  One of the most interesting predicted applications of graphene monolayer
based devices is as high quality sensors. In this letter we show, through
systematic experiments, a chemical vapor sensor based on the measurement of low
frequency resistance fluctuations of single layer graphene
field-effect-transistor (SLG-FET) devices. The sensor has extremely high
sensitivity, very high specificity, high fidelity and fast response times. The
performance of the device using this scheme of measurement (which uses
resistance fluctuations as the detection parameter) is more than two orders of
magnitude better than a detection scheme where changes in the average value of
the resistance is monitored. We propose a number-density fluctuation based
model to explain the superior characteristics of noise measurement based
detection scheme presented in this article.
