Magnetotactic bacteria and microjets: A comparative study

We provide a comparative study between two self-propelled microrobots, i.e., magnetotactic bacteria and microjets. This study includes characterization of their fluidic properties (linear and rotational drag coefficients) based on their morphologies and characterization of their magnetic properties using the rotating-field technique. Further, the control characteristics of our microrobots are evaluated in the transient- and steady-states. The average boundary frequencies of our magnetotactic bacteria and microjets are 2.2 rad/s and 25.1 rad/s, respectively. The characterized fluidic properties and boundary frequencies are used in the characterization of the magnetic properties of our microrobots. The average magnetic dipole moments of our magnetotactic bacteria and microjets are 1.4×10^-17 A.m² and 1.5×10^-13 A.m² at magnetic field of 2 mT and linear velocities of 32 μm/s (approximately 6 body lengths per second) and 119 μm/s (approximately 2 body lengths per second), respectively. These characterized magnetic dipole moments are utilized in the realization of closed-loop control systems for the magnetotactic bacteria and microjets. Our closed-loop control system positions the magnetotactic bacteria and the microjets within the vicinity of reference positions with average diameters of 23 μm (approximately 4 body lengths) and 417 μm (approximately 8 body lengths), respectively.