Researchers have discovered how the geometry of double emulsions can dramatically influence flow patterns, enriching our knowledge of active matter systems. This groundbreaking research reveals rich dynamical states within active double emulsions, where one or more passive droplets are suspended within larger, actively moving droplets.
Active matter is becoming increasingly significant across various fields, from biological systems to advanced materials science. It consists of self-propelling components, like cells or synthetic particles, whose collective movements lead to complex behaviors. The latest study focuses on active nematics — systems characterized by the orientational order of their components — and provides new insights on how their topology can be manipulated.
The researchers utilized elaborate computer simulations to explore this novel system's spatiotemporal dynamics and morphology. Their approach allowed them to examine how internal structures influenced the broader characteristics of these active systems, testing varying conditions such as droplet size and activity levels.
One of the study's significant findings is the ability of these double emulsions to exhibit self-motility, transitioning between different movement regimes based on activity strength. When activity is low, the emulsion remains stable and non-motile; as activity increases to moderate levels, the emulsions can translate along rectilinear trajectories. At higher activities, the system enters a rotating regime, where vortices form and drive circular motions.
"These emulsions provide an example of self-assembled topological active material with tunable internal patterns," the authors noted, highlighting the potential applications of these findings. The study revealed not just the mechanical behaviors of the emulsions, but how they maintain defect-free configurations even as they dance through their active motions.
Interestingly, the introduction of multiple passive droplets leads to non-trivial topological states, giving rise to charged disclination loops — structures important for the study of soft matters. These findings suggest the emulsions could be engineered to create specific flow patterns or to serve as models for other complex systems.
Another key aspect of this research is the interplay between topology and activity leading to various motility modes. The coherent connection between the external fluid dynamics and the topological properties of the embedded droplets opens up exciting possibilities for designing new materials responsive to external conditions.
"Topology is controlled at a global level via the number of passive cores included in the emulsion, whereas the patterns can be selected by tuning the value of the dipolar activity," the authors reflected on the broader scientific implications of their work.
Overall, the study adds depth to the rapidly growing field of topological materials and active matter physics, indicating pathways for future exploration, from the design of biomimetic systems to useful technologies based on active emulsion systems.