limit of the frequency range of stress that the deformation of the polymer matrix can follow, and can be determined, for example, by dynamic viscoelasticity measurement. Furthermore, "microvibrations" refer to vibrations with an amplitude of 1 μm or less. Although not limited, typically, a mechanical vibration element capable of applying microvibrations with an amplitude of 1 μm or less and a frequency of 30 MHz or more can be used as the high-frequency mechanical vibration element 10.

[0015] The amplitude of the micro-vibration applied by the high-frequency mechanical vibration element 10 can be, for example, 1 nm to 1 μm. The frequency of the micro-vibration applied by the high-frequency mechanical vibration element 10 can be, for example, 10 MHz to 10 GHz. The difference between the frequency of the micro-vibration applied by the high-frequency mechanical vibration element 10 and the upper limit of the frequency at which the deformation of the polymer base material can follow the stress can be, for example, 10 MHz to 100 GHz.

[0016] Examples of the high-frequency mechanical vibration element 10 include a surface acoustic wave element having a piezoelectric thin film and a comb-shaped electrode disposed on the thin film, a mechanical vibration element having a membrane structure in which a thin film is provided on an actuator, and a mechanical vibration element having a beam-like structure in which a beam is provided on an actuator. The beam constituting the beam-like structure may be a cantilever beam or a beam with both ends fixed.

[0017] (Composite Material Portion) The composite material portion 20 provided on the surface of the vibrator 12 in the high-frequency mechanical vibration element 10 is a portion including a composite material of a polymer matrix 22 and a functional material 24 whose physical properties change with strain.

[0018] The shape of the composite material section 20 is not particularly limited, and can be selected appropriately depending on the form of the vibrator 12. Examples of the shape of the composite material section 20 include a film shape, a plate shape, and a block shape. The thickness of the composite material section 20 can be, for example, 100 nm to 100 μm. The thickness of the composite material section 20 is the average value of thicknesses measured at any five locations.

[0019] Examples of composite materials of a polymer matrix 22 and a functional material 24 include composite materials in which the functional material 24 is bonded to the polymer matrix 22, and composite materials in which the functional material 24 is dispersed in the polymer matrix 22.

[0020] <Polymer matrix> Examples of the polymer matrix 22 include elastomers made of a polymer network, organogels made of a polymer network and a lipophilic solvent, and hydrogels made of a polymer network and an aqueous solvent. The term "polymer network" refers to a polymer having a three-dimensional network structure formed by chemical crosslinking or physical entanglement. The polymer matrix 22 may be used alone or in combination of two or more types.

[0021] Examples of elastomers include silicone rubbers such as polydimethylsiloxane, natural rubbers made of latex, and synthetic rubbers such as styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), acrylic rubber (ACM), fluororubber (FKM), and urethane rubber (U). Other examples include thermoplastic resins such as polyethylene, polyvinyl chloride, polypropylene, polystyrene, polymethyl methacrylate, and polyethylene terephthalate, as well as thermosetting resins such as phenolic and epoxy resins. These elastomers may be used alone or in combination. For example, by using a liquid crystal elastomer as a stimulus-responsive elastomer, a polymeric base material can be obtained that can modulate the frequency range that the polymeric base material can follow. However, this is not limited thereto.

[0022] A plasticizer can be added to control the physical properties of the elastomer. Examples of plasticizers include phthalates, adipates, trimellitates, polyesters, phosphates, citric acid esters, epoxidized vegetable oils, sebacates, azelates, maleates, and benzoates. These plasticizers may be used alone or in combination of two or more.

[0023] Examples of organogels include those obtained by adding a lipophilic solvent that has good affinity with the elastomer to the above-mentioned elastomer. Examples of lipophilic solvents include methanol, ethanol, acetone, toluene, benzene, propanol, butanol, hexane, dimethyl sulfoxide, propylene carbonate, dichloroethane, tetrahydrofuran, ethyl acetate, n-octane, and N,N-dimethylformamide. These lipophilic solvents may be used alone or in combination of two or more. The content of the lipophilic solvent in the organogel may be adjusted appropriately depending on the desired physical properties of the organogel.

[0024] Examples of polymers that make up hydrogels include synthetic water-soluble polymers such as polyacrylamide and polyvinyl alcohol; polysaccharides such as chitosan, agarose, alginic acid, and cellulose; and cross-linked proteins such as collagen, albumin, and gelatin.

