New insight into rheology and flow properties of complex fluids with Doppler optical coherence tomography.

Antti I. Koponen,Juha Salmela,Sanna Haavisto

doi:10.3389/fchem.2014.00027

Abstract

Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT) is an emerging technique capable of simultaneous measurement of the internal structure and motion of most opaque materials, with resolution in the micrometer scale and measurement frequency up to 100 kHz. This mini-review will examine the recent results on the use of Doppler-OCT in the context of flows and rheological properties of complex fluids outside biomedical field.

Highlights

Complex fluids are typically composed of several nonhomogeneously mixed components
In this article we review some of the recent developments and applications of Optical Coherence Tomography (OCT) outside of medical fields
We focus our review to the use of OCT to measure flow properties and rheology of complex fluids

Summary

INTRODUCTION

Complex fluids are typically composed of several nonhomogeneously mixed components. These fluids are often homogeneous at macroscopic scales but disordered at microscopic scales and possess structures of mesoscopic length scales, which play a key role in determining the usually quite intricate properties of the fluid. Flow behavior can be characterized with either a single temperature dependent coefficient of viscosity (Newtonian fluids) or with relatively simple relations between the stress and the strain rate (non-Newtonian fluids) These material properties can be accurately measured using conventional rheological methods. Acquiring rheological data with complex fluids is not straightforward due to non-uniform and inconstant behavior such as apparent wall slip and wall depletion (Barnes, 1995), particle migration (Leighton and Acrivos, 1987) and shear banding (Olmsted, 2008) that can arise during the experiment Mechanisms underlying these complicated and poorly understood phenomena are related to the presence of the mesoscopic length scales and its consequences on boundary layer flow (Stickel and Powell, 2005).

ORIGIN AND METHODS

CONCLUSION