Monitoring spatially heterogeneous dynamics in a drying colloidal thin film

Abstract

We report on a new type of experiment that enables us to monitor spatially and temporally heterogeneous dynamic properties in complex fluids. Our approach is based on the analysis of near-field speckles produced by light diffusely reflected from the superficial volume of a strongly scattering medium. By periodic modulation of an incident speckle beam we obtain pixel-wise ensemble averages of the structure function coefficient, a measure of the dynamic activity. To illustrate the application of our approach we follow the different stages in the drying process of a colloidal thin film. We show that we can access ensemble averaged dynamic properties on length scales as small as ten micrometers over the full field of view.

To appear in Soft Materials

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Cited by in corpus (5)

• Noise in laser speckle correlation and imaging techniques
• Simultaneous measurement of the microscopic dynamics and the mesoscopic displacement field in soft systems by speckle imaging
• Spatially-resolved measurements of micro-deformations in granular materials using DWS
• Differential Variance Analysis of soft glassy materials: a direct method to quantify and visualize dynamic heterogeneities
• Time-resolved rheometry of drying liquids and suspensions