There’s something about ink on skin that intrigues people. A cross-cultural phenomenon that has lasted at least since Neolithic times, tattoos have served a wide range of purposes, not just as personal adornment. We’ve written about several tattoo applications in health tech including temporary tattoo stickers to measure blood glucose, measure blood alcohol content (BAC), and read vital signs. We’ve noted enabling technologies such as building near field communications (NFC) capability into tattoos and Rotex’s multifunction, flexible, disposable tattoo sensor set.

Researchers at the University of Minnesota are developing 3D printing technology that can print tactile sensor electronics directly on skin. The first stage in the research is directed at giving robots a sense of touch. If the work went no further than robots, it could still reap significant benefits. By 3D printing bionic skin for surgical robots, for example, the sensors would enable the machines to use the sense of touch during surgery. When giving shots between bones, for example, it’s handy to be able to actually feel the bones and not just rely on cameras for “best-guess” estimates.

The work in Minnesota has not yet extended to human applications, but that’s one of the eventual goals. Bionic skin with printed sensors has potential applications for prostheses as well as “printing” directly on a person’s wrist, for example, for real-time pulse monitoring. The Minnesota group’s purpose-built 3D printer has four nozzles for separate sensor layers: silicone base, top and bottom electrodes, a coil-shaped pressure sensor, and a top “sacrificial” layer that holds everything else in place. The materials can all be applied and set at room temperature and the “skin” can stretch up to three times original size for fit and flexibility. Next steps in the work include printing with semiconductor inks and printing on real bodies.