Verification of the flexoelectric effect in PET polymer films for EH applications

Abstract

The flexoelectric effect of solids represents a new branch of research. As an electromechanical conversion mechanism, it occurs in all dielectric materials. This offers new applications based on a large number of possible materials. Based on that, an investigation of properties and conversion conditions are of great importance. It is important to find out the significance of flexoelectric energy conversion in relation to other conversion mechanisms. This paper attempts to verify the flexoelectric effect in simple dielectric materials and to investigate the applicability in the area of energy harvesting (EH). In our studies, dielectric Polyethylene-Terephthalate (PET) polymer films were used in two different plate capacitor configurations. Two different measurement setups were built to enable the evaluation of polymer films under changing conditions. Main verification parameter of the energy conversion is the electrical voltage change in a differential measurement setup. Changing strain gradients, the basis of the flexoelectric conversion, were generated in two separate ways in thin PET-films. First results clearly show the presence of flexoelectric conversion. The height of the voltage pulses by mechanical loading of the samples cannot be explained by capacitive energy conversion only. Another effect is required to explain the electrical response - FLEXOELECTRICITY