Selected glass slides from Table 1, and locations of surface roughness measurements. The open channels in sample 2–sample 4 are 100 μm deep and 9.5 mm wide. Sample 1 is not shown in this figure, because it was used for wettability measurements only. A) Sample 2–sample 4 had measurements with atomic force microscopy made at the indicated locations. B) Sample 2–sample 4 had stylus instrument measurements made at the indicated locations. C) Sample 5 had stylus instrument measurements made at the indicated locations.