Figure 1.

The granule funnel: (a) vortices develop at the right of the granule; (b) saturation of the double layer saturates at the pole when counter-ions exiting the granule and field screening occurs; (c) a converging coion electromigration flux toward the positively charged pole neutralizes the concentrated protons; and (d) polar ejection and symmetric vortices on the other hemisphere (the white area in the image in Fig. 1 is due to the scattered light that reflects from a coarse surface). Reprinted with permission from Wang et al. Biomicrofluidics 2, 014102 (2008). Copyright 2008 American Institute of Physics.