The singular parabolic problem ut - Delta u - lambda f(x)/(1+u)(2) on a bounded domain Omega of R-N with Dirichlet boundary conditions, models the dynamic deflection of an elastic membrane in a simple electrostatic Micro-Electromechanical System (MEMS) device. In this paper, we analyze and estimate the quenching time of the elastic membrane in terms of the applied voltage represented here by lambda. As a byproduct, we prove that for sufficiently large lambda, finite-time quenching must occur near the maximum point of the varying dielectric permittivity profile f(x).