Effect of piezoelectric layers on the size-dependent pull-in instability analysis of electrostatically actuated MEMS

With piezoelectric layers attached, the electrostatically actuated microbeam-based MEMS (Micro-Electro-Mechanical Systems) is modelled to study the pull-in instability based on a modified couple stress theory. The nonlinear differential governing equation and boundary conditions of the beam are derived by using Hamilton´s principle. The results show that the piezoelectric layers can decrease the pull-in voltage by only applying very small voltage on the MEMS. The study may be helpful to characterize the mechanical and electrostatic properties of small size MEMS, or guide the design of microbeam-based devices for a wide range of potential applications.