QCM-D, Quartz Crystal Microbalance with Dissipation monitoring, is just as its name claims: a balance. It operates with an oscillating piezoelectric quartz crystal with a certain resonance frequency which changes with variations on the surface. With QCM changes in the frequency and energy dissipation is registered and can through data analysis give both a figure on the total adsorbed mass (hydration water included) and the viscoelastic property of the adsorbed layer.

The applications can be briefly exemplified as follows:
Adsorption and desorption, of polymers, surfactants and proteins. Useful to check fouling and cleaning processes.
Conformational changes as swelling and de-swelling with water and rearrangements on the surface.
Rheological changes such as effects of crosslinking, curing and melting of gels upon addition of agents or external stress.
Cell adhesion attachment and the formation of a biofilm on an implant.