Reconfigurable 3D-printed 1-bit coding metasurface for simultaneous acoustic focusing and energy harvesting at low-frequency regime

This study explores the development of a reconfigurable 3D-printed 1-bit coding space-coiling metasurface, which integrates a triboelectric nanogenerator (TENG) to achieve low-frequency acoustic focusing and energy harvesting. By controlling the effective acoustic path, the proposed metasurface is able to achieve effective acoustic manipulation using binary coding units with opposite phase responses. The transmission efficiency and phase shift of the coding units are validated by analytical and numerical models, as well as experimental results from 3D-printed units made with photosensitive resin via stereolithography. The proposed metasurface has demonstrated arbitrary acoustic focusing at low frequencies (i.e., 600-900 Hz) by reconfiguring its coding units into designated coding sequences. The enhanced performance of acoustic energy harvesting through the integration of the metasurface with a resonator-free TENG device has demonstrated the crucial role of the metasurface in facilitating efficient energy harvesting through effective wave focusing. The findings presented here could offer important insights for creating advanced acoustic devices and potential applications that serve a dual purpose: controlling sound while harvesting energy from ambient environments.