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CN-121985725-A - Flexible piezoelectric electret device, preparation method thereof and piezoelectric sensor

CN121985725ACN 121985725 ACN121985725 ACN 121985725ACN-121985725-A

Abstract

The invention provides a flexible piezoelectric electret device, a preparation method thereof and a piezoelectric sensor, wherein the flexible piezoelectric electret device comprises a piezoelectric main body and a packaging assembly which completely wraps the piezoelectric main body, the piezoelectric main body comprises a first electrode, a negative polarity flexible lamination assembly, an intermediate dielectric layer with a micro-nano pore structure, a positive polarity flexible lamination assembly and a second electrode, which are sequentially laminated from bottom to top, the negative polarity flexible lamination assembly is prepared by sequentially laminating a plurality of negative polarity electret films along the same polarity direction through a physical compounding process, and the positive polarity flexible lamination assembly is prepared by sequentially laminating a plurality of positive polarity electret films along the same polarity direction through the physical compounding process. The flexible piezoelectric electret device provided by the invention can break through the technical bottleneck after being optimized in structure and configuration, can be finally adapted to high-requirement application scenes such as wearable skin electronics, implanted medical monitoring and the like, and has the potential of large-scale mass production.

Inventors

  • HUANG LIANG
  • Ling Yuyang
  • Yang Aokai
  • TAN CHAORAN

Assignees

  • 华中科技大学

Dates

Publication Date
20260505
Application Date
20260116

Claims (10)

  1. 1. The flexible piezoelectric electret device is characterized by comprising a piezoelectric main body and a packaging assembly which completely wraps the piezoelectric main body, wherein the piezoelectric main body comprises a first electrode, a negative-polarity flexible laminated assembly, an intermediate dielectric layer with a micro-nano pore structure, a positive-polarity flexible laminated assembly and a second electrode which are sequentially laminated from bottom to top; The positive polarity flexible lamination assembly is prepared by sequentially laminating a plurality of positive polarity electret films along the same polarity direction and adopting a physical compounding process.
  2. 2. The flexible piezoelectric electret-like device according to claim 1, wherein the negative electret film in the negative flexible laminate assembly is a negative fluoroethylene propylene copolymer film having a lamination number of 2 to 5 layers and a thickness of 12.5 to 25 μm per layer, and the positive electret film in the positive flexible laminate assembly is a positive fluoroethylene propylene copolymer film having a lamination number of 2 to 5 layers and a thickness of 12.5 to 25 μm per layer.
  3. 3. The flexible piezoelectric electret-like device of claim 1, wherein the first and second electrodes are each made of at least one of gold, silver, copper, aluminum, carbon, conductive metal oxide or conductive polymer, and the intermediate dielectric layer is made of at least one of polyvinylidene fluoride, polyimide, polydimethylsiloxane, polyurethane, polyvinyl alcohol or polymethyl methacrylate.
  4. 4. The flexible piezoelectric electret-like device of claim 1, wherein the package assembly comprises an inner package layer that completely encapsulates the piezoelectric body and an outer package layer that completely encapsulates the inner package layer, wherein the inner package layer comprises polyurethane and the outer package layer comprises polydimethylsiloxane.
  5. 5. A method for manufacturing a flexible piezoelectric electret-like device according to any one of claims 1 to 4, comprising: s10, forming a first electrode on the surface of a first flexible electret film, and forming a second electrode on the surface of a second flexible electret film; S20, carrying out negative polarity corona polarization treatment on the surface of the first flexible electret film far away from the first electrode to convert the first flexible electret film into the negative polarity electret film, and simultaneously, carrying out positive polarity corona polarization treatment on the surface of the second flexible electret film far away from the second electrode to convert the second flexible electret film into the positive polarity electret film; s30, physically superposing a plurality of electret films with negative polarity along the same polarity direction to prepare a flexible lamination assembly with negative polarity; S40, spreading the middle dielectric layer on one side surface of the negative-polarity flexible laminated assembly, which is far away from the first electrode, covering one side surface of the positive-polarity flexible laminated assembly, which is far away from the second electrode, on the middle dielectric layer, and forming the piezoelectric main body of the sandwich composite structure through electrostatic adsorption after contact stability; And S50, leading out leads from the first electrode and the second electrode of the piezoelectric main body respectively, packaging the piezoelectric main body, forming a packaging assembly on the surface of the piezoelectric main body, and finally completing the preparation of the flexible piezoelectric electret-like device.
  6. 6. The method for manufacturing the flexible piezoelectric electret device according to claim 5, wherein in the step S10, the first electrode and the second electrode are both manufactured by adopting a magnetron sputtering process, and the materials are gold-chromium composite alloy, and the specific process parameters of the magnetron sputtering process are as follows, wherein the metal deposition sequence is that plating is performed firstly, plating is performed secondly, plating is performed, plating current is 0.1-0.2A, plating sputtering time is 0.5-1.5 min, plating current is 0.15-0.25A, and plating sputtering time is 6-8 min.
  7. 7. The method for manufacturing the flexible piezoelectric electret device according to claim 5, wherein in the step S20, the technological parameters of the negative polarity corona polarization treatment and the positive polarity corona polarization treatment are as follows, the distance from the first flexible electret film or the second flexible electret film to a grid is 1.5-2.5 cm, the distance from the first flexible electret film or the second flexible electret film to a corona needle array is 4.5-5.5 cm, the negative polarization current and the positive polarization current are both 0.02-0.04 mA, the negative polarization voltage is-15-20 kV, and the positive polarization voltage is +15- +20kV.
  8. 8. The method for preparing a flexible piezoelectric electret-like device according to claim 5, wherein the method for preparing the intermediate dielectric layer in step S40 specifically comprises: Firstly, preparing a dielectric layer precursor solution; Secondly, preparing a dielectric film with a micro-nano pore structure by adjusting technological parameters by utilizing an electrostatic spinning process, a spin coating process or a spray coating process; and finally, placing the dielectric film in a vacuum drying oven at 60.0 ℃ for drying to obtain the intermediate dielectric layer.
  9. 9. The method for preparing the flexible piezoelectric electret device, according to claim 8, characterized in that when the electrostatic spinning technology is adopted to prepare the dielectric film, a solvent is a mixed solution of N, N-dimethylformamide and acetone, a solute is polyvinylidene fluoride, the concentration of the mixed solution is 15-20wt%, the advancing speed of an injector is 1.0-2.0 ml/h, the voltage applied between a nozzle and a receiving electrode is 20-25 kV, the receiving distance is 15-20 cm, and when the spin coating technology or the spray coating technology is adopted to prepare the dielectric film, the film forming thickness of the dielectric film is 20-60 mu m.
  10. 10. A pressure sensor comprising a flexible piezoelectric electret-like device according to any one of claims 1 to 4.

