The pen draws wires on paper with silver ink. Photo: Bok Yeop Ahn. Professors Jennifer Lewis and Jennifer Bernhard at the University of Illinois have come up with a way to draw circuits with a pen.
Not circuit diagrams. Any old pen can do that. No, the pen is a rollerball with silver ink that can actually draw real, working circuits. The ink dries to leave silver trails behind on the paper, and these are tough enough to survive bends and folds and still conduct electricity. And it doesn't need to be paper.
Gadget Lab, Pen Draws Working Circuits With Silver Ink