A MEMS-based Air Flow Sensor with a Free-standing Micro-cantilever Structure

Yu-Hsiang Wang; Chia-Yen Lee; Che-Ming Chiang

doi:10.3390/s7102389

A MEMS-based Air Flow Sensor with a Free-standing Micro-cantilever Structure

Sensors (Basel). 2007 Oct 17;7(10):2389-2401. doi: 10.3390/s7102389.

Authors

Yu-Hsiang Wang¹, Chia-Yen Lee², Che-Ming Chiang³

Affiliations

¹ Department of Mechanical and Automation Engineering, Da-Yeh University, Changhua, Taiwan.
² Department of Mechanical and Automation Engineering, Da-Yeh University, Changhua, Taiwan. cy@mail.dyu.edu.tw.
³ Department of Architecture, National Cheng Kung University, Tainan, Taiwan 701. cmchiang@mail.ncku.edu.tw.

Abstract

This paper presents a micro-scale air flow sensor based on a free-standingcantilever structure. In the fabrication process, MEMS techniques are used to deposit asilicon nitride layer on a silicon wafer. A platinum layer is deposited on the silicon nitridelayer to form a piezoresistor, and the resulting structure is then etched to create afreestanding micro-cantilever. When an air flow passes over the surface of the cantileverbeam, the beam deflects in the downward direction, resulting in a small variation in theresistance of the piezoelectric layer. The air flow velocity is determined by measuring thechange in resistance using an external LCR meter. The experimental results indicate that theflow sensor has a high sensitivity (0.0284 ω/ms^-1), a high velocity measurement limit (45ms^-1) and a rapid response time (0.53 s).

Keywords: Flow sensor; Micro-cantilever; Micro-electro-mechanical-system (MEMS); Residual stress..