TWI881315B - Piezoelectric harvester, tire equipped with same, and method for preparing the same - Google Patents

Abstract

Described herein is piezoelectric harvester providing both desired levels of power generation and conformity to arcuate surfaces, comprising a threshold hardness silicone polymer used to produce a cross-linked silicone polymer and piezoelectric particles disposed therein. In some embodiments, the silicone polymer may be platinum doped. Also described is a method for making a piezoelectric harvester having such power generation and conformity characteristics.

Description

Piezoelectric collector, tire equipped with the same, and preparation method thereof

The present invention relates to a piezoelectric harvester. Specifically, the present invention relates to a flexible piezoelectric composite material, comprising a three-dimensional interconnected piezoelectric ceramic framework based on an organic template having sufficient rigidity and infiltrated with a flexible polymer matrix.

Unless otherwise indicated in this invention, the materials described in this invention are not prior art to the technical solutions in this application and are not admitted to be prior art by inclusion in this section.

The piezoelectric effect is the induction of electric charge in response to an applied mechanical strain, which can be used to convert mechanical energy into electrical energy. Therefore, piezoelectric materials have been widely used to scavenge energy from the environment and body movements to provide power for personal electronic devices, nanodevices, and wireless sensors. In order to expand the application field of piezoelectric materials, good mechanical flexibility is generally considered to be desirable. However, bulk piezoelectric ceramics such as lead zirconium titanate (PZT) have high piezoelectric coefficients but low flexibility, while piezoelectric polymers such as polyvinylidene fluoride (PVDF) have good flexibility but relatively low piezoelectric coefficients. PVDF is limiting in that it can be difficult to conform to three-dimensional curved surfaces due to lack of stretchability and PVDF-based piezoelectric harvesters can be easily detached or peeled off from the attached surface by repeated deformation. This can be a particularly difficult problem when the target surface is constantly flexing, such as on the inner surface of a vehicle's pneumatic tire. Polydimethylsiloxane (PDMS or polysilicone)-based harvesters have been described, but while known piezocomposites using PDMS are resistant to deformation, the power produced is significantly low.

Therefore, a piezoelectric collector with both flexibility and high piezoelectric coefficient is needed to provide an effective collector for non-planar substrates.

Embodiments of the present invention generally relate to a piezoelectric harvester architecture for generating power in the context of a non-planar environment.

In some embodiments, the piezoelectric collector includes a piezoelectric layer, which includes a cross-linked polysilicon elastomer matrix and piezoelectric particles, wherein the piezoelectric particles are dispersed in the elastomer matrix. In some embodiments, the piezoelectric collector further includes a pair of elastic electrodes placed on the upper and lower sides of the piezoelectric layer. In some embodiments, the piezoelectric collector has a tensile strength of 0.5 to 5 megapascals (MPa) at 1% elongation. In some embodiments, the cross-linked elastomer matrix can be formed by a reactive polysilicon oligomer having a hardness of 45 to 90, which is measured by the Shaw hardness scale type A. In some embodiments, the reactive polysiloxane oligomer has a reactive functional unit fraction of 5 mol% or more in the reactive elastomer matrix. In some embodiments, the elastomer matrix may include a reactive oligomer having a reactive functional group selected from hydroxyl, vinyl, alkoxy and hydride. In some embodiments, the elastomer matrix may include a doped polyalkylsiloxane matrix and piezoelectric particles dispersed in the polyalkylsiloxane matrix. In some embodiments, the dopant may be platinum (Pt). In some embodiments, the polyalkylsiloxane may include polydimethylsiloxane. In some embodiments, the volume fraction of the piezoelectric particles in the piezoelectric layer may be 35 to 65%. In some embodiments, the cross-linked elastomer matrix may include 65% to 35% volume fraction of polysilicon. In some embodiments, the elastomer electrodes may include carbon as a conductive element. In other embodiments, the tire includes the piezoelectric harvester described above. Some embodiments include a method for preparing a piezoelectric harvesting composite material. In some embodiments, the method may include preparing a mixture comprising a polysilicon oligomer and piezoelectric particles dispersed therein, the oligomer having a hardness of 45 to 90 as measured by Shaw A after curing; casting the mixture on a thin layer of an elastic electrode to form a composite sheet; curing the composite sheet; coating the composite sheet with a thin elastic electrode layer to form a three-layer composite structure; and polarizing the piezoelectric particles in the three-layer composite structure.

