A Millifluidic Bulge Test for Multiscale Properties of Engineered Biofilms

Citation

Chittur, Priya K. (2023) A Millifluidic Bulge Test for Multiscale Properties of Engineered Biofilms. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/e1yv-mr74. https://resolver.caltech.edu/CaltechTHESIS:08282022-230140735

Abstract

Biofilms – communities of bacterial cells associated with their extracellular polymeric matrices – are complex materials whose features span many length scales, ranging from bulk cohesive material properties, to mesoscale structural and compositional heterogeneity, down to the microscopic cellular morphology and cell-cell interaction chemistry.

Here, we demonstrate a tool to study the mechanical properties of biofilms across length scales from the mesoscale (0.2 mm) to the bulk (1 mm) using a simplified model system based on genetically engineered E. coli. Using a custom millifluidic device that suspends a 3 mm dia. biofilm across a support, we impose tunable hydrostatic pressure drops in the Pa-kPa range across the biofilm. The resulting deformation of the film through an aperture is visualized with optical coherence tomography and used to estimate bulk and mesoscale mechanical properties of the film. Our method requires only microliters of material, causes minimal disruption to the film structure, and allows for estimates of both average properties as well as local heterogeneity as a function of cell-cell interaction chemistry and biofilm damage and healing. In the final chapter we introduce other model biofilm systems for their unique optical and mechanical properties.

Thesis Files