Mechanical description of interfacial slips for quartz crystal microbalances with viscoelastic liquid loading

Acoustic wave devices, such as quartz crystal microbalances (QCM), are extended to applications in liquid environments. An interfacial slip phenomenon is expected to occur at the interface between the surface of a quartz crystal sensor and the contacted liquid environment. Assumptions of continuous displacement and stress at the liquid-solid interface mask the physical details of the contact interface. In this paper, the motion equations of the interfacial particles are employed to replace the interfacial continuous displacement and continuous stress assumptions. The electrical impedance of QCM in the liquid environment is derived based on this proposed modeling. The comparison of the present result with that of the continuous stress and displacement model is presented. The slip parameter, which is defined as the amount of displacement transmission between the quartz crystal top surface and bottom liquid particles, is presented as a function of the contact properties. The effects of interactive force strength, liquid viscosity and attached-particles size are included in the numerical studies. The detailed modeling of the interface is useful in interpreting the slip phenomenon between the sensor surface and the liquid.