MIT team lights it up -- without wires
By Chris Reidy and Carolyn Johnson, Globe Staff | June 8, 2007

The latest MIT news flash could finally allow consumers to cut their
power cords: A Massachusetts Institute of Technology research team
has figured out how to wirelessly illuminate an unplugged light bulb
from seven feet away.

MIT physicist Marin Soljacic foresees a day when people could forgo
the tangle of wires that keeps laptop, iPod, and cellphone users on a
short leash. Instead, they could use a carefully designed magnetic
field to deliver power to devices over the air. "At this point, this
is a proof of principle -- the main point of our research was to see
if we could transfer energy wirelessly," said Soljacic, who was
inspired by the annoying beeps his cellphone made in the middle of
the night when he forgot to charge it. "It occurred to me that it
would be so great if the thing took care of its own charging."

Details about WiTricity, or wireless electricity, were reported
yesterday in Science Express, an online publication of the journal
Science.

In the demonstration, Soljacic and his team generated a magnetic
field on one copper coil. Seven feet away, a similar coil specially
tuned to resonate with the field received enough power to light up a
60-watt bulb. Typically, a laptop requires about 30 to 40 watts, he
said, and an iPod or cellphone might require a few watts.

Already, some products have been developed that allow consumers to
wirelessly charge their devices over very short distances.

But if Soljacic's idea bears fruit, consumers could be truly
unplugged -- their rechargers and bulky adapters replaced by a device
that transmits power wirelessly. The Army Research Office, the
National Science Foundation, and the Department of Energy funded his
research.

Chris Reidy can be reached at reidy@globe.com and Carolyn Johnson at
cjohnson@globe.com.

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