Researchers have built a device resembling a knee brace that can generate usable amounts of electrical energy as a person walks. The brace, described in an article in the journal Science, stores the energy lost when a human brakes the knee after swinging the leg forward to take a step.
Last year, scientists created a backpack frame that translates the up-and-down motion of a frame-mounted backpack to electrical energy. Other researchers are studying ways to harvest energy from footsteps with devices mounted in the soles of shoes.
Max Donelan, one of the creators of the new knee-mounted device, talks about harvesting energy from human movement.