Yes, now that’s what we call the ultimate power walk. A new device collects energy from everyday motions to power phones, GPS units, and more.

Researchers have found a way for 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 without requiring much additional energy from the person. It’s pretty much 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 first practical use for the generator is likely to be in producing power for artificial limbs.

The generator weighs about 3.5 pounds so users do burn energy carrying it on their knee, but they don’t notice whether it is switched on or off when walking on a treadmill.