Soft acoustic metamaterials: From broadband tunable metagels to directional emission

Abstract

In this invited talk, we report the experimental investigation of hybrid meta-gel, a class of designed hydrogel composites with tunable acoustic properties over broadband frequencies. The meta-gel consists of patterned channels in a tough hydrogel matrix, where air, water, or liquid metal can be purged through the channels to tune the meta-gel’s acoustic transmission over broadband frequencies on demand. We show that the acoustic properties of the meta-gel can be tuned by varying the volume ratio of the channels, properties and ratio of the different filler materials with combined experiments, theory, and simulations. We validated that the hybrid metamaterial significantly increased directivity and main lobe energy over a broad bandwidth both numerically and experimentally. The meta-gel enables novel functions such as adjustable imaging regions of ultrasound, demonstrating tangible applications in underwater acoustics and medical imaging.