Analysis and experimental verification of a metallic suspended plate resonator for viscosity sensing

The measurement of 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 metallic shear mode resonators with Lorentz-force actuation, read out by a motion-induced voltage. The fluid–structure interaction mechanism is dominated by decaying shear waves excited by the oscillating surfaces. The damping behavior is thus comparable to that of quartz thickness shear mode (TSM) resonators. However, the relatively 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. We present the device modeling by finite elements analysis and an electrical equivalent circuit model. Measurements verify the fluid–structure interaction model and demonstrate the applicability to selected examples of complex liquids.