Acoustic Metasurface Harvester

Acoustic metasurface have demonstrated unusual capacity in controlling low-frequency sound phase modulation, reflection, and absorption. In this report, an analytical vibro-acoustic-electromagnetic coupling is developed to study sound absorption, acoustic-electric energy conversion, and energy harvesting coefficient of a proposed acoustic metasurface harvester (AMH) model composed of a membrane-type acoustic metamaterial (MAM) backed by a cavity, a magnet coil attached to the mass of the MAM, and a permanent magnet coin placed right behind the magnet coil. The theoretical analysis which employs the Green's functions of the upstream and the cavity to account for the acoustic near fields shows excellent agreement with the finite element method. The sound absorption, acoustic-electric energy conversion, and harvesting coefficient of the AMH model have been quantitatively investigated by varying the parameters of the AMH model. It is found that the AMH model can reach to perfect acoustic absorption, more than 80% in acoustic-electric conversion, and more than 70% in harvesting coefficient in very low frequency region. The developed model can serve as an efficient tool for designing magneto-based acoustic harvester.