New graphene printing technology can produce electronic circuits that are low-cost, flexible, highly conductive, and water-repellent. Low-cost, inkjet-printed graphene can be tuned with a laser to make functional materials.
The inkjet printing technology is used to create electric circuits on flexible materials. In this case, the ink is flakes of graphene, which is a great conductor of electricity and heat, as well as being strong, stable, and biocompatible.
The printed flakes, however, aren’t highly conductive, and have to be processed to remove non-conductive binders and weld the flakes together, boosting conductivity and making them useful for electronics or sensors. The post-print process typically involves heat or chemicals, but the new rapid-pulse laser process treats the graphene without damaging the printing surface, even if it’s paper.
The process also creates graphene-printed circuits that can hold water droplets (hydrophilic) and turn them into circuits that repel water (superhy-drophobic). The surface of the inkjet-printed graphene is micro-patterned. The laser aligns the graphene flakes vertically, like pyramids stacking up; this induces the hydrophobicity.
The energy density of the laser processing can be adjusted to tune the degree of hydrophobicity and conductivity of the printed graphene circuits, opening up possible applications for new electronics and sensors, including flexible electronics, washable sensors in textiles, microfluidic technologies, drag reduction, de-icing, electrochemical sensors, and technology that uses graphene structures and electrical stimulation to produce stem cells for nerve regeneration.