Rice University scientists create patterned graphene onto food, paper, cloth, cardboard
Rice University scientists who introduced laser-induced graphene (LIG) have enhanced their technique to produce what may become a new class of edible electronics.
The Rice lab of chemist James Tour, which once turned Girl Scout cookies into graphene, is investigating ways to write graphene patterns onto food and other materials to quickly embed conductive identification tags and sensors into the products themselves.
“This is not ink,” Tour said. “This is taking the material itself and converting it into graphene.”
The process is an extension of the Tour lab’s contention that anything with the proper carbon content can be turned into graphene. In recent years, the lab has developed and expanded upon its method to make graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film.
The foam consists of microscopic, cross-linked flakes of graphene, the two-dimensional form of carbon. LIG can be written into target materials in patterns and used as a supercapacitor, an electrocatalyst for fuel cells, radio-frequency identification (RFID) antennas and biological sensors, among other potential applications.
The new work reported in the American Chemical Society journal ACS Nano demonstrated that laser-induced graphene can be burned into paper, cardboard, cloth, coal and certain foods, even toast.
“Very often, we don’t see the advantage of something until we make it available,” Tour said. “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.”
He said LIG tags could also be sensors that 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.”
Multiple laser passes with a defocused beam allowed the researchers to write LIG patterns into cloth, paper, potatoes, coconut shells and cork, as well as toast. (The bread is toasted first to “carbonize” the surface.) The process happens in air at ambient temperatures.
“In some cases, multiple lasing creates a two-step reaction,” Tour said. “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.”
The researchers turned to multiple lasing and defocusing when they discovered that simply turning up the laser’s power didn’t make better graphene on a coconut or other organic materials. But adjusting the process allowed them to make a micro supercapacitor in the shape of a Rice “R” on their twice-lased coconut skin.
Defocusing the laser sped the process for many materials as the wider beam allowed each spot on a target to be lased many times in a single raster scan. That also allowed for fine control over the product, Tour said. Defocusing allowed them to turn previously unsuitable polyetherimide into LIG.
“We also found we could take bread or paper or cloth and add fire retardant to them to promote the formation of amorphous carbon,” said Rice graduate student Yieu Chyan, co-lead author of the paper. “Now we’re able to take all these materials and convert them directly in air without requiring a controlled atmosphere box or more complicated methods.”
The common element of all the targeted materials appears to be lignin, Tour said. An earlier study relied on lignin, a complex organic polymer that forms rigid cell walls, as a carbon precursor to burn LIG in oven-dried wood. Cork, coconut shells and potato skins have even higher lignin content, which made it easier to convert them to graphene.
Tour said flexible, wearable electronics may be an early market for the technique. “This has applications to put conductive traces on clothing, whether you want to heat the clothing or add a sensor or conductive pattern,” he said.
Learn more: Graphene on toast, anyone?
The Latest on: Laser-induced graphene
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The Latest on: Laser-induced graphene
- Laser-induced graphene gets tough on February 14, 2019 at 1:43 am
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- Handy graphene foam combos keep surfaces ice-free on February 13, 2019 at 8:53 am
Here, a hydrophilic composite of laser-induced graphene and other materials readily soaks up water. (Credit: the Tour Group): In 2014, the lab of James Tour, chair in chemistry as well as a professor ... […]
- Laser-induced graphene foam gains new super powers on February 13, 2019 at 8:47 am
A while back, researchers at Rice University pioneered a novel manufacturing method that produced graphene with a laser. The resulting flaky foam of the atom-thick carbon, however, lacked real-life fu... […]
- Laser-induced graphene gets tough, with help: Rice University lab combines conductive foam with other materials for capable new composites on February 12, 2019 at 7:19 pm
The labs of Rice University chemist James Tour and Christopher Arnusch, a professor at Ben-Gurion University of the Negev in Israel, introduced a batch of LIG composites in the American Chemical Socie... […]
- Laser-induced graphene gets tough, with help on February 12, 2019 at 1:10 pm
Rice University scientists have combined laser-induced graphene with a variety of materials to make robust composites for a variety of applications. Credit: Tour Group/Rice University Laser ... […]
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- Rice University Researchers Continue Work with 3D Graphene Foam on September 21, 2018 at 9:14 pm
This technique is a continuation of the university’s innovative work from 2014, which resulted in the first production of laser-induced graphene, or LIG, which can be made at room temperature in macro... […]
- Graphene foam sculpted for energy storage and sensors on June 15, 2018 at 4:59 am
The project was carried out at the Tour Lab at Rice, which produced the world’s first laser-induced graphene in 2014. By burning plastic with a laser, it is possible to transform the surface of the pl... […]
- Edible Electronics? Lasers are Bringing "Super Material" Graphene to Everyday Surfaces on March 9, 2018 at 11:37 am
Back in 2014, Tour’s lab reported that by shining a laser on a type of plastic called polyimide, they converted the illuminated surface into graphene. They called the result laser induced graphene, or ... […]
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