  We experimentally demonstrate the phenomenon of electroosmotic dipole flow
that occurs around a localized surface charge region under the application of
an external electric field in a Hele-Shaw cell. We use localized deposition of
polyelectrolytes to create well-controlled surface charge variations, and show
that for a disk-shaped spot, the internal pressure distribution that arises,
results in uniform flow within the spot and dipole flow around it. We further
demonstrate the superposition of surface charge spots to create complex flow
patterns, without the use of physical walls.