Other features and advantages will be described in this description. These features and advantages can be realized and obtained by means of the instruments and combinations particularly pointed out in the subsequent description and the accompanying embodiments, examples and drawings.

10: Piezoelectric collector

12: Layer

14: Side

16: Side

18: Electrode

20: Electrode

22: Matrix

24A: Particles

26A: Arrow

200:Module

202: Patches

204:Unit

206: Power source

208: Mounting surface

210: Sensor area

212: Follow-up agent

214: Protective layer

216: One or more corresponding electrical connectors

218: Casing or packaging agent

300: Energy generation circuit

302: Power generation components

304:EHS module

306:Energy storage circuit

308:Battery

FIG. 1 illustrates an example piezoelectric harvester described herein.

FIG. 2 illustrates the piezoelectric harvester of FIG. 1 divided into several layers.

FIG. 3 illustrates an example sensor element described herein.

FIG. 4 is a diagram of energy generating circuits and/or components described herein.

For the purpose of promoting an understanding of the present invention, reference will now be made to the following embodiments and specific language will be used to describe them. Nevertheless, it should be understood that the scope of the present invention is not intended to be limited thereby, and such variations and further modifications of the subject matter, and such further applications of the disclosed principles as described herein are contemplated as being generally understood by those skilled in the art to which the present invention pertains.

The present invention generally relates to piezoelectric power generating elements (also referred to as piezoelectric harvesters). In some embodiments, the piezoelectric harvesters described herein include materials having one or more material properties that provide a balance between hardness and flexibility, such as a balance between the volume fraction of piezoelectric particles and polymers (e.g., PDMS) to simultaneously provide flexibility to enable power generation. In some embodiments, the piezoelectric harvester can exhibit improved conformality to a three-dimensional shape with sufficient toughness to increase durability under conditions consistent with its use (e.g., inside a car tire).

In the present invention, a piezoelectric collector is described. As shown in Figures 1 and 2, the piezoelectric collector (such as piezoelectric collector 10 ) may include a piezoelectric layer, such as layer 12 , which has a first piezoelectric layer side (such as side 14 ) and a second piezoelectric layer side (such as side 16 ) and a first elastic electrode (such as electrode 18 ) and a second elastic electrode (such as electrode 20 ). In some embodiments, the first elastic electrode may be configured on the first piezoelectric layer side and the second elastic electrode may be configured on the second piezoelectric layer side. In some embodiments, the piezoelectric layer may include a cross-linked elastomer matrix, such as matrix 22. In some embodiments, the elastomer matrix may include a reactive oligomer (not shown) and a plurality of piezoelectric particles (such as particles 24A ), wherein the piezoelectric particles may be dispersed in the elastomer matrix. In some embodiments, the piezoelectric particles may be polarized (the orientation of the dipole moment of the piezoelectric particles), as indicated by arrow 26A . In some embodiments, the aforementioned piezoelectric harvester may have a device tensile strength of about 0.5 to about 5 MPa, about 0.7 to 3 MPa, about 1 to 3 MPa, about 0.5-2 MPa, or about 0.55 MPa, about 0.75 MPa, about 0.76 MPa, about 1 MPa, about 1.4 MPa, about 1.6 MPa at 1% elongation, or any tensile strength within the range bounded by any of these values.

In some embodiments, polysilicon (e.g., PDMS) may be used to form a crosslinked elastomeric matrix. In some embodiments, the crosslinked elastomeric matrix may have a hardness ranging from about 45 to about 90, measured using the Shaw Hardness Scale Type A (hereinafter referred to as Shaw A). In some embodiments, the crosslinked elastomeric matrix may have a Shaw A hardness of about 50 to 90, about 65 to 90, about 50 to 55, about 55 to 60, about 60 to 65, about 65 to 70, about 70 to 75, about 75 to 80, about 80 to 85, about 85 to 90, or about 50, about 80, or any Shaw A hardness within a range bounded by any of these values.

