Would you like some edible graphene on your toast?

14 Feb 2018

A piece of toast featuring laser-induced graphene, a technique that can also be applied to other objects such as wood or cloth. Image: Jeff Fitlow/Rice University

If you thought the idea of wearable graphene electronics sounded cool, how about ones you can eat?

When the topic of graphene comes up, it is usually to reveal some new breakthrough that would allow for the creation of an almost impossibly thin, wearable device, or a super-effective sieve for water impurities.

But now, researchers from Rice University in the US may have found a use for the atom-thick material that could allow us to not only wear electronics, but eat them, too.

In a paper published to the journal ACS Nano, the team revealed that it has reached a point where it can allow for graphene tags and sensors to be written onto food items.

Led by chemist James Tour, the lab has spent the past few years pushing graphene technology to its limits, working on the idea that anything with the proper carbon content can be turned into graphene in a process known as laser-induced graphene (LIG).

During this time, it developed a method of creating graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film.

Consisting of microscopic, cross-linked flakes of graphene, the foam can be written into target materials, with uses ranging from a supercapacitor to biological sensors.

So now, LIG has been fine-tuned to allow for graphene to be burned into paper, cardboard, cloth, coal and certain foods, such as biscuits and even toast.

“This is not ink. This is taking the material itself and converting it into graphene,” Tour said.

“Very often, we don’t see the advantage of something until we make it available. Perhaps all food will have a tiny RFID tag that gives you information about where it’s been, how long it’s been stored, its country and city of origin, and the path it took to get to your table.”

Food safety

If the idea of eating sensors sounds a little bit unpalatable, Tour said that one of its uses could actually prevent people from getting sick as the LIG tags would be able to detect E coli or other microorganisms on food.

“They could light up and give you a signal that you don’t want to eat this,” Tour said. “All that could be placed not on a separate tag on the food, but on the food itself.”

Testing on other tougher materials, including coconuts, the team found that simply upping the laser power will not create LIG.

Rather, a process of multiple lasers with a defocused beam was found to do the trick, allowing the team to make a micro-supercapacitor in the shape of an ‘R’ on the twice-lased coconut skin.

Colm Gorey was a senior journalist with Silicon Republic