A multiplexed impedance analyser for characterising polymer-coated QCM sensor arrays

This paper describes the development and evaluation of a custom-built impedance analyser, which uses a multiplexing bridge circuit to characterise an array of polymer-coated quartz crystal microbalance (QCM) sensors. The analyser is constructed on a single printed circuit board with minimum components and is sufficiently compact for integration into a hand-held format. The custom-built device is used to observe the changes that occur in QCM sensors when experimental conditions such as polymer coating film thickness, odorant vapour pressure, and relative molecular mass are varied. An equivalent electric circuit for a QCM is used to model the conductance and susceptance data captured by the analyser. The measured response of an array of QCM sensors demonstrates that the custom-built device is a suitable instrument for detecting different gases and understanding polymer-vapour interactions.