Previous research had hinted at a built-in cleaning process for gecko feet, but just how the creatures kept their toes tidy remained a mystery because they neither groom their footpads nor secrete fluids. Kellar Autumn and Wendy R. Hansen of Lewis and Clark College measured the amount of force between the setae and different surfaces both when they were dirt-free and in the presence of particulate contamination. They found that it takes only a few steps for setae to shed tiny silica spheres. "Self-cleaning in gecko setae may occur because it is energetically favorable for particles to be deposited on the surface rather than remain adhered to the spatulae," they write in the current issue of the Proceedings of the National Academy of Sciences.
The findings indicate that gecko foot cleaning occurs even under extreme exposure to clogging particles. To best imitate this property in synthetic adhesives the authors posit that an array of adhesive nanostructures should be made out of a relatively hard material having a small surface area and low surface energy for optimum performance.