[0025] While the type of hydrogel is not particularly limited, the use of an external stimulus-responsive material can result in a polymer matrix that can modulate the frequency range to which the polymer matrix can deform. Examples of external stimulus-responsive hydrogels include heat-responsive hydrogels composed of poly(N-isopropylacrylamide), poly(methyl vinyl ether), etc.; pH-responsive hydrogels composed of polymer electrolytes synthesized from anionic or cationic monomers; and light-responsive hydrogels composed of polymers having spiropyran or azobenzene in their skeletons. A mechanism for changing the degree of swelling in response to light stimuli may be introduced by using an inclusion complex of azobenzene and cyclodextrin as a crosslinking point. Furthermore, multiple of these polymers may be mixed to produce a hydrogel that responds to multiple stimuli. Tough hydrogels such as double-network gels, slide-ring gels, Tetra-PEG gels, and nanoclay gels may also be used.

[0026] Examples of the aqueous solvent include water and alcohol. These aqueous solvents may be used alone or in combination of two or more.

[0027] The synthesis method of the hydrogel is not particularly limited. For example, in the case of an acrylic polymer, chemical crosslinking by polymerization of acrylic groups can be used. In the case of polysaccharides and proteins, gelation by physical bonding can be used, or a chemical crosslinking agent such as glutaraldehyde can be used.

[0028] The type of polymerization reaction is not particularly limited, and examples thereof include radical polymerization using a water-soluble photopolymerization initiator, such as 2-oxoglutaric acid, 4'-(2-hydroxyethoxy)-2-hydroxy-2-methylpropiophenone (Irgacure 2959), lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate (LAP), and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] (VA-086).

[0029] Radical polymerization using a thermal polymerization initiator may also be used. Examples of thermal polymerization initiators include ammonium peroxodisulfate (APS) and potassium peroxodisulfate (KPS). Polymerization may also be carried out in combination with the polymerization accelerator N,N,N',N'-tetramethylethane-1,2-diamine (TEMED). This allows polymerization to occur within a few minutes even at room temperature. To prevent polymerization inhibition by oxygen, glucose and glucose oxidase may be added as oxygen scavengers, or the polymerization reaction may be carried out after thorough degassing under an inert gas atmosphere such as nitrogen or argon.

[0030] <Functional Material> As the functional material, a material whose physical properties change due to minute strain generated by the high-frequency minute vibration applied by the high-frequency mechanical vibration element 10 can be used. One type of functional material may be used alone, or two or more types may be used in combination.

[0031] By incorporating mechanochromic molecules with mechanophores, which are molecular skeletons whose luminescence properties such as absorption wavelength and luminescence intensity change with strain, into a polymer matrix, it is possible to create a composite material whose optical properties can be controlled by high-frequency micro-vibrations.

[0032] The mechanophore is not particularly limited, and examples thereof include spiropyran-based molecules whose molecular structure changes upon cleavage of a covalent bond, supramolecular mechanophores that utilize a rotaxane interlock structure and a fluorescence quencher, Flexible and Aromatic Photofunctional system (FRAP) that utilizes the bending-to-planar structural transition of molecules formed by rigid π-conjugated molecules and flexible π-conjugated molecules, and mechanophores that utilize a complex structure formed by polybutyl acrylate and copper atoms.

[0033] Although the manner in which the mechanochromic molecules are incorporated into the polymer matrix is ​​not particularly limited, a structure that efficiently transmits mechanical stimuli applied to the polymer matrix is ​​preferred. Suitable examples include a form in which the mechanochromic molecules are introduced between molecular chains of the polymer matrix by crosslinking, or a form in which the mechanochromic molecules are directly introduced into the molecular chains of the polymer matrix.

[0034] The content of the mechanochromic molecules in the composite material can be adjusted as appropriate, for example, to 0.1 to 1 part by mass per 100 parts by mass of the polymer matrix.

[0035] By incorporating a luminescent rare earth complex as a functional material into a polymer matrix, a composite material can be obtained whose optical properties can be controlled by high-frequency micro-vibrations. Examples of rare earth metals constituting the rare earth complex include europium, terbium, and neodymium. Examples of ligands constituting the rare earth complex include organic ligands used in known luminescent rare earth complexes, such as hexafluoroacetylacetonate (hfa) and triphenylphosphine oxide (TPPO). Examples of rare earth complexes include tris(hexafluoroacetylacetonate)europium(III)bis(triphenylphosphine oxide).

