Fig. 2.

Weight supported by synthetic gecko tapes is compared with the force supported by a live gecko for a 0.16-cm² area. (A) The shear force supported by unpatterned and patterned gecko tapes on mica substrate. Inset shows the geometry we used in the shear measurements. (B) The shear stress for 0.16-cm² unpatterned gecko tape on mica, glass, poly(methyl methacrylate), and poly(octadecyl acrylate) (comb polymer) surfaces. The surface energies of mica and glass are >100 mJ/m². The surface energy of poly(methyl methacrylate) is ≈40 mJ/m², and that of comb polymer is 20–25 mJ/m². (C) Different weights (y axis) were suspended on a viscoelastic tape using shear geometry, and the maximum time it can support that particular weight is plotted on the x axis. As a comparison, the gecko tapes (0.16-cm² area and 500-μm setae) support 20 N/cm² shear force, recorded over a period of 8–12 h, without any cohesive break.