In some embodiments, the polysilicone used to form the crosslinked elastomer matrix may contain about 75% polysilicone, about 85% polysilicone, about 90% polysilicone, about 95% polysilicone, about 99% polysilicone, about 99.5% polysilicone, or about 99.9% polysilicone. In some embodiments, the polysilicone may be substantially pure polysilicone. Specific polysilicone polymers, dopants, and/or crosslinkers may help balance stiffness and flexibility and the amount of power generated by the piezoelectric functionality of the piezoelectric harvester. Any suitable means of determining hardness may be employed, such as using ASTM D2240 Standard Type A (hardened steel bar 1.1 mm to 1.4 mm diameter, with a truncated 35° cone, 0.79 mm diameter, with an applied mass of approximately 0.822 kg (kilograms (kg)) and a resulting force of approximately 8.064 Newtons (N)). A suitable means of determining the tensile strength of a material may be using a tensile tester utilizing a stroke speed of 5 mm/min, as described in the experimental information in the Examples herein.

In some embodiments, the piezoelectric layer comprises a crosslinked elastomer matrix. In some embodiments, the elastomer matrix may comprise a polysiloxane elastomer. In some embodiments, the polysiloxane elastomer matrix may comprise a polyalkylsiloxane. In some embodiments, the polyalkylsiloxane may comprise polydimethylsiloxane (PDMS). The type of crosslinking reaction of polysiloxane is not limited to noble metal catalysis, and may include any suitable method of crosslinking reaction of polysiloxane. In some embodiments, the polyalkylsiloxane may be doped with a noble metal. In some embodiments, the noble metal doping agent may comprise Ag, Au, Pd, Ni, Pt, or a combination thereof. It is believed that the noble metal dopant can catalyze the crosslinking reaction. In some embodiments, the noble metal is platinum (Pt). In some embodiments, the PDMS elastomer matrix can be doped with 0.001 wt % to about 5 wt % of a noble metal, such as Pt. Doping of the polysilicon elastomer matrix can promote hardening of the elastomer matrix to achieve a hardness level of about 45 to 90 Schroder A. In some embodiments, the presence of the dopant can catalyze the crosslinking of the piezoelectric layer.

In some embodiments, the crosslinked elastomer matrix may include a reactive polysilicone oligomer. In some embodiments, the reactive oligomer may include a reactive functionalized polysilicone monomer. In some embodiments, the reactive functionalized polysilicone monomer may include a reactive hydride (e.g., polysilicone hydride), a reactive vinyl group, a reactive hydroxyl group, a reactive alkoxy group, or a combination thereof. In some embodiments, the reactive elastomer matrix may include polysilicone hydride (polysilicone reactive functional group) and/or a polysilicone vinyl group (another polysilicone reactive functional group). In some embodiments, the fraction of reactive functional units in the reactive elastomer matrix may be about 5 to 10 mol%, about 8 to 10 mol%, about 5 to 6 mol%, about 6 to 7 mol%, about 7 to 8 mol%, about 8 to 9 mol%, about 9 to 10 mol%, or about 8.5 mol%, about 9.4 mol%, or any mol% within the range bounded by any of these values.

In some embodiments, the piezoelectric particles are lead zirconate titanate (also known as lead zirconate titanate, abbreviated as PZT). In some embodiments, the piezoelectric harvester may include PZT piezoelectric particles dispersed or disposed in a polymer matrix. In some embodiments, the volume fraction of the piezoelectric particles in the piezoelectric layer may be about 35 to 65%, about 35 to 40%, about 40 to 45%, about 45 to 50%, about 50 to 55%, about 55 to 60%, about 60 to 65%, or about 44%, about 50%, or any volume percentage within a range bounded by any of these values to adjust power generation. In some embodiments, the volume fraction of the piezoelectric particles in the piezoelectric layer may preferably be about 40 to 60%, about 40 to 45%, about 45 to 50%, about 50 to 55%, about 55 to 60%, or about 44%, about 50%, about 56%, or any volume percentage within the range bounded by any of these values to adjust toughness.

