Impedance analysis of the thickness shear mode resonator for organic vapour sensing

The impedance analysis of thickness shear mode (TSM) resonator coated with calixarene films was successfully exploited for the registration of organic solvent vapours of relatively high (pre-explosive) concentrations. The impedance analysis consisted of fitting the experimental admittance spectra of TSM resonators to the equivalent circuit model using a highly accurate and reliable least squares algorithm. This approach allowed simultaneous monitoring of the changes in mass and viscoelastic properties of the sensitive membrane caused by adsorption of organic vapours and therefore enables both quantification and discrimination between the vapours of different types of organic solvents, such as hexane and toluene. (C) 2003 Elsevier B.V. All rights reserved.