Electrical Impedance And Energy Dissipation Analyses Of Quartz Crystal Microbalance For Polymer Coating

Abstract

Electrical impedance analysis and energy dissipation methods are the two main methods to evaluate the damping behaviour of the quartz crystal. The motional resistance of the quartz crystal, which can reflect the quality factor (Q), is monitored in the electrical impedance analysis and the dissipation factor (D), which is inversely proportional to the Q, is measured in the energy dissipation methods. A comparison of the Q from electrical impedance analysis, termed as "electrical Q" and from the energy dissipation methods, termed as "mechanical Q" is presented in this work. The damping behavior of 5 MHz QCMs subjected to polymer caotings are studied by both methods. The resonant frequency, f, and Q before and after polymer coatings are measured using the network analyzer and a QCM-energy dissipation (QCM-D) instrument. The frequency shifts from both methods are quite comparable and the changes of the dissipation factor and the Q factor are also similar. Possible factors accounting for the Q change such as m...