UK team sounds off with metamaterial bricks

Researchers from the Universities of Sussex and Bristol have developed a new metamaterial capable of bending, shaping and focusing acoustic waves.

(Credit: Interact Lab, University of Sussex)

Metamaterials have long been employed in the manipulation of light, where spatial light modulators (SLMs) alter the amplitude and phase of beams. Until now, the acoustic equivalent of an SLM has not existed. The new study, published in the journal Nature Communications, shows that similar levels of acoustic control are possible.

The team created a layer of metamaterials using 16 varieties of small 3D printed bricks that each manipulate sound in a different way. Depending on how the layer of bricks is configured, incoming sound waves can be transformed into an acoustic field of any shape.

“Our metamaterial bricks can be 3D printed and then assembled together to form any sound field you can imagine,” said project lead Dr Gianluca Memoli, from Sussex University’s Interact Lab.

“We also showed how this can be achieved with only a small number of different bricks. You can think of a box of our metamaterial bricks as a do-it-yourself acoustics kit.”

According to the team, the technology has a wide range of applications, including loudspeaker design, ultrasound imaging and therapy, acoustic levitation and ultra-haptics. Another potential use would be to focus high-intensity ultrasound to destroy tumours deep within the body.

“In the future, I think there will be many exciting applications of this technology,” said Bruce Drinkwater, Professor of Ultrasonics at Bristol’s Department of Mechanical Engineering.

“We are now working on making the metamaterial layers dynamically reconfigurable. This will mean we can make cheap imaging systems which could be used either for medical diagnostics or crack detection.”