Broadband acoustic energy harvesting metasurface with coupled Helmholtz resonators

We report a broadband acoustic energy harvesting metasurface consisting of periodic arrangements of coupled Helmholtz resonators. Theoretical analysis and numerical and experimental results show that a high output voltage can be obtained at a wide band (460 Hz–680 Hz) under the push-pull effect on the piezoelectric composite sheet (PCS) between the two coupled cavities, which is because the acoustic pressure phases in the two coupled cavities are nearly opposite to each other. Each output can be directly connected in parallel without any rectification circuit because the output voltage from every PCS has the same phase on account of the symmetry of the proposed metasurface. The proposed design has an efficient and easy-to-integrate structure, and it can be used in broad applications for acoustic energy harvesting devices and acoustic insulators.