NEWS: Graphene Tag can be Etched on Food

28-02-2018

Graphene is already well known as a ‘wonder ‘ material because it is extremely thin and strong, a great conductor of heat and electricity, is antibacterial and can even hunt cancer. But now you can have your wonder material and eat it, too! James Tour at Rice University has demonstrated a way to etch a graphene ‘ label’ onto food like bread and potatoes, as well as materials like cardboard and cloth, where it could then act as an RFID tag.

The development builds on previous work developing a new kind of the material called laser-induced graphene (LIG). This technique involves using a laser to heat the surface of a material to create a flaky, foamy form of graphene. Originally, that base material was a polymer known as polyimide, but later the team at Rice managed to use the same process to create LIG on the surface of wood.

"In some cases, multiple lasing creates a two-step reaction," observed Tour. "First, the laser photo-thermally converts the target surface into amorphous carbon. Then on subsequent passes of the laser, the selective absorption of infrared light turns the amorphous carbon into LIG. We discovered that the wavelength clearly matters."

The team found the technique could work with food like bread, potatoes, and coconuts. The key seems to be an organic polymer known as lignin, which is present in all those materials and is also what enables dried wood to form graphene.

As these graphene etchings are conductive, they can potentially allow RFID tags and sensors to be embedded on foods directly, telling you the history of the item or warning you of potential micro-organic contaminants. "Perhaps all food will have a tiny RFID tag  giving information about where it's been, how long it's been stored, its place of origin and the path it took to get to the table," says Tour. "All that could be placed not on a separate tag on the food, but on the food itself."

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