Operational Features of MEMS with an Even Number of Electrodes

Abstract

The results of investigations on the influence of the nonparallelism of electrodes on electromechanical interactions in imbalanced Micro Electro Mechanical Systems (MEMS) with comb electrode structures in the modes with a controllable voltage and charge are presented. The formulas for the calculation of the potential energy, electrostatic force, critical voltage, critical charge, and the magnitude of critical displacement of a movable electrode under different inclinations of the electrodes, which are necessary for the MEMS design, taking into account their real design features, are derived. It was stated that increasing the mutual inclination and the number of electrodes reduces the modulation depth of the capacitance Cmax/Cmin of the imbalanced capacitors with nonparallel electrodes, which can significantly limit the achievable modulation depth of the capacitance of tunable MEMS, especially when there are a large number of electrodes. It is revealed that in imbalanced MEMS, in the case of controllable voltage, when increasing the relative inclination of the electrodes, the electrostatic attraction force between charged electrodes decreases and the magnitudes of the critical voltage and displacement increase. Increasing the number of electrodes of an imbalanced capacitor will lead to a decrease in the range of the controllable displacement of the movable electrodes and the magnitude of the critical voltage. It is stated that under an invariable charge and nonparallel electrodes in imbalanced MEMS with a comb electrode structure a pull-in effect appears. When increasing the relative inclination of the electrodes, the electrostatic attraction force between the charged electrodes increases and the quantities of the critical charge and displacement decrease. When increasing the number of electrodes in imbalanced MEMS with a comb electrode structure in the invariable charge mode, the value of the critical displacement decreases monotonically and the magnitude of the critical charge rises.