Role of Teflon and LiCl on the humidity-sensing properties of porous anodized alumina film

The electrical properties of capacitive humidity sensors, based on an aluminium film anodized in phosphoric acid, are investigated. The properties of teflon-deposited or LiCl-coated porous alumina film are also measured. It is found that sensitivity of porous alumina film increases after teflon or LiCl deposition. Moreover, the teflon-deposited alumina sensor exhibits shorter response time.