Water nanodroplets zip across graphene faster than a cheetah

In a new study, researchers have propelled water nanodroplets across a graphene surface at speeds of up to 250 km (155 miles) per hour—which, for comparison, is about twice as fast as a sprinting cheetah. The water droplets' ultrafast velocities don't require any pump, but instead occur simply due to the geometric patterns on the graphene surface, which create different contact angles at the front and back of the moving droplets to propel them forward.