Sound-powered mobiles work on hot air

Imagine a mobile that never needs to be plugged in, and that recharges just by the sound of you talking.

That's just one of the advances promised by new research into piezoelectric materials from scientists at the Texas A&M University in Houston.

Professor Tahir Cagin found that a certain type of piezoelectric system can convert energy at a 100 per cent increase when manufactured at a very small size – around 21 nanometers in thickness.

Piezoelectric materials (usually crystals or ceramics) create small amounts of electricity when twisted or stressed, but Cagin discovered that when the materials are made to be extremely thin, the amount of energy they can capture doubles.

Sound investment

This raises the possibility of self-powered devices that harvest the energy they need from motion, impact or noise.

"Even the disturbances in the form of sound waves such as pressure waves in gases, liquids and solids may be harvested for powering nano- and micro devices of the future, if these materials are processed and manufactured appropriately for this purpose," Cagin said.

While the amounts of energy produced by Cagin's nanotechnology systems today are far too small to power a mobile phone, tiny self-powering sensors and detectors may only be a handful of years away.