Microelectromechanical system (MEMS) viscosity sensor for fluid health monitoring

A micro-electromechanical system (MEMS) viscosity sensor, comprising:

• a MEMS variable capacitor comprising a plurality of capacitor plates capable of being submerged in a liquid;
• an actuator for placing a driving force on the variable capacitor which causes relative movement between said plates;
• said movement creating a shear force between each moving plate and said liquid which damps the movement of said plate and increases the capacitor's response time to said force in accordance with the liquid's viscosity;
• and
• a sensor coupled to the variable capacitor for sensing said response time as an indicator of the liquid's viscosity.

A micro-electromechanical system (MEMS), comprising:

• a substrate;
• a moveable suspension system carried by said substrate;
• a variable comb capacitor having two sets of interdigitated plates;
• a support holding one of said sets of plates stationary with respect to said substrate;
• a connector coupling the other of said sets of plates to move with said suspension system to vary the overlap between said sets of plates, and thus the capacitance of said capacitor, and
• a sensor coupled to sense the rate of change of said capacitance as an indication of viscosity of liquid in which the capacitor is immersed.

A method for measuring viscosity of a liquid having a viscosity value using a MEMS device having a variable capacitor, the variable capacitor comprising a plurality of plates, the plates being configured to interleave, a drive actuator and a sensor, wherein the rate of change in the capacitance between the capacitor plates allow the sensing of the viscosity value of the liquid, comprising the steps of:

• submerging at least a portion of the MEMS device into the liquid;
• applying, from the drive actuator, a driving force to said variable capacitor, the application of the driving force causing relative movement between said plates such that at least a portion of the plates overlap, the overlap of said plates causing a rate of change of capacitance, said movement creating a shear force between each moving plate and said liquid, said shear force damping the movement of said plate;
• sensing said rate of change of capacitance;
• and
• determining said viscosity value, wherein said viscosity value corresponds to said capacitance change.

A micro-electromechanical system (MEMS) capable of being submerged in a liquid, comprising:

• a substrate;
• a thin plate having a surface area, disposed parallel to said substrate and spaced apart therefrom;
• the plate being configured to move with respect to the substrate;
• said surface of said plate providing predominantly shear interaction with said liquid;
• and
• a motion actuator carried by said substrate coupled to move said plate.