FLOW CHARACTERISTICS OF LIQUID FILMS DRIVEN BY PERIODIC ELECTRO-OSMOSIS IN BIOCHIPS

The flow of a thin film on a solid substrate driven by periodic electro-osmosis is studied in the present paper. To describe the relation between potential of electric double layer and charge density, the Poisson-Boltzmann equation is utilized under the Debye-Hückel approximation. An analytical solution for the film is obtained by solving the periodic electro-osmosis driven system, coupling with the Navier-Stokes equation for incompressible viscous fluid. Results indicate that amplitude of the flow velocity in the thin film strongly depends on the Reynolds number, i.e., the amplitude decreases as the Reynolds number increasing. The influence of the ζ potential, as well as the viscosity, is also analyzed on the flow velocity at the free surface and phase difference of the oscillating velocity.