[0036] Although the manner in which the rare earth complex is incorporated into the polymer matrix is ​​not particularly limited, a structure that efficiently transmits mechanical stimuli applied to the polymer matrix is ​​preferred. A preferred example is a structure that uses a polymer matrix having functional groups that easily interact with the ligands of the rare earth complex.

[0037] The content of the rare earth complex in the composite material can be adjusted as appropriate, for example, to 0.1 to 1 part by mass per 100 parts by mass of the polymer matrix.

[0038] By incorporating a conductive filler into a polymer matrix, a composite material can be obtained whose conductivity can be controlled by high-frequency micro-vibrations. The conductive filler is not particularly limited, and examples thereof include carbon nanomaterials such as graphene, carbon nanotubes, and carbon black, and metal nanomaterials such as gold nanoparticles, silver nanoparticles, and copper nanoparticles.

[0039] The manner in which the conductive filler is incorporated into the polymer matrix is ​​not particularly limited, but it is preferable to disperse the conductive filler in the polymer matrix in an amount sufficient to exhibit conductivity, i.e., to form a conductive path or exhibit a tunnel effect.

[0040] For example, the conductive filler may be subjected to a surface treatment with a high affinity for the polymer matrix, such as a surface treatment with a silane coupling agent, which enhances the interaction between the polymer matrix and the conductive filler, allowing the distance between the dispersed conductive filler particles to change efficiently when high-frequency micro-vibrations are applied to the composite material.

[0041] The content of the conductive filler in the composite material can be adjusted as appropriate, for example, to 1 to 10 parts by mass per 100 parts by mass of the polymer matrix.

[0042] By incorporating a piezoelectric material into a polymer matrix, a composite material can be obtained that can control power generation by high-frequency micro-vibrations. The piezoelectric material is not particularly limited, and examples thereof include lithium niobate crystal (LiNbO ３ ), zinc oxide (ZnO), aluminum nitride (AlN), and gallium arsenide (GaAs).

[0043] The piezoelectric material is preferably incorporated into the polymer matrix in a manner that allows efficient transmission of mechanical stimuli applied to the polymer matrix. A suitable example is one in which the piezoelectric material is dispersed in the polymer matrix.

[0044] The content of the piezoelectric material in the composite material can be adjusted as appropriate, for example, to 1 to 10 parts by mass per 100 parts by mass of the polymer matrix.

[0045] <Optional Components> In addition to the polymer matrix 22 and the functional material 24, the composite material portion 20 may include optional components other than the polymer matrix 22 and the functional material 24. Examples of optional components include dyes, pigments, ionic liquids, magnetic fluids, and liquid metals. One type of optional component may be used alone, or two or more types may be used in combination.

[0046] There are no particular limitations on the method for forming the composite material portion 20 on the surface of the vibrator 12. The composite material portion 20 may be in physical contact with the vibrator 12, but it is preferable that the composite material portion 20 be physically adsorbed or adhered to the vibrator 12, or chemically adsorbed or adhered to the vibrator 12.

[0047] Examples of methods for physically adsorbing or adhering the composite material part 20 to the vibrator 12 include a method of forming the composite material part 20 by using a film-forming technique such as dip coating or spin coating to coat the surface of the vibrator 12 with the composite material.

[0048] Examples of methods for chemically adsorbing or adhering the composite material portion 20 to the vibrator 12 include treating the surface of the vibrator 12 with a silane coupling agent or the like to form an adhesive layer, and then creating a composite material on the surface of the adhesive layer to firmly immobilize the composite material portion 20 via covalent bonds or dynamic bonds such as hydrogen bonds, ionic bonds, or hydrophobic interactions. In particular, it is preferable to form an adhesive layer using a silane coupling agent having a polymerizable group such as 3-(trimethoxysilyl)propyl methacrylate, and then synthesize a polymer matrix on the surface of the adhesive layer by a polymerization reaction such as radical polymerization in the presence of a functional material to form the composite material portion. This forms a covalent bond between the silane coupling agent in the adhesive layer and the polymer matrix in the composite material, thereby firmly immobilizing the composite material portion 20 to the vibrator 12.

