Various research institutes have already developed skin-applied electronics, that are pre-made and simply adhered to the user's body. Researchers at the University of Minnesota, however, have taken a different approach. They've developed a method of 3D-printing custom electronics directly onto the skin.

Led by Prof. Michael McAlpine, the scientists are utilizing an adapted inexpensive 3D printer, that extrudes a special conductive ink made of silver flakes. Unlike other such inks, which need to cure at high temperatures and would thus burn the skin, theirs cures at room temperature.

Because no one can hold their body completely still, an array of temporary dot-like markers are initially placed on the skin, after which the skin is scanned. The printer subsequently uses a computer vision system to track these markers during the printing process, automatically moving its print nozzle to stay in alignment with the curving contours of its subtly-moving target.

The resulting electronics could be powered wirelessly (as is the case with the LED seen in the video below), although McAlpine tells us that in the future, it should also be possible for the system to 3D-print batteries or solar cells. Once users were done with the electronics, they could just be peeled or washed off.

"We are excited about the potential of this new 3D-printing technology using a portable, lightweight printer costing less than $400," says McAlpine. "We imagine that a soldier could pull this printer out of a backpack and print a chemical sensor or other electronics they need, directly on the skin. It would be like a 'Swiss Army knife' of the future with everything they need all in one portable 3D-printing tool."

It should also be noted that by using a bioink in the printer, the team was able to print cells onto a live mouse's skin wound – so the technology has potential medical applications, as well.

A paper on the research was recently published in the journal Advanced Materials.