Harvesting ambient acoustic energy using acoustic resonators.

Abstract

There is currently a high demand for the development of powering systems to supply electricity to small wireless electronic devices. This has led to various energy harvesting concepts aimed to harvest potential energy sources, such as solar, thermal, wind, and vibration/wave energies. Harvesting acoustic energy has been rarely investigated because of its lower energy density compared with other resources. Even though a single acoustic wave has the lowest energy density among the above candidates, sound is abundant in our everyday life and is currently wasted. Therefore, harvesting sound energy would be a good alternative to already existing other energy harvesters. In this work, a computational model for harvesting acoustic energy using a Helmholtz resonator will be presented. To convert acoustic energy to electricity, piezoelectric wires are placed inside a Helmholtz resonator. When an external sound excites the resonator at acoustic resonant frequencies, the amplified acoustic pressure is developed and generates the vibration motion of the piezoelectric wires resulting in electricity generation. Fundamental mechanisms coupling the electrical power generation by acoustic resonant behavior of Helmholtz resonators will be presented. The effects of geometries of Helmholtz resonators and piezoelectric wires on electricity generation have been studied numerically and will be presented.