[0049] (Effects) Hereinafter, the effects of the mechanical stimulus responsive element according to the embodiment will be described, taking as an example a case where a composite material in which mechanochromic molecules are bonded to a polymer matrix 22 is used as the functional material 24 .

[0050] As shown in Figure 2, in the state (i) before the application of a mechanical stimulus, the molecular chains of the polymer matrix 22 are relaxed. When a mechanical stimulus is applied in the prior art, the molecular chains of the polymer matrix 22 are stretched by the applied stress F, passing through a state (ii). When the molecular chains of the polymer matrix 22 are fully stretched and tensed, the stress F is transmitted to the functional material 24, causing strain in the functional material 24, resulting in light emission. As shown in Figure 3, a graph with the composite material strain on the horizontal axis and the fluorescence intensity on the vertical axis shows that no light emission occurs in the state (ii) where the strain in the composite material is due to the deformation of the polymer matrix 22. However, light emission occurs in the state (iii) where the molecular chains of the polymer matrix 22 are fully stretched and strain is generated in the functional material 24, with the light emission intensity increasing in proportion to the magnitude of the strain. Thus, in the prior art, in order to change the light-emitting properties of the functional material 24, a strain sufficient to fully stretch the molecular chains of the polymer matrix 22 must be generated throughout the composite material, typically a large strain of several percent or more.

[0051] In contrast, in the mechanostimulus-responsive element 1 according to the embodiment, the high-frequency mechanical vibration element 10 applies high-frequency microvibrations exceeding the frequency at which the deformation of the polymer matrix 22 can follow the stress. With such high-frequency vibrations, the polymer matrix 22 does not deform, and its molecular chains do not expand or contract, so it behaves like a substantially hard material, and even microvibrations are efficiently transmitted to the functional material 24. As a result, as shown in Fig. 4, by applying high-frequency microvibrations using the high-frequency mechanical vibration element 10, the deformation of the polymer matrix 22 is suppressed, while the stress F is efficiently transmitted to the functional material 24, generating microstrain and causing the functional material 24 to emit light. As shown in Fig. 5, a graph with the composite material strain on the horizontal axis and the fluorescence intensity on the vertical axis shows that the strain generated in the composite material is almost entirely the strain generated in the functional material 24, and therefore the emission intensity increases in proportion to the strain in the composite material.

[0052] As described above, the present invention focuses on the fact that as the vibration frequency increases, the polymer matrix behaves essentially like a hard material because the deformation cannot keep up. In the present invention, by utilizing a high-frequency mechanical vibration element that applies micro-vibrations that are highly controlled spatially and temporally, strain can be selectively generated in the functional material within the composite material, enabling more precise and efficient control of the physical properties of the functional material. Furthermore, in the present invention, the strain required to express or control the function of the composite material is only small, and large deformation of the entire composite material is not necessary, making it possible to easily fabricate an on-chip mechanical stimulus-responsive element. Furthermore, by changing the combination of the polymer matrix and the functional material, it is possible to create a stimulus-responsive element that can control various functions, such as light emission characteristics, light absorption characteristics, and conductivity.

[0053] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0054] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following descriptions.

[0055] Example 1: A composite material consisting of a polymer matrix and mechanochromic molecules, a functional material, is placed on the vibrator of a mechanical vibration element capable of applying high-frequency microvibrations exceeding the upper limit of the frequency at which the deformation of the polymer matrix can follow stress, and optical properties are controlled by the microvibrations. Specifically, as shown in Figure 6, a comb-shaped electrode is placed on a piezoelectric thin film, which is the vibrator 121, to fabricate a surface acoustic wave element 101 capable of applying microvibration strain at a frequency that the polymer matrix cannot follow. Furthermore, a two-liquid mixture of polydimethylsiloxane is prepared as the polymer matrix 221, and a composite material is prepared by mixing mechanochromic molecules in solution as the functional material 241. The composite material is then coated on the surface of the vibrator 121 by spin coating to form a thin film, and the polymer matrix is ​​hardened by heat treatment to form the composite material part 201. This results in a mechanostimulus-responsive element 1A that can precisely control the optical properties by efficiently generating minute strains in the functional material 241 through high-frequency micro-vibrations by the surface acoustic wave element 101 that exceed the upper limit of the frequency at which the deformation of the polymer matrix 221 can follow the stress. Observation with a fluorescence microscope 301 arranged above the composite material part 201 allows quantitative evaluation of the luminescence properties of the composite material part 201 in the mechanostimulus-responsive element 1A.

