Sound-speed Modifying Acoustic Metasurfaces for Acoustic Holography.

Acoustic metasurfaces offer unique capabilities to steer and direct acoustic fields, though these are generally comprised of complex 3D structures, complicating their fabrication and applicability to higher frequencies. Here, we demonstrate an ultrathin metasurface approach utilizing planarized micropillars in a discretized phase array. This sub-wavelength metasurface is easily produced via a single-step etching process and is suitable for MHz-scale applications. We further demonstrate the flexibility of this metasurface approach in the production of complex acoustic patterns via acoustic holography. This metasurface approach, with models used to predict their behavior, has broad potential in applications where robust, high-frequency acoustic manipulation is required, including microfluidics, cell/tissue engineering and medical ultrasound. This article is protected by copyright. All rights reserved.