Simulation and automated characterisation of optimal load for flexible composite generators based on piezoelectric ZnO nanowires

Abstract

This paper reports the experimental and numerical study of flexible piezoelectric transducers made of a thin active composite material (∼3 μm thick) over a thin flexible metallic foil (∼25 μm of stainless steel). The active piezo-layer consists of vertical ZnO nanowires (NWs) embedded into dielectric fillers of different composition. The voltage over a known resistance was measured with an automatic bending setup, and the corresponding power was computed and compared to numerical simulations as a function of load resistance and dielectric matrix in the composite structure. FEM simulations show that the output power can be higher than conventional thin-film devices. These results confirm previous findings and provide important guidelines to optimize flexible piezoelectric transducers for applications as sensors and generators for the Internet of Things. Comparison with a commercial thick-film piezoelectric energy harvester was also made experimentally.