Description

Flexible piezoelectric electret device, preparation method thereof and piezoelectric sensor Technical Field The invention belongs to the field of flexible electronic devices and energy conversion manufacturing, and particularly relates to a flexible piezoelectric electret device, a preparation method thereof and a piezoelectric sensor; the flexible piezoelectric electret device prepared by the invention has the advantages of ultrahigh surface potential, excellent mechanical flexibility, good biocompatibility and extremely high force-electricity conversion sensitivity, which breaks through the limitation of single-layer materials, and is particularly suitable for wearable sensors and micro-energy acquisition systems. Background Electrets are a class of dielectric materials that quasi-permanently store space charges and dipole charges, and have wide application in the fields of modern acoustic sensors, flexible actuators, and micro-energy harvesting (e.g., nano-generators). Among them, fluoroethylene propylene copolymer (FEP) is the first choice material for constructing high-performance flexible piezoelectric electret-like devices by virtue of excellent chemical stability, excellent charge storage life and heat resistance. The core working principle of the quasi-piezoelectric electret (Piezoelectrets) is that a macroscopic dipole is formed by combining a film layer with different polarity charges and a middle micropore structure. When the device is deformed under the action of external mechanical force, the thickness of the micropore structure is changed, so that the change of macroscopic dipole moment is induced, and charges are induced on the surface of the electrode by the change, so that the device shows remarkable piezoelectric effect. Essentially, this process is a result of the coupling of electrostatic induction effects with mechanical deformations of the material. However, the existing piezoelectric electret-like device technology still has obvious limitations that firstly, the technology is limited by dielectric breakdown strength and surface energy level trap density of an FEP material, the phenomenon of 'surface potential saturation' exists in the traditional single-layer FEP film in the corona polarization process, when the potential reaches a specific threshold value, the film is subjected to micro-breakdown or reverse charge injection after the polarization voltage is continuously increased, the surface charge density cannot be further improved, the built-in electric field strength of the device is directly limited, and the final output power and the sensing sensitivity of the device are further limited, secondly, in order to construct a needed micropore structure, a hard micro-processing template or a simple air gap structure is mainly adopted in the prior art, the whole Young modulus of the device is larger due to the hard structure, the sensitivity is low, the flexibility is lacking, and the simple air gap structure is easy to collapse under long-term stress, so that the performance of the device is attenuated. Therefore, in order to further improve the overall output performance of the flexible piezoelectric electret device, it is needed to develop a preparation method capable of breaking through the charge storage limit of the single-layer film and having excellent mechanical deformation capability. Disclosure of Invention The invention aims to provide a flexible piezoelectric electret device, a preparation method thereof and a piezoelectric sensor, which are used for solving the problems of limited charge density, poor flexibility of a micropore structure and easy attenuation of performance of a single-layer electret film of the traditional device. The flexible piezoelectric electret device breaks through the charge storage limit of a single-layer electret film by adopting a homopolar multilayer superposition strategy, and combines an intermediate dielectric layer of a positive-negative opposite structure and a micro-nano structure to prepare the flexible piezoelectric electret device with excellent performance. In order to solve the technical problems, the invention firstly provides a flexible piezoelectric electret device which comprises a piezoelectric main body and a packaging assembly completely wrapping the piezoelectric main body, wherein the piezoelectric main body comprises a first electrode, a negative polarity flexible laminated assembly, an intermediate dielectric layer with a micro-nano pore structure, a positive polarity flexible laminated assembly and a second electrode which are sequentially laminated from bottom to top; The positive polarity flexible lamination assembly is prepared by sequentially laminating a plurality of positive polarity electret films along the same polarity direction and adopting a physical compounding process. The flexible piezoelectric electret-like device breaks through the polarization bottleneck of a single-layer film through a homopolar multil