The secret of what enables the agile gecko lizard to stroll upside-down across glass and perform other remarkable sticky-footed feats has been revealed…. Microscopic suction cups provide Gekko gecko his phenomenal grip. Using a scanning electron microscope, … [Joseph F.] Gennaro observed that the chevron-shaped pads on the lizard’s toe were composed of an array of brushlike structures called setae … capped by minute suction cups which help the lizard cling to the surface. — Science News, September 6, 1969
Gennaro was partly correct. Gecko feet don’t have suction cups, but the feet have enough tiny setae — hundreds of thousands — to increase adhesion via van der Waals forces, which are very weak forces between molecules. Collectively, the hairs create enough adhesive force for the reptiles to stick even to slick surfaces, scientists discovered in 2000. Gecko feet have inspired new materials and technology, such as a robotic gripper for grabbing space junk (SN: 6/28/17) and hand pads to help people climb glass panes (SN: 11/18/14).