LIQUID droplets have been made to “walk” across horizontal surfaces and even uphill – quite literally under their own steam. Such self-propelled liquids could be used to cool microprocessors.
To get droplets of water and other liquids to do this, Heiner Linke and his colleagues from the University of Oregon in Eugene and the University of New South Wales in Sydney, Australia, used a brass surface etched with ratchet-like corrugations at a temperature considerably hotter than the boiling point of the liquid (see Graphic).
Because the surface is so hot, 220 °C for water droplets, for instance – a layer…
