Acoustic wave biosensors: physical models and biological applications of quartz crystal microbalance

Piezoelectric sensors are acoustic sensors that enable the selective and label-free detection of biological events in real time. These sensors generate acoustic waves and utilize measurements of the variation of the wave propagation properties as a signal for probing events at the sensor surface. Quartz crystal microbalance (QCM) devices, the most widespread acoustic resonators, allow the study of viscoelastic properties of matter, the adsorption of molecules, or the motility of living cells. In a tutorial-like approach, this review addresses the physical principles associated with the QCM, as well as the origin and effects of major interfering phenomena. Special attention is paid to the possibilities offered by QCM that go beyond microweighing, and important recent examples are presented.