FYI.

This story is over 5 years old.

wearables

This Sweat-Powered E-Tattoo Could One Day Charge Your Phone

This temp tatt creates electric power with your nasty post-workout perspiration.

This article originally appeared on our sister-site, Motherboard. Check out their rad coverage here.

E-tattoos are pretty gnarly wearable tech: tiny, barely noticeable, always on, and soon, powered by sweat.

Researchers at the University of California San Diego have designed an electronic tattoo—a small, flexible circuit board that can be worn just like the Spiderman temp tats I used to stick on my face—that produces an electrical current.

Advertisement

It works by stripping the electrons from lactate, a byproduct of sweat, with an enzyme imprinted on the e-tattoo’s sensor. In other words, it produces power from your nasty workout juice. And, the researchers say, the technology could eventually generate enough electricity to run devices like phones, smart watches, and heart monitors.

"These represent the first examples of epidermal electrochemical biosensing and biofuel cells that could potentially be used for a wide range of future applications," said research lab director Joseph Wang in a statement.

In their study, the researchers got 15 volunteers to hop on stationary bikes for 30 minutes and monitored their lactate production levels with e-tattoos. The most electricity the participants were able to produce was 70 microWatts per cm² of skin, which sounds impressive, since a watch only needs around 10 microWatts to run. However, the team’s electrodes were only a couple millimetres in size and could produce just 4 microWatts of energy on their own.

"The current produced is not that high, but we are working on enhancing it so that eventually we could power some small electronic devices," Wenzhao Jia, one of the researchers who conducted the study, explained. “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.”

Until now, powering e-tattoos has remained a recalcitrant problem. So far, researchers have toyed with solutions like a small battery pack that fits in your pocket—not exactly elegant. Powering an e-tattoo with your sweat could conceivably solve this problem.

Lactate levels are commonly used to monitor the fitness levels of professional athletes, the researchers noted. Naturally, the harder you train, the more sweat, and thus lactate, you produce. And there’s the rub when it comes to powering electronics with your perspiration: the fitter you are, the less electricity you can produce.

The researchers found that the least fit of their test subjects produced the most power, and the test subjects who worked out three times a week or more produced the least amount of juice, figuratively speaking.

Clearly, there are a few hurdles to overcome before you’ll be able to power your phone with a sweat-collecting e-tattoo, like how to keep it powered when you’re not working out and how to generate enough electricity in the first place. It is, without a doubt, a futuristic vision. Still, this latest research is another step forward for e-tattoos and their eventual adoption into the mainstream tech world.

For more on wearable technology, check out our video series Make It Wearable: The Concepts