InterPore2025

Comparison of Contrast Agents for Reliable microCT Imaging of Biofilm Growth in Porous Media

20 May 2025, 15:05

1h 30m

Poster Presentation (MS10) Advances in imaging porous media: techniques, software and case studies Poster

Speaker

Ashtin Hofert (Oregon State University Graduate Student)

Description

Biofilm formation in porous media is crucial for understanding microbial processes in subsurface environments, bioremediation, and engineered systems. Previous research has successfully used microCT imaging to generate 3D images of biofilm architectures grown in porous media using synchrotron radiation (e.g. Ostvar et al. 2018). However, when using the same methodology on a polychromatic x-ray microCT system, there appears to be issues with settling of the contrast agent during the longer scan times. Barium sulfate solution (Micropaque® from Guerbet) is a particle suspension that provides excellent contrast for microCT imaging of biofilm architecture and distribution in porous media, but the particles can settle over time creating a density gradient and resulting artifacts that affect the image quality. Also, barium sulfate is fairly viscous and can cause shear stress and biofilm breakage, possibly impacting fluid flow if the viscosity of the solution is not appropriately controlled. This study explores the use of isotonic Lugol (Schröer et al., 2024) as an alternative to barium sulfate as a contrast agent by comparing micromodel images acquired using an optical microscope with microCT imagery for accurate biofilm structure visualization.
In this study, Shewanella oneidensis biofilms were grown in vertical 2D micromodels and imaged using microscopy before a contrast agent was added. The biofilm was then imaged (video recorded) over time as each contrast agent was added to assess potential viscosity and settling effects. Different concentrations of barium sulfate suspension were used and compared to an isotonic Lugol solution. Finally, the micromodel underwent microCT imaging with either contrast agent present to distinguish the biofilm, and the images were compared to the microscope images to assess settling and viscosity effects.