Year: 2025
Type: article
Abstract: Acoustic metasurfaces (AMs) are engineered structures that control acoustic wave propagation, enabling applications such as sound absorption, beam steering, and acoustic holography. Most AMs are planar and operate in a single direction, limiting the spatial extent of target acoustic fields. The simultaneous manipulation of waves in multiple directions remains largely unexplored, and omnidirectional AMs have yet to be realized. This study introduces a design and fabrication approach for omnidirectional AMs capable of generating custom acoustic fields anywhere in 3D space. Inspired by Goldberg polyhedra, a method is developed for tiling a sphere with custom phase‐shifting unit cells to form 3D metasurfaces. The design balances high sphericity, which ensures omnidirectionality, with high spatial resolution, which prevents spatial aliasing and enables diffraction‐limited fields. A fabrication strategy is also presented, covering design, optimization, and construction of an internal omnidirectional acoustic source. Numerical and experimental results demonstrate the effectiveness of the unit cells and metasurfaces for positioning focal points in 3D space and forming complex acousto‐holographic patterns, such as letters. This work demonstrates for the first time the acoustic equivalent of spherical electromagnetic displays and opens new avenues for applications in noise management, multi‐user haptics, multi‐functional materials, and integrated acoustic devices.
Source: Advanced Functional Materials
Institution: University College London
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,790
OpenAlex ID: W4409954513