  We discuss an evolution free boundary problem of mixed type with two free
boundaries modeling an idealized electrostatically actuated MEMS device. While
the electric potential is the solution of an elliptic equation, the dynamics of
the membranes' displacement is modeled by two parabolic equations. It is shown
that the model is locally well-posed in time and that solutions exist globally
for small source voltages whereas non-existence holds for large voltage values.
Moreover, our model possesses a steady state solution that is asymptotically
stable. Finally, we show that in the vanishing aspect ratio limit, solutions of
the model converge towards solutions of the associated small aspect ratio
problem.
