A Novel Oscillating Shear Viscosity Sensor for Complex Liquids

The frequency response of resonant structures immersed in liquid media allows the derivation of the physical properties of the fluid. We present a novel class of non-piezoelectric metallic shear mode resonators with Lorentz force actuation, which are read out by a motion-induced voltage. The fluid structure interaction mechanism is dominated by decaying shear waves excited near the oscillating surfaces. The response is thus comparable to that of quartz thickness shear mode (TSM) resonators. However, the comparably low resonance frequency qualifies the presented principle for the rheological analysis of complex structured liquids like suspensions, emulsions, or polymer solutions, where quartz TSM sensors fail due to their high oscillation frequency and the associated small penetration depth. Measurements verify the fluid structure interaction model and demonstrate the applicability to selected examples of complex liquids.