Dancing performance of organic droplets in aqueous surfactant solutions

Droplet systems remain the subject of a constant fascination in science and technology. Here we focus on organic droplets floating on the surface of aqueous surfactant solutions. These droplets can exhibit intriguing interactions. Recently we have found independently in two laboratories that we can observe almost the same complex collective behaviour in two different droplet systems. The aim of this paper is to compare both droplets systems, present their differences and show their similar oscillatory behaviour. The first system consists of decanol droplets floating on a sodium decanoate solution. In the second one, the droplets consist of a mixture of ethyl salicylate and liquid paraffin and they are placed on the surface of an aqueous sodium dodecyl sulphate solution. Although the mechanism of these spatio-temporal interactions of droplets is not fully understood yet, we believe that this behaviour is based on the same phenomena.