Researchers from Iowa State University (ISU) have developed a computer-controlled laser process that increases the electrical conductivity of graphene by a thousand times. Irradiating inkjet-printed graphene oxide to improve its conductivity could ultimately help move graphene to commercial applications.
The research was featured on the front cover of the journal Nanoscale on 21 September, and is being supported by two three-year grants from the National Institute of Food and Agriculture and the Roy J Carver Charitable Trust in America.
Iowa State University researchers Suprem Das and Jonathan Claussen have developed a pulsed-laser process to treat inkjet-printed multi-layer graphene electric circuits and electrodes. The process improves the electrical conductivity of the graphene without damaging paper, polymers or other fragile printing surfaces – a drawback of current graphene treatment methods.
The process uses computer-controlled laser technology that selectively irradiates the graphene to remove ink binders and reduces graphene oxide to graphene – physically stitching together millions of tiny graphene flakes.
‘The laser works with a rapid pulse of high-energy photons that do not destroy the graphene or the substrate,’ Das said. ‘They heat locally. They bombard locally. They process locally.’
The localised laser processing changes the shape and structure of the printed graphene from a flat surface to one with raised, 3D nanostructures, which the researchers said are like tiny petals rising from the surface. The rough and ridged structure increases the electrochemical reactivity of the graphene, making it useful for chemical and biological sensors.
‘The breakthrough of this project is transforming the inkjet-printed graphene into a conductive material capable of being used in new applications,’ said Claussen. These applications could include sensors with biological applications, energy storage systems, electrical conducting components and even paper-based electronics.
‘This work paves the way for not only paper-based electronics with graphene circuits,’ the researchers wrote in the paper, ‘it enables the creation of low-cost and disposable graphene-based electrochemical electrodes for myriad applications including sensors, biosensors, fuel cells and [medical] devices.’