The fluid viscosity measurement based on variable cross-section MEMS cantilever under torsional excitation

A Micro-electromechanical systems (MEMS) sensor with the variable cross-section micro-cantilever was designed to measure the fluid viscosity. Due to the quality factor of micro-cantilever under the torsional resonance is much higher than that under the first order flexural resonance, the fluid viscosity measuring accuracy under the torsional resonance is much higher. Then an exciting method named the torsional excitation was presented when the direction of magnetic induction lines was parallel with the width direction of the micro-cantilever. Thus, the micro-cantilever could be driven to vibrate directly under the torsional mode by the Lorentz force. The measuring experiments of the fluid viscosity were completed in seven kinds of alkanes under different resonance modes, the results showed that the accuracy and stability of the fluid viscosity measurement can be improved effectively under the torsional resonance mode.