A MEMS device is provided that includes a piezoelectric film, a first electrode and a second electrode sandwiching the piezoelectric film, a protective film that covers at least part of the second electrode and having a cavity that opens part of the second electrode, a third electrode that contacts the second electrode at least in the cavity and is provided so as to cover at least part of the protective film, and a first wiring layer having a first contact portion in contact with the third electrode.

A multilayer piezoelectric ceramic is constituted by: piezoelectric ceramic layers which do not contain lead as a constituent element, have a perovskite compound expressed by the composition formula Li.sub.xNa.sub.yK.sub.1−x−yNbO.sub.3 (where 0.02<x≤0.1, 0.02<x+y≤1) as the primary component, and contain 0.2 to 3.0 mol of Li relative to 100 mol of the primary component; and internal electrode layers which are constituted by a metal that contains silver by 80 percent by mass or more; wherein the multilayer piezoelectric ceramic is such that Li compounds other than the primary component are localized therein. The multilayer piezoelectric element can offer excellent insulating property.

A photoacoustic and ultrasonic endoscope includes an optical fiber, a light diffuser configured to radially diffuse a laser beam transmitted through the optical fiber, and an array transducer having a cylindrical shape and surrounding the light diffuser, the array transducer being configured to transmit the diffused laser beam therethrough and to generate an ultrasonic wave or detect an ultrasonic wave generated by an object to be examined.

A piezoelectric actuator is formed like a rectangular flat plate, and includes a substrate layer, a lower electrode layer, a piezoelectric layer, and an upper electrode layer formed in this order from bottom to top in a thickness direction. The upper electrode layer is constituted of a plurality of electrode segments separated in a surface direction, and connection wires connecting the electrode segments which are adjoining in the surface direction.

A piezoelectric actuator is formed like a rectangular flat plate, and includes a substrate layer, a lower electrode layer, a piezoelectric layer, and an upper electrode layer formed in this order from bottom to top in a thickness direction. The upper electrode layer is constituted of a plurality of electrode segments separated in a surface direction, and connection wires connecting the electrode segments which are adjoining in the surface direction.

An electroactive device may include (1) an electroactive polymer element having a first surface and a second surface opposite the first surface, the electroactive polymer element comprising a nanovoided polymer material, (2) a primary electrode abutting the first surface of the electroactive polymer element, and (3) a secondary electrode abutting the second surface of the electroactive polymer element. The electroactive polymer element may be deformable from an initial state to a deformed state by application of an electrostatic field produced by a potential difference between the primary electrode and the secondary electrode. Various other devices, systems, and methods are also disclosed.

There is provided a head including: a piezoelectric layer; a plurality of individual electrodes located below the piezoelectric layer in an up-down direction; a common electrode located below the piezoelectric layer. The plurality of individual electrodes includes: a first individual electrode array including a plurality of first individual electrodes aligned in a first direction; and a second individual electrode array including a plurality of second individual electrodes aligned in the first direction. The common electrode includes: a plurality of first facing portions which are demarcated to correspond to the plurality of first electrodes, respectively; a plurality of second facing portions which are demarcated to correspond to the plurality of second electrodes, respectively; and a connecting portion located between the plurality of first facing portions and the plurality of second facing portions, and connecting the plurality of first facing portions and the plurality of second facing portions.

There is provided a head including: a piezoelectric layer; a plurality of individual electrodes located below the piezoelectric layer in an up-down direction; a common electrode located below the piezoelectric layer. The plurality of individual electrodes includes: a first individual electrode array including a plurality of first individual electrodes aligned in a first direction; and a second individual electrode array including a plurality of second individual electrodes aligned in the first direction. The common electrode includes: a plurality of first facing portions which are demarcated to correspond to the plurality of first electrodes, respectively; a plurality of second facing portions which are demarcated to correspond to the plurality of second electrodes, respectively; and a connecting portion located between the plurality of first facing portions and the plurality of second facing portions, and connecting the plurality of first facing portions and the plurality of second facing portions.

A mounting structure includes: a first substrate that has a first surface on which a functional element is provided; a wiring portion that is provided at a position, which is different from a position of the functional element on the first surface, and is conductively connected to the functional element; a second substrate that has a second surface that is opposite to the first surface; and a conduction portion that is provided on the second surface, is connected to the wiring portion, and is conductively connected the functional element. The shortest distance between the functional element and the second substrate is longer than the longest distance between the second substrate and a position where the wiring portion is connected to the conduction portion.

A mounting structure includes: a first substrate that has a first surface on which a functional element is provided; a wiring portion that is provided at a position, which is different from a position of the functional element on the first surface, and is conductively connected to the functional element; a second substrate that has a second surface that is opposite to the first surface; and a conduction portion that is provided on the second surface, is connected to the wiring portion, and is conductively connected the functional element. The shortest distance between the functional element and the second substrate is longer than the longest distance between the second substrate and a position where the wiring portion is connected to the conduction portion.