Reactance-locked loop for driving resonant sensors

Quartz tuning fork resonators are suitable sensors for the measurement of density and viscosity of a surrounding gas. For the continuous measurement with these sensors, a digital reactance-locked loop is proposed in this contribution. Furthermore, insight on the theoretical background of density and viscosity measurement with tuning fork resonators is given and the application of the system for simultaneous density and viscosity measurement in gases with a tuning fork resonator is presented.