ZIFs are a category of metal-organic frameworks made up of metal ions [e.g., Zn(II), Co(II), Fe(II), Cu(II)] tetrahedrally-coordinated to imidazolate-based ligands to form an extended network, giving a crystal with nano-sized cavities capable of adsorbing gas. ZIFs often exhibit zeolite-like topologies owing to the similarity between their metal-imidazolatemetal angles and the Si-O-Si angles in zeolites. ZIFs are sensitive recognition elements due to their high internal surface areas onto which gases adsorb. More, the topology, pore size, and internal surface chemistry (e.g., the metal and the functional groups on the imidazolate ligand) of ZIFs can be tuned to arrive at a diverse set of structures for a gas sensor array. As a result of different adsorptive selectivities for various species in the gas phase among the ZIFs in a sensor array, a QCM-ZIF sensor array will produce a response that contains much information about the gas composition . More, ZIFs tend to be chemically and thermally stable .