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
via Google News
The Latest on: Laser-induced graphene
- New graphene laser technique opens door for edible electronics on February 28, 2019 at 7:11 am
Several years ago, James M. Tour and colleagues heated the surface of an inexpensive plastic with a laser in air to create something called laser-induced graphene (LIG). LIG is a foam made out of tiny ... […]
- Laser-induced graphene gets tough on February 14, 2019 at 1:42 am
The Tour lab first made LIG in 2014 when it used a commercial laser to burn the surface of a thin sheet of common plastic, polyimide. The laser's heat turned a sliver of the material into flakes of ... […]
- Handy graphene foam combos keep surfaces ice-free on February 13, 2019 at 8:52 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 gets tough, with help: Rice University lab combines conductive foam with other materials for capable new composites on February 12, 2019 at 7:17 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 ... […]
- Laser-induced graphene gets tough, with help on February 12, 2019 at 4:58 pm
Laser-induced graphene combines with many materials to make tough, conductive composites for wearable electronics, anti-icing, antimicrobial applications, sensors and water treatment. Laser-induced ... […]
- Laser-induced graphene gets tough, with help on February 12, 2019 at 1:08 pm
Laser-induced graphene (LIG), a flaky foam of the atom-thick carbon, has many interesting properties on its own but gains new powers as part of a composite. The labs of Rice University chemist James ... […]
- Laser-induced graphene gets tough, with help on February 12, 2019 at 1:00 pm
HOUSTON - (Feb. 12, 2019) - Laser-induced graphene (LIG), a flaky foam of the atom-thick carbon, has many interesting properties on its own but gains new powers as part of a composite. The labs of ... […]
- Laser-induced graphene formation creates tailor-made sensors on February 4, 2019 at 1:52 am
The team created a sensor that accurately records salinity even after long-term submersion. The sensor can form the basis of a marine animal monitoring device that records multiple underwater habitat ... […]
- 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 ... […]
via Bing News