Principles of Motion Control of Bacterial Micro-Robots Using Oxygen Gradients

We introduce a method of motion control for bacterial microrobots using oxygen gradients. The bacteria (magnetotactic coccus strain MC-1) have a strong preference for a particular oxygen concentration and reverse swimming direction in order to remain at that oxygen concentration. At the same time, MC-1 consume oxygen, changing the dynamics of the system. We propose that we can use this behavior to passively control the motion of bands of MC-1 by carefully setting oxygen inputs. Mode of operation is introduced and displacement control by varying oxygen concentration in air adjacent to the bacterial medium is experimentally demonstrated. We develop a test channel and measure response of bands of MC-1 to various fixed concentrations of oxygen over time, as well as a finite concentration of oxygen.