In some embodiments, the elastic electrodes may contain carbon as a conductive filler element. The conductive fillers may be dispersed in a polymer matrix. The conductive filler may be introduced into the medium by any suitable method. The conductive filler is a compound that causes an electric current to appear in the medium in the presence of an electric current. The conductive filler may be a graphitized or partially graphitized carbon black, also called conductive black. In some embodiments, for example, the conductive blacks may be those sold by Timcal under the trade name "Ensaco 350G" (wherein the specific surface area is 770 square meters per gram (m ² /g) (BET, measured according to standard ASTM D3037)) or "Ensaco 260G" (wherein the specific surface area is 70 m ² /g). In some embodiments, the conductive filler may be a conductive or graphitized carbon black having a specific surface area (BET, measured by standard ASTM D3037) greater than 65 ^m2 /g, greater than 100 ^m2 /g, or greater than 500 ^m2 /g. In some embodiments, the amount of conductive filler in the polymer matrix composition may range from about 35 volume % to about 65 volume %, about 35 to 40%, about 40 to 45%, about 45 to 50%, about 50 to 55%, about 55 to 60%, about 60 to 65%, or about any amount within the range bounded by any of these values. The size of the conductive fillers may vary from 50 nm to 500 μm.

In some embodiments, the piezoelectric materials may have their dipole moments aligned by an external electric field. In some embodiments, the volume fraction of the piezoelectric particles may be about 40% to about 65%, about 40 to 45%, about 45 to 50%, about 50 to 55%, about 55 to 60%, about 60 to 65%, or any amount within a range bounded by any of these values.

In some embodiments, the tires of vehicles (cars, trucks, tractors, motorcycles, bicycles, aircraft, amphibious craft, etc.) may be equipped with and/or include piezoelectric harvesters (such as described herein). The piezoelectric harvesters described herein may be suitable for use with capacitive tire sensors (such as those described in International Patent Cooperation Treaty (PCT) application PCT/US2021/018825 filed on February 19, 2021 (published as WO 2021/168286 on August 26, 2021)), which is incorporated herein by reference in its entirety.

3 illustrates an example sensor module, such as module 200 , which may generally include a detector patch, such as patch 202 , and an electronic unit, such as unit 204 , and optionally an electrical power source, such as source 206. In some embodiments, electronic unit 204 is connected to detector patch 202 and electrical power source 206 , wherein the electrical power source may include a piezoelectric harvesting system, such as described herein.

The detector patch 202 may include a mounting surface 208 and one or more sensor areas 210. The mounting surface 208 may be structured to attach to the surface of a tire or other object and/or may include an underlying or bottom surface of the detector patch 202. Alternatively or in addition, the mounting surface 208 may include an adhesive (such as adhesive 212 ) configured thereon to attach the detector patch 202 to a desired location (e.g., within a tire cavity or outside of an inner tube of a tire). The adhesive 212 may include a thermoplastic adhesive or any other suitable adhesive. The sensor area 210 may generally include a capacitor. In some embodiments, the capacitor and/or the sensor area 210 may be flexible, extensible, expandable, deformable, layered and/or sheet-like. Alternatively or additionally, the sensor area 210 may be at least partially covered, connected and/or surrounded by one or more protective layers (such as protective layer 214 ) as part of the detector patch 202. The protective layer 214 may include an elastomeric material, such as polysilicone or the like. Although the electrical power source 206 has been described as including a piezoelectric harvester, as described herein, more generally, the electrical power source 206 may include a battery, an energy generating circuit, an energy harvesting system (EHS) module, a dielectric elastomer matrix generating material, a piezoelectric harvester as described herein, and/or a receiving coil and circuit of an inductive charging unit. The electronic unit 204 may be in electrical communication with the detector patch 202 and the power source 206 via one or more corresponding electrical connectors 216. Alternatively or additionally, the electronic unit 204 and the power source 206 may be mechanically coupled together by epoxy and/or may be disposed within a housing or encapsulant (such as housing or encapsulant 218 ) that is mechanically coupled to the detector patch 202 .

