Friction is the force between two surfaces that are sliding, or trying to slide, across each other. For example, when you try to push a book along the floor, friction makes this difficult. Friction ...

Introduction Have you ever driven up a mountain, seen a sign reading "Hazard! Icy Roads Ahead," and wondered why ice makes roads dangerous to drive on? The answer has to do with friction—specifically, ...

Electrically tunable ionic hydrogels use small voltages to switch friction at metal contacts between high-friction and ultra-low-friction states, enabling voltage-programmed grip, release and motion ...