Smart tattoo harvests energy from your sweat © Getty Images

Smart tattoo harvests energy from your sweat

Sweating is often the sign of a good workout, but in the future it may also be a sign that your phone is charging.

Scientists from the University of California have developed a temporary tattoo that generates energy as you exercise. The tattoo, made by layering a flexible sensor on temporary tattoo paper, reacts with lactate, a chemical produced in sweat. The sensor uses an enzyme that strips electrons from the lactate, generating a small electrical current.

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The researchers combined this technology with a rechargeable ‘biobattery’ to test how much power they could produce. Fifteen volunteers worked up a sweat on exercise bikes, and the experiment was a success: the tattoo generated electricity.

The tattoo itself is small and subtle in design, but larger tattoos would be able to collect more power by covering a larger area (image credit: Joseph Wang)
The tattoo itself is small and subtle in design, but larger tattoos would be able to collect more power by covering a larger area (image credit: Joseph Wang)

“The current produced is not that high, but we are working on enhancing it so that eventually we could power some small electronic devices,” says Dr Wenzhao Jia. “Right now, we can get a maximum of 70 microWatts per cm2, but our electrodes are only 2 by 3 millimetres in size and generate about 4 microWatts – a bit small to… run a watch, for example, which requires at least 10 microWatts.”

These biobatteries offer clear advantages over regular batteries, with the source of their charge being renewable and readily available… well, as long as you’re willing to put in the effort. The team hopes that their invention could be used to power watches, medical devices like heart rate monitors, and even your phone.


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