Possibilities of using flexoelectric effect for energy harvesting applications

Flexoelectricity is a relatively new phenomenon in research. It bases on a change in polarization caused by changing mechanical strain gradients in dielectric materials. Flexoelectricity is present in all dielectric materials. Different other energy conversion principles are used in energy harvesting or sensor applications. The flexoelectric effect of solids is in a very early stage of research and still far away from practical applications at the moment. Achieving electrical signals by flexoelectric conversion requires changes of mechanical strain gradients in dielectric materials. To generate that, not simple but more complex structures are needed. Furthermore, flexoelectricity of solids is not completely understood yet. Additional investigations in this area of research are necessary to prove the usability of this effect. This paper starts with investigations in this field and discusses a first approach for using the flexoelectric effect from an application-based point of view. As dielectric material, Polyethylene-Terephthalate (PET) polymer films were used in a plate capacitor configuration. A complex measurement setup was built to enable the evaluation of polymer films under changing conditions. The main parameter to verify an energy conversion is the change of system capacitance. First results show a small change in capacitance with time and a capacitance difference dependency on the movement frequency of actuation.