A chaotic electroosmotic stirrer.

Two-dimensional, time-independent, and time-dependent electroosmotic flows driven by a uniform electric field in a conduit with nonuniform zeta potential distributions along its walls are investigated theoretically. The time-independent flow fields are computed with the aid of Fourier series. The series' convergence is accelerated so that highly accurate solutions are obtained with just a few terms in the series. The analytic solution is used to compute flow patterns for various distributions of the zeta potential along the conduit's boundaries. Subsequently, it is demonstrated that by time-wise periodic alternations of the zeta potentials, one can induce chaotic advection. This chaotic flow can be used to efficiently stir and mix fluids in microfluidic devices.