With the success of polyimide-based LIG, Tour and his team wondered if they could expand their laser technique to other materials. For example, one of the oft-cited applications of graphene is to make thin, flexible circuitry for next-generation RFID tags and sensors. Packages could be embedded with tiny antennas and processors that track a product’s origin, shipping route, and environmental conditions in real time.
What if these flexible graphene circuits could be etched directly into the surface of a cardboard box, or stamped right on the skin of a potato? There was only one way to find out.
To burn graphene directly into organic matter like coconuts and bread, Tour and his lab crew developed a multiple lasing technique. On the first pass of the laser, a thin layer at the surface is transformed into amorphous carbon, the charred material found on a nicely grilled steak or the crispy crust of toast. On subsequent passes with the laser, the amorphous carbon selectively absorbs wavelengths of infrared light that transform it into LIG.
The Rice team was not only able to etch nifty LIG images of “R”s and owls (the Rice mascot) into wood and bread, but it also embedded a simple supercapacitor into the surface of a coconut. The coconut circuit successfully held a charge and discharged current, something that the Professor on Gilligan’s Island would have surely appreciated.