MEMS Piezoelectric Accelerometer for Vibration Sensing in Harsh Environments

This master thesis presents a detailed overview of various MEMS accelerometers used as vibrometers in harsh environments. Commercial and scientific literature accelerometers are compared to determine the best accelerometer for said application. This comparison resulted in the selection of a piezoelectric accelerometer with charge output as the best transduction method. Further inspection into the state of the art yielded a piezoelectric accelerometer with a circular geometry design that utilized the bending mode for sensing. Analytical equations paired with COMSOL aided in the design of piezoelectric accelerometers for high and low frequency application in harsh environments. A novel method for vibration sensing was also explored which utilizes a thick layer of SU-8 on a SiN membrane to maximize charge sensitivity. Process flows for said accelerometers were designed and carried out in the CMi cleanroom. Fabrication non-idealities for said accelerometers are discussed as well as their potential solutions.