Analytical advantages of monitoring a particular characteristic frequency in a thickness shear mode acoustic wave sensor

The oscillator or active method, where just the series resonance frequency (fs) can be measured, has been the method of choice for analytical applications of bulk acoustic wave sensors. However, the present work shows that an increase in the analytical signal can be obtained if the frequency at minimum impedance (fn) is measured. An example is given, where quantitative analysis is only possible if fn is measured instead of fs. Sensitivity of a particular analysis can be improved if a previous study is performed in order to select the most suitable characteristic frequency (fs, fn or fp) to be monitored.