Application of piezoelectric tuning forks in liquid viscosity and density measurements

Low frequency commercial piezoelectric tuning forks (QTFs) were applied to the measurement of physicochemical properties of liquids. Viscosity and density of the test liquids were correlated with the resistance and resonance frequency of the QTF equivalent electric circuit fitted to the measured impedance spectra. Sensor calibration procedure based on the theoretical model was performed. The applied measurement technique based on the analysis of the QTF equivalent electric circuit proved its usefulness for determining liquid viscosity in the range up to 16 cP.