Flexible generators turn movement into energy

Developed by a group at Rice University in Texas the devices exploit the properties of laser-induced graphene (LIG) a graphene foam produced when chemicals are heated on the surface of a polymer or other material with a laser.

Like rubbing a balloon on hair, putting LIG composites in contact with other surfaces produces static electricity that can be used to power devices.

In experiments, the researchers connected a folded strip of LIG to a string of light-emitting diodes and found that tapping the strip produced enough energy to make them flash. A larger piece of LIG embedded within a flip-flop let a wearer generate energy with every step, as the graphene composite's repeated contact with skin produced a current to charge a small capacitor.

"This could be a way to recharge small devices just by using the excess energy of heel strikes during walking, or swinging arm movements against the torso," said project leader Professor James Tour.