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

  • 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’.

 

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Watch how the acoustic smart material works

Biomimicry Story

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. Sharks can completely switch the skin flow drag by reversing the orientation of the skin denticles.