Graphene Ink Moves Bendy Gadgets Closer to Reality

Eventually, graphene inks could lead to “applications in printable electronics like RFID tags, conductive transparent coatings, anything from sensors to flexible display applications

A digital screen that you can fold up like paper, solar cells embedded in house paint and a battery printed on the bottom of your phone — all this may soon be possible thanks to the so-called graphene ink, printed circuits made from graphene — a one-atom-thick layer of carbon that is the strongest, thinnest and most conductive material discovered yet.

Conductive inks — printed circuits — are already widely used to make touch screens, RFID tags (radio-activated ID chips) and small antennas in mobile phones. However, today’s conductive inks are usually metal-based, using materials like silver or copper powder.

These inks are expensive, can be toxic and require high temperatures to print. Graphene has long been seen as a cheaper and easier-to-use alternative, and many research teams — from Northwestern University in the U.S. to Northwestern University in the U.K. — have tried to make it work.

Among the few that seem to be succeeding is Haydale, a spin-off from Swansea University in Wales. The company currently mass-produces about one ton of graphene for commercial purposes a year — enough to make more than ten tons of conductive ink, the firm’s commercial director Ray Gibbs tells us. To make the ink, Haydale has recently partnered with Gwent Electronic Materials, a firm that supplies conductive inks for sensors and electronic instruments.

To produce the ink, Haydale uses very fine powered graphite – material widely used as lead in pencils – and puts it in a modified plasma reactor — a reactor where the plasma cloud is generated. Plasma is gas with charged particles, and the company uses it to turn the graphite into graphene. [See also Researchers Shrink Particle Accelerator to Table-top Size]

The process first purifies the graphite and then creates the one atom thick sheets of graphene. The material is then used to make the conductive ink.

Graphene-based inks are easier to handle than traditional metal-based ones, said Gibbs – less toxic, cheaper and easier to dry. If metal-based inks are not dried properly, they can swell, “which pushes the metal particles apart and reduces conductivity. Moreover, it can lead to failure when the ink is subject to bending, creasing or scratching.” Drying metal-based inks requires temperatures of 212 degrees Fahrenheit (100 degrees Celsius) or more; for graphene, about 140F (60 C) is enough.

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