Figure 5.

High-speed imaging of water removal during blotting. (A) Shown is a schematic of the experimental setup to produce optical interference bands, indicating the height of the lubrication layer. (B) Continuous lubrication exists immediately after contact with the filter paper. (C) Fingers of air begin to propagate from the edges of the grid as capillary pressure draws water deeper into the filter paper. (D) Air continues to propagate. Aqueous solution above region “i” remains continuous with the wetted filter paper, whereas region “ii” is possibly dewetted. Scale bars, 500 μm. To see this figure in color, go online.