Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1988-11-16
1990-01-23
Raevis, Robert R.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
361285, G01R 2726
Patent
active
048960985
ABSTRACT:
A microbridge is used for the accurate measuring of time varying shear forces in the presence of fluctuating pressure. A microdimensioned plate is suspended by arms to form a microbridge. The microdimensions enable the smallest turbulence scales of interest to be sensed uniformally throughout the entire surface of the plate. The cavity beneath the microbridge is so small that a viscous drag is created in the air within the cavity and dampens normal movement of the plate. The microdimensions in conjunction with the damping effect of the cavity enable the sensor to be substantially insensitive to pressure and thus sense lateral forces independent of normal forces. The microbridge sensor is fabricated by surface micromachining. A sacrificial layer is deposited over a substrate. A structural layer is deposited and patterned to form the plate and support arms over the sacrificial layer. The cavity is formed by a selective etchant removing the sacrificial layer and leaving the rest of the microbridge structure suspended above the substrate. In a differential capacitance readout scheme, a conducting layer in the plate of the microbridge is capacitively coupled with conductors in the substrate. A sensed change in capacitive coupling generates an indication of plate deflection and thereby shear stress independent of vertical movement. Optic readout schemes may also be employed and are readily incorporated in the fabrication process. A mounting member presses the microbridge sensor into a holding plate which fits in a matching slot flush with the target wall.
REFERENCES:
patent: 3462223 (1969-08-01), Tiemann et al.
patent: 3641812 (1972-02-01), Vick
patent: 3714824 (1973-02-01), Bush
patent: 4141252 (1979-02-01), Lodge
patent: 4423371 (1983-12-01), Senturia et al.
patent: 4451780 (1984-05-01), Ogasawara
patent: 4475392 (1984-10-01), Ajagu et al.
patent: 4543526 (1985-09-01), Burckhardt et al.
patent: 4592238 (1986-06-01), Busta
patent: 4703663 (1987-11-01), Oppermann
patent: 4744863 (1988-05-01), Guckel et al.
patent: 4783821 (1988-11-01), Muller et al.
patent: 4816125 (1989-03-01), Muller et al.
"Measurement of Wall Shear Stress", T. J. Hanratty and J. A. Campbell Fluid Mechanics Measurements, R. J. Goldstein (Editor), Hemisphere Publ. Corp., 1983, pp. 559-615.
"An Outline of the Techniques Available for the Measurement of Skin Friction in Turbulent Boundary Layers", K. G. Winter, Prog. Aerospace Sci. 1977, vol. 18, pp. 1-57, Pergamon Press.
"Improved Sensing Element for Skin-Friction Balance Measurements", J. M. Allen, AIAA Journal, vol. 18, No. 11, Article No. 80-0049R, pp. 1342-1345.
"Application of the Force-Balance Principle to Pressure and Skin Friction Sensors", J. M. Paros, 1970 Proceedings, Inst. of Enviromental Sciences, 16th Annual Tech Mtg., Apr. 12-16, 1970, Boston, MA, pp. 363-368.
"Direct Measurements of Skin Friction in a Turbulent Boundary Layer with a Strong Adverse Pressure Gradient", D. Frei and H. Thomann, J. Fluid Mech. (1980), vol. 101, Part 1, pp. 79-95, Cambridge University Press.
"The instrumentation of a modern fluid mechanics research laboratory", M. P. Escudier, Measurement and Control, vol. 6, No. 7, Jul. 1983, (Dorking, GB), pp. 267-271.
"A servo force-balance instrument for the direct measurement of wall shear stress on circular cylinders", D. B. Macvean et al., J. Physics E: Sci. Instrum., vol. 11, No. 10, Oct. 1978, The Institute of Physics, pp. 1048-1050.
"Resonant-Microbridge Vapor Sensor", Howe, et al., IEEE, Transactions on Electron Devices, vol. ED-33, No. 4, Apr. 1986, IEEE, (New York, US), pp. 499-505.
"Integrated silicon PI-FET accelerometer with proof mass":, P. L. Chen, et al., Sensors and Actuators, vol. 5, No. 2, Feb. 1984, Elsevier Sequoia, (Lausanne, CH), pp. 119-126.
"Silicon sensors meet integrated circuits", Philip W. Barth, IEEE Spectrum, vol. 18, No. 9, Sep. 1981, IEEE, (New York, US), pp. 33-39.
Haritonidis Joseph H.
Howe Roger T.
Schmidt Martin A.
Senturia Stephen D.
Massachusetts Institute of Technology
Raevis Robert R.
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