Water droplet research could inspire new engineering systems

Water stains are the bane of every proud car owner or dinner party host, left behind by raindrops drying on a vehicle’s surface or rinse water on a wine glass.
But we have discovered a new way of controlling the evaporation of liquid droplets that cause watermarks using a technology inspired by nature. Our research could not only produce new treatments for minimizing water stains on cars but also find other applications such as improving cooling devices used to prevent smartphones overheating.
The droplet evaporation process that forms watermarks seems simple but involves a complex interplay between heat transfer, fluid flow, and surface friction. Water evaporates when the molecules at its surface have enough energy to break free from the liquid and become water vapor. To gain this energy, the water absorbs heat from its surroundings, which is why sweat cools you down.