Optimizing Voided Piezoelectric Polymers For Acoustic Sensors

Abstract

Polymer piezoelectric materials offer lower density and more flexibility than piezoelectric ceramics for applications where rugged and lightweight acoustic sensors are required. This paper discusses constraints imposed by material stiffness and dielectric constants and aims to derive a generalized closed‐form solution for optimizing charged foamed polymers. Optimized solutions are reached in the limits of very large and small void fraction and permittivity ratio. The permittivity ratio is the ratio of the dielectric constants of the polymer and the material that fills the voids. Demonstrations indicate that, in the oblique asymptote, the optimized void fraction becomes equivalent to the permittivity ratio. This effort was conducted under the auspices of the Undersea Warfare Business Area (UWBA) Independent Research & Development (IRAD) Board of the Johns Hopkins University Applied Physics Laboratory (JHU/APL).