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 element including: a first electrode; an intermediate layer made of a silicone rubber composition containing a silicone rubber; and a second electrode, where the first electrode, the intermediate layer, and the second electrode are disposed in this order, wherein a peak intensity ratio (10955 cm.sup.1/10255 cm.sup.1) of an infrared absorption spectrum of the intermediate layer varies along a vertical direction relative to a surface of the first electrode, and to a surface of the second electrode.

An electretized film of the present invention includes a cyclic olefin polymer, in which the electretized film is a non-porous film, and a piezoelectric constant d.sub.33 in a thickness direction, which is measured by applying a pressing force to the electretized film in the thickness direction, under conditions of a load of 0.5 N, a dynamic load of 0.25 N, a frequency of 110 Hz, a temperature of 23 C., and a humidity of 50%, is equal to or more than 100 pC/N.

An object of the present invention is to provide a low pressure-loss type of filter which has a high dust collecting capability and suppresses the lowering of the dust collecting capability even after cleaning. The present invention relates to an electret-treated sheet including at least a surface layer, a high dielectric layer and a back-surface layer, while having the high dielectric layer between the surface layer and the back-surface layer, wherein the surface layer and the back-surface layer are each a thermoplastic resin film having a relative dielectric constant of smaller than 6 at 100 kHz; the high dielectric layer is a material having a relative dielectric constant of 6 or larger at 100 kHz; and the surface layer and the back-surface layer each have a static charge due to electrostatically charge; and to a filter using the same.

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 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.

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.

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.

A variable capacitor device that includes a dielectric layer comprising a shape-memory polymer, a first metal plate and a second metal plate, wherein the dielectric layer is sandwiched between the first and the second metal plates. The shape-memory polymer has a first thickness at a first temperature under a first external compressive load, a second thickness at a second temperature under a second external compressive load, wherein the first thickness is greater than the second thickness, the second temperature is greater than the first temperature, and the second external compressive load is greater than the first external compressive load. The shape memory polymer having the second thickness is configured to convert to the shape-memory polymer having the first thickness when sequentially subjected to the first external compressive load and the second temperature.

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.