Organic vapour sensors based on quartz crystal microbalance coated with self-assembled monolayers

Alkanethiols incorporating two different ω-functional groups (HS(CH2)6X; X=–OH(I), –OCH2Ph(II)) were coated onto the gold electrodes of quartz crystal microbalance (QCM) via the molecular self-assembly process to afford stable monolayers. The adsorption behaviour and interaction mechanism of organic vapours on QCM sensors coated with these self-assembled monolayers (SAM) were investigated. The hydrogen bonding and dipole-induced/dipole interaction between the vapour molecules and the coating layer enable excellent response of the sensors to organic vapours which bear strong electron attracting groups, such as acetic acid and alcohols. The response is rapid and the sensors exhibit good reversibility owing to the thin monolayer coating film. This work describes a convenient and simple method of preparing QCM vapour sensors.