Effect of quantity and configuration of attached bacteria on bacterial propulsion of microbeads

Flagellated chemotactic bacteria have been utilized as actuators for propulsion of polystyrene microbeads by randomly attaching several bacteria on their surface. In this work, a plasma-based bacteria patterning technique is developed and used to limit bacteria attachment to approximately half of the microbead's surface. Consequently, the effect of quantity and configuration of the attached bacteria on propulsion speed is studied experimentally. It is shown that the correlation between the propulsion speed and the number of bacteria is a strong function of the configuration of the bacteria and it follows one of the two distinct trends quantified by the proposed stochastic model.