Electronic Nose

September 23rd, 2014 by

Researchers from University of Illinois Chicago have created a 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. When a graphene lattice or sheet is formed, its polycrystalline structure has random boundaries between the single-crystal grains. In many applications, grain boundaries are considered faults because they scatter electrons and may weaken the lattice. The first discovery was that gas molecules are attracted to the grain boundary and accumulate there, rather than on the graphene crystal, making it the ideal spot for sensing gas molecules. A grain boundary’s electrical properties attract molecules to its surface. The researchers were able to explain this attraction and additional electronic properties of the grain boundary. The irregular nature of the grain boundary produces hundreds of electron-transport gaps with different sensitivities. Gas molecules accumulate on the grain boundary, there is a charge transfer, and because the channels are all paralleled together the channels abruptly open or close. The researchers can synthesize these grain boundaries on a micrometer scale in a controlled way. 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”.

Source: EurekAlert

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