Fabrication and characterization of flexible piezoelectric thin films from polyvinylidene fluoride and polylactic acid composites for biocompatible energy harvesting

Abstract

Piezoelectricity is the phenomenon where certain materials exhibit electric charge accumulation and polarization in response to mechanical deformation. The reverse is also true for such materials, as applying an electric voltage can cause them to change shape. Piezoelectric materials have their applications in sensors and energy harvesting technologies. These materials tend to be crystals, ceramics, and some biological materials. They possess this ability because of their non-centrosymmetric crystal structures. Certain polymers such as PVDF and PLA also have intrinsic piezoelectric properties, but have lackluster performance when compared to conventional rigid ceramics. However, PVDF and PLA polymer thin films offer flexibility and biocompatibility, making them suitable for flexible electronics and biomedical based applications such as harvesting power for pacemakers. This study attempts to create novel composites by incorporating PZT and BTO ceramic fillers into PVDF and PLA, in order to maintain polymer advantages while also enhancing piezoelectric output. This research investigates factors such as polymer type, ceramic filler type, filler percentage, and Electric-poling and their effect on d₃₃ responses. All four factors were found to have an influence on d₃₃ coefficients and PVDF composites were found to be more ideal than PLA composites. Compared to BTO, PZT additives were found to exhibit dominance in enhancing d₃₃ values. Additionally, cantilever beam energy harvesting trials were made for polymer composite thin films to examine DC voltage outputs.