Efficient Piezoelectric Energy Harvesters Utilizing (001) Textured Bimorph PZT Films on Flexible Metal Foils

Extracting energy from low vibration frequencies (<10 Hz) using piezoelectric energy harvester promises continuous self-powering for sensors and wearables. The piezoelectric compliant mechanism (PCM) design provides a significantly higher efficiency by fostering a uniform strain for its 1st mode shape, and so is interesting for this application. In this paper, a PCM energy harvester with bimorph Pb(Zr,Ti)O₃ (PZT) films on Ni foil deposited by rf magnetron sputtering is shown to have high efficiency and large power for low frequency mechanical vibration. In particular, {001} textured PZT films are deposited on both sides of polished Ni foils with (100) oriented LaNiO₃ seed layers on HfO₂ buffer layers. The performance of PCM with an active area of 5.2 cm² is explored for various excitation accelerations (0.02–0.16 g [g = 9.8 m s⁻²]) around 6 Hz. The PCM device provides a power level of 3.9 mW cm⁻² g² and 65% mode shape efficiencies.