Single macropillars as model systems for tilt angle dependent adhesion measurements

Adhesion tests were performed on single macroscopic pillars as model systems for artificial gecko surfaces. Polydimethylsiloxane macropillars with 400 μm diameter and aspect ratios ranging from 1 to 5 were fabricated. The tip geometries were modified to achieve spherical, flat and mushroom shaped tips. Unlike spherical tips, flat tip pillars exhibited a strong angle dependency of the pull-off force. For mushroom shaped tips the pull-off force was tilt angle dependent only for low preload, where no complete tip contact was formed. No clear influence of pillar aspect ratio on adhesion could be identified. Implications of the results for the adhesion performance of fibrillar arrays are addressed.