Tiny bits of conductive metal are crucial components of modern electronics, but future generations may not need high-precision machines. Circuit boards could be drawn by hand, enabling paper electronics, disposable antennas and a wide range of other items.
Researchers at the University of Illinois at Urbana-Champaign (and many other teams) are making conductive ink from silver nanoparticles, which they shrink using acid. The nanoparticles are suspended in a cellulose solution, so they have a greater viscosity and can flow from a pen, quite literally. A line drawing becomes a silver wire that can carry a current, enough to power an antenna or even a small LED display, like the light bulb at the top of the house in this lovely drawing.
The pen allows circuits to be embedded on uneven surfaces--and it enables a new type of creative design.