Advanced application of the impedance spectrum of a lateral field excited sensor

An AT-cut quartz crystal in lateral field excitation has been theoretically and experimentally investigated. The effect of a z-directed electrical field in the plane of the quartz crystal has been studied and conclusions regarding the generated mechanical stresses are made. Further, the influence of external conditions on the excitation mechanism has been discussed.Measurements are performed on the lateral field excited (LFE) sensor exposed to deionised (DI) water and 2-propanol–water-mixtures of different concentrations. It is shown that the impedance spectrum is mainly dependent on electrical material parameters instead of mechanical material parameters. The impedance spectrum in the presence of a shielding electrode connected to ground potential allows the discussion of changes in the field distribution without adding an acoustic load onto the sensor.