Tunable acoustic metasurface based on PVDF/polyimide unimorph sheets

Abstract

We propose a tunable metasurface unit based on a composite sheet of polyvinylidene fluoride (PVDF) membrane and polyimide tape. The deformation of the sheet can be adjusted by applying a voltage to the PVDF membrane, and the phase of reflected acoustic waves can be continuously tuned and spans the full 2π range. Various acoustic functions can be achieved by applying different voltages on the units. The experiment is also given to prove the unit’s ability to control acoustic waves. Our design shows the possibility of dynamically manipulating acoustic waves and designing integrated acoustic devices by piezo-membrane micromechanical system.

Acoustic metalens with switchable and sharp focusing

“…[7][8][9][10][11] Usually, the studies of dynamically tunable or switchable acoustic metalens were based on phase-gradient metasurfaces, and were realized through the continuous tuning of the resonant-cavity volume, [12][13][14][15][16] the dynamic modulation of a rotating airflow, 17) or integrating piezoelectric materials into the meta-atoms. [18][19][20] An alternative method to realize broadband tunable focusing is based on the utilizing of coding acoustic metasurfaces. 21,22) Although interesting and switchable focusing effect was convincingly demonstrated in these works, they were designed for air-borne sounds only.…”