A piezoelectric polyvinylidene fluoride (PVDF) material, a method for manufacturing the same, and a fingerprint recognition module are provided. The polyvinylidene PVDF material includes PVDF, a first solvent, a second solvent, a fluorosurfactant, and an inducing material. Material of the inducing material is one of carbon nanotubes, carbon black, and gold nanorods. Because of the high anisotropy of the inducing material, molecular orientation of the PVDF material is induced, thereby improving piezoelectric performance of the piezoelectric PVDF material. Problems of conventional piezoelectric PVDF materials, which are used in ultrasonic fingerprint recognition modules, such as poor piezoelectric performance and high-energy loss are improved.

An electrostatic protection device includes: a first conductive layer, a second conductive layer and a polarization film layer, in which the polarization film layer is disposed between the first conductive layer and the second conductive layer and formed of a piezoelectric material which is capable of deforming when applied with electricity; a conductive cantilever, disposed on the second conductive layer and including a free end; and a charge diffusion layer, disposed at a side of the conductive cantilever away from the polarization film layer, electrically connected with the first conductive layer and spaced apart from the conductive cantilever, in which upon a voltage difference between the first conductive layer and the second conductive layer reaching a predetermined value, the polarization film layer deforms to allow the conductive cantilever to connect with the charge diffusion layer.

A method for polarizing a piezoelectric film is described. In this method, a piezoelectric film is formed by using an injection deposition method. The piezoelectric film is flat adhered to a surface of a conductive substrate. A polarization process is performed on the piezoelectric film while the piezoelectric film is flat adhered to the surface of the conductive substrate.

Provided are an electroacoustic transduction film capable of reproducing a sound with a sufficient sound volume at a high conversion efficiency, a manufacturing method thereof, an electroacoustic transducer, a flexible display, a vocal cord microphone, and a sensor for a musical instrument. The electroacoustic transduction film includes: a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature; two thin film electrodes laminated on both surfaces of the polymer composite piezoelectric body; and two protective layers respectively laminated on the two thin film electrodes, in which an intensity ratio α.sub.1=(002) plane peak intensity/((002) plane peak intensity+(200) plane peak intensity) between a (002) plane peak intensity and a (200) plane peak intensity derived from the piezoelectric body particles in a case where the polymer composite piezoelectric body is evaluated by an X-ray diffraction method is more than or equal to 0.6 and less than 1.

A multi-layer piezoelectric microactuator assembly has at least one poled and active piezoelectric layer and one poled but inactive piezoelectric layer. The poled but inactive layer acts as a constraining layer in resisting expansion or contract of the first piezoelectric layer thereby reducing or eliminating bending of the assembly as installed in an environment, thereby increasing the effective stroke length of the assembly. Poling only a single layer would induce stresses into the device; hence, polling both piezoelectric layers even though only one layer will be active in use reduces stresses in the device and therefore increases reliability.

A piezoelectric material having a large electromechanical coupling coefficient is provided. The material is manufactured by a method including the steps of: heating a piezoelectric material having a low-temperature side ferroelectric phase A and a high-temperature side ferroelectric phase B between which the phase of the piezoelectric material transitions according to a temperature change, from room temperature to a temperature range higher than T.sub.(B.fwdarw.A) at which temperature a change from the ferroelectric phase B to the ferroelectric phase A occurs in a temperature lowering process and lower than T.sub.(A.fwdarw.B) at which temperature a change from the ferroelectric phase A to the ferroelectric phase B occurs in a temperature rising process; starting application of an electric field to the piezoelectric material in a state where it is held within this temperature range; and continuing and finishing the electric field application at a temperature lower than T.sub.(A.fwdarw.B).

A piezoelectric device comprises at least one piezoelectric composite layer P inserted between two conductive composite layers E, each layer E forming an electrode, characterized in that: the layer P is a rubber composition containing more than 50 parts by weight per hundred parts by weight rubber, phr, of diene elastomer, a cross-linking system and at least 5 vol. %, in relation to the total volume of the rubber composition, of piezoelectric inorganic charges; and each layer E is a rubber composition containing at least 50 phr of diene elastomer, a cross-linking system, and conductive charges. A method for producing the device and a tire comprising the device are also disclosed.

A piezoelectric element includes a piezoelectric material layer and an electrode layer, wherein the piezoelectric material layer and the electrode layer are stacked on top of each other, the piezoelectric material layer includes a barium titanate-based material, and two coercive fields Ec1 and Ec2 of the piezoelectric element have the same sign and satisfy (|Ec2|−|Ec1|)≥8 kV/cm.

A fiber scanning system includes a fiber optic element having an actuation region and a motion actuator mechanically coupled to the fiber optic element. A continuous bond line is present between the actuation region and the motion actuator. The fiber scanning system also includes a retention collar mechanically coupled to the motion actuator.

Provided is a piezoelectric element according to the invention including a stacked body in which a piezoelectric layer and an internal electrode layer are stacked. In addition, the internal electrode layer contains at least one kind of element selected from palladium, nickel, platinum, gold, and silver, and copper, and the content of copper contained in the internal electrode layer is 1 to 50 at % in terms of a copper element.