Design and Analysis of a MEMS Fabry-Perot Pressure Sensor

[摘要] Accurate dynamic pressure measurements in the jet engine compressors are the key point in the detection of instabilities that are often precursors to surge or rotating stall. Localizedpressure measurements are also very helpful in vehicles aerodynamics performanceoptimization. A new MEMS pressure sensor capable of measuring pressures between 14.7psi to 100 psi is presented in this work. The sensor is based on the effect of the viscousdamping force on the frequency response of a micro cantilever beam. The frequencyresponse of a micro cantilever beam is affected by two types of damping, squeeze filmdamping and air flow damping. Both these effects are modeled here. The airflow damping isdependent on the air pressure and increases with pressure. This sensitivity to pressure isutilized to predict the ambient air pressure. In order to measure the beam frequency response,a Fabry-Perot interferometer is fabricated using the cantilever beam and the substrate. Anelectro-optical measurement system is setup to measure the frequency response of the sensor.A custom made pressure chamber is designed and fabricated to allow high pressure tests.The measured frequency response of the cantilever beams are compared with the modelresults. The experimental results are fitted to the model predictions using pressure as thefitting parameter. The estimated pressure is then compared with the applied pressure. Theestimated pressure is in good agreement with the actual pressure for pressures below 40 psi.For the PolyMUMPs fabricated sensors, the error is less than 4% for pressure values smaller than 40 psi.

[发布机构] University of Waterloo

[关键词] Mechanical Engineering