Better red than dead: On the influence of Oil Red O dye on complexity of evolution of a camphor-paraffin droplet on the water surface

Droplets of paraffin can show self-motion when powered by camphor. We investigated the motion of such droplets when varying concentrations of camphor and the dye, Oil Red O, as well as the droplet volume. Experiments have shown that the presence of the Oil Red O dye in the system can significantly increase the complexity of droplet evolution, if compared to the case where the dye is absent. Just by increasing the concentration of Oil Red O, the droplet achieves a complex evolution of motion before it splits into many self-propelled secondary objects expressing motion similar to the progenitor droplet. Therefore, the system replicates and the behavior persists. When many division events occur from a single droplet, the collective motion appears similar to swarming behavior of living creatures. This system provides a wet lab, artificial life model to study the temporal evolution of behavior.

European Union’s Horizon 2020 Marie Skodowska-Curie grant agreement No. 711859, Polish Ministry of Science and Higher Education