[0056] Example 2: A composite material consisting of a polymer matrix and a conductive filler functional material is placed on the vibrator of a mechanical vibration element capable of applying high-frequency microvibrations exceeding the upper limit of the frequency at which the deformation of the polymer matrix can follow stress, thereby controlling conductivity through microvibrations. Specifically, as shown in FIG. 7, a comb-shaped electrode is placed on a piezoelectric thin film (vibrator 121) to fabricate a surface acoustic wave element 102 capable of applying microvibration strain at a frequency that the polymer matrix cannot follow. Furthermore, a two-component polydimethylsiloxane is prepared as the polymer matrix 221, and a conductive filler is mixed in solution as the functional material 242 to fabricate a composite material. A two-component polydimethylsiloxane is prepared as an example of a polymer matrix, and a conductive filler is mixed and dispersed in solution as the functional material 242 to fabricate a composite material. The composite material is then coated on the surface of the vibrator 121 by spin coating to form a thin film, and the polymer matrix is ​​cured by heat treatment to form a composite material portion 202. This results in a mechanostimulus-responsive element 1B that can precisely control the conductivity by efficiently modulating the distance between the conductive filler particles, which are the functional material 242, using high-frequency micro-vibrations by the surface acoustic wave element 102 that exceed the upper frequency limit at which the deformation of the polymer matrix 221 can follow the stress. By providing electrodes 302, 303 on the composite material part 202 and electrically connecting them to an electrical characteristic evaluation device 304 to measure the electrical resistivity of the composite material part 202, the conductivity of the composite material part 202 in the mechanostimulus-responsive element 1B can be quantitatively evaluated.

[0057] The mechanical stimulus responsive element of the present invention is useful as a method for stimulating a composite material of a polymer matrix and a functional material with high-frequency micro-vibrations, and is applicable to a wide range of fields such as optical elements, memory elements, current modulation elements, and power generation elements.

[0058] REFERENCE SIGNS LIST 1, 1A, 1B Mechanical stimulus response element 10 High frequency mechanical vibration element 12, 121 Vibrator 20, 201, 202 Composite material part 22, 221 Polymer base material 24, 241, 242 Functional material 101, 102 Surface acoustic wave element 301 Fluorescence microscope 302, 303 Electrode 304 Electrical property evaluation device

Claims

1. A mechanical stimulus responsive element comprising: a high-frequency mechanical vibration element; and a composite material part provided on the surface of a vibrator in the high-frequency mechanical vibration element, wherein the composite material part includes a composite material of a polymer base material and a functional material whose physical properties change with strain; the high-frequency mechanical vibration element is a mechanical vibration element that applies high-frequency micro-vibrations that exceed the upper frequency limit at which deformation of the polymer base material can follow stress; and the high-frequency micro-vibrations from the high-frequency mechanical vibration element change the physical properties of the functional material.

2. The mechanical stimulus responsive element according to claim 1, wherein the high-frequency mechanical vibration element is a surface acoustic wave element.

3. The mechanical stimulus responsive element according to claim 1, wherein the high-frequency mechanical vibration element is a mechanical vibration element having a membrane structure in which a thin film is provided on an actuator, or a beam-like structure in which a beam is provided on an actuator.

4. A mechanical stimulus response element as described in claim 1, wherein high-frequency micro-vibrations caused by the high-frequency mechanical vibration element generate high-frequency micro-strains in the functional material while suppressing deformation of the polymer matrix, thereby changing the physical properties of the functional material.

5. A mechanical stimulus responsive element as described in claim 4, wherein the composite material contains mechanochromic molecules as the functional material, and high-frequency micro-vibrations caused by the high-frequency mechanical vibration element generate high-frequency micro-strains in the mechanochromic molecules, thereby changing the luminescence characteristics.

6. A mechanical stimulus responsive element as described in claim 4, wherein the composite material contains a conductive filler as the functional material, and the high-frequency mechanical vibration element generates high-frequency micro-strain in the conductive filler, thereby changing the conductivity.

7. A mechanical stimulus responsive element according to claim 4, wherein the composite material contains a piezoelectric material as the functional material, and high-frequency micro-vibrations caused by the high-frequency mechanical vibration element generate high-frequency micro-strains in the piezoelectric material, thereby generating electricity.

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