A Flexible Piezoelectric Pulsewave Energy Harvester for Application to High-Efficiency Multi-Functional Skin Patches

A piezoelectric pulsewave energy harvester composed of flexible three-layers generates electrical power from human arterial pulsewaves. We present the simple structure and novel fabrication process of the flexible three-layers, having a silver inter-electrode layer between a P(VDF-TrFE) piezoelectric layer and a polyimide support layer. The triple functions and the purposes of the silver inter-electrode layer are designed, acting as an electrode for piezoelectric poling, an electrode for piezoelectric energy harvesting, as well as an etch stop barrier for window patterning on the polyimide support layer. We also developed special processes for the window patterning on the polyimide support layer with the polyimide residue removal on the silver electrode, thereby increasing the piezoelectric energy generation efficiency and support flexibility, as well as achieving an electric contact to the silver electrode through the patterned window. The fabricated energy harvester generates 0.2~1.9 μW from the human pulsewave in the range of 50~220 BPM, where the effect of window formation is demonstrated to increase energy efficiency and flexibility in the amount of 45% and 8%, respectively. The flexible energy harvester is capable to integrate additional physiological sensors for the applications to the multi-functional self-powered skin patches.