Acoustic Power Transfer Along Metal Surfaces by Audio Transducers

Abstract Acoustic power transfer is a promising method for providing power to sensing microsystems installed in locations in which battery replacement, wiring, or energy harvesting from ambient energy is impractical or limited. In this paper, an evaluation of acoustic power transfer along metal surfaces is presented. Commercial audio band magnetostrictive and piezoelectric transducers are used as the transmitter and the receiver, respectively. The study was performed on a 1 m long, 0.5 mm wide, and 3 mm thick aluminum plate, emulating industrial infrastructure or vehicle panels. A power delivery of 44 μW is demonstrated at a 0.8 m transmitter–receiver distance, at a setup-specific 3.64 kHz resonance frequency. The corresponding open-circuit voltage amplitude is over 0.7 V, which is adequate for efficient power management. The receiver mass and volume are 1.57 g and 200 mm 3 respectively, yielding 200 μW/cm 3 and 25 μW/g power density. This power density is adequate for supporting low-power wireless sensor platforms by integration of acoustic piezoelectric receivers with an acceptable volume overhead compared with the size of typical sensor nodes.