Card-type Piezoelectric Energy Harvesters of Pb(Zr,Ti)O3 Thin Films on Stainless Steel Foils

In this study, we fabricated flexible card-type piezoelectric energy harvesters (PEHs) composed of Pb(Zr,Ti)O3 (PZT) thin films on stainless steel foils for wearable applications and measured their power generation performance under hand-bending motion. The PZT thin films with preferential c-axis orientation were deposited on LaNiO3 (LNO)-coated stainless steel substrates of 30 μm in thickness by RF magnetron sputtering. Five PZT thin-film PEH elements were stacked with each connected in parallel. The stack was placed in the middle of a card divided into two parts. We measured the output power while applying a large hand-bending deformation to the card-type PEHs. During periodic bending motion at 1 Hz the maximum output power reached 177 μW at a load resistance of 80 kΩ, and we successfully turned 10 LEDs on intermittently.