Research and testing on graphene sensors have been conducted by a group of researchers at UIC and they have discovered “a way to create a highly sensitive chemical sensor based on the crystalline flaws in graphene sheets. The imperfections have unique electronic properties that the researchers were able to exploit to increase sensitivity to absorbed gas molecules by 300 times.”
Usually grain boundaries are a negative attribute in compounds because they cause electrons to scatter but the research group discovered that “these imperfections are important to the working of graphene-based gas sensors. They created a micron-sized, individual graphene grain boundary in order to probe its electronic properties and study its role in gas sensing,” the researchers said.
“When a graphene lattice or sheet is formed, its polycrystalline structure has random boundaries between the single-crystal grains. The properties of the lattice are significantly affected by these ‘grain boundaries,’” Amin Salehi-Khojin, UIC assistant professor of mechanical and industrial engineering, said.
“It’s as though we have multiple switches in parallel. Gas molecules accumulate on the grain boundary; there is a charge transfer; and, because these channels are all paralleled together, all the channels abruptly open or close. We see a very sharp response,” Poya Yasaei, first author on the research group’s paper, said.
“It should be possible to ‘tune’ the electronic properties of graphene grain-boundary arrays using controlled doping to obtain a fingerprint response — thus creating a reliable and stable ‘electronic nose.’ With the grain boundary’s strong attraction for gas molecules and the extraordinarily sharp response to any charge transfer, such an electronic nose might be able to detect even a single gas molecule,” Salehi-Khojin said.
Researchers have been attempting to develop such a sensor for many years and have finally figured out how to do so. “We can synthesize these grain boundaries on a micrometer scale in a controlled way. We can easily fabricate chip-scale sensor arrays using these grain boundaries for real-world use,” UIC postdoctoral fellow Bijandra Kumar, said.
