Microelectromechanical system (MEMS) viscosity sensor for fluid health monitoring
First Claim
1. A micro-electromechanical system (MEMS) capable of being submerged in a liquid, comprising:
- a substrate;
a capacitor comprising;
first and second thin sets of conductive plates spaced apart from each other and having parallel respective surface areas, the first set of plates being configured to interleave with the second set of plates such that their surface areas at least partially overlap to produce a capacitance which varies with the amount of overlap, at least one of said sets of plates being moveable to vary said overlap, said surface of said plates providing predominantly shear interaction with said liquid; and
a motion actuator carried by said substrate coupled to move said at least one set of plates.
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Accused Products
Abstract
Embodiments of the present invention are directed to a MEM viscosity sensor that is configured to be operated submerged in a liquid. The MEMS viscosity sensor comprises a MEMS variable capacitor comprising a plurality of capacitor plates capable of being submerged in a liquid. An actuator places a driving force on the variable capacitor which causes relative movement between the plates, where the movement creates a shear force between each moving plate and the liquid, which damps the movement of the plate and increases the capacitor'"'"'s response time to the applied force in accordance with the liquid'"'"'s viscosity. To determine the actual viscosity of the liquid, a sensor is coupled to the variable capacitor for sensing the response time of the plates as an indicator of the liquid'"'"'s viscosity.
35 Citations
28 Claims
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1. A micro-electromechanical system (MEMS) capable of being submerged in a liquid, comprising:
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a substrate;
a capacitor comprising;
first and second thin sets of conductive plates spaced apart from each other and having parallel respective surface areas, the first set of plates being configured to interleave with the second set of plates such that their surface areas at least partially overlap to produce a capacitance which varies with the amount of overlap, at least one of said sets of plates being moveable to vary said overlap, said surface of said plates providing predominantly shear interaction with said liquid; and
a motion actuator carried by said substrate coupled to move said at least one set of plates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A micro-electromechanical system (MEMS) viscosity sensor, comprising:
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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. - View Dependent Claims (16, 17)
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18. A micro-electromechanical system (MEMS), comprising:
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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. - View Dependent Claims (19, 20, 21)
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22. A micro-electromechanical system (MEMS) device being configured for movement within a fluid having a fluid viscosity so as to sense said fluid viscosity of the fluid, comprising:
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an actuator for placing a driving force on said MEMS device to cause said MEMS device to move within said fluid; and
a sensor coupled to said MEMS device for sensing said relative movement of said MEMS device.
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23. 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:
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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. - View Dependent Claims (24, 25)
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26. A micro-electromechanical system (MEMS) capable of being submerged in a liquid, comprising:
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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. - View Dependent Claims (27, 28)
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Specification