Balance dielectric layer for micro electrostatic switches in the presence of capillary effect

• The microactuator is subjected to capillary and electrical forces.
• A distributed parameter model is used to model the microbeam actuator.
• The modified Adomian decomposition method is utilized to solve governing equation.
• The capillary force can significantly affect the pull-in deflection and resultant stresses of microbeam actuators.
• There is a dielectric parameter that the pull-in deflection is independent of capillary parameter.

In this paper, the influence of capillary force on the deflection and pull-in instability of electrostatic micro actuator beams is investigated in the presence of a dielectric layer. A distributed parameter model is used to simulate the deflection of microbeam subject to the applied forces. The obtained governing differential equation of the beam is solved using the modified Adomian decomposition method (MADM). The results of MADM are compared with the numerical results of the Runge–Kutta–Fehlberg method, and they are found to be in good agreement. It is found that the voltage parameter, the capillary parameter and the dielectric parameter are the most significant parameters which affect the pull-in instability of the micro actuator. The results show that there is a specific value of dielectric parameter in which the variation of the dimensionless capillary parameter does not affect the value of maximum deflection of the micro actuator at the onset of pull-in instability. We introduced this value of dielectric parameter as Balance Dielectric Layer (BDL) because of its unique properties. There are also specific BDL values for internal stress and bending moment of the micro actuators. The BDL values are of interest for design of micro actuators in applications in which the capillary effects appeared.