Draw Circuits Almost Anywhere with a Cheap Permanent Marker — Then Blast Them with a Laser
Researchers find a way to turn cheap ink, on almost any surface, into conductive graphene traces.
Researchers from the Graz University of Technology, University of Florence, the Istituto Italiano di Tecnologia, and the Scuola Superiore Sant’Anna have come up with a way to make an electric circuit by simply drawing with a permanent marker — then blasting it with a high-powered laser.
"Passing a laser beam over the ink transforms it into a form of porous and conductive carbon called 'laser-induced graphene' (LIG)," explains project lead Francesco Grego of the team's work. "So far, we believed that it was possible to obtain this LIG only from particular plastic materials and polymers, and this somehow limited its applications. An ink or paint, on the other hand, can be used easily and anywhere, to coat other objects. They also represent an economically advantageous alternative."
The project was inspired by an accident: postdoc researcher Alexander Dallinger had been attempting "laser writing" on a range of different materials, but without success. One sample had a note written on it in red permanent marker — and it was where the laser passed over the note by accident that it was blackened, with later analysis revealing it had be turned into conductive graphene.
The team's experiments are simple: a substrate — which can be anything from a sheet of paper or glass to a coffee cup — is colored in permanent marker, then placed under a laser that marks out the traces necessary for a functional circuit. "This approach, called 'Paint & Scribe,' integrates a graphene-based electrical circuit on any surface, induced by a laser," Greco explains. "Paint an object, then pass the laser over it and you get a circuit. It is an innovative system, considering that until now, graphene-based electrical circuits were only obtained on polymeric precursors.
"Instead of installing circuits or sensors (often heavy, expensive and bulky) on the objects to be sensorized, we can now think of 'writing' them directly where they are needed. This could give a boost to applications in many sectors: printable electronics, biomedical sensors, robotics, automation, environmental sensors. We are already working on some of these applications. We have also started to study other dyes derived from natural materials, with the aim of creating green electronics."
The team's work has been published in the journal Advanced Science under open-access terms.