Discontinuous Thinning in Active Microrheology of Soft Complex Matter

TL;DR

This paper uses theory and simulations to reveal a sudden drop in microviscosity, called discontinuous force thinning, occurring when a probe moves through a dense, attractive soft medium beyond a critical force.

Contribution

It introduces the concept of discontinuous force thinning in active microrheology and demonstrates its occurrence through theoretical and numerical methods.

Findings

Discontinuous drop in microviscosity at critical force

Occurs in dense media with strong attractive interactions

Microviscosity decreases by about an order of magnitude

Abstract

Employing theory and numerical simulations, we demonstrate discontinuous force thinning due to the motion of an external probe in a host medium, which we approximate as structureless. When the driving of the probe exceeds a critical force, the microviscosity of the medium drops abruptly by about an order of magnitude. This phenomenon occurs for strong attractive interactions between probe and a sufficiently dense host medium.