Push-button Kinetic Energy Harvester with Soft-X-ray-charged Folded Multilayer Piezoelectret

Abstract

Piezoelectret using space-charged porous polymer attracts much attention recently for its softness and high piezoelectric coefficient. It has already been applied to tactile or pressure sensing as well as to kinetic/vibrational energy harvesting. In the present study, a push-button energy harvester based on soft-X-ray charged folded multilayer piezoelectret is proposed. The folded structure with CYTOP-coated parylene-C membranes yields an extremely low stiffness with effective Young's modulus as low as 14 kPa. With the early prototype, 15.5 μJ/push has been obtained with a maximum force of only 1 N, which corresponds to the record-high piezoelectric coefficient d33 of 30000 pC/N. In addition, LED light-up is also demonstrated upon finger press.