An electret includes a composite oxide having an ABO.sub.3 type perovskite structure containing two different metal elements A and B. The composite oxide is in a polarized state, at least a part of one of the metal elements A and B is substituted with a dopant element having a lower valence than the one of the metal elements A and B, and the composite oxide has a bandgap energy of 4 eV or more.

This invention provides electrically conductive electret, electret-based direct-current power source and structural electret, with applications including the self-sensing of damage, stress and strain (including structural self-sensing) and electric powering (including structural self-powering). The electret is an electrically conductive material comprising mobile charge carriers (electrons, holes or ions), which exhibit a gradient in the carrier concertation along a line connecting the positive charge center and negative charge center in the electret. The carriers create an electric dipole. The material is electrically continuous along this line, which is along the path of least electrical resistance. The material exhibits microstructure comprising microscopic features that are positioned along said line and that interact with said carriers, with the interaction enhancing said dipole. The materials are preferably metals, carbons and their composites. The electret's electric field preferably ranges from 10 V/m to 1 V/m. The electrical conductivity preferably ranges from 10.sup.3.sup.1.Math.m.sup.1 to 10.sup.8.sup.1.Math.m.sup.1.

An electret element includes: an Si layer, an SiO.sub.2 layer formed at a surface of the Si layer; and an electret formed at the SiO.sub.2 layer near an interface of the SiO.sub.2 layer and the Si layer.

Aspects of the subject disclosure may include, for example, a method in which a selection is made for a first major constituent, a second major constituent and a minor constituent for forming a desired material. The method can include mixing the first major constituent, the second major constituent and the minor constituent in a single mixing step to provide a mixture of constituents. The method can include drying the mixture of constituents to provide a dried mixture of constituents and calcining the dried mixture of constituents to provide a calcinated mixture of constituents. The method can include processing the calcinated mixture of constituents (by a process including vacuum annealing and hot-pressing) to provide a sputtering target. Other embodiments are disclosed.

Provided is a watch, including: an exterior case having electroconductivity; an operating member having electroconductivity, which is inserted into the exterior case through an opening formed through the exterior case, and which is configured to accept an operation performed by a user; and an electrostatic motor including: an electret substrate having an electret surface on which electret films being electrically charged are provided; a counter substrate, on which electrodes to be arranged so as to be opposed to the electret films are provided; and a rotary shaft configured to rotate the electret substrate and the counter substrate relative to each other, wherein the operating member and the exterior case are electrically continuous with each other via a conduction path formed so as to avoid overlapping with the electret surface in plan view.

A capacitive sensor is disclosed. The capacitive sensor includes a substrate, a first electrode and a second electrode formed on the substrate, an insulation layer formed on the substrate on which the first electrode and the second electrode are formed, and a sensing layer that is formed on the insulation layer and includes graphene.

An electret element includes: an electret film that contains silicon oxide; and a protective film formed over the electret film and constituted of aluminum oxide deposited through an atomic layer deposition method.

Novel dielectric capacitor devices include an electrically conductive porous scaffold forming a first conductor, a conformal thin dielectric uniformly coating the pores, and a metal or alloy which fills the conformal dielectric coated pores of the scaffold forming a second conductor. This structure's design provides high surface area for high energy storage and capacitance density as well as high thermal conductivity. The metal or alloy can be a liquid metal and flowed within the device to change the electrical or mechanical properties of the device.

An electret includes a substrate and an electret layer formed above a surface of the substrate. The electret layer is a composite metal compound containing two or more different metal elements, and is obtained by subjecting a thin film mainly composed of an inorganic dielectric material having a bandgap energy of 4 eV or more to a polarization treatment.

An electret includes an electret layer. The electret layer is formed by subjecting a composite film in which inorganic dielectric particles are dispersed and held in a base film to a polarization treatment. The inorganic dielectric particles are mainly composed of an inorganic dielectric material having a bandgap energy of 4 eV or more.