How much mass range do the QCMs actually have?
A general rule for the maximum frequency shift is to divide the fundamental frequency by 100. For example: a 15 MHz QCM has a sensitivity of 5.09 x 108 Hz/gm/cm2. The maximum mass it would be able to measure would then be a 150 KHz shift, or 9.33 x 10-5 grams. This is assuming that you could get that much mass to adhere well to the crystal. There is the distinct possibility that some of the mass would be in a gelatinous state, that it would not all move with the crystal because it was not a solid. In this case, the crystal movement would be dampened at a substantially lower frequency.
