Powercast unveils wireless power unit

Startup company Powercast has revealed a breakthrough technology that allows low-voltage devices to be powered wirelessly. 

The principle behind the radio wave technology is surprisingly simple. A unit is plugged into the wall which transmits using the 900MHz band.

These transmissions are picked up by a small receiver built into the device, about the size of a coin, which converts the radio waves into low voltage power.

The system currently works up to a distance of around a metre, which means that devices such as mobile phones and MP3 players could be recharged wirelessly while sitting on a desk.

More importantly, implanted devices such as pacemakers and defibrillators could be wirelessly recharged, eliminating the need for surgery when the batteries go flat.

"The sky's the limit," said John Shearer, chief executive at Powercast, who estimates shipping millions of units by the end of 2008.

The concept of wireless power has been around for some time, but scientists have had a hard time capturing the signals efficiently and safely.

Part of the problem has been that the signal changes frequency when reflected or refracted by objects.

But the boffins at Powercast have developed a receiver tuned to multiple frequencies at the same time, thereby allowing it to harvest almost all the transmitted energy.

The receiving circuits can also output a constant DC voltage despite variations in field strength, which means that there is no chance of batteries being overcharged or sensitive electronics being damaged.

Powercast has signed agreements with more than 100 companies to develop products using Powercast, including Philips. 

The first product will be a wireless LED light stick, due out later this year, with a range of wirelessly powered computer peripherals due in 2008.

"Everyone is looking to cut that last cord," said Alex Slawsby, a consultant at research firm Innosight. 

"Think of the billion cellphones sold last year. If you could get Powercast into a small percentage of the high-end models, those would be huge numbers."

The low range and power of the system has allowed Powercast to make sure the system remains safe, and the technology has already received FCC approval.

As the system has a maximum output of 6V, it is limited to small devices that do not require large amounts of power.

But as technology marches onward the number of devices with power demands low enough to be serviced by Powercast will continue to grow.