Photothermally-activated piezo-pyroelectric multifunctional hybrid energy harvester for motion sensing and thermal therapy

Herein a piezoelectric-pyroelectric hybrid energy harvester (PPEH) is developed for the simultaneous conversion of mechanical and thermal energy into electrical power. In this work, poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) is selected as the polymer matrix due to its flexibility, light weight, easy processing, and biocompatibility, while nanoparticles of a photothermal poly(2-ethylaniline) (PEAn) are added as a dopant to enhance the piezoelectric output and simultaneously endow the composite material with pyroelectric properties. As a result, the output voltage under solar irradiation is enhanced by up to 3.26 times relative to that of an energy harvester based on the piezoelectric property alone. Moreover, the application of this dual-functional material is demonstrated in a wearable electronic device that is capable of detecting motion in diverse joint regions and providing thermal therapy, suggesting the potential to function as both a sensor and a therapeutic tool, thereby demonstrating its viability as a multifunctional wearable device.