In some embodiments, the capacitive tire sensor may include an energy generating circuit and/or element and the energy generating circuit and/or element may include some or all of the piezoelectric harvesters, as described herein. As shown in FIG. 4 , the energy generating circuit (e.g., energy generating circuit 300 ) may include an electric power generating element (e.g., power generating element 302 ), an energy harvesting module (or energy harvesting system, or EHS) (e.g., EHS module 304 ), an energy storage circuit (e.g., energy storage circuit 306 ) and/or a battery (e.g., battery 308 ). In some embodiments, the EHS module 304 may be electrically coupled to the power generating element 302 , the energy storage circuit 306 and/or the battery 308 . In some embodiments, the power generating element 302 may include a dielectric generating material, a piezoelectric generating material, or other material, system, or device that generates electricity when subjected to motion, mechanical stress, or other input, or a combination thereof. In some embodiments, the power generating element may be a piezoelectric harvester as described herein. In some embodiments, deflection of the power generating element 302 (e.g., implemented as a piezoelectric harvester as described herein and/or a portion of a detector patch having such materials) may generate a charge on the surface of the power generating element 302. In some embodiments, the power generating element may be disposed adjacent to a tread portion, a shoulder portion, and/or a sidewall portion of a tire.

The following embodiments are described.

Embodiment

Embodiment 1. A piezoelectric collector comprises: a piezoelectric layer comprising a cross-linked polysilicon elastomer matrix and piezoelectric particles, wherein the piezoelectric particles are dispersed in the elastomer matrix; and a pair of elastic electrodes placed on the upper and lower sides of the piezoelectric layer; and wherein the tensile strength at 1% elongation is 0.5 to 5 MPa.

Embodiment 2. The piezoelectric harvester of embodiment 1, wherein the cross-linked elastomer matrix is formed of a reactive polysilicon oligomer having a Shore A hardness of 45 to 90 after curing.

Embodiment 3. A piezoelectric collector as in Embodiment 1, wherein the fraction of the reactive functional units in the reactive elastomer matrix is 5 mol% or more.

Embodiment 4. The piezoelectric collector of Embodiment 1, wherein the elastomer matrix comprises a doped polyalkylsiloxane matrix and piezoelectric particles, and the piezoelectric particles are dispersed in the polyalkylsiloxane matrix.

Embodiment 5. The piezoelectric harvester of the embodiment, wherein the elastomer matrix comprises a reactive oligomer having a reactive functional group selected from hydroxyl, vinyl, alkoxy and hydride.

Embodiment 6. The piezoelectric collector of Embodiment 4, wherein the doped polyalkylsiloxane comprises Pt.

Embodiment 7. The piezoelectric collector of Embodiment 4, wherein the polyalkylsiloxane comprises polydimethylsiloxane.

Embodiment 8. The piezoelectric collector of Embodiment 2, wherein the volume fraction of the piezoelectric particles in the piezoelectric layer is between 35 and 65%.

Embodiment 9. The piezoelectric collector of embodiment 2, wherein the cross-linked elastic body matrix is mainly composed of polysilicon.

Embodiment 10. The piezoelectric collector of embodiment 2, wherein the elastic electrodes comprise carbon as a conductive element.

Embodiment 11. A tire equipped with a piezoelectric collector as described in any one of Embodiments 1 to 10.

Embodiment 12. A method for preparing a piezoelectric harvesting composite material, comprising: providing a polysilicon oxide oligomer having a hardness of 45 to 90 Shore A after curing; providing a mixture comprising the polysilicon oxide oligomer and piezoelectric particles, wherein the piezoelectric particles are dispersed in the polysilicon oxide oligomer; casting the mixture to form a composite sheet; curing the composite sheet; and polarizing the piezoelectric particles in the composite material.

