Separate experimental investigation of the influence of liquids’ mass densities and viscosities on the ferquency 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 ρ. 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.