Simulation of conventional and induced-charge electroosmotic flows

Schonfeld, F.1, Hardt, S.2
1 Institut für Mikrotechnik Mainz GmbH
2 Darmstadt University of Technology

The fluidic motion driven by Coulomb forces on charge clouds in the vicinity of charged walls immersed into an electrolyte is termed electroosmotic flow (EOF). Since the generated EOF pressure increases with decreasing hydrodynamic diameter, such actuation mechanisms are ideally suited for microfluidic applications and are widely discussed in the literature (see e.g. Li 2004). In addition to that, EOF flows display an almost plug-like velocity profile and usually induce a smaller hydrodynamic dispersion than pressure-driven flows.

Here various electrokinetic applications are studied by means of finite-element simulations. The objective of the work presented in this paper is twofold. First we propose the application of bifurcating channels acting as delay loops in the context with conventional EOF. Secondly, we investigate induced-charge electroosmosis (ICEO), a particular variant which relies on the induction of charge clouds within an external electric field experiencing a force by the same field.