Wireless generators `harvest` energy from vibrations

A team of British researchers has developed a technology that turns vibrations into energy to power devices such as sensors, microprocessors and transmitters. The scientists, based at Southampton University, have set up a company called Perpetuum to commercialise the maintenance-free technology which, they believe, could open up new wireless applications.

The technology consists of an arrangement of magnets on a vibrating beam which generate power as they move past a coil. The first version of the generator is a matchbox-based device that can generate up to 4mW. It can be "tuned" to different vibrations in the range 50-300Hz by using different beam sizes. The energy is stored and released from capacitors under microprocessor control.

The Perpetuum team is now working with the nanotechnology specialist Innos to develop a chip-based version. "The next crucial step in the development of this device is to reduce the size and cost considerably by embedding it in silicon," explains Perpetuum`s chief executive, Roy Freeland.

The two companies have produced a MEMS (microelectromechannical systems) micro-generator (shown above) measuring 5mm x 5mm x 1.5mm, that can generate a few hundred milliwatts. This is sufficient to drive sensors, small microprocesssors, and RF transmitters, "producing a completely self-powered system," says Freeland.

"This breakthrough has truly revolutionary possibilities for industry," adds Innos` chief executive, Andrew Monk.

Potential applications include:

• condition monitoring of motors, pumps and gearboxes;

• powering and transmitting signals from sensors on rotors, shafts and other moving parts;

• tracking vehicles, containers or assets; and

• embedding in inaccessible structures such as bridges.

The Southampton scientists have been working together for more than 15 years. Before coming up the electromechanical device, they tried other technologies, including piezoelectrics. Perpetuum has received funding from two venture capital organisations.