Electrostatic micro-electro-mechanical system (MEMS) is a special branch with a wide range of applications in
sensing and actuating devices in MEMS. In this paper the perturbation analysis of the electrostatically actuated
MEMS resonant sensors which represented by a modiØed Du±ng - Van der Pol equation subjected to weakly
non-linear parametric and external excitations is studied by using a perturbation technique (multiple time scales).
Harmonic resonance and subharmonic resonances of order (
1
2
and
1
3
) are investigated. For each resonances we
obtain the modulation equations in the amplitude and phase, steady state solutions, frequency-response equations
and stability conditions are determined. EÆects of diÆerent parameters on the system behavior are investigated
numerically. Results are presented graphically and discussion is provided.