  We study electrophoretic mobility of metal-dielectric Janus particles with
dipolar director profile in two nematic liquid crystals (LCs) having same
(positive) conductivity anisotropy and opposite dielectric anisotropy. The
applied ac electric field is parallel and perpendicular to the director for the
positive and negative dielectric anisotropy LCs, respectively. The velocity of
the Janus particles in both LCs is significantly higher than that of the
non-Janus particles. We map the electroosmotic flow fields surrounding the
particles using microparticle image velocimetry ($\mu$-PIV) and show that the
flows on the metal hemisphere is stronger than that on the dielectric
hemisphere and the pumping of LC along the direction of motion of the Janus
particles is more than that of the non-Janus particles. For a given liquid
crystal, particles with asymmetric surface properties is useful for enhancing
their electrophoretic mobility and activity.
