Quartz Crystal Microbalance with Dissipation monitoring

The basis of this measuring method is a thin quartz crystal with deposited electrodes, which is forced to oscillate at its resonant frequency (typically 5 MHz) by an alternating voltage due to the piezoelectric effect. When molecules (e.g., proteins, lipids, polymers) are adsorbed onto the crystal surface, the total mass of the oscillating system increases, and the decrease in the resonant frequency is directly proportional to the bound mass. Since the frequency change is extremely sensitive, QCM allows for the monitoring of mass changes on the order of nanograms.

In addition, it is also possible to measure energy dissipation, which is the degree of damping of the crystal's oscillation after the driving voltage is turned off. This dissipation provides information about the mechanical properties of the layer deposited on the crystal. By combining the measurement of frequency change and energy dissipation change, QCM-D provides comprehensive information not only about the amount of bound material but also about its structural changes, conformation, and mechanical properties in real-time.

In our laboratory, we have the QCM-D QSense Explorer system available, which can be further combined with spectroscopic ellipsometry.