Article ID Journal Published Year Pages File Type
736774 Sensors and Actuators A: Physical 2015 7 Pages PDF
Abstract

•Novel concept of MEMS flow sensor using the micro-fabricated paddle and comb-drive transducer.•The device model has been described by theory analysis and FEM calculations.•The prototype has been successful fabricated on Silicon-On-Insulator wafers using only three photo-lithographic mask layers.•Experimental results showed that output capacitance of the device is a quadratic function of air velocity.•Experimentation also showed the capacitance readout mechanism is insensitive to temperature changing.

This paper presents the design, fabrication, and experimental results of an in-plane MEMS capacitive flow sensor that uses the displacement of a micro-fabricated paddle caused by dynamic gas pressure for measuring the velocity of the flow of surrounding gas. The fabrication process is simple; the prototype is fabricated on 100-μm device Silicon-On-Insulator wafers using only three photo-lithographic mask layers. The device area is 5.5 mm by 5.5 mm. A comb-drive capacitance is used as the transducer for the flow sensor. Measurements show that the output capacitance C   is a quadratic function of the gas velocity vv, C = k1v2v2 + k2vv + Cp, where k1 = −8.5 fF/(m/s)2, k2 = 73.6 fF/(m/s) and Cp = 16 pF. The advantage of using a capacitive sensing mechanism is that it is virtually insensitive to changes in ambient temperature. Experimental results show that the output capacitance changed only slightly, about 0.21–0.34%, when the temperature changed from 23 °C to 43 °C. Simplicity of fabrication, combined with insensitivity to variations in ambient temperature makes this sensor ideal for widespread deployment to monitor the flow in natural gas pipelines.

Related Topics
Physical Sciences and Engineering Chemistry Electrochemistry
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