Separate experimental investigation of the influence of liquids´ mass densities and viscosities on the frequency response of resonant sensors using designated liquid series

For resonant viscosity and mass density sensors, oscillating in a test liquid with viscosity η, mass density ρ and temperature T, usually, resonance frequency fr and quality factor Q are evaluated and subsequently related to η and p. As both, fr and Q depend on η, ρ as well as on T, it is often difficult to separate the origin of these fr and Q changes. Separate experimental investigations of the effects of η and ρ on fr and Q are thus desired. For this purpose, new models for binary and ternary liquid mixtures have been elaborated for calculating the necessary mixing ratio to obtain a desired η and ρ at a certain T. This allows mixing liquid series with constant ρ but varying η (and vice versa). These liquid series and their modeling are discussed in detail and measurement results obtained with such resonant liquid series are shown.