Acoustic Energy Harvesting of Piezoelectric Ceramic Composites

Abstract

Acoustic energy is an often overlooked but increasingly prevalent source of ambient energy that could be scavenged to power a wide range of devices. Piezoelectric materials are often used, but the tradeoff between acoustic impedance matching and the amount of ceramic piezoelectric material as the active material has not previously been investigated. In this work, commercially available 1–3 dice and fill composites with various fill factors (25%, 45%, and 65% of Pb(Zr,Ti)O3) and different acoustic impedance values were tested using an impedance tube and then modeled using a KLM equivalent circuit model. As expected, a higher amount of ceramic material resulted in a higher acoustic absorption coefficient. Experimentally, the highest fill factor with the highest piezoelectric coefficient also resulted in larger output power at all dB levels, reaching a maximum of 115 nW (84 nW/cm3) at 111 dBSPL for the 65% fill sample. In the model, the 25% fill factor with the best acoustic impedance matching shows the highest expected output power instead, but this discrepancy is most likely due to a lowered piezoelectric coefficient during testing due to the clamping conditions.