Design and Analysis of MEMS Comb Drive Capacitive Accelerometer for SHM and Seismic Applications

This work presents the design of a MEMS accelerometer that is specifically intended for Structural Health Monitoring (SHM) applications where sensing low frequency low amplitude accelerations with high resolution is essential. The surface micromachined comb drive capacitance accelerometer structure has been considered in this design. The simulation experiments conducted on these devices using IntelliSuite MEMS design tool show that it has excellent displacement sensitivity of 21.39 mu m/g, a capacitive sensitivity of 1.22 pF/g and voltage sensitivity of 1783 mV/g/V when it is designed to measure 0-0.1 g. Further, it is seen that it has a very low noise floor of 1.32 mu g/root Hz and therefore high resolution. Since the accelerations can be as low as 0.04 g in SHM applications, excellent resolution is the primary goal in this design. Further, one more sensor specifically meant for strong motion seismic application has also been reported. This device has a bandwidth of 0-250 Hz and a noise floor of 5.612 mu g/root Hz in addition to a sensor level voltage sensitivity of 97.9 mV/g/V. Finally, the comparison of these results with other similar devices reported in the past clearly illustrates the comparable performance of the present devices. Further, these devices, unlike the commercial low frequency accelerometers and other similar devices reported in the past can be fabricated by surface micromachining and CMOS compatible processes. (C) 2016 Elsevier Ltd. All rights reserved.