The deflection and stability of microfabricated rectangular membrane strips driven electrostatically are analyzed theoretically in this paper with the attractive Casimir force between the conducting surfaces under consideration. The analytical results of the deflection of the membrane strip under the combined electrostatic and Casimir forces show that the effect of the Casimir force on the deflection is dependent on the values of the initial gap between the membrane and the substrate w(0), the applied voltage V and the fourth power of span to thickness ratio L-4/h. The Casimir effect on the membrane system is dominant for smaller gap w(0) and lower voltage V. yet it decreases with the gap width and the voltage increasing. When the value of w(0) and V is large enough, it is feasible to neglect the Casimir force. The Casimir effect on the deflection increases with the increasing L-4/H as well. The static stability of the membrane structure can be determined by a dimensionless parameter K related to the geometrical parameters of the membrane structure. The critical value K-C, over which the system will become unstable and the membrane strip will collapse to the substrate, is solved through numerical calculations, and it is found that an electrostatically driven membrane structure can be designed to avoid the potential instability with a high aspect ratio (L/h).
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