Abstract:
Under the influence of an AC electric field, electrolytes on a planar microelectrodes exhibit
steady fluid flow, termed as AC electroosmosis. A numerical model using finite element
method has been developed to solve the electrokinetic flow parameters of the AC
electroosmosis in a slit microchannel. A thin-layer, low-frequency, nonlinear analysis of the
system is performed including Faradaic currents from electrochemical reactions at the
electrodes. The non equilibrium model consists of Navier-Stokes, continuity, Nernst–Planck
and Poisson equations. In the first step, transient simulations are carried out to obtain a
homogeneous steady state stable periodic regime. The obtained stable period solutions are
then analyzed to compute the time averaged net velocity and other characteristics of the AC
electroosmotic flow. Net flow velocity and flow rate are observed for different geometric
parameters, electric field parameters, electrode position, Debye length and effective
thickness. Dependency of different parameters on the frequency of AC signal is analyzed for
optimal design of AC electroosmotic micropump. Such mechanism can be used to transport,
mix, separate, and manipulate various molecular or colloidal entities e.g. DNA, protein,
polymers etc. in microfluidic chips.