Preparation of composite materials

Example 1

The electrode ink, which was a homogeneous mixture of 60.5 g polydimethylsiloxane (PDMS) (prepared as described in Sci Rep 9, 1 (2019)), 6.3 g carbon black, and 131.7 g toluene, was coated on a fluorinated polymer substrate (PTFE-coated glass fabric, Tapes and Technical Solutions, LLC, Nashville, TN), followed by heat treatment in an oven at 80°C for 15 minutes and then at 200°C for 15 minutes to produce a flexible electrode thin layer.

14g of piezoelectric (PZT) particles were mixed with 2g of polydimethylsiloxane (PDMS) (Short A hardness 80, reactive unit at 9.4 mol%) and 2.8g of toluene in a planetary centrifugal mixer for 4 minutes. A uniform slurry was obtained. The slurry was cast on top of the elastic electrode layer with a wet thickness of 24 mils using a film applicator. The cast film was then heated in an oven at 80°C for 15 minutes to remove the solvent and then heated at 200°C for 30 minutes to complete the crosslinking reaction. A composite film was obtained.

The same electrode ink was coated on top of the composite film, followed by heat treatment in an oven at 80°C for 15 minutes and then at 200°C for 15 minutes to form a second elastic electrode layer. A 3-layer composite structure was obtained.

The composite structure was then sandwiched between two copper plates on a hot plate set at 130°C. A voltage of 6.0 kV was applied to one of the copper plates to generate an electric field at both ends of the composite structure to polarize the PZT particles dispersed therein for 60 minutes. A polarized composite sample was obtained.

Examples 2 to 6

Examples 2 to 6 were prepared in a similar manner to Example 1, except that the hardness and/or molar fraction of the reactive unit of polysilicone and/or the amount of PZT material used to form the elastomeric polymer matrix were varied as shown in Table 1.

Comparison Examples 1 to 11

Comparative Examples 1 to 11 were prepared in a manner similar to Example 1, except that the hardness and/or molar fraction of the reactive unit of polysilicone used to form the elastomeric polymer matrix and/or the amount of PZT material were varied as shown in Table 1.

Measure the strain at 1% elongation

Cut a 1 x 3 cm ² specimen from the composite sample. Measure the average thickness of the 1 x 1 cm ² at the center of the specimen. Clamp the specimen on an AGS-X tensile tester (Shimadzu, Japan) so that the center 1 x 1 cm ² is stretched at a stroke rate of 5 mm/min. Record the strain value at 1% elongation (0.1 mm).

Measuring power generation

計算得。 The composite sample was fixed on an ACT165DL linear actuator (Aerotech, Pittsburgh, PA). Its elastic electrode was connected to an oscilloscope with a load resistor R of 1 kΩ. The sample was subjected to a 3% tensile deformation at a frequency of 20 Hz. The power generated was given by

Calculated.

Sample conformality

A 10 x 10 cm ² sample is pressed onto a patch on the tire inner liner that has been previously sanded to make the surface smooth. If there are no wrinkles, no peeling, or no cracks, the sample is considered to have good conformity. On the other hand, if there are wrinkles, partial peeling, or cracks, the conformity is considered to be poor.

result

The results in Table 1 above illustrate the benefits that may be provided by one or more embodiments herein. For example, when the piezoelectric generator is constructed as described herein, the presently disclosed improved piezoelectric harvester embodiments may provide a desired degree of conformality and power generation at 3% tensile strain.

For the disclosed processes and/or methods, the functions performed by the processes and/or methods may be implemented in different orders, as indicated by the context. In addition, the steps and operations outlined are provided by way of example only, and some steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations.

The present invention may sometimes illustrate different components contained within or connected to different other components. Such depicted architectures are merely examples, and many other architectures may be implemented that achieve the same or similar functionality.

The terms used in the present invention and the accompanying embodiments are generally intended to be "open" terms (for example, the term "including" should be interpreted as "including (but not limited to)", the term "having" should be interpreted as "having (having) at least", the term "includes" should be interpreted as "including (but not limited to)", etc.). In addition, if a specific number of elements is introduced, this can be interpreted as including at least the cited number, as the context indicates (for example, a bare quotation of "two quotations" without other modifiers includes at least two quotations or two or more quotations). As used in the present invention, any transition conjunction and/or phrase presenting two or more alternative terms should be understood to cover the possibility of including one of the terms, any term, or both terms. For example, the phrase "A or B" should be understood to include the possibility of "A" or "B" or "A and B".

