An electrostatically actuated microsensor for determination of micropolar fluid physical properties

Micropolar fluids as complex non-Newtonian fluids admittedly have numerous applications in various fields, especially in medicine. Blood as a micropolar fluid plays an important role in regulating the body’s system and maintaining homeostasis. Physical properties of micropolar fluids, especially their viscosity, affect their rheological behavior significantly. Therefore, measurement of viscosity of these complex fluids especially human blood seems very necessary as it is considered a key parameter in the diagnosis and treatment of several diseases. In this paper, a new comb-drive microsensor for estimation of physical properties of micropolar fluids is presented. Driving and sensing combs, a sensing plate attached to the shuttle of the resonator form the structure of the electrostatic sensor. The nonlinear dynamic behavior of the sensor due to the presence of the electrostatic force has been investigated to obtain the limitations of the linear behavior of the structure. It has been shown that calculating the resonance frequency and resonance amplitude variations of the lumped dynamic model of the sensor arising from damping and inertial effects of the fluid can lead to the determination of the physical properties of a micropolar fluid. The effects of the geometrical parameters of the sensor and the applied exciting voltage on the performance of the sensor have also been studied.