Microfluidic rheology of soft colloids above and below jamming

TL;DR

This study investigates the flow behavior of soft colloids near the jamming transition using microfluidic rheometry, revealing critical scaling and phase transition characteristics with interaction-dependent exponents.

Contribution

It introduces a microfluidic rheometer to analyze soft colloid rheology near jamming, demonstrating critical scaling and phase transition features.

Findings

Non-Newtonian behavior below jamming

Yield stress behavior above jamming

Data collapse onto two critical scaling branches

Abstract

The rheology near jamming of a suspension of soft colloidal spheres is studied using a custom microfluidic rheometer that provides stress versus strain rate over many decades. We find non-Newtonian behavior below the jamming concentration and yield stress behavior above it. The data may be collapsed onto two branches with critical scaling exponents that agree with expectations based on Hertzian contacts and viscous drag. These results support the conclusion that jamming is similar to a critical phase transition, but with interaction-dependent exponents.