Methods for wirelessly providing power from an external source to sensors and actuators have been required in various scenes. In this research, we aim to transfer power from an external energy source using ultrasound. In particular, we attempt the sound-to-heat energy conversion, which is more straightforward than the electroacoustic transduction in specific applications. By attaching a thin layer of porous material to the heating target, the irradiated ultrasound is absorbed as heat by the sound absorption effect and transmitted to the target. In the experiment, urethane foams with different widths were compared to maximize the energy conversion efficiency from acoustic energy to heat. As a result, urethane foam with a width of 5mm could transmit 26% of the presented sound power to the heating target. In this paper, details and results of our method are introduced.
Matsumura et al. (Thu,) studied this question.