Quartz crystal impedance studies at 10 MHz of viscoelastic liquids and films

A rapid measurement of the components R and X-L of AT-cut quartz crystal electroacoustic impedance at 10 MHz is reported. Parametric impedance plane plots (X-L vs. R) are introduced to analyse the effect of mass/volume and viscoelastic changes in the films and liquids in contact with the quartz crystal during dynamic chemical or electrochemical processes. Experimental data for selected systems, viscoelastic films and liquids, self-assembled layers and electroactive polymers, are presented. These results are discussed on the basis of the model of Granstaff and Martin to describe the real and imaginary components of the Butterworth-van Dyke (BVD) equivalen circuit impedance in terms of the density, mass and shear modulus of the viscoelastic film or liquid. The possibility of separating the inertial (rigid) mass and the viscoelastic components of quartz impedance when dynamic processes take place is analysed for the selected experimental data presented.