MIT Makes Breakthrough in Wireless Electricity

Researchers at the Massachusetts Institute of Technology have made a breakthrough in what the scientists call “WiTricity,” or wireless electricity. MIT researchers this month announced that they successfully lit a 60-watt light bulb from a power sour

August 3, 2007 – Today’s consumers are plagued with having to remember to charge their cell phones, plug in their laptops, and, for photographers, recharge their camera batteries. But researchers at the Massachusetts Institute of Technology have made a breakthrough in what scientists call "WiTricity," or wireless electricity. MIT researchers last month announced they successfully lit a 60-watt light bulb from a power source two meters away without a wired connection, signaling that some day consumers may be able to power electronics without cords.

"Look behind your desk. There are a number of annoying wires," said MIT Ph.D. candidate Aristeidis Karalis in an interview with "It would be great to get rid of them."

With hopes to cut out the use of power cords, MIT researchers used a specific kind of energy, electromagnetic radiation. When two objects vibrate at the same frequency, the pair makes for a strong couple that can effectively transfer energy. The researchers used two cooper coils as magnetically coupled resonators; one for sending out the non-radiative energy, and one to receive it (in this case, the light bulb).

The research team was able to light the 60-watt bulb from one coil to the other coil two meters (6.56 feet) away. The first trial experiment of WiTricity had a 40 percent efficiency rate, explained Karalis. That is, 40 percent of the power from the first coil made it to the light bulb, leaving 60 percent of energy absorbed by the wire.

*MIT has demonstrated wireless power transmission from the coil on the left to the coil on the right, where it powers a 60-watt light bulb. Members of the team that performed the experiment are, front row: Peter Fisher (left) and Robert Moffatt; second row: Marin Soljacic; third row: Andre Kurs (left), John Joannopoulos,and Aristeidis Karalis. (Photo / MIT News Office)*

While the numbers may sound low, Karalis explained that a laptop, a common household electronic, only produces 70 percent efficiency and that most people would not need to power it from more than a meter away.

"[For a first trial], the numbers are promising," Karalis said.

While some consumers are jumping at the chance to cut the cord, others may have concerns about the side effects of radiation.

The magnetic fields that achieved this coupling do not interact with surrounding objects, such as biological tissue, said Karalis. If WiTricity were to be commercialized for consumers, he added, the wireless energy would need to follow international regulations set by the FCC (Federal Communications Commission) and IEEE (Institute of Electrical and Electronics Engineers).

If WiTricity were successfully commercialized, Karalis said the wireless power could be used for applications in consumer electronics or the medical field. Wireless power could be used for critical medical devices such as artificial pacemakers, a battery-operated device which is traditionally replaced through surgery.

As far as future plans go, Karalis said increased efficiency and distance could be improved with WiTricity. In addition, the size of the coils could be reduced from the tested dimensions of 60 centimeters in diameter to smaller resonators, better suited to actual consumer devices such as cell phones and cameras.

Consumers can continue to hope for the day when they can toss out their cords as the MIT research team continues to change WiTricity theory into reality.

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