  Manipulation of particles by a uniform electric field, known as
electrophoresis, is used in a wide array of applications. Of especial interest
is electrophoresis driven by an alternating current (AC) as it eliminates
electrode blocking and produces a steady motion. The known mechanisms of AC
electrophoresis require that either the particle or the surrounding medium are
asymmetric. This asymmetry is usually assured before the field is applied, as
in the case of Janus spheres. We report on a new mechanism of AC
electrophoresis, in which the symmetry is broken only when the field exceeds
some threshold. The new mechanism is rooted in the nature of electrophoretic
medium, which is an orientationally ordered nematic liquid crystal. Below the
threshold, the director field of molecular orientation around a spherical
particle is of a quadrupolar symmetry. Above the threshold, the director forms
a polar self confined perturbation around the inclusion that oscillates with
the frequency of the applied field and propels the sphere. The director
perturbations are topologically trivial and represent particle like solitary
waves, called "director bullets" or "directrons". The direction of
electrophoretic transport can be controlled by the frequency of the field. The
AC directron induced liquid crystal enabled electrophoresis can be used to
transport microscopic cargo when other modes of electrophoresis such as induced
charge electrophoresis are forbidden.
