Washington - (AP) - Researchers have developed a device that generates electrical power from the swing of a walking person's knee. With each stride the leg accelerates and then decelerates, using energy both for moving and braking.

A device that helps the leg decelerate could generate power without requiring much additional energy from the person. Like the way that hybrid-electric cars produce electricity from braking.

With the device, a minute of walking can power a cell phone for 10 minutes. Other potential uses include powering a portable GPS locator, a motorized prosthetic joint or implanted drug pumps.

The generator weighs about 3.5 pounds so users do burn energy carrying it on their knee. With one generator on each knee, people walking on a treadmill were able to generate about 5 watts of power.
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