The yellow-coloured Ormia ochracea fly can pinpoint the location of a chirping cricket with remarkable accuracy because of its freakishly acute hearing, which relies upon a sophisticated sound processing mechanism that really sets it apart from all other known insects.
The 2-millimetre-wide device developed by researchers at the University of Texas Austin 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.
"Minimising power consumption is always an important consideration in hearing-aid device technology," said Hall.
There are military and defence applications as well. In dark environments, for instance, where visual cues are not available, localising events using sound may be critical.
The pioneering work in discovering the fly's unusual hearing mechanism was done by Ronald Miles at Binghamton University and colleagues Ronald Hoy and Daniel Robert, who first described the phase amplification mechanism the fly uses to achieve its directional hearing some 20 years ago.
Inspired by Miles's prior work, Hall and his graduate students Michael Kuntzman and Donghwan Kim built a miniature pressure-sensitive teeter-totter in silicon that has a flexible beam and integrated piezoelectric materials.
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.