Magnetic induction could soon spell the end of tangled cables and a frustrating hunt for the gadget's charger.

Two firms at CES showed off ways to use the phenomenon to re-charge batteries inside gadgets when they are laid on a special mat.

Sensing systems allow devices with very different voltages to be charged at the same time.

The technology can also be used to power household objects such as flat screen TVs or kitchen appliances.

The company Powermat uses RFID tags to identify what is being laid down to charge. The RFID tags are held in a case made to fit around popular gadgets such as iPods, laptops, and mobile phones.

When a gadget is laid down on a Powermat, it reads the RFID tag to ensure that each device only gets the charge it needs.

"It can charge a 100-watt gadget side by side with an iPod Nano that is very low power," said Ron Ferber, president of Powermat. "It knows what's on the mat."

A series of Powermats, including travel versions, should be on sale in the U.S. by Autumn 2009, said Mr. Ferber.

Also at CES, Leggett and Platt showed off a line of devices called eCoupled, made by Fulton Innovation, which uses a different method of identifying gadgets.

Leroy Johnson, senior director of emerging technologies at Leggett and Platt, said its system embeded a signal in the induction coil fitted to a gadget that helps charge it up.

"Inside each device is a coil that sends an identification signal that says 'I'm a flashlight with a three-volt Li-on battery'," he explained.

"It's almost like plugging it in, but instead you just set it down," he added. The first products fitted with the eCoupled technology should appear by late 2009, said Mr. Johnson.

He said the technology was safer too, because it almost removed the need to plug devices into a wall socket.

Source: BBC