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Next stop for mobiles: Wireless recharging

Posted: 11 Jun 2007 ?? ?Print Version ?Bookmark and Share

Keywords:wireless power sending? battery charging? WiTricity?

cellphones may soon have no need for cables to get recharged.

Researchers at the Massachusetts Institute of Technology (MIT) announced that it made a 60W light bulb glow up by sending the power wirelessly from a device 2m away. The technology is touted as "WiTricity."

While the idea of sending power wirelessly is not new, its wide-scale application has been considered inefficient due to electromagnetic energy generated by the charging devices, which would radiate in all directions.

Until recently, MIT physics professor Marin Soljacic claimed he had found a way to use specially tuned waves. The key, according to Soljacic, was to get the recharging device and the gadget the needs power to resonate the same frequency to allow them to exchange power more efficiently.

While the technology brings a possibility of eliminating cables in many portable gadgets, and even the need for batteries if devices can get power through the air, it still has a long way to go before it becomes practical.

The system is about 40 to 45 percent efficient, with most of the energy from the charging device unable make it to the light bulb. Soljacic admitted that the system needs to be twice as efficient to match charging the chemical batteries in portable gadgets.

In addition, the copper coils that transmit the power are about .61m wide, too big to be feasible for devices like laptops. The 2m range of the wireless handoff could also be increased so that one charging device may automatically power all the gadgets in a room.

Soljacic said he is optimistic that the needed improvements are within reach. The MIT team also stressed that the "magnetic coupling" process in the technology is safe on humans and other living things. Also, in the light bulb experiment, no damage was done to cellphones, electronics equipments and credit cards in the room.

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