Quartz crystal microbalance

Measuring a small amount of mass gain or loss on a surface, when the phenomena involved are sub-micrometric, requires the use of an appropriate method. In this case, conventional weighing methods cannot be used because of their low sensitivity and the difficulty of using them in a variety of media, particularly liquids (the reader is referred to the file [1] ). The quartz crystal microbalance (QCM) is a method based on the piezoelectric properties of quartz. It is highly sensitive, enabling the measurement of very small mass variations (down to the fraction of a monolayer). QCM is very simple to implement, and the equipment required is low-cost. Finally, in its electrochemical variant, the electrochemical potential of the measurement surface can be controlled, enabling adjustment of the surface charge and/or the redox state of the species present.

However, the use of QCM requires certain precautions, due to the operating principle of the sensor used (a quartz crystal) and its sensitivity to parameters other than deposition or material loss. These parameters are essentially: temperature, contact with a solution, pressure and stresses exerted on the quartz. The method has a wide range of applications, going far beyond layer deposition or electrodeposition. These are detailed in paragraph 2 of this dossier.