“…Fabrication and handling of graphene and carbon nanotubes can be complicated because CNTs will aggregate together and graphene will stick together in sheets . Carbon nanotubes and graphene have shown high selectivity for NH 3 , NO 2 , and O 2 , and some sensitivity for CO 2 inherently, but for VOC sensing, functionalization is often necessary. ,,,− Adding carbon nanotube ”forests” to the surface of the gravimetric sensor has been shown to degrade the quality factor if its thickness is not carefully controlled, but graphene shows no indication of altering the Q of the device for thin layers. , Hybrid sensitizers where carbon nanotubes are added to other sensitizers, most commonly polymers, have been popular. ,− This approach can mitigate some of the difficulty in handling the carbon nanotubes, increase the sensitivity of the primary layer, and add selectivity to the carbon nanotubes instead of functionalization.…”