Self-Organization of Active Droplets into Vortex-like Structures

• DOI: 10.1021/acs.langmuir.1c01615
• Publication Date: 2021-08-04T20:17:51Z
• Authors: Boris Kichatov; Alexey Korshunov; Vladimir Sudakov; Vladimir Gubernov; Alexandr Golubkov; Alexey Kiverin
• Keywords: 0301 basic medicine; 03 medical and health sciences

Natural or artificial active objects can demonstrate mirror asymmetry of collective motion when they are moving coherently in a vortex. The majority of known cases related to the emergence of collective dynamical chirality are referred to as active objects with individual structure chirality and/or dynamical chirality. Here, we demonstrate that dynamically and structurally achiral active droplets can self-organize into vortex-like structures. Octane droplets dispersed in the aqueous solution of an anionic surfactant are activated with ammonia addition. The motion of droplets is due to the Marangoni flow emerging at the interfaces of the droplets. We found out that different modes of vortex motion of droplets in the emulsion can arise depending on the size of the region that confines the motion of the droplets and their number density and velocity.