Electroosmotic flow control in complex microgeometries

Numerical simulation results for pure electroosmotic and combined electroosmotic/pressure driven Stokes flows are presented in the cross-flow and Y-split junctions. The numerical algorithm is based on a mixed structured/unstructured spectral element formulation, which results in high-order accurate resolution of thin electric double layers with discretization flexibility for complex engineering geometries. The results for pure electroosmotic flows in cross-flow junctions under multiple electric fields show similarities between the electric and velocity fields. The combined electroosmotic/pressure driven flows are also simulated by regulating the flowrate in different branches of the cross-flow junctions. Flow control in the Stokes flow regime is shown to have linear dependence on the magnitude of the externally applied electric field, both for pure electroosmotic and combined flows. This linear behavior enables utilization of electroosmotic forces as nonmechanical means of flow control for microfluidic applications.