Network analysis based interface electronics for quartz crystal microbalance

The application of resonant sensors such as quartz crystal microbalance (QC M) resonators requires interface electronics to measure parameters that cha racterize sufficiently the resonant behavior of the sensor due to effects u nder investigation. Common oscillators as sensor electronics have two major disadvantages. Since they measure the resonant frequency shift as the only parameter their employment is restricted to mass sensing of thin and rigid films in terms of QCM. Because of spurious phase shifts the measured reson ant frequency may be erratic. In order to characterize the sensor itself or a material on the sensor surface more parameters such as damping are to be measured. Therefore, a sensor electronics was developed that precisely acq uires the impedance spectrum of the resonant sensor in a small frequency ra nge which reflects properties like thickness of a sensor coating, its densi ty, and shear moduli or the density-viscosity product when measuring in liq uids. Originally developed as a sensor interface electronics this novel dev ice can help researchers to investigate any effects or material parameters affecting the impedance spectrum of the sensor. In this article the measure ment concept of the network analysis based device will be explained followe d by details of realization on single printed cardboard. Measurement errors are estimated by simulation and by a comparison of measurement results fro m a commercially available network analyzer as a reference. Examples of lab oratory and industrial applications will be given. (C) 2001 American Instit ute of Physics.