Flexible and Wearable Thermo/Piezo-Electric Hybrid Energy Harvesters

Thermoelectric and piezoelectric hybrid generators (TPHGs) are attractive candidates for powering wearable body sensor networks continuously and permanently owing to their excellent access to human-generated energy. First, to achieve the enhanced piezoelectricity of flexible piezoelectric composites-based films, we have demonstrated the flexoelectric-boosted electromechanical properties of piezoelectric nanoparticles using an induced built-in strain gradient in heterogeneous core-shell nanostructure for enhancing the intrinsic piezoelectricity of pure BaTiO₃ nanoparticles. We have also demonstrated the enhanced poling efficiency in nanocomposite made of P(VDF-TrFE) and porous BaTiO₃ nanofibers. Moreover, we have developed the high-temperature workable f-PEH comprising the high Tc KNN-based ceramics and a thermally stable polyimide (PI) matrix which can be a promising candidate for developing f-PEH and self-powered sensors working in high-temperature environments. Next, to realize the flexible thermoelectric energy harvesting technology, we have fabricated the tailorable f-TEHs based on thermoelectric films and papers made by dispersing the Bi₂Te₃ particles inside polymeric and cellulose matrices, respectively. Finally, the hybrid generator was assembled through simple drop-casting and gravitational settling effect, for the first time. The film layer sedimented with the conductive thermoelectric particles simultaneously served as an electrode and a bottom substrate for piezoelectric energy harvesting. The proposed design concept for f-TPHGs can aid in the development of high-performance multisource energy harvesting devices for wearable sensors.