  Since a long time the application of small electric potentials on biological
membranes (iontophoresis) proved enabling control and improvement of
transdermal delivery of substances across this barrier. In spite of a large
experimental data, the detailed molecular mechanism of iontophoresis is absent.
In the present work the interaction among the external continuous electric
field with the outermost layer of the skin (\textit{stratum corneum}) was
studied by coarse-grained molecular dynamics. Our results pointed out the
occurrence of water-rich vesicles formation depending on the field strength.
The corresponding phase diagram indicated that the large set of phenomena
(vesicle formation, reversibility, phase transition, disruption) could be
completely controlled by tuning external continuous electric fields.
Interestingly, electric field shielding effects are in the origin of observed
effects and followed a general Arrhenius-like time dependence. Direct current
(DC) electric field usage would also have booster diffusion effects due to
vesicles creation and reincorporation which would have direct beneficial
absorption effects on water-soluble topical agents (vitamins) or dermal
jet-injection of drugs by fine needles.
