Physics of Fluids - Publications

Chemotactic self-caging in active emulsions

Open Access
Proceedings of the National Academy of Sciences 119, e2122269119 (2022)

Authors

	Babak Vajdi Hokmabad
	Jaime Agudo-Canalejo
	Suropriya Saha
	Corinna Maaß

BibTeΧ

@article{
doi:10.1073/pnas.2122269119,
author = {Babak Vajdi Hokmabad  and Jaime Agudo-Canalejo  and Suropriya Saha  and Ramin Golestanian  and Corinna C. Maass },
title = {Chemotactic self-caging in active emulsions},
journal = {Proceedings of the National Academy of Sciences},
volume = {119},
number = {24},
pages = {e2122269119},
year = {2022},
doi = {10.1073/pnas.2122269119},
URL = {https://www.pnas.org/doi/abs/10.1073/pnas.2122269119},
eprint = {https://www.pnas.org/doi/pdf/10.1073/pnas.2122269119},
abstract = {The out-of-equilibrium dynamics of chemotactic active matter‚Äîbe it animate or inanimate‚Äîis closely coupled to the environment, a chemical landscape shaped by secretions from the motile agents, fuel uptake, or autochemotactic signaling. This gives rise to complex collective effects, which can be exploited by the agents for colony migration strategies or pattern formation. We study such effects using an idealized experimental system: self-propelled microdroplets that communicate via chemorepulsive trails. We present a comprehensive experimental analysis that involves direct probing of the diffusing chemical trails and the trail‚Äìdroplet interactions and use it to construct a generic theoretical model. We connect these repulsive autochemotactic interactions to the collective dynamics in emulsions, demonstrating a state of dynamical arrest: chemotactic self-caging. A common feature of biological self-organization is how active agents communicate with each other or their environment via chemical signaling. Such communications, mediated by self-generated chemical gradients, have consequences for both individual motility strategies and collective migration patterns. Here, in a purely physicochemical system, we use self-propelling droplets as a model for chemically active particles that modify their environment by leaving chemical footprints, which act as chemorepulsive signals to other droplets. We analyze this communication mechanism quantitatively both on the scale of individual agent‚Äìtrail collisions as well as on the collective scale where droplets actively remodel their environment while adapting their dynamics to that evolving chemical landscape. We show in experiment and simulation how these interactions cause a transient dynamical arrest in active emulsions where swimmers are caged between each other‚Äôs trails of secreted chemicals. Our findings provide insight into the collective dynamics of chemically active particles and yield principles for predicting how negative autochemotaxis shapes their navigation strategy.}}