Abstract

In recent years, experiments have shown the feasibility of utilising bacteria as micro-scale robotic devices. There has been special attention paid to the development of bacteria-driven microswimmers, as it is possible to take advantage of the built-in actuation and sensor mechanisms in the cells. Several studies have proposed stochastic models to describe the diffusive behaviour of microscopic particles propelled by surface-attached bacteria, but no theoretical framework has been proposed to predict their motility characteristics. Here I present a stochastic fluid dynamic model for microscopic particles driven by E. coli bacteria attached to their surface. Assuming low Reynolds number flow, a large number of attached bacteria N and negligible thermal noise compared to the random activity of each cell, I compute analytical expressions for the rotational diffusion coefficient and the mean squared displacement (MSD), in the ballistic and diffusive regimes. Next I discuss the effects of external chemical gradients and the possibility of artificial chemotaxis.