Fly-inspired hearing aids soon

Researchers have now developed a tiny prototype device that mimics a parasitic fly's hearing mechanism and may be useful for a new generation of hypersensitive hearing aids.

The two millimetre-wide device uses piezoelectric materials which turn mechanical strain into electric signals.

The use of these materials means that the device requires very little power.

"Synthesising the special mechanism with piezoelectric readout is a big step forward towards commercialisation of the technology," said Neal Hall, an assistant professor in the Cockrell School of Engineering at UT Austin.

Inspired by a fly species called Ormia Ochracea that can locate the direction of a cricket's chirp even though its ears are less than two mm apart, Hall and his team built a miniature pressure-sensitive teeter-totter in silicon that has a flexible beam and integrated piezoelectric materials.

The fly's ear has a structure that resembles a tiny teeter-totter seesaw about 1.5 mm long.

The use of piezoelectric materials was their original innovation, and it allowed them to simultaneously measure the flexing and the rotation of the teeter-totter beam.

Simultaneously measuring these two vibration modes allowed them to replicate the fly's special ability to detect sound direction in a device essentially the same size as the fly's physiology.

The new technology could enable a generation of hearing aids that have intelligent microphones that adaptively focus only on those conversations or sounds that are of interest to the wearer.

The research was published in the journal Applied Physics Letters.