Laser-induced Graphene to generate electricity. Wearable devices that harvest energy from movement are not a new idea but now more practical to make.

“The Rice lab of chemist James Tour has adapted laser-induced graphene (LIG) into small, metal-free devices that generate electricity. Like rubbing a balloon on hair, putting LIG composites in contact with other surfaces produces static electricity that can be used to power devices.
 
For that, thank the triboelectric effect, by which materials gather a charge through contact. When they are put together and then pulled apart, surface charges build up that can be channeled toward power generation.
 
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,” Tour said.
 
LIG is a graphene foam produced when chemicals are heated on the surface of a polymer or other material with a laser, leaving only interconnected flakes of two-dimensional carbon. The lab first made LIG on common polyimide, but extended the technique to plants, food, treated paper and wood.
 
The lab turned polyimide, cork and other materials into LIG electrodes to see how well they produced energy and stood up to wear and tear. They got the best results from materials on the opposite ends of the triboelectric series, which quantifies their ability to generate static charge by contact electrification.

 
Flexible generators turn movement into energy

Source: Phys Org
Image: Rice University postdoctoral researcher Michael Stanford holds a flip-flop with a triboelectric nanogenerator, based on laser-induced graphene, attached to the heel. Walking with the flip-flop generates electricity with repeated contact between the generator and the wearer’s skin. Stanford wired the device to store energy on a capacitor. Credit: Jeff Fitlow/Rice University

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