In a piezoelectric device, a layered portion includes, at a position at least above a recess, a single crystal piezoelectric layer and a pair of electrode layers to apply voltage to the single crystal piezoelectric layer. At least a portion of the pair of electrode layers includes a lower electrode layer extending along a surface of the single crystal piezoelectric layer, the surface being closer to a base. The lower electrode layer is present only inside the recess.

Provided is an energy conversion film excellent in charge retention performance and suppressed in deterioration of piezoelectricity even if it is exposed to a high temperature environment and an energy conversion element and the like using the film. An energy conversion element comprising: an energy conversion film at least comprises a charged resin film consisting of a resin film at least containing a thermoplastic resin and a metal soap; and an electrode provided on at least one of the two surfaces of the energy conversion film.

An acoustic wave device includes a functional electrode provided on a first main surface of an element substrate, extended wiring lines that are electrically connected to the functional electrode and that are adjacent to each other on a second main surface facing away from the first main surface, external terminals that are connected to the extended wiring lines, respectively, and that are provided on the second main surface, a first resin portion that seals the acoustic wave device, and a second resin portion that is provided at a position which is between the element substrate and the first resin portion and which is on the second main surface.

Provided is a piezoelectric ceramics having a gradual change in piezoelectric constant depending on an ambient temperature. Specifically, provided is a single-piece piezoelectric ceramics including as a main component a perovskite-type metal oxide represented by a compositional formula of ABO.sub.3, wherein an A site element in the compositional formula contains Ba and M.sub.1, the M.sub.1 being formed of at least one kind selected from the group consisting of Ca and Bi, wherein a B site element in the compositional formula contains T1 and M.sub.2, the M.sub.2 being formed of at least one kind selected from the group consisting of Zr, Sn, and Hf, wherein concentrations of the M.sub.1 and the M.sub.2 change in at least one direction of the piezoelectric ceramics, and wherein increase and decrease directions of concentration changes of the M.sub.1 and the M.sub.2 are directions opposite to each other.

A piezoelectric micromachined ultrasound transducer (PMUT) array may comprise PMUT devices with respective piezoelectric layers and electrode layers. Parasitic capacitance can be reduced when an electrode layer is not shared across PMUT devices but may expose the devices to electromagnetic interference (EMI). A conductive layer located within the structural layer or on a shared plane with the electrode layers may reduce EMI affecting the PMUT array operation.

A piezo-resistor sensor includes a diffusion of a first conductivity type in a well of an opposite second type, contacts with islands in the diffusion, interconnects with the contacts, and a shield covers the diffusion between the contacts and extends over side walls of the diffusion between the contacts. Each interconnect covers the diffusion at the corresponding contact and extends over edges of the diffusion, and each island is at a side covered by its interconnect. A guard ring of the second type is around the diffusion. The shield covers the well between the diffusion and the ring and the edge of the ring facing the diffusion. If a gap between the shield and the interconnect is present, the ring bridges this gap, and/or the edges of the diffusion are completely covered by the combination of the shield and the interconnects.

There is provided a piezoelectric actuator, including: a vibration plate; a first piezoelectric body; a second piezoelectric body; a first electrode disposed on a first surface of the first piezoelectric body; a second electrode disposed on a second surface of the second piezoelectric body; an intermediate electrode disposed on an intermediate surface of the first piezoelectric body and overlapping with the first and second electrodes; an intermediate trace connected to the intermediate electrode on the intermediate surface and drawn out to one side in a first direction beyond the first piezoelectric body and the second piezoelectric body; a first trace overlapping with the intermediate trace in the thickness direction and being conducted with the intermediate trace; and a second trace overlapping with the intermediate trace in the thickness direction and being conducted with the intermediate trace.

An optical element includes a primary electrode, a secondary electrode overlapping at least a portion of the primary electrode, and an electrostrictive ceramic layer disposed between and abutting the primary electrode and the secondary electrode, where the electrostrictive ceramic may be characterized by a relative density of at least approximately 99%, an average grain size of at least approximately 300 nm, a transmissivity within the visible spectrum of at least approximately 70%, and bulk haze of less than approximately 10%. Optical properties of the electrostrictive ceramic may be substantially unchanged during the application of a voltage to the electrostrictive ceramic layer and the attendant actuation of the optical element.

In some embodiments, a piezoelectric biosensor is provided. The piezoelectric biosensor includes a semiconductor substrate. A first electrode is disposed over the semiconductor substrate. A piezoelectric structure is disposed on the first electrode. A second electrode is disposed on the piezoelectric structure. A sensing reservoir is disposed over the piezoelectric structure and exposed to an ambient environment, where the sensing reservoir is configured to collect a fluid comprising a number of bio-entities.

A multilayer piezoelectric element includes a piezoelectric body containing a piezoelectric ceramic material, a first electrode, and a second electrode. The piezoelectric body includes a first main surface and a second main surface opposing each other. The first electrode includes an external electrode formed on the first main surface. The second electrode includes an internal electrode formed inside the piezoelectric body to oppose the external electrode. The piezoelectric body includes an active region between the external electrode and the internal electrode, and includes an inactive region opposite to the active region with the internal electrode interposed therebetween. A stress received by the piezoelectric body from the external electrode is larger than a stress received by the piezoelectric body from the internal electrode. A polarization direction of the active region is a direction directed from the external electrode to the internal electrode.