The Use of Graphene and its Derivatives in Chemical and Biological Sensing

Abstract\ud A chemical sensor is defined as a transducer comprised of, or coated with, a layer that responds\ud to changes in its local chemical environment. Chemical sensors convert various forms of energy\ud into a measurable signal. For instance, the chemical energy involved with bonds breaking or\ud forming can change the electronic properties of the transducer, creating an observable signal\ud such as an increase or decrease in electrical resistance. Chemical sensing is important in many\ud facets of research including environmental, bio-medical/pharmaceutical, industrial, automotive,\ud and human safety. For a sensor to be practical it must interact preferentially with the target\ud chemical analyte. A sensor should be precise, accurate, robust, cost efficient to manufacture, low\ud in power consumption, portable otherwise the sensor is undesirable. Another key value of\ud chemical sensors is it must exhibit rapid detection. Prior to portable sensors chemical analysis\ud was performed in a laboratory on large, expensive instruments, which is costly in time,\ud equipment fees, and personnel wages to operate. These sophisticated instruments are accurate\ud and precise, however, it is far more beneficial to have a miniature, on-site detection apparatus.\ud The first environmental, on-site sensor was used by the mining industry to monitor subterranean\ud air quality; the canary. Carbon monoxide and methane (colorless, odorless gases) are large\ud iv\ud problems in the mining industry; smaller life forms are more susceptible to being poisoned by\ud toxic gases. Today sensor constructs are far different from that of a canary, however, they serve\ud the same purpose. Carbon nanomaterials such as graphene and single-walled carbon nanotubes\ud and other derivatives prove to be of great importance in sensor research due to their unique\ud electronic properties, and they’re high aspect ratio allowing them to be highly sensitive to small\ud perturbations in local electronic environments