Figure 2.

Exclusion of beads (Fig. 2A) and rhodamine 123 (Fig. 2B) from a channel entrance. In both cases, hydrodynamic flow is from left to right. Before the application of an electric field, the spheres (Fig 2A, left) and dye (Fig. 2B, left) travel with the hydrodynamic flow through the system. Once an electric field is induced, the beads (Fig. 2A, right, 300 V/cm) and dye (Fig. 2B, right, −300 V/cm) are excluded in the reservoir, near the channel entrance.