  Gas sensors are an indispensable ingredient of the modern society, finding
their use across a range of industries that include manufacturing,
environmental protection and control, automotive and others. Novel applications
have been arising, requiring new materials. Here we outline the principles of
gas sensing with a focus on chemiresistive-type devices. We follow up with a
summary of the advantages and use of graphene as a gas sensing material,
discussing the properties of different graphene production methods. Finally, we
showcase some recent results that point to novel applications of graphene-based
gas sensors, including respiration monitoring and finger proximity detection.
