Edible Electronics? Lasers are Bringing "Super Material" Graphene to Everyday Surfaces
|Rice University graduate student Yieu Chyan, left, and Professor James Tour. |
Image Credit:Photo by Jeff Fitlow.
In research recently published in the journal ACS Nano, a team of researchers led by Rice University chemist James Tour describes how to pattern the surface of food, cloth, paper, cork and even Kevlar with graphene by illuminating the material with an infrared laser.
The school-spirited food makes for a good photo op, but the technique behind its creation could have far more exciting applications, according to Tour—applications like tracking food from farm to kitchen with RFID tags, or purifying water. It could likely form the basis for flexible electronics, or even biodegradable and edible electronics, say the authors.
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 LIG. More recently, the team converted wood into graphene though a similar process, but one that had to take place inside of a chamber with a controlled atmosphere.
In their latest work, the team describes how to pattern high-quality LIG onto any material with a lot of carbon, as long as the material can withstand the laser. In addition, they show that it can be done in open air, using widely available equipment.
The laser of choice, a carbon dioxide (CO2) laser, produces the pulses of infrared light that are essential to the process. CO2 lasers are relatively common, and are often used for engraving, laser cutting, and surgery. It turns out that the key to creating high-quality LIG on carbon-rich materials is "multiple lasing": hitting the surface with the a series of light pulses at a certain power and wavelength.
When you shine the laser on a sheet of polyimide, the photons stimulate a chemical reaction that rearranges some of the carbon atoms' bonds into graphene's characteristic structure. However, the researchers found that if you hit the same part of the sheet multiple times with the laser, more atoms undergo this process and the quality of the graphene increases. For other materials, they found that a first pass of the laser doesn’t produce graphene, but multiple passes do.
Why? In many cases, the first pass of the laser converts the illuminated surface into a disorganized arrangement of carbon atoms called amorphous carbon, while subsequent passes convert this mess into the organized, hexagonal pattern that defines graphene. Through simple multiple lasing, the team showed that LIG can be produced on cotton, cardboard, and other organic matter; to demonstrate the new technology's versatility, they patterned a tiny, working electrical component right on the surface of a coconut.
|...meaning we might be a few short years away from video actually recorded on a potato.|
Image Credit:Wiki User AlexanderAlUS (CC BY-SA 3.0)
Tour’s team is getting right to work on applications for LIG, collaborating with researchers at Ben-Gurion University in Israel to develop antimicrobial water filters through the company TerraForma. If you run electricity through LIG electrodes, their research shows that the electrodes become “bug zappers” for bacteria. LIG also prevents dead bacteria and other microorganisms from building up on wet surfaces, which means that the electrodes can kill and repel bacteria. Combined, these properties hold great promise for water purification systems.
Laura Mirren said...
Interesting post. I can't wait to see how this edible electronics thing will go in the future.
Tuesday, March 13, 2018 at 9:57 AM