Acoustic metamaterial from the University of Southern California uses magnets to shift acoustic states and alter transmission.
Benefits
- Flexible
- Tunable
- Responsive
Applications
- Electronic devices
- Surveillance
UN Sustainable Development Goals Addressed
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Goal 9: Industry Innovation & Infrastructure
The Challenge
Acoustic metamaterials are designed to control, direct and manipulate soundwaves as they pass through different mediums. They can be used to dampen or transmit sound within a structure, such as headphones or submarines. Traditional acoustic metamaterials have complex geometries and are made of metal or hard plastic. Once they are created, it is difficult to change their properties, limiting their use.
Innovation Details
Smart materials allow for multiple, changing properties within one structure. The smart acoustic metamaterial was inspired by the dual properties created by the dermal denticles on shark skin. It is made from rubber and magneto-sensitive nanoparticles. To make the nanoparticles responsive to acoustic transmission, researches had to be able to actively block or conduct acoustic input. They used Mie resonator pillar (MRP) arrays that are magnetically deformable. If the pillars are closer together, the acoustic wave is unable to pass through. If the pillars are further apart, the acoustic wave will easily pass through. External magnetic fields help to bend and unbend the pillars to achieve this type of ‘state switching’.
Watch how the acoustic smart material works
Biological Model
Fast-swimming sharks have skin denticles that are shaped like “V” trenches and aligned in the direction of fluid flow. The skin denticles can significantly reduce the flow drag because the V-shaped trenches are able to guide a turbulent flow to become laminate flow. The denticles are also able to bristle upwards up to 50 degrees above the horizontal. This allows them to block the backward flow of any turbulence that does arise, and then nearly instantly settle back down when the turbulence is broken and main flow resumes.