The terms and words used are not limited to the bibliographical meanings, but are used only to enable a clear and consistent understanding of the present invention. It should be understood that the singular forms "a", "an", and "the" include plural referents unless the context clearly indicates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more such surfaces.

By the term "substantially" it is meant that the referenced characteristic, parameter or value need not be achieved exactly, but deviations or variations (including, for example, tolerances, measurement errors, measurement precision limitations and other factors known to those skilled in the art) may not preclude the occurrence of the amount of the effect that the characteristic is intended to provide.

Without departing from the spirit or essential features of the invention, aspects of the invention may be implemented in other forms. The aspects described should be considered in all aspects as illustrative rather than restrictive. The subject matter implemented is indicated by the accompanying embodiments rather than by the foregoing description. All changes within the meaning and scope of equivalence of the embodiments should be included in their scope.

Cross-reference to related applications

This application claims priority to U.S. Provisional Application No. 63/325,527 filed on March 30, 2022, the entire text of which is incorporated by reference.

Claims (15)

A piezoelectric collector comprises: a piezoelectric layer comprising a cross-linked polysilicon elastomer matrix and piezoelectric particles, wherein the piezoelectric particles are dispersed in the cross-linked polysilicon elastomer matrix; and a first elastic electrode placed on a first side of the piezoelectric layer and a second elastic electrode placed on an opposite second side of the piezoelectric layer; and wherein the tensile strength of the piezoelectric collector is about 0.5 MPa to about 5 MPa at 1% elongation. A piezoelectric harvester as claimed in claim 1, wherein the cross-linked polysilicon elastomer matrix is formed from a reactive polysilicon oligomer having a hardness of 45 to 90 after curing, the hardness being measured using the Shaw hardness scale type A. A piezoelectric collector as claimed in claim 2, wherein the reactive polysiloxane oligomer comprises polyalkylsiloxane. A piezoelectric collector as claimed in claim 2 or 3, wherein the reactive polysiloxane oligomer has a reactive functional group fraction of about 5 mol% to about 10 mol%. A piezoelectric collector as claimed in claim 4, wherein the reactive functional groups include hydroxyl, vinyl, alkoxy, hydride or a combination thereof. A piezoelectric collector as claimed in claim 1, wherein the cross-linked polysilicon elastomer matrix comprises a doped polyalkylsiloxane matrix and wherein the piezoelectric particles are dispersed in the polyalkylsiloxane matrix. A piezoelectric collector as claimed in claim 6, wherein the polyalkylsiloxane matrix is doped with a precious metal. A piezoelectric collector as claimed in claim 7, wherein the precious metal comprises platinum (Pt). A piezoelectric collector as claimed in claim 3, wherein the polyalkylsiloxane is polydimethylsiloxane (PDMS). A piezoelectric collector as claimed in claim 1, wherein the volume fraction of the piezoelectric particles in the piezoelectric layer is about 35% to about 65%. A piezoelectric collector as claimed in claim 1, wherein the piezoelectric particles include lead zirconate titanate (PZT). A piezoelectric collector as claimed in claim 1, wherein the first elastic electrode and the second elastic electrode comprise carbon. A piezoelectric collector as claimed in claim 1, wherein the piezoelectric particles include piezoelectric particles polarized by an external electric field. A tire equipped with a piezoelectric collector as described in any one of claims 1 to 13. A method for preparing a piezoelectric collector as claimed in any one of claims 1 to 13, comprising: preparing a mixture comprising a polysilicon oligomer having a hardness of 45 to 90 after curing and piezoelectric particles, the hardness being measured using the Shaw hardness scale type A, wherein the piezoelectric particles are dispersed in the polysilicon oligomer; casting the mixture onto a first layer of an elastic electrode to form a first composite film; curing the first composite film; coating the cured first composite film with a second layer of an elastic electrode to form a second composite film; curing the second composite film; and applying an electric field to the cured second composite film to polarize the piezoelectric particles in the cured second composite film.