Charger

Scientists have invented a knee brace that generates electricity when you walk. If it is light enough you will see these on long distance hikers. Hikers are carryind cell phones, mp3 players, cameras, and who knows what other devices in the future.

"It generates a fairly substantial amount of power compared to previous devices and it does so in a way that doesn't affect the user very much," Kuo said in a telephone interview.

"You could easily power 10 cell phones at once. There are some low power computers that you could power. You could imagine devices like GPS locaters, satellite phones," he said.

With a device placed on each leg, volunteers walking on treadmills generated about 5 watts of electricity walking at a leisurely 2.2 mph (3.5 kph). Each of the devices weighs about 3.5 pounds (1.6 kg), which Kuo said was still too unwieldy.

"Even though we've demonstrated this new way to generate power, we don't mean to say this is a usable product at this time. The principal limitations are that our prototype is pretty heavy and bulky," Kuo said, adding that he thinks it can be made smaller and more practical.