73th Annual Meeting of the APS Division of Fluid Dynamics (November 22, 2020 — November 24, 2020)

P0015: Curved crack patterns by drying bacteria suspensions

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Authors

• Zhengyang Liu, Department of Chemical Engineering and Materials Science, University of Minnesota
• Tianyi Lin, Department of Chemical Engineering and Materials Science, University of Minnesota
• Yiming Qiao, Department of Chemical Engineering and Materials Science, University of Minnesota
• Xiang Cheng, Department of Chemical Engineering and Materials Science, University of Minnesota
• Xiaolei Ma, Department of Chemical Engineering and Materials Science, University of Minnesota

DOI: https://doi.org/10.1103/APS.DFD.2020.GFM.P0015

Particulate suspensions are prone to crack as the tensile stress in the film builds up when undergoing drying. In contrast to straight cracks in dried colloidal films, two new types curved crack patterns are found by drying drops of bacteria Escherichia coli (E. coli) in water on glass slides. Spiral-like cracks are observed in dried E. coli tumbler drops, whereas dried E. coli swimmer drops display circular cracks. These results suggest bacteria mobility could alter the direction of tensile stress development, leading cracks to propagate in different directions.