Paper Number
PO16 

Session
Poster Session

Title
Visualization and image processing of colloid roughness in dense suspensions

Presentation Date and Time
October 12, 2022 (Wednesday) 6:30

Track / Room
Poster Session / Riverwalk A

Authors (Click on name to view author profile)

1. Waheibi, Rony A. (North Carolina State University, Chemical and Biomolecular Engineering)
2. Hsiao, Lilian (North Carolina State University, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Rony A. Waheibi and Lilian Hsiao
Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27606

Speaker / Presenter 
Waheibi, Rony A.

Keywords
experimental methods; colloids; glasses; microscopy; suspensions

Text of Abstract
The impact of particle surface roughness on the rheological behavior of many colloidal suspensions, including academic and industrial systems, has now been established. However, it is challenging to characterize the surface morphology of colloids in suspension using direct imaging techniques due to inherent assumptions of particle sphericity and symmetry in common methods, such as the brightness-weighted centroid detection algorithm. Here, we investigate the use of alternative edge-detection methods to identify particle edges for fluorescent, sterically stabilized poly(methyl methacrylate) colloids. High volume fractions, 𝜙, of smooth (2a = 1.65 µm ± 4%, 𝜙 = 0.42 - 0.62) and rough colloids (2a = 1.49 ± 6%, 𝜙 = 0.36 - 0.49) are suspended in squalene, a refractive index-matched solvent that generates hard particle-like interactions and reduces scattering. Confocal laser scanning microscopy is used to generate 3D images, which are initially processed using morphological and distance transformations to identify approximate particle locations and remove interference from non-focal planes. Then, image segmentation is performed through the watershed algorithm that accurately identifies the edges of these particles. After determining particle surface geometries, a higher accuracy centroid will be determined through a simple center of mass approach. Using this method, we will determine the distribution of edge-to-edge distances between nearest neighbors. These methods are able to provide a more accurate determination of interparticle distances between asperities, which consequently determine solvent and lubrication forces in dense suspensions of rough colloids.