Inertial Sensors: CMOS-MEMS capacitive accelerometer with piezoresisitive stress sensors

Fall 2011

Debjani Biswas
Gary Fedder
Project description

Inertial sensors such as accelerometers and gyroscopes are widely used in industries such as aerospace military, automotive and marine industries. One application of a MEMS accelerometer is in GPS-denied environment (e.g. underground areas, near buildings or valleys, indoors). In CMOS-MEMS accelerometers, environmental variables such as temperature, stress and shock can affect the sensitivity and output of the accelerometer, leading to compounding error over time. Measuring applied stress from one chip stress sensor and correlating it with accelerometer output will lead to a better understanding of the impact of residual stress on the accelerometer signal, yielding compensation models. Current commercial MEMS accelerometers are not integrated with sense electronics within a single chip. The CMOS-MEMS capacitive accelerometer design has the advantage of smaller size, weight and obstacles due to integration on a single chip. (A. Wung, "CMOS-MEMS High Gee Capacitive Accelerometers", a Master of Science dissertation, Dept. of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, Unites States, 2007). I am working on a MEMS capacitive accelerometer with piezoresistive stress sensors. My objectives are to test the sensitivity of a CMOS-MEMS accelerometer. Through this project I plan to gain knowledge of MEMS support circuitry, and to apply this knowledge in fabricating a stress testbed for the accelerometer and testing the accelerometer and stress sensor output under various chip stress conditions.

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