A MEMS-Based Flow Rate and Flow Direction Sensing Platform with Integrated Temperature Compensation Scheme

This study develops a MEMS-based low-cost sensing platform for sensing gas flow rate and flow direction comprising four silicon nitride cantilever beams arranged in a cross-form configuration, a circular hot-wire flow meter suspended on a silicon nitride membrane, and an integrated resistive temperature detector (RTD). In the proposed device, the flow rate is inversely derived from the change in the resistance signal of the flow meter when exposed to the sensed air stream. To compensate for the effects of the ambient temperature on the accuracy of the flow rate measurements, the output signal from the flow meter is compensated using the resistance signal generated by the RTD. As air travels over the surface of the cross-form cantilever structure, the upstream cantilevers are deflected in the downward direction, while the downstream cantilevers are deflected in the upward direction. The deflection of the cantilever beams causes a corresponding change in the resistive signals of the piezoresistors patterned on their upper surfaces. The amount by which each beam deflects depends on both the flow rate and the orientation of the beam relative to the direction of the gas flow. Thus, following an appropriate compensation by the temperature-corrected flow rate, the gas flow direction can be determined through a suitable manipulation of the output signals of the four piezoresistors. The experimental results have confirmed that the resulting variation in the output signals of the integrated sensors can be used to determine not only the ambient temperature and the velocity of the air flow, but also its direction relative to the sensor with an accuracy of ± 7.5° error.

[1]  Po-Ying Li,et al.  A biocompatible Parylene thermal flow sensing array , 2008 .

[2]  Sekwang Park,et al.  A circular-type thermal flow direction sensor free from temperature compensation , 2003 .

[3]  Sung Jin Kim,et al.  Electrokinetic flow meter , 2007 .

[4]  Lung-Ming Fu,et al.  A Smart Flow Sensor for Flow Direction Measurement , 2008 .

[5]  Göran Stemme,et al.  A lift force sensor with integrated hot-chips for wide range flow measurements , 2003 .

[6]  Jurgen Kosel,et al.  Contactless flow detection with magnetostrictive bilayers , 2008 .

[7]  Frédérick Mailly,et al.  Anemometer with hot platinum thin film , 2001 .

[8]  Chien-Hsiung Tsai,et al.  Elastic–plastic modeling of heat-treated bimorph micro-cantilevers , 2006 .

[9]  Massimo Piotto,et al.  A double heater integrated gas flow sensor with thermal feedback , 2005 .

[10]  Qingping Yang,et al.  DP flow sensor using optical fibre Bragg grating , 2001 .

[11]  Chien-Hsiung Tsai,et al.  Design and characterization of MEMS-based flow-rate and flow-direction microsensor , 2009 .

[12]  C. Chiang,et al.  A MEMS-based Air Flow Sensor with a Free-standing Micro-cantilever Structure , 2007, Sensors.

[13]  Sekwang Park,et al.  Measurement of flow direction and velocity using a micromachined flow sensor , 2004 .

[14]  Walter Lang,et al.  A high-temperature thermopile fabrication process for thermal flow sensors , 2006 .

[15]  W. Benecke,et al.  A high-temperature thermopile fabrication process for thermal flow sensors , 2005, The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05..

[16]  Bin Li,et al.  Monolithic integrated spreading-resistance silicon flow sensor , 1997 .

[17]  Tsugihiko Takumi,et al.  A polysilicon flow sensor for gas flow meters , 1996 .

[18]  Hongjian Zhang,et al.  Investigation of the pressure probe properties as the sensor in the vortex flowmeter , 2007 .

[19]  Yu-Chong Tai,et al.  A MEMS multi-sensor chip for gas flow sensing , 2005 .

[20]  Péter Fürjes,et al.  Thermal characterisation of a direction dependent flow sensor , 2004 .

[21]  H. S. Wolff,et al.  iRun: Horizontal and Vertical Shape of a Region-Based Graph Compression , 2022, Sensors.

[22]  Alan G. R. Evans,et al.  Characterization of a highly sensitive ultra-thin piezoresistive silicon cantilever probe and its application in gas flow velocity sensing , 2002 .

[23]  Remco J. Wiegerink,et al.  Miniaturized thermal flow sensor with planar-integrated sensor structures on semicircular surface channels , 2008 .

[24]  Hiroaki Niitsuma,et al.  A water flowmeter using dual fiber Bragg grating sensors and cross-correlation technique , 2004 .