Chaotic and periodical dynamics of active chiral droplets

TL;DR

This study uses lattice Boltzmann simulations to explore how active chiral liquid crystal droplets exhibit various dynamic behaviors, including chaotic, turbulent, and periodic motions, influenced by active forces and chirality.

Contribution

It reveals new dynamical regimes of active chiral droplets, including chaotic and periodic behaviors driven by active force and torque dipoles, advancing understanding of biological chirality effects.

Findings

Active force dipoles cause defect loops and erratic motility.

Inward active torque dipoles lead to stable, intermittent, and turbulent regimes.

Outward torque dipoles sustain periodic defect nucleation and annihilation.

Abstract

The interplay between the chirality of many biological molecules and the energy injected at small length-scales as the result of biological processes is at the base of the life of the cells. With the aim of unveiling the connection between these two features, here we analyze by means of lattice Boltzmann simulations the behavior of an active droplet of cholesteric liquid crystal under the effect of intense active doping, within the framework of active gel theory. We find that a droplet of chiral liquid crystal, fueled by active force dipoles, develops defect loops (closed disclination lines) that pierce the interior of the droplet, leading the droplet to develop an erratic motility mode. When the droplet is fueled by in-warding active torque dipoles, three different dynamical regimes develops at varying both the thermodynamic chirality and the strength of active energy injection: a stable rotational state at low activity, an intermittent disclination dance regime, and a turbulent state where closed disclination lines formation is inhibited and new pairs of oppositely charged surface defects leads to the development of chaotic rotational motion. Finally, we show that out-warding torque dipoles are able to sustain a periodical dynamics at higher chirality characterized by the nucleation/annihilation of pairs of disclination rings.