ABSTRACT: Microorganism-structure interactions occur in almost every aspect of ecology, the environment, and public health. Despite such pervasiveness, the mutual impacts of individual sizes and structural geometries on the transport of microorganisms are still poorly understood. Using artificial microstructures fabricated as arrays of micropillars, we show that cell size can be an important factor for determining the long-term transport of bacteria in structured media. For instance, short cells do not always benefit from less contact with pillars for efficient navigation. Instead, they are often attracted by pillar surfaces and exhibit localized circulating motions. Long cells, on the other hand, can navigate smoothly through the pillar lattice due to more frequent interactions with pillars. We show that this anomalous size dependence in transport can be well addressed by geometry, without considering the detailed cell-wall interactions. In addition to guiding bacteria by solid structures, we also introduce structured flows for advanced 3D manipulations, using microfluidics.

BIO: Dr. Bin Liu is an Assistant Professor in Physics at the University of California at Merced. He received his Ph.D. in physics at New York University. Before joining UC Merced, he conducted postdoctoral research under several different disciplines, including physics, applied mathematics, and mechanical engineering. His research interests focus on the underlying geometric, topological, and symmetry-based principles in complex mechanics, especially those involved in bacterial transport and cell-environment interactions.