Wireless electricity produced
Friday, 08 Jun 2007 17:52
Laptops could soon be charged without wires
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Wireless power transfer could soon see mobile phones, laptop computers and mp3 players being charged without ever being plugged in, scientists claim today.
Researchers from Massachusetts Institute of Technology (MIT) and Institute for Soldier Nanotechnologies claim to have lit a 60W light bulb from a power source seven feet away with no physical connection between them.
The method behind this has been described as "WiTricity", or wireless electricity.
To create the power connection, scientists used a technique called near-field magnetic resonance between two copper coils.
One coil is attached to the power source and is the sending unit. This coil fills the space around it with non-radiative magnetic field moving at megahertz frequencies, rather than with electromagnetic waves.
The nature of the process ensures a strong interaction between the two coils, while the interaction with the rest of the environment is weak.
"The crucial advantage of using the non-radiative field lies in the fact that most of the power not picked up by the receiving coil remains bound to the vicinity of the sending unit, instead of being radiated into the environment and lost," explained researcher Robert Moffatt.
Because magnetic fields interact so weakly with biological organisms they have important safety benefits.
Writing online in Science Express, the researchers argue that the design could create power levels across a room sufficient to run a laptop.
"As long as the laptop is in a room equipped with a source of such wireless power, it would charge automatically, without having to be plugged in. In fact, it would not even need a battery to operate inside of such a room," said Professor Peter Fisher from MIT.
The research team argue that their system could one day reduce society's dependence on batteries.
