Autonomously Probing Viscoelasticity in Disordered Suspensions

TL;DR

This paper uses simulations to understand how active probes can reveal viscoelastic properties of disordered suspensions, showing enhanced diffusion linked to structural transitions.

Contribution

It introduces a microscopic simulation model that explains rotational diffusion enhancement in colloidal glasses, connecting active probe behavior to medium structure and transitions.

Findings

Diffusive enhancement peaks at a second-order transition.

Simulation reproduces experimental features of colloidal glasses.

Effective description applicable to various viscoelastic suspensions.

Abstract

Recent experiments show a strong rotational-diffusion enhancement for self-propelled microrheological probes in colloidal glasses. Here, we provide microscopic understanding using simulations with a frictional probe-medium coupling that converts active translation into rotation. Diffusive enhancement emerges from the medium's disordered structure and peaks at a second-order transition in the number of contacts. Our results reproduce the salient features of the colloidal glass experiment and support an effective description that is applicable to a broader class of viscoelastic suspensions.