  Electrostatic and Casimir interactions limit the range of positional
stability of electrostatically-actuated or capacitively-coupled mechanical
devices. We investigate this range experimentally for a generic system
consisting of a doubly-clamped Au suspended beam, capacitively-coupled to an
adjacent stationary electrode. The mechanical properties of the beam, both in
the linear and nonlinear regimes, are monitored as the attractive forces are
increased to the point of instability. There "pull-in" occurs, resulting in
permanent adhesion between the electrodes. We investigate, experimentally and
theoretically, the position-dependent lifetimes of the free state (existing
prior to pull-in). We find that the data cannot be accounted for by simple
theory; the discrepancy may be reflective of internal structural instabilities
within the metal electrodes.
