Quartz crystal microbalance (QCM) is an acoustic sensor built around a disk shaped quartz crystal. It makes use of the converse piezoelectric effect. QCM, and extended versions such as QCM-D, has been widely used for protein adsorption studies, especially, real time monitoring of label-free protein adsorption. In addition to the adsorption studies, QCM-D also provides information regarding elastic moduli, viscosity, and conformational changes