From the headphones to favorite songs or podcasts, to sonic camouflage employed by submarines, how sound transmitted and experienced is a vital part of how humans engage with the surrounding world.
Acoustic metamaterials are materials designed to control, direct and manipulate soundwaves as they pass via different platforms. As such, they can be developed and inserted into a structure to dampen or transmit sound.
The problem is, traditional acoustic metamaterials have advanced geometries. Often fabricated from steel or hard plastic, once they’re created, they cannot be modified. For instance, an acoustic device developed to dampen outgoing sound in a submarine, so that it could achieve stealthiness. If a different situation arose, for example, an ally the submarine wanted to communicate with passes by, the same acoustic system wouldn’t allow for sound to be transmitted externally.
Wang and his group, along with USC Viterbi Ph.D. candidates Kyung Hoon Lee, Kunhao Yu, An Xin and Zhangzhengrong Feng, and postdoctoral scholar Hasan Al Ba’ba’a, detailed the discoveries in their paper “Shark skin-Inspired Magnetoactive Reconfigurable Acoustic Metamaterials,” lately featured in Research.
Inspired by the dual properties developed by the dermal denticles on the surface of a shark’s skin, the group built a new acoustic metamaterial that contains magneto-sensitive nanoparticles that will bend under the force of magnetic stimuli. This force can change the structure remotely and on-demand, accommodating different transmission conditions.