A team of scientists from Nanjing University in China and the University of Illinois at Urbana-Champaign is exploring the use of metamaterials to create devices that manipulate sound in versatile and unprecedented ways. This was reported in the journal, Applied Physics Letters.
Their design for a device, called an acoustic field rotator, can twist wave fronts inside it so that they appear to be propagating from another direction, like a ventriloquist can “throw his voice.” The team designed what they believe to be the first feasible acoustic rotator model and also fabricated a prototype to validate it. By using metamaterials, they say, acoustic waves can be rotated in a manner similar to their electromagnetic or liquid wave counterparts.
The team hopes their acoustic rotator, with its ability to freely manipulate acoustic wavefronts, will improve the operation of devices like medical ultrasound machines, which require the precise control of acoustic waves. The ability to rotate the sound waves could improve the contrast of ultrasound devices and allow them to image damaged tissue or diagnose diseases in ways they currently cannot. This is significant because ultrasound devices may be cheaper than other imaging modalities and do not use x-rays.
In the future, acoustic rotators could serve as useful building blocks for constructing more complex structures with richer acoustic manipulation functionalities, if properly combined with other kinds of components, they explained.
