Don’t have power for your wearable device? Don’t sweat it! Or if a new research product is successful, sweat may be all you need to get the electricity you want.

Scientists at the University of California San Diego’s Jacobs School of Engineering have developed a flexible patch that generates power from human sweat. Tiny gold dots serve as anodes and cathodes, which are then bridged by spring-shaped gold wires to provide connections that can bend and stretch. A matrix of carbon nanotubes is deposited on each dot, which then carry the enzyme that reacts with the lactic acid in sweat to produce electricity. According to the researchers, this approach produces 10 times as much power for a given surface area than any other existing wearable biofuel cells.

The initial design was used to light an LED while test subjects rode a stationary bike. The amount of lactic acid in their sweat declines over time, and the subjects were only able to power the light for about four minutes. The researchers want to find ways to store the generated power and release it gradually as needed. They also want to improve the stability of the materials used. This design does demonstrate an energy harvesting strategy that could play a role in powering wearable sensors and other devices without the need to recharge batteries.