Knee device makes phone charging a walk in the park – tech – 07 February 2008 – New Scientist

A knee-mounted brace that generates electricity from a person’s stepping action, and requires little extra effort, brings new meaning to the phrase “power walk”. The generator could be used to power cellphones, prosthetic limbs, or medical implants, researchers argue.

The new device harnesses the energy of a person’s leg as it swings forward during a step. The knee straightens towards the end of the leg-swing before the foot hits the ground. That spins gears inside the device, which drive an electric generator.