Seven-shaped beam design for improving the sensitivity of two-dimensional MEMS sensors

Abstract

The spring constant of the connecting beam is one of the most crucial factors that affect the detection sensitivity of MEMS sensors. Existing researches reduce the spring constant by changing the parameters or number of connecting beams. In this paper, we propose a seven-shaped beam structure to modify the spring constant of MEMS sensors. The acute angle between the two segments of seven-shaped structure lowers spring constant. Compared with the crab-leg beam, it can bring a maximum sensitivity gain of 1.29 times through different angle designs. At the same time, compared with those combined beams, seven-shaped combined beams can bring a maximum sensitivity gain of 1.6 times. The two-dimensional MEMS sensor with seven-shaped beam has been designed and fabricated. According to the experimental results, the sensor reached a detection sensitivity of 25 fF/g. The relative error of the differential capacitance change between the measurement result and the simulation result is only 8.6%.