Periodic collective behaviors of organic solvent droplets on the surface of aqueous surfactant solutions

Active matter sometimes exhibits life-like complex spatiotemporal patterns. Here we report on complex oscillatory behaviors of droplets floating on an aqueous surfactant solution. Even if the droplets consist of only simple chemicals, the behaviors they exhibit are unexpectedly complicated. They are likely induced by the interaction among droplets, which is mediated through the surface tension field as well as Marangoni flow field created by the droplets themselves.