Sensitivity Determination of a Quartz Crystal Resonator for Practical Materials

A sensitivity determination method for a quartz crystal resonator is proposed, and its performance is examined with mass loading in gas and liquid phase applications. For the deposition of a known amount of mass on the resonator surface, dilute solutions of sodium chloride and stearic acid are utilized in air and water measurements, respectively. The resonator surfaces loaded with the practical materials are also observed with a microscope for the inspection of the material deposition. In both measurements, a linear relation of frequency drop and mass loading is yielded up to a loading of 150 ng, and a slightly lower sensitivity is obtained with more loading due to the base frequency reduction. The sensitivities are found to be 0.99 and 1.00 ng/Hz in air and in water applications, respectively. It is also demonstrated that the proposed technique is relatively simple in the measurement of sensitivity both in gas and in liquid phase utilizations.