Figure 2
Critical rotational velocities versus substrates with varying surface roughness and wettability. Results show that the suckers perform better adhesion ability with decreasing surface roughness. The blue bars are the PDMS replicas of original mold sand paper (red bars on the left). The sand paper is more hydrophilic than its replicas. The glass slide is hydrophilic whereas the Teflon is hydrophobic, both of which are smooth (with roughness <5 μm.).
