(5a) Enhanced Diffusion Due to the Active Swimmers on Fluid Interfaces | AIChE

(5a) Enhanced Diffusion Due to the Active Swimmers on Fluid Interfaces


Deng, J. - Presenter, University of Pennsylvania
Molaei, M., University of Pennsylvania
Stebe, D. K. J., University of Pennsylvania
Active colloids can move at fluid interfaces inducing spatially decaying flow field. Such flow fields could be harnessed to enhance interfacial mixing and interphase transport. In this study, we seek to understand motion of interfacially trapped bacteria, as important self-propelled colloids, to design active interfaces. To study the enhanced transport arising from active sheets of bacteria with organized activity and persistent orientations, we use magnetotactic bacteria, Magnetospirillum magneticum AMB-1 as a model organism. Using a magnetic field, we control their swimming direction and motility pattern on the oil-water interfaces. Using correlated displacement velocimetry, we measure the flow field induced by single AMB-1 bacterium with persistent straight paths or curly paths. We also measure the enhanced motion of tracer particles in the bulk phase due to the motion of bacteria at interfaces. Based on bacteria-tracer hydrodynamic interactions, we predict tracer displacements in the adjacent bulk fluid. We compare the results with the presence of coherent swimming bacteria with bacteria showing randomized swimming directions. This work gives us insight in the implications on microrobots and interfacial transportation.