Origami inspired phononic structure with metamaterial inclusions for tunable angular wave steering

Abstract

The ability to create directional sound beams is fundamental to acoustic sensing. Traditionally, acoustic beams are most commonly produced by phased arrays, which increase the cost and complexity of the systems in which they are implemented. Phononic structures have theoretically been shown to possess Dirac cones that can be manipulated to produce angular collimated beams. Dirac cones are usually encountered in phononic crystals with inclusions significantly more compressible than the surrounding media, e.g., rubber inclusions in a water medium, a characteristic not easily realized in air. In addition, there are no effective and practical means to tune phononic structures that can achieve a broad range of Dirac point manipulation, which is essential to changing the direction and focus of acoustic beams. To advance the state of the art, this research proposes a novel approach to produce steerable collimated beams in air by harnessing reconfigurable origami phononic structures with adjustable metamaterial inclusions. The proposed structure is shown to produce dramatic lattice reconfiguration and control of Dirac points in a broad range, and thus achieve collimated beams with on-demand tunable frequency and angle. These advancements provide a simple, cost-effective alternative to acoustic phased arrays, greatly expanding the potential of acoustic sensing.