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Lab Burns Graphene Circuits into Food, Fabrics

Graphene produced in fabric

Graphene in the image of the Rice University owl mascot produced in fabric (Jeff Fitlow, Rice University)

14 February 2018. A chemistry lab at Rice University devised a process for producing graphene, a material that conducts electricity, in materials containing carbon, including fabrics and even food. The process, with applications in a wide range of industries, is described in yesterday’s issue of the journal ACS Nano (paid subscription required).

Graphene is a material closely related to graphite like that used in pencils, one atom in thickness and arrayed in an hexagonal atomic pattern. The material is very light, strong, chemically stable, and can conduct both heat and electricity, with applications in electronics, energy, manufacturing, distribution, and health care.

The lab of Rice chemistry professor James Tour in Houston studies the generation of graphene from a variety of sources. The lab’s process employs lasers delivered in multiple beams for disrupting carbon-based materials to produce graphene directly on its surface. This process, called laser-induced graphene, generates a form of graphene made of interconnected nanoscale flakes, rather than the elegant atomic hexagons in pure graphene. But what laser-induced graphene may lack in elegance, it makes up in economics. It produces graphene at room temperature and ambient conditions, rather than high temperatures in a carefully controlled atmosphere.

As Tour explains in a university statement, the process produces laser-induced graphene, or LIG, in 2 steps. “First, the laser photothermally converts the target surface into amorphous carbon,” says Tour. “Then on subsequent passes of the laser, the selective absorption of infrared light turns the amorphous carbon into LIG.”

As the new study shows, graphene can also be produced on a range of materials containing carbon. In an earlier study, reported in Science & Enterprise, Tour and colleagues produced graphene on polymide plastic film, where sending an electric current through the graphene produced hydrogen peroxide able to kill resistant bacteria found in hospitals and some public water systems.

In the new study, the Rice team, with associates from Ben-Gurion University of the Negev in Israel, extended the process to several other common materials, and simplified the technique to produce multiple beams in a single pass of the laser head. The researchers demonstrated the process on fabrics, wood, cardboard, and even food, producing graphene patterns including the Rice University logo and mascot. The materials used by the researchers were all high in lignin, an organic polymer that forms rigid cell walls in many plants, and thus found in wood, cork, coconut shells, and potato skins.

But beyond images, the graphene burned into these materials can also conduct an electric current, making it possible to embed circuits into common objects. An immediate application could be replacing quick-response or radio-frequency ID (RFID) tags now added to items, with graphene circuits burned into the materials. “Perhaps all food will have a tiny RFID tag,” says Tour, “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.”

Another application is sensors to detect pathogens in food. “They could light up and give you a signal that you don’t want to eat this,” notes Tour. “All that could be placed not on a separate tag on the food, but on the food itself.”

Tour and graduate student Yieu Chyan, the paper’s first author, tell more about the process in the following video.

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