Shear force microsensor
First Claim
1. A sensor for measuring shear stress at a solid boundary in a fluid flow, including:
- a floating element being suspended by a plurality of support arms for resilient movement in all directions in a single plane for measuring shear stress in that plane, said element being spaced from a substrate to form a cavity therebetween, the substrate comprising a two-dimensional array of sensors for measuring the displacement of said element in both magnitude and direction, the measured displacement providing an indication of the magnitude and direction of shear stress in the plane.
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Abstract
A micro-dimensional sensor measures the shear force, both in magnitude and direction, at the surface of a solid boundary as a fluid flows over that boundary. The sensor is a micro-mechanical capacitor-transducer system that includes a micro-dimensioned floating upper plate above a fixed lower plate supported on a substrate. The floating upper plate is mounted and held over the substrate by a number of zig-zap form supporting arms. The flow passing over the upper plate displaces the upper plate in a downstream direction, which results in a measurable change of the capacitance in the capacitor-transducer system. The direction and magnitude of the shear forces can then be obtained from the measured capacitance through specially designed circuitry.
47 Citations
28 Claims
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1. A sensor for measuring shear stress at a solid boundary in a fluid flow, including:
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a floating element being suspended by a plurality of support arms for resilient movement in all directions in a single plane for measuring shear stress in that plane, said element being spaced from a substrate to form a cavity therebetween, the substrate comprising a two-dimensional array of sensors for measuring the displacement of said element in both magnitude and direction, the measured displacement providing an indication of the magnitude and direction of shear stress in the plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 24, 25, 27, 28)
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22. A method for measuring shear stress at a solid boundary in a fluid flow, said method including the steps of:
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providing at said solid boundary a floating element arranged for resilient movement in all directions in a single plane, said element being spaced form a substrate to form a cavity therebetween, providing said substrate with a two-dimensional array for circuitry for providing signals representing a measure of the displacement of said floating element in said plane; and
processing said signals to provide an output representing the magnitude and direction of the shear stress at said solid boundary. - View Dependent Claims (23, 26)
electrically connecting the conductive plates of said substrate array to processing circuitry to provide said signals representative of the capacitive coupling between the floating element conductive plate and the individual conductive plates of said substrate array.
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26. The method in claim 22, further comprising:
supporting said element using a plurality of radially arranged support arms.
Specification