In an animated TED-Ed lesson, educator Eleanor Nelsen explains how geckos seem to defy gravity due to the governing principles behind the van der Waals force.
Electrons are always on the move, and sometimes they pile up temporarily in one spot. That flicker of charge is enough to attract molecules to each other. Such interactions between uncharged molecules are called van der Waals forces. They’re not as strong as the interactions between charged particles, but if you have enough of them, they can really add up. That’s the gecko’s secret. Gecko toes are padded with flexible ridges. Those ridges are covered in tiny hair-like structures, much thinner than human hair, called setae. And each of the setae is covered in even tinier bristles called spatulae. Their tiny spatula-like shape is perfect for what the gecko needs them to do: stick and release on command. When the gecko unfurls its flexible toes onto the ceiling, the spatulae hit at the perfect angle for the van der Waals force to engage.
