Analysis of lateral instability of in-plane comb drive MEMS actuators based on a two-dimensional model

Abstract This paper presents a development of the lateral instability analysis of in-plane comb drive MEMS actuators based on a two-dimensional model considering both lateral translational and rotational stiffness. Analytic solutions of the critical voltage are developed. Numerical comparison reveals that the critical voltage obtained from the two-dimensional model is always less than those obtained from a one-dimensional model considering only the lateral translational stiffness or only the rotational stiffness. How a defined stiffness ratio influences the critical voltage is discussed based on numerical calculation. The effect of lateral and angular offsets on the critical voltage is analyzed. Numerical calculation shows that when there exists a lateral offset of 10, 20 or 50% of the one side gap, the critical voltage drops 25, 40 or 72%, respectively. A representative example is presented. Results show that the critical voltage could be in the range of a practical design voltage if there exists a lateral or angular offset.