Nonlinear model of open-loop mode capacitive micro-accelerometer

To enhance the measurement range of capacitive micromachined accelerometer, a nonlinear model in open loop mode is proposed. It is pointed out that in the relation curve between input acceleration and output voltage; there is maximum measurand acceleration a_max which is decided by both the original distance d between electrodes and the ratio lambda of spring constant to mass. The accelerometer can´t work when d is less than a critical point, which is determined by transducer coefficient n and, if the optimum of eta being from 1 times 10¹⁹ to 2 times 10¹⁹, the pull in point is beyond 95% of the full travel range of the moveable electrode. The model can be applied to the nonlinear error´s correction of open loop capacitive accelerometer and is valuable for the accelerometer´s design