Design, modelling and characterization of comb drive MEMS gap-changeable differential capacitive accelerometer

This paper presents design optimization, numerical modelling, fabrication and characterization of a single-axis comb drive MEMS gap-changeable differential capacitive accelerometer with a compact footprint of 2 mm x 2 mm. High sensitivity is achieved by optimizing the ratio of the anti-finger gap to finger gap spacing. It is found that a gap ratio of 3.44 leads to a displacement sensitivity of 0.0139 mu m/g and a capacitive sensitivity of 80 fF/g. Finite element analysis is used to find the mode shape and frequency. Scanning electron microscope and capacitance-voltage measurements are employed to confirm the devices work. An enlarged static capacitance of 14.46 +/- 0.42 pF is measured due to the enlarged stator anchor width. Electrical sensitivity of 35.93 mV/g is obtained by using the capacitance readout circuit at the system level, and the electrical sensitivity is practically constant over the frequency range of 100-200 Hz.

Automated summary

This study presents the design, optimization, fabrication, and characterization of a compact MEMS accelerometer with high sensitivity. Finite element analysis is used to determine mode shape and frequency, while scanning electron microscope and capacitance-voltage measurements confirm device functionality. The electrical sensitivity remains constant over a certain frequency range, demonstrating the effectiveness of the device.