The future of portable electronic devices is technology that will let you forget about them completely until you actually need to use them. As much as people love their smartphones, tablets, Fitbits, and smart watches, the hassle of actually using them is substantial. You need somewhere to put them, they have to be charged, and they’re often fragile. These electronic temporary tattoos may make those problems a thing of the past.
This technology was created by a team of researchers from Carnegie Mellon University’s College of Engineering and Portugal’s University of Coimbra. Their development makes it possible to print very thin and flexible circuits directly onto temporary tattoo paper. Those circuits can then be applied onto skin with water, just like the temporary tattoos you enjoyed as a kid. For now, the circuits themselves are fairly simple single-layer designs, but that can be improved with more research and development.
That’s all possible thanks to the printing technique that the team created. Using an ordinary desktop inkjet printer, they printed traces of conductive silver nanoparticles onto the temporary tattoo paper. Then a layer of gallium indium alloy was applied over those traces to increase their conductivity and strength. Unlike most other flexible circuit fabrication techniques, this is inexpensive and well-suited to the disposable nature of the tattoos. The team envisions this being used for biomonitoring and flexible displays, but it could eventually replace traditional portable electronic devices.