Scalable 100% yield production of Conductive Graphene Inks

Conductive inks are useful for a range of applications, including printed and flexible electronics such as radio frequency identification (RFID) antennas, transistors or photovoltaic cells. The advent of the internet of things is predicted to lead to new connectivity within everyday objects, including in food packaging. There is a clear need for cheap and efficient production of electronic devices using stable, conductive and non-toxic components.

A new method for producing high quality, water-based conductive graphene inks with high concentrations has been developed by researchers from the Graphene Flagship working at the Cambridge Graphene Centre at the University of Cambridge, UK. The novel method uses ultrahigh shear forces in a microfluidization process to exfoliate graphene flakes from graphite. The process converts 100% of the starting graphite material into usable flakes for conductive inks, avoiding the need for centrifugation and reducing the time taken to produce a usable ink.

The inks produced by the microfluidization process have high concentrations of up to 100 g of graphene flakes per litre and can be optimised for screen printing. These inks can also be used to create novel composites, coatings and energy storage devices. This method can easily be applied to other layered materials, such as hexagonal boron nitride or transition metal dichalcogenides, to provide a family of printable circuit components – conductor, insulators and semiconductors – with which to build printed electronics with different functionalities. These inks are ideal for applications where low-cost is important.

With the 100% yield of the microfluidization method, it is now possible to produce high quality graphene inks in sufficient quantities for commercial products. Inks produced using this method have already been commercialised via a University of Cambridge spin out company, Cambridge Graphene, which was recently acquired by engineering solutions company Versarien. The inks are also supplied to Novalia, an innovative print company based in Cambridge, for use in their interactive touch-based printed electronic demos.

Chris Jones of Novalia said “For viable marketable applications, the materials need to be cost effective, easy to handle and show consistent performance. We ran these inks on ordinary industrial screen printing equipment without modification and achieved consistent results, printing hundreds of interactive demonstrators for Mobile World Congress. This is a very exciting point – a critical juncture between the laboratory and the public.”

Mar García-Hernandez of the Spanish National Research Council (CSIC) said. “Microfluidization is a huge leap ahead towards applications of affordable and environmentally friendly graphene inks in organic photovoltaics, RFID antennas, electrically conductive coatings or nanocomposites. The method is certainly well suited for the synthesis of a variety of other layered material inks, which will enlarge the scope of applications of layered materials in real world devices.”
http://graphene-flagship.eu/scalable-graphene-inks