Mode switching of active droplets in macromolecular solutions

Abstract

Typical bodily and environmental fluids encountered by biological swimmers consist of dissolved macromolecules such as proteins or polymers, rendering them even non-Newtonian at times. Active droplets mimic the essential propulsive...

Dynamics of Active SiO2–Pt Janus Colloids in Dilute Poly(ethylene oxide) Solutions

“…Here, spontaneously generated Marangoni stresses at the droplet interface lead to their propulsion . While the propulsion mechanisms mentioned above may differ among the different artificial swimmers, their characteristics remain the same: a directed ballistic motion at short time scales followed by a random motion at longer time scales. , However, the translational and rotational diffusivities depend on various parameters such as swimmer size, the magnitude of the propulsion force , and also the presence of solutes in the surrounding medium. − Microswimmer–wall effects have also been known to affect the motion characteristics significantly. − Self-propelled JCs have been studied by subjecting them to diversified environments such as externally imposed flow, − topological obstacles, , and fluid interfaces ,, or placing them in a pool of passive tracers. − Recent studies have also demonstrated tuning of the dynamics of active JCs by altering their surface morphologies. , …”

“…For biological swimmers such as Escherichia coli, Patteson et al demonstrated that the elasticity of the polymer solution resulted in an enhanced swimmer speed and reduced tumbling tendency . Very recently, for active droplets in a viscoelastic media, Dwivedi et al demonstrated a Peclet-induced transition in the swimming mode and also deformation in their shapes . For phoretic colloids, numerous theoretical and computational studies have attempted to understand the behavior of self-propelled colloids in complex media. − So far, light-activated JCs have been chiefly used to study the dynamics of active JCs in viscoelastic media experimentally. ,,, Gomez-Solano et al demonstrated that the bulk viscoelastic stresses decouple the translational and rotational dynamics of the active JC .…”