(171a) Physically intelligent colloidal systems

Active colloids include bacteria which swim by action of flagella and biomimetic self-propelled colloids that move by consumption of chemical fuel. We have been developing the concept of Active Surface Agents, active colloids trapped at fluid interfaces to promote interfacial transport. Fluid interfaces are highly non-ideal, complex domains that impose constraints that alter swimming behavior. We study the bacterium Pseudomonas Aeruginosa (PA01) at interfaces and characterize several distinct swimming behaviors. We measure the flow generated by these swimmers using a recently developed flow visualization method correlated displacement velocimetry. The flow field has unexpected asymmetries whose structure we describe fundamentally using hydrodynamic theory. We explore the implications of our results on mixing in the interface and in the design of biomimetic systems. By understanding how biological swimmers move at fluid interfaces, we can develop design rules for artificial biomimetic systems to promote transport at fluid interfaces with broad implications in chemical engineering processes.