Touchscreen technology works by using nano-scale electrodes on the surface of the screen to receive input from a user’s fingers. Currently, more than 90% of touchscreen electrodes are made with indium tin oxide (ITO). While ITO is good to use because of its high transparency and well-researched production methods, it has drawbacks – including moderate conductivity and high cost. However, a team of researchers from the Swiss Federal Institute of Technology in Zurich has developed a new manufacturing method that uses gold and silver to create touchscreen electrodes that perform better and are more cost effective than ITO electrodes.
The research team used a 3D printing process called “NanoDrip,” which was developed about three years prior by the head of the research team, Dimos Poulikakos. NanoDrip is a form of electrohydrodynamic ink-jet printing. Basically, it works by using an “ink” made up of gold or silver nanoparticles held in a solvent. The ink is dispersed in tiny droplets with the aid of an electrical field. After dispersal, the solvent evaporates, creating a solid structure of precious metal.
Gold and silver are already used in many types of electronics, but they’ve never been useful for touchscreen technology until now. Unlike ITO, gold and silver are not transparent – which would be necessary to see what the screen is projecting. But with NanoDrip, the electrodes are printed extremely small – between 80 and 500 nanometers thick. According to the researchers, this creates touchscreen electrodes that have a higher conductivity and are more transparent than those made of indium tin oxide.
The next challenge for the team is to adapt NanoDrip to industrial-scale production. Since it provides many cost and performance advantages, “gold touchscreens” may become a reality very soon.
