Jan. 3, 2007 — These days it seems absurd to see a telephone handset tethered via
curly-cue cord to its base station. Yet most of us still plug in to power up PDAs, laptops,
cell phones, MP3 players, televisions and stereos.
Now researchers have built a wireless power transmitter that could cut
the cord, so to speak.
The device is a 1-millimeter-thick sheet containing electronic
parts made from flexible, plastic semiconductor materials.
Thin
and lightweight, the sheet can be imbedded into desktops, walls,
floors or ceilings, to power nearby electronic devices. The result: ubiquitous charging without any
tripping over cords.
"The system selectively feeds power as high as 30 watts to electronic
objects placed upon it," said associate professor Takao Someya of
University of Tokyo, who developed the technology with colleague
Takayasu Sakurai.
"Thirty watts is enough to drive a small laptop computer," said Someya.
Unlike transmitting information through the air — think wireless
Internet — transmitting energy is tricky. The challenge is that the
energy disperses, making the transfer inefficient.
And there is also the issue of safety, said assistant professor Marin
Soljacic of the Massachusetts Institute of Technology.
"You want to deliver watts from a source to a device and hopefully not
burn humans or cats or whatever lives in the room," he said.
Soljacic's team is working on a system of power transmission analogous
to the wireless Internet — energy would flow over a few feet and
electronic devices would simply have to be in the same room as a
transmitter to be charged.
