  Electrokinetic boundary conditions are derived for AC electrokinetic (ACEK)
phenomena over leaky dielectric (i.e., semiconducting) surfaces. Such boundary
conditions correlate the electric potentials across the
semiconductor-electrolyte interface (consisting of the electric double layer
(EDL) inside the electrolyte solutions and the space charge layer (SCL) inside
the semiconductors) under AC electric fields with arbitrary wave forms. The
present electrokinetic boundary conditions allow for evaluation of induced zeta
potential contributed by both bond charges (due to electric polarization) and
free charges (due to electric conduction) from the leaky dielectric materials.
Subsequently, we demonstrate the applications of these boundary conditions in
analyzing the ACEK phenomena around a semiconducting cylinder. It is concluded
that the flow circulations exist around the semiconducting cylinder and are
shown to be stronger under an AC field with lower frequency and around a
cylinder with higher conductivity.
