Programmable Acoustic Metasurfaces

TLDR

Metasurfaces enable unprecedented wave engineering with subwavelength sheets, yet current acoustic metasurfaces suffer from poor reconfigurability for distinct on‑demand functions. The study reports a programmable acoustic metasurface with tunable subwavelength unit cells to overcome reconfigurability limits and enable versatile two‑dimensional wave manipulation. Each unit cell consists of a straight channel and five shunted Helmholtz resonators whose effective mass is tuned by a robust fluidic system, allowing dynamic, continuous modulation of phase and amplitude of transmitted acoustic waves at subwavelength scale, thereby enabling versatile wave manipulation. Acoustic field‑scanning experiments visually demonstrate multiple wave‑manipulation functions—steering, beam engineering, and on/off acoustic energy flow—using a single metasurface design, indicating broad potential for imaging, communication, levitation, and tweezers.

Abstract

Abstract Metasurfaces open up unprecedented potential for wave engineering using subwavelength sheets. However, a severe limitation of current acoustic metasurfaces is their poor reconfigurability to achieve distinct functions on demand. Here a programmable acoustic metasurface that contains an array of tunable subwavelength unit cells to break the limitation and realize versatile two‐dimensional wave manipulation functions is reported. Each unit cell of the metasurface is composed of a straight channel and five shunted Helmholtz resonators, whose effective mass can be tuned by a robust fluidic system. The phase and amplitude of acoustic waves transmitting through each unit cell can be modulated dynamically and continuously. Based on such mechanism, the metasurface is able to achieve versatile wave manipulation functions, by engineering the phase and amplitude of transmission waves in the subwavelength scale. Through acoustic field scanning experiments, multiple wave manipulation functions, including steering acoustic waves, engineering acoustic beams, and switching on/off acoustic energy flow by using one design of metasurface are visually demonstrated. This work extends the metasurface research and holds great potential for a wide range of applications including acoustic imaging, communication, levitation, and tweezers.