Novel method for gated inductive readout for highly sensitive and low cost viscosity and density sensors

This paper proposes a novel method for an inductive readout of vibrating MEMS cantilever structures submerged in a liquid. The excitation of the system is separated in time from the detection of the cantilever oscillation. With this strategy the resonance frequency and damping are quantified overcoming the problem of measuring a small amplitude signal while applying a large amplitude signal for the excitation at the same time. An application to loop and plate shaped viscosity and density sensors is shown. Measurements with mixtures of glycerol, ethylene glycol and water are presented. The sensors exhibit very high sensitivity while requiring simple instrumentation.