Characterizing live Shear-Resistant (SR-) biofilm interacting with substrates containing various energy landscapes by digital holographic microscopy and eChip fluidics*

Studies reveal that biofilm can be developed under severe shear flow and can resist to shear erosion. Evidence suggests correlation between biofilm structures and the substrate energy landscapes under the structure. In this study, we present an experimental technique combining the ecology-on-a-chip (eChip) fluidics platform to in-situ grow SR-biofilm and digital holographic microscopy to provide real-time 3D bacterial motility while they interact with surface energy landscape. Apart from homogeneous substrates, seven chemically patterned substrates (e.g., hydrophobic squares and circles of 20, 50, 100um on hydrophilic background as well as an anti quorum sensing substrate) are also used. During each experiment, pure culture of Pseudomonas will be cultivated in-situ in an eChip under high flow shear. Thousands of bacteria are tracked simultaneously in 3D at 40X. cell motility (e.g., swimming speed, reorientation motility, translational/angular dispersions) and their wall interactions (attachment rate, motility modification, colony characteristics), will be calculated from the measured 3D trajectories.