  The morphology of spherically confined flexoelectric fluid membrane vesicles
in an external uniform electric field is studied numerically. Due to the
deformations induced by the confinement, the membrane becomes polarized
resulting in an interaction with the external field. The equilibrium shapes of
the vesicle without electric field can be classified in a geometrical phase
diagram as a function of scaled area and reduced volume [1,2]. When the area of
the membrane is only slightly larger than the area of the confining sphere, a
single axisymmetric invagination appears. A non-vanishing electric field
induces an additional elongation of the confined vesicle which is either
perpendicular or parallel depending on the sign of the electric field
parameter. Higher values of the surface area or the electric field parameter
can reduce the symmetry of the system leading to more complex folding. We
present the resulting shapes and show that transition lines are shifted in the
presence of an electric field. The obtained folding patterns could be of
interest for biophysical and technological applications alike.
