Sticky mushroom feet fail last, but fail fast

This shape works well when upside-down, too.

UC Santa Barbara

When singer Bryan Ferry said that we should stick together, I wondered two things: Did he really like me that much? And how exactly were we going to stick to each other?

Many scientists have been pondering questions related to adhesion for a long time. Why can a gecko run up a wall? How do bacteria stay attached to a surface? And why can flies attach themselves to pretty much any surface?

But they've also been slowly uncovering various approaches to adhesion. One structure seems to be fairly ubiquitous: a sort of mushroom-shaped foot. The mechanism of adhesion between the face of the mushroom and a surface is electrostatic, so you might think it would be better to use a flat surface, which is structurally simpler. Early studies had revealed that despite their similarities, the failure of adhesion is different for flat and mushroom-shaped feet. But although there was some speculation about the differences, no one really knew why the two failed in different ways. Until now, that is.