Quantitative Image Analysis for Evaluating the Coating Thickness and Pore Distribution in Coated Small Particles

Abstract

Purpose. This study aims to develop a characterization method for coating structure based on image analysis, which is particularly promising for the rational design of coated particles in the pharmaceutical industry. Methods. The method applies the MATLAB image processing toolbox to images of coated particles taken with Confocal Laser Scanning Microscopy (CSLM). The coating thicknesses have been determined along the particle perimeter, from which a statistical analysis could be performed to obtain relevant thickness properties, e.g. the minimum coating thickness and the span of the thickness distribution. The characterization of the pore structure involved a proper segmentation of pores from the coating and a granulometry operation. Results. The presented method facilitates the quantification of porosity, thickness and pore size distribution of a coating. These parameters are considered the important coating properties, which are critical to coating functionality. Additionally, the effect of the coating process variations on coating quality can straight-forwardly be assessed. Conclusions. Enabling a good characterization of the coating qualities, the presented method can be used as a fast and effective tool to predict coating functionality. This approach also enables the influence of different process conditions on coating properties to be effectively monitored, which latterly leads to process tailoring.

In-line spatial filtering velocimetry for particle size and film thickness determination in fluidized-bed pellet coating processes

“…In different studies image analysis was applied to evaluate the film characteristics, such as film thickness or integrity [10][11][12][13][14][15][16][17]. The often applied dynamic image analysis measures the particle size of a high number of particles, which are detected as a particle flow passing through a measuring field [18][19][20][21].…”

Microstructural evaluation of deep-fat fried chicken nugget batter coating using confocal laser scanning microscopy

“…Coating thickness, porosity and pore size distribution 0260-8774/$ -see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2010.08.002 of particle coatings were obtained by CLSM imaging (Laksmana et al, 2009). Bouchon and Aguilera (2001) used CLSM to study fried potatoes and showed that oil is located in the interior pockets or around intact cells.…”

Assessment of coating quality by use of dissolution kinetics

“…Optical methods like the 30 confocal laser scanning microscopy or micro-computed X-ray tomography are capable of producing optical slices through the particles. The thickness as well as the porosity of the shell can then be measured by image analysis techniques, as several authors reported previously [3,4].…”