Flexible electronics are gaining popularity, and the idea of using paper that can easily be bent or folded has been around for a while. But the equipment and conditions needed to print liquid metals onto paper rule out easy, large-scale production.
Now, a team led by Jing Liu of the Chinese Academy of Sciences has found a way to print flexible circuits at room temperature. They used commercially available paper and equipment, with a few modifications, such as adding a brush-like porous tip to the dispensing nozzle to prevent the ink clogging. The ink itself is a gallium–indium alloy, which stays liquid at room temperature, and is coated with silicone after printing. The resulting electronics work well and can be bent without breaking.