Every step you take could soon be the power source for your mobile phone, MP3 player or portable GPS device. A group of university researchers from the United States and Canada have developed a prototype knee brace that captures energy in a way that's similar to how some hybrid cars charge their batteries by converting energy while they brake.
"There is power to be harvested from various places in the body, and you can use that to generate electricity. The knee is probably the best place," said Arthur Kuo, an associate professor of mechanical engineering at the University of Michigan, in a statement released yesterday.
Kou and colleagues determined that when a person stops his or her lower leg from swinging forward into a step, the majority of the energy expended is just lost. The new prototype knee brace is built to capture and store that energy more efficiently than other human powered electricity generators. For example, a hand-crank generator requires 6.4 watts of metabolic power from a person to generate one watt of electricity because of inefficiencies -- but the knee brace requires less than one watt of metabolic power to produce one watt of electricity.
The challenge for the team of researchers, which also includes staff from Simon Fraser University in Canada and the University of Pittsburgh, is to make the device lighter so it doesn't tire the wearer. For now it is too bulky and heavy to be practical.
Kuo says that in the future, a light device could be very useful to hikers or soldiers who don't have quick access to an energy source. For people with a prosthetic limb, the energy capture device could be on one knee while a battery is implanted within the fake limb.
From The Daily Mail, Engadget and Reuters.
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