Response of a Complex Fluid at Intermediate Distances

TL;DR

This paper develops a theoretical framework for understanding the intermediate-distance response of complex fluids, experimentally confirming it by measuring the dynamic correlation length and viscoelastic properties of F-actin networks.

Contribution

It introduces a generalized microrheology framework that includes subdominant responses, enabling measurement of dynamic correlation lengths in complex fluids.

Findings

Validated the theoretical model experimentally

Measured the dynamic correlation length of F-actin networks

Enhanced understanding of mesoscopic viscoelastic behavior

Abstract

The viscoelastic response of complex fluids is length- and time-scale dependent, encoding information on intrinsic dynamic correlations and mesoscopic structure. We derive the subdominant response of such fluids at intermediate distances and show that it governs their dynamics over surprisingly large length scales. Generalizing the framework of microrheology to include this response, we experimentally confirm the theory, thereby measuring the dynamic correlation length of F-actin networks, as well as their bulk and local viscoelastic properties.