Propulsion of magnetically actuated achiral swimmers in complex fluids