Silver ink yields small, high performance electronics

While most conductive inks rely on tiny metal particles suspended in the ink, the particle-free transparent solution created by the Illinois team is made up of silver acetate and ammonia. When printed, its liquid component quickly evaporates, leaving behind lines of dry, conductive silver. "We are really excited about the wide applicability and excellent electrical properties of this new silver ink," said Professor Jennifer Lewis, who led the team. "It dries and reacts quickly, which allows us to immediately deposit silver as we print." As well as offering superior stability, Prof Lewis claims the ink is much faster to make compared to its particle-based counterparts. It can also print, she says, through 100nm nozzles, an order of magnitude smaller than particle based inks and an important feature for printed microelectronics. "The ink's low viscosity makes it suitable for inkjet printing, direct ink writing and airbrush spraying over large, conformal areas," Lewis noted. "Our ink remains stable for very long periods. For fine scale nozzle printing, that's a rarity." The reactive silver ink also boasts a low annealing temperature of 90°C, approaching that of pure silver. The team is now looking to use it to pattern large area transparent conductive surfaces.