A group of chemists at Rice University have developed a type of wearable generator that could power future implants and medical devices. To do this, the team adapted laser-induced graphene (LIG) into small, metal-free devices that generate electricity through movement. The device utilizes the triboelectric effect, where materials can gather a charge through contact, to produce static electricity when rubbed on a surface. This static electricity is then converted into energy that can power electronic devices. The results of this project were recently detailed in the journal ACS Nano.
“The nanogenerator embedded within a flip-flop was able to store 0.22 millijoules of electrical energy on a capacitor after a 1-kilometer walk,” says Michael Stanford, postdoctoral researcher at Rice University and lead author of the paper. “This rate of energy storage is enough to power wearable sensors and electronics with human movement.”
From the Rice University article: "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.
In the folding configuration, LIG from the tribo-negative polyimide was sprayed with a protecting coating of polyurethane, which also served as a tribo-positive material. When the electrodes were brought together, electrons transferred to the polyimide from the polyurethane. Subsequent contact and separation drove charges that could be stored through an external circuit to rebalance the built-up static charge. The folding LIG generated about 1 kilovolt, and remained stable after 5,000 bending cycles.
The best configuration, with electrodes of the polyimide-LIG composite and aluminum, produced voltages above 3.5 kilovolts with a peak power of more than 8 milliwatts."
Read more about the wearable generator that can power medical devices at Rice University.