A micromachined flow shear-stress sensor based on thermal transfer principles

Author

Liu, Chang ; Huang, Jin-Biao ; Zhu, Zhenjun Alex ; Jiang, Fukang ; Tung, Steve ; Tai, Yu-Chong ; Ho, Chih-Ming

Author_Institution

Microelectron. Lab., Illinois Univ., Urbana, IL, USA

Volume

8

Issue

1

fYear

1999

fDate

3/1/1999 12:00:00 AM

Firstpage

90

Lastpage

99

Abstract

Microhot-film shear-stress sensors have been developed by using surface micromachining techniques. The sensor consists of a suspended silicon-nitride diaphragm located on top of a vacuum-sealed cavity. A heating and heat-sensing element, made of polycrystalline silicon material, resides on top of the diaphragm. The underlying vacuum cavity greatly reduces conductive heat loss to the substrate and therefore increases the sensitivity of the sensor. Testing of the sensor has been conducted in a wind tunnel under three operation modes-constant current, constant voltage, and constant temperature. Under the constant-temperature mode, a typical shear-stress sensor exhibits a time constant of 72 μs

Keywords

flow measurement; micromachining; microsensors; shear deformation; stress measurement; Si; SiN; flow shear stress sensor; heat sensing element; heating element; microhot film; polycrystalline silicon; silicon nitride diaphragm; surface micromachinig; thermal transfer; vacuum cavity; wind tunnel; Drag; Fabrication; Fluid flow measurement; Force measurement; Micromachining; Pressure measurement; Stress measurement; Temperature sensors; Testing; Thermal sensors;

fLanguage

English

Journal_Title

Microelectromechanical Systems, Journal of

Publisher

ieee

ISSN

1057-7157

Type

jour

DOI

10.1109/84.749408

Filename

749408