Researchers at the University of Illinois at Urbana-Champaign have developed a liquid metal “ink” that, when used in a ballpoint pen, allows circuits to be hand-drawn. Circuits can be drawn on flat surfaces, like paper, as well as irregular surfaces. In the photo above, researchers used the pen to hand-draw circuits that connected to LEDs (light-emitting diodes) powered by a battery connected to the paper. During testing it was shown that a circuit drawn on a piece of paper using the liquid metal ink could survive intact even if the paper was folded thousands of times.

The practical upshot:

“Pen-based printing allows one to construct electronic devices ‘on-the-fly’,” says Jennifer Lewis, one of the engineering profs who came up with the new pen at Illinois uni. “This is an important step toward enabling desktop manufacturing (or personal fabrication) using very low cost, ubiquitous printing tools.”