  We provide a clear energetic insight into the catastrophic nature of the
so-called creasing and pull-in instabilities in soft electro-active elastomers.
These phenomena are ubiquitous for thin electro-elastic plates and are a major
obstacle to the development of giant actuators; yet they are not completely
understood nor modelled accurately. Here, in complete agreement with
experiments, we give a simple formula to predict the voltage thresholds for
these instability patterns and model their shape, and show that equilibrium is
impossible beyond their onset. Our analysis is fully analytical, does not
require finite element simulations, and can be extended to include pre-stretch
and to encompass any material behaviour.
