Figure 1: Some of the commercially available QCM instruments. Maxtek RQCM is manufactured by INIFICON (http://www.inficonoptics.com/en/ thinfilmdeposition/maxtekrqcm.html). QCM200 is manufactured by Stanford Research Systems (http://www.thinksrs.com/products/QCM200.htm). Q-Sense E4 is made by Q-Sense, Inc. (http://www.q-sense.com/products). The images were adapted from the websites of the manufacturers.