Quantitative Imaging of Aggregated Emulsions

Abstract

Noise reduction, restoration, and segmentation methods are developed for the quantitative structural analysis in three dimensions of aggregated oil-in-water emulsion systems imaged by fluorescence confocal laser scanning microscopy. Mindful of typical industrial formulations, the methods are demonstrated for concentrated (30% volume fraction) and polydisperse emulsions. Following a regularized deconvolution step using an analytic optical transfer function and appropriate binary thresholding, novel application of the Euclidean distance map provides effective discrimination of closely clustered emulsion droplets with size variation over at least 1 order of magnitude. The a priori assumption of spherical nonintersecting objects provides crucial information to combat the ill-posed inverse problem presented by locating individual particles. Position coordinates and size estimates are recovered with sufficient precision to permit quantitative study of static geometrical features. In particular, aggregate morphology is characterized by a novel void distribution measure based on the generalized Apollonius problem. This is also compared with conventional Voronoi/Delauney analysis.

The generalized identification of truly interfacial molecules (ITIM) algorithm for nonplanar interfaces

“…70 we derive the expressions for the radius R and position r = (x, y, z) of the center of the sphere which is touching four other ones, having given radii and center positions R i and r i = (x i , y i , z i ) (i = 1, 2, 3, or 4), respectively. The conditions of touching can be expressed with the following nonlinear system of four equations:…”

Affine and nonaffine motions in sheared polydisperse emulsions

“…Using the 3D data from static samples, we determine the droplet radii using custom software implementing the method of Ref. [25]. The size distribution obtained from this method is shown in Fig.…”

Quantitative Imaging of Concentrated Suspensions Under Flow

“…Faster scanning methods will obviously extend the upper limit of flow rates that can be studied. The development of algorithms for identifying [182] and tracking particles in polydisperse systems will significantly extend the range of systems that can be studied -there has been no quantitative study to date of polydisperse suspensions under flow by imaging. Further use of confocal imaging combined with (simultaneous) bulk rheometry will give a wealth of information on the relation between micro-scale dynamics and bulk flow and provide a crucial test ground for various theories.…”