A novel pull-in accelerometer based on cantilever beam mass structure

Described in this paper is a novel accelerometer, which measures the pull-in time to obtain the acceleration. As the pull-in time can be measured with a full digital circuit, no analog circuit is needed. The structure is very compact and can be scaled down further since the device bypasses the capacitive sensing. The accelerometer is based on a cantilever structure with one driving electrode and one detecting electrode on each side. The driving electrodes are around the center of the cantilever, while the detecting electrodes are around the tip. The device features a small traveling ratio, which is defined as the ratio between the maximum traveling distance of the center and the initial cantilever-electrode-gap, due to the characteristics of the cantilever structure. A small traveling ratio leads to a better performance according to the analysis. The prototype is fabricated with the bulk micromachining. The design, fabrication and the initial measurement is presented