Sweat power, or sweat equity, just got a lot more meaningful with electronic tattoos. The new technology is from the University of California at San Diego, where Joseph Wang and fellow researchers have devised a way to extract electrical power from body sweat.
Researchers were able to create smart tattoos by embedding lactate sensors onto temporary tattoo paper that is attached to the skin during exercise. The strip contains an enzyme that strips electrons from lactate compounds.
In general, the more intense the exercise, the more lactate the body produces. During strenuous physical activity, the body needs to generate more energy, so it activates a process called glycolysis. Glycolysis produces energy and lactate, the latter of which scientists can detect in the blood.
Of course you can’t just sweat enough. The tattoos are only capable of extracting 70 microwatts per cm2 of skin, hardly enough to power any of your smartphones, tablets or fitness gear. In order to be economically viable, the team will need to develop a better battery.
“Right now, we can get a maximum of 70 microwatts per cm2, but our electrodes are only 2 by 3 millimeters in size and generate about 4 microwatts — a bit small to generate enough power to run a watch, for example, which requires at least 10 microwatts. So besides working to get higher power, we also need to leverage electronics to store the generated current and make it sufficient for these requirements,” said Wenzhao Jia, Ph.D.