Fig. 6.
Scaling of the soft adhesion system compared with a flat microfiber array and biological gecko adhesives. The scaling of geckos’ foot-hair adhesion is for shear stress (σsr) on a flat substrate, whereas the other results in the soft system are for normal adhesion stress (σad) on both 3D curved (circles) and flat surfaces (rhombuses). Dashed lines are the least-squares trends in the adhesion stress of a single fiber, the microfiber array, and the soft system measured on both flat glass and spheres with 15-, 30-, and 60-mm diameters with (blue) and without (red) a negative initial pressure. The green line is the scaling from the single fiber to the microfiber array. Each data point indicates an average of five experimental measurements.