Temporary Tattoos Provide Permanent Biodata


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For reasons peculiar to human psychology, the permanent tattoo has long been considered orders of magnitude cooler than its baby sibling, the temporary tattoo. Despite the advantage of being able to change your skin art as you tire of old images, there’s something about permanence—and pain—that makes stick-ons seem inferior. You don’t see temporary tattoo parlors crop up in the latest gentrified neighborhood.

All that is about to change. Now, thanks to researchers at Tokyo’s Waseda University, the temporary tattoo will be electronic, nanometers thin, comfortable, and will cost only slightly more than those currently found in goody bags at toddler birthday parties. And it will offer a lot more than a boost for the fashion conscious. The electronic temporary tattoo has the potential to work as a medical sensor and monitor, a data gatherer for biologists and sports researchers, and even an alert system for the elderly.

 

The new tattoo isn’t the first to be electronic. In 2011, researchers at Northwestern came up with a version that was also thin and comfortable. But the reason we haven’t seen them on skin in the hospital, the baseball diamond, or the runway, is that they’re extremely expensive to produce.

 

“They were state-of-the-art devices, that required precise conditions, high temperature processes, and a very pure vacuum,” says Toshinori Fujie, a materials scientist at the university. “You could get very beautiful devices, but there are problems for fabrication on a mass level.”

 

An ultrathin stick-on patch printed on a nanosheet is able to conduct electricity. Image: Waseda University

Fujie’s tattoos, on the other hand, use a conductive ink and a cheap elastomer film so they can be popped out of an inkjet printer. The ink is made of silver nanoparticles and is sandwiched between two layers of the film. The soldering-free process doesn’t require high temperatures that would damage the elastomer. Thanks to the cost, availability, and maturity of the materials, the tattoo has the potential to be produced on an industrial scale with roll-to-roll printing or stamping.

Regardless of the type of printer that spits them out, the tattoos will be extraordinarily thin and flexible. “The nanosheet can easily conform to wrinkles and corrugations of skin surface,” says Fujie. As a result, it needs no adhesive, so people with allergies or sensitive skin can still use the tattoo. “What you find is that you really don’t feel anything,” says Fujie.

 

Thanks to its unobtrusive nature, the tattoos may soon provide us with information that has remained elusive. Sports scientists, for example, have long wanted to monitor the hands of pitchers as they throw a ball. Previous attempts to gather such information were done with sensors that could be detected by the pitchers’ sensitive hands, conceivably altering their pitches and the data. “Maybe we can avoid this type of feeling,” says Fujie.

 

Fujie and his colleagues work in Waseda’s Institute of Advanced Active Aging, which aims to conduct research that supports “active aging in our inevitable future of the super-aged society,” as their website puts it. To those ends, Fujie hopes his tattoo will be used to monitor the heart rates and body temperatures of the elderly as they go about their day. An abnormal reading could alert their doctor or hospital. Or LEDs could let them know when they need to change a behavior or take a medication.

 

The dancing hula girl on the bicep could be the fitness tracker of the future. And the eyes of the skull on your wrist could light up to remind you to take your insulin. The electronic temporary tattoo will be a lot more useful, and maybe even cooler, than the permanent kind.

 

Michael Abrams is an independent writer.

The nanosheet can easily conform to wrinkles and corrugations of skin surface. What you find is that you really don’t feel anything.

Prof. Toshinori Fujie, Waseda University

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May 2017

by Michael Abrams, ASME.org