Emergence of bimodal motility in active droplets
Abstract
To explore and react to their environment, living micro-swimmers have developed sophisticated strategies for locomotion - in particular, motility with multiple gaits. To understand the physical principles associated with such a behavioural variability,synthetic model systems capable of mimicking it are needed. Here, we demonstrate bimodal gait switching in autophoretic droplet swimmers. This minimal experimental system is isotropic at rest, a symmetry that can be spontaneously broken due to the nonlinear coupling between hydrodynamic and chemical fields, inducing a variety of flow patterns that lead to different propulsive modes. We report a dynamical transition from quasi-ballistic to bimodal chaotic motion, controlled by the viscosity of the swimming medium. By simultaneous visualisation of the chemical and hydrodynamic fields, supported quantitatively by an advection-diffusion model, we show that higher hydrodynamic modes become excitable with increasing viscosity, while the recurrent mode-switching is driven by the droplet's interaction with self-generated chemical gradients. We further demonstrate that this gradient interaction results in anomalous diffusive swimming akin to self-avoiding spatial exploration strategies observed in nature.
Keywords
Cite
@article{arxiv.2005.12721,
title = {Emergence of bimodal motility in active droplets},
author = {Babak Vajdi Hokmabad and Ranabir Dey and Maziyar Jalaal and Devaditya Mohanty and Madina Almukambetova and Kyle A Baldwin and Detlef Lohse and Corinna C Maass},
journal= {arXiv preprint arXiv:2005.12721},
year = {2021}
}