Fully integrated mass flow, pressure, density and viscosity sensor for both liquids and gases

This paper reports on a fluid viscosity sensor consisting of pressure sensors fully integrated with a Coriolis mass flow sensor. The sensor is capable of measuring viscosities of both liquids and gases through a mathematical model. For liquids, this model is simply the Hagen-Poiseuille equation. For gases, a more elaborate model is derived, taking into account compressibility and additional pressure losses due to channel geometry. Viscosities of (mixtures of) water and isopropanol were measured and correspond well with values found in literature. Viscosities of nitrogen and argon were measured with accuracies of -0-12%, depending on input pressure and mass flow rate. Improvement of the mathematical model could lead to higher accuracy and less dependence on mass flow or pressure.