Periodic asperity arrays

CREATION OF PERIODIC ASPERITY ARRAYS BY FOCUSED ION BEAM... 

Figures 2.1-2.4 show examples of periodic asperity arrays used in this experiment, which were measured by a conventional sharp probe that had a nominal radius of curvature of less than 40 nm. Figures 2.1 and 2.2 are two-dimensional...

FIGURE 2.10 Friction and pull-off forces measured on a silicon periodic asperity array, (a) Pull-off forces were measured on each pattern without surface scanning between the measurements. (b) Pull-off forces were measured before and after each friction measurement at the same scanning area and were averaged. 

The experiment in the previous section revealed that the capillary force was predominant between the flat probe and the periodic asperity array. In fig. 2.21, the capillary geometry shows that a capillary can be formed even if one of the surfaces is hydrophobic, and eq. (2.7) shows that the adhesion force exists between the surfaces when 01 H- 02 < 180°. Thus, the water capillary could form between the hydrophilic probe and SAM-coated asperity peaks, even though the SAM-coated surfaces are hydrophobic and the adhesion force is given by eq. (2.7). 

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