The device works by detecting and responding to lactate, which is naturally present in sweat. Wang's team imprinted a flexible lactate sensor onto temporary tattoo paper. The sensor contained an enzyme that strips electrons from lactate, generating a weak electrical current.
"The current produced is not that high, but we are working on enhancing it so that eventually we could power some small electronic devices," said Jia. Notably, in an experiment with volunteers with a range of fitness levels, the least fit people generated the most energy. As researchers develop wearable sensors for health and fitness and medical monitoring, they will need to figure out how to power them without adding the bulk of heavy conventional batteries. Wang is also the director of the new Center for Wearable Sensors at UC San Diego Jacobs School of Engineering.
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