Interest in printed electronics has surged in the past decade as a way to mass produce RFID tags and sensors at low cost. But printing digital logic devices on a substrate today involves multiple steps beyond the printer, such as rinsing or curing in an oven. Now, researchers have made the first fully printed transistors—ones that emerge from a printer with all of their components in place, ready to be used
Work on printed circuitry typically has focused on inkjet printers, which use tiny nozzles to deposit ink droplets onto a substrate. The inks are suspensions of different materials—conductive nanoparticles, semiconducting carbon nanotubes, or insulating polymers—used to print different layers of thin-film transistors over several runs through the printer. But after printing, the process requires washing away unwanted materials and heating at high temperature to cure the insulating layer.