  When a liquid mixture is subjected to external electric fields, ionic
screening leads to field gradients. We point out that if the mixture is
initially in the homogeneous phase, this screening can bring about a robust
phase-separation transition with two main features: (i) the phase separation is
expected to occur in any electrode geometry, and (ii) the voltage required is
typically of the order of 1 V and even less. We discuss several applications of
the effect relevant to the field of microfluidics, focusing on the creation of
a nanometer-scale lubrication layer in the phase-separation process.
