A MEMS-based methodology for measurement of effective density and viscosity of nanofluids

Due to the importance of the usage of nano-technology based fluids in several industrial processes, the presented research deals with mathematical modeling of a comb-drive MEMS-based sensor for determinations of the physical properties of nanofluids. The proposed sensor is made up of a driving comb, sensing comb, and a sensing plate. It is actuated longitudinally via the electrostatic force created by applying an AC voltage to the driving section of the sensor. The coupled equations of the vibration of the lumped dynamic mass and the nanoscale fluid field have been derived and solved simultaneously. Frequency analysis of the dynamic model indicates that a nanofluid has inertial and damping effects on the longitudinal vibration of the structure. Therefore, the viscosity and density of a nanofluid can be measured simultaneously via the detection of the resonance frequency and resonance amplitude changes of the structure. The practical restrictions of the applied AC voltage for the linear dynamic behavior of the structure have also been presented.