Graphene is extremely thin and strong, a great conductor of heat and electricity, is antibacterial and can even hunt down cancer – and now you can have your wonder material and eat it, too. The lab of James Tour at Rice University has demonstrated a way to etch graphene onto food like bread and potatoes, as well as materials like cardboard and cloth, where it could then act as an RFID tag.
The Rice team is building off previous work in developing a new kind of the material called laser-induced graphene (LIG). As its name suggests, 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 managed to use the same process to create LIG on the surface of wood.
Now, the researchers have managed to apply the technique to a whole range of materials. Honing the method through experimentation, they found that the best results come when the laser is "defocused" and makes several passes over the material.
"In some cases, multiple lasing creates a two-step reaction," says Tour. "First, the laser photothermally 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."
Along with materials like cardboard, paper, cloth, cork and coal, 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 allowed dried wood to form graphene.
So what's the point of graphene in your food? According to the Rice researchers, these graphene etchings are conductive, potentially allowing RFID tags and sensors to be embedded on foods directly, telling you the history of the item or warning you of potential microorganism contaminants.
"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," says Tour. "All that could be placed not on a separate tag on the food, but on the food itself."
With the success in cloth, other applications could include wearable sensors or even clothing that warms up easier, thanks to graphene's thermal conductivity.
The research was published in the journal ACS Nano. The team demonstrates the process and results in the video below.
Source: Rice University