Simultaneous measurement of the microscopic dynamics and the mesoscopic displacement field in soft systems by speckle imaging

TL;DR

This paper introduces a speckle imaging technique that simultaneously measures microscopic particle motion and mesoscopic drift in soft matter systems, enabling detailed analysis of their dynamic behavior.

Contribution

A novel speckle imaging method that concurrently captures microscopic dynamics and mesoscopic displacement fields in soft matter systems.

Findings

Successfully tested on translating Brownian suspension

Effectively measured shear-induced displacements in colloidal glass

Provides a comprehensive view of microscopic and mesoscopic motions

Abstract

The constituents of soft matter systems such as colloidal suspensions, emulsions, polymers, and biological tissues undergo microscopic random motion, due to thermal energy. They may also experience drift motion correlated over mesoscopic or macroscopic length scales, \textit{e.g.} in response to an internal or applied stress or during flow. We present a new method for measuring simultaneously both the microscopic motion and the mesoscopic or macroscopic drift. The method is based on the analysis of spatio-temporal cross-correlation functions of speckle patterns taken in an imaging configuration. The method is tested on a translating Brownian suspension and a sheared colloidal glass.