Printable radios as new use for graphene
British engineers have printed a radio frequency antenna using compressed graphene ink, in what could be one of the first commercial applications for the high-tech material.
The antennae could be used as radio-frequency identification (RFID) tags and wireless sensors, as they can be cheaply produced and printed onto virtually any surface.
By using a malleable ink, the team made the antenna flexible, environmentally friendly and ready for mass-production.
Researchers have been on a quest to make practical use of graphene’s amazing electrical and mechanical properties since it was first isolated in 2004.
Conductive ink has been the subject of many early trials, in the hope that it can be made for a low cost and be mechanically flexible, to bring an advantage over other types of conductive ink and nanoparticle solutions.
“The point is that graphene is no longer just a scientific wonder,” said research coordinator Kostya Novoselov, from the University of Manchester.
“It will bring many new applications to our daily life very soon.”
Previously, to make the ink graphene flakes were mixed with a solvent to help it stick.
But using a solvent binder makes materials act as an insulator, until they undergo a high-heat process called annealing.
Annealing limits the surfaces onto which graphene ink can be printed, as it must be applied at a high temperature that destroys surfaces like paper or plastic.
The University of Manchester research team found a way to get adequate conductivity from graphene ink without using a binder.
They did this by first printing and drying the ink, and then rolling it flat like new pavement with a road roller.
The team found that compressing the ink increased its conductivity by more than 50 times, creating a “graphene laminate” that was also almost two times more conductive than graphene ink made with a binder.
Because of its high conductivity, the compressed ink can be used for efficient radio frequency radiation.
They tested its application as an antenna by printing the graphene laminate onto a piece of paper.
It formed an antenna approximately 14 centimetres long and 3.5 millimetres across, which radiated radio frequency power effectively, said Xianjun Huang, first author of a paper on the study, published in the journal Applied Physics Letters.
Printing RFID tags onto cheap, flexible materials like paper and plastic could see them used to transmit identifying info on everything from cattle to car parts, the researchers say.
Graphene laminate could be used to cut down on the cost compared to existing RFID tags too, which are typically made from more expensive metals like aluminium and copper, and require complicated fabrication processes.
The full report - Binder-free Highly Conductive Graphene Laminate for Low Cost Printed Radio Frequency Applications – will be published in Applied Physics Letters, soon.