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EARTHDATE: February 10, 2008

Official News page 7


GEEK TOY: CHARGE YOUR GADGETS WITH THE KNEE DYNAMO

by Hazed

US and Canadian scientists have come up with a device that harvests energy from human movements, allowing you to charge up batteries while you walk. It is an adapted knee brace and just one minute of walking can generate enough energy to power a mobile phone for about half an hour.

It's actually intended for a less frivolous use than that: amputees who are being fitted with increasingly sophisticated prosthetics could benefit from the ability to generate power to operate their artificial limbs. "All of the new developments in prosthetics require large power budgets," says Dr Douglas Weber of the University of Pittsburgh, one of the authors of a paper describing the new technology which has been published in the journal Science. "You need power to run your neural interface; you need it to run your powered joint, and so on."

The knee generator works using a process known as "generative braking", similar to the systems found in hybrid-electric cars. It engages itself only during the "braking" period of walking, when the knee is bending to absorb the body's weight after a footfall, and it puts out an average of 5W when fitted to a slow-walking person. That's more than enough to charge up a phone.

Another of the study's authors, Arthur Kuo of the University of Michigan, sees systems of this kind being used by soldiers, to charge the increasing load of electronics they carry. The idea could also power implanted medical gear like pacemakers.

Right now, the generator is way too cumbersome and bulky, but it demonstrates proof of concept. Give it a few years, during which the technology can be refined, and it may turn out to be something everyone is wearing.


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