WASHINGTON -- As students, soldiers and hikers can testify, it takes energy to haul around a heavy backpack. Now, researchers have developed a backpack that turns that energy into electricity.
It doesn't crank out a lot of juice but it's enough to run things like an MP3 player, a personal data assistant, night vision goggles, a handheld global positioning system or a GSM cell phone.
The researchers used a backpack fastened to the carrying frame -- a rigid frame similar to regular backpacks -- by springs. The up-and-down motion caused by walking powers a small generator, producing electricity that can be used directly or stored in a capacitor or battery.
The device, developed by Lawrence C. Rome of the University of Pennsylvania, and colleagues, was reported in Friday's issue of the journal Science.
The electricity-generating frame weighs about 10 pounds, Rome said. He's working to lighten it so it will weigh only a couple of pounds more than a standard backpack.