‘Dancing’ holes in droplets submerged in water-ethanol mixtures

Researchers have observed the formation of holes that move by themselves in droplets of ionic liquids (IL) sitting inside water-ethanol mixtures. This curious, complex phenomenon is driven by an interplay between how ionic liquids dissolve, and how the boundary around the droplet fluctuates. Self-driven motion is a key feature of active matter, materials that use ambient energy to self-propel, with potential applications to drug delivery and nano-machine propulsion.