Ultrafast QCM
The resonance of a 5 MHz quartz crystal is tracked. Top panels show the instantaneous resonance curve of the crystal at the last measurement point. Lower plots show trace of four extracted parameters from the resonance curve versus time. After a few seconds the crystal was disturbed by humid air which slowly evaporate over the next 5 - 10 seconds.
Quartz crystal microbalance is a method in which a disk of piezo-electric quartz is used as a balance. By monitoring the mechanical resonance frequency and quality factor of the disk one can obtain the mass absorbed to the disk surface. The Multifrequency Lockin Amplifier, MLA-3, can be used to track resonance and damping coefficients at high rates using multifrequency comb excitation allowing for for ultrafast quartz crystal microbalance.
Electrochemical quartz crystal microbalance
The MLA-3 was also used to realize electrochemical quartz crystal microbalance in work by Professor Diethelm Johannsmann at TU Clausthal. They were able to observe fast pH-driven viscosity changes in albumin solutions.
