Bacterial Flows: Mixing and Pumping in Microfluidic Systems Using Flagellated Bacteria

ii The objective of the proposed thesis is to demonstrate the use of bacteria as control-lable elements of a microfluidic network in micro-engineered systems. We utilize flagellated bacteria (Escherichia coli and Serratia marcescens) whose motors are extremely powerful and reasonably well understood. We are strongly against the removal of the motor from the bacterium or the fabrication to mimic the microflagellar system since the full organism is already naturally designed to accomplish many engineering tasks. The core of the proposed study relies on the use of flagellated bacteria to actuate surrounding fluid in a controlled and directed manner. Flagellated bacteria are used both as individual actuators and in arrays (bacterial carpet), where the collective effort of the organisms can be applied to complete mi-crofluidic systems such as a chaotic mixer and a fluidic pump. The effect of bacterial motion on the diffusion of a molecule of high molecular weight is studied by observing the mixing of two streams of fluid in a microfluidic flow cell. The presence of motile E.coli bacteria in one of the streams results in a remarkable increase in the effective diffusion coefficient. If a large number of Serratia marcescens are encouraged to dock to the walls of a microchannel