Instabilities, motion and deformation of active fluid droplets

TL;DR

This paper investigates minimal models of active fluid droplets, revealing how activity-induced instabilities lead to complex behaviors like motion, deformation, and oscillations, resembling cell cytoskeleton dynamics.

Contribution

It introduces two simplified models of active droplets, analytically predicts activity-driven instabilities, and compares these predictions with simulation results.

Findings

Active droplets exhibit spontaneous motion and deformation.

Instabilities in concentration and polarization fields drive complex dynamics.

Models replicate behaviors similar to cell cytoskeleton movements.

Abstract

We consider two minimal models of active fluid droplets that exhibit complex dynamics including steady motion, deformation, rotation and oscillating motion. First we consider a droplet with a concentration of active contractile matter adsorbed to its boundary. We analytically predict activity driven instabilities in the concentration profile, and compare them to the dynamics we find from simulations. Secondly, we consider a droplet of active polar fluid of constant concentration. In this system we predict, motion and deformation of the droplets in certain activity ranges due to instabilities in the polarisation field. Both these systems show spontaneous transitions to motility and deformation which resemble dynamics of the cell cytoskeleton in animal cells.