A panel acoustic energy harvester based on the integration of acoustic metasurface and Helmholtz resonator

We propose and demonstrate an acoustic energy harvester based on the integration of an acoustic metasurface and Helmholtz resonator. The acoustic metasurface can transform the incident propagating acoustic waves into evanescent waves that converge at the center of the metasurface, where a Helmholtz resonator is applied to further enhance the efficiency of energy harvesting at the working frequency. This mechanism is verified by both numerical simulations and acoustic experiments. The metasurface is capable of increasing the sound intensity by ten times and increasing the open voltage by 3.2 times combined with the Helmholtz resonator in comparison with the case of only using the Helmholtz resonator. Our work opens a practical approach of acoustic energy harvesting with attractive features including high efficiency, flat geometry, and scalability to large sizes.