A study of a QCM sensor based on pentacene for the detection of BTX vapors in air

In this work we report the results concerning the integration of a thin layer of an organic polymer (pentacene) on a quartz crystal microbalance (QCM) used for pollutant detection at room temperature. Volatile organic compounds (VOC) are one of the major air pollutants. They are directly involved in the photochemistry of the ozone layer and can affect human health. Exposure to VOC may happen in indoor or outdoor environments, both for short or longer period of time in domestic or working conditions. Among VOCs, mono aromatic compounds such as benzene, toluene or xylenes (often referred as BTX) have carcinogenic, narcotic and neurotoxic properties. Thin films of pentacene were obtained by thermal physical vapor deposition both on transducers and silicon substrates. Structural and morphological characterizations by FTIR and AFM analysis confirm analogy between layered material before and after BTX exposition. QCM was chosen as a transducer due to the kind of interactions involved between material and the target gases. The device was exposed to BTX both in dry and wet conditions. The measurements results where compared also with those collected during the exposure toward humidity and ethanol. A clear discrimination between the different analytes was found.