Abstract: A new method for fabricating electret-containing devices is disclosed. The inventive method includes a new technique for fabricating electrets, which involves applying a voltage across an electrically polarizable body. Large-scale breakdown effects in the body are avoided by reducing the voltage across at least a portion of the body undergoing polarization in response to a current indicating the onset of a breakdown in the body.

Abstract: Electrically polarizable material (e.g., PVDF film) is poled by applying an electric field across the film. In the inventive technique, insulation is provided on the surface of the film. In a typical embodiment, a compliant dielectric annulus insulates the polarized region from the edges of the film. This substantially eliminates breakdown at the edges of the film, allowing increased poling voltages. The technique can reduce poling time to typically a few seconds at room temperature, as compared to minutes or hours by prior art techniques, some of which required elevated temperatures.

Abstract: A method of producing piezoelectric and pyroelectric polyvinylidene fluoride (PVDF) films is shown. A stretched PVDF film having a predominantly .beta.-type crystal structure is rolled for thickness reduction. The rolling orients a substantial percentage of b axes of .beta. crystals normal to the film surface, as determined by X-ray diffraction patterns. An optional annealing step is shown, wherein the rolled film is heated, optionally while under pressure. Improvement in the piezoelectric constant of 25 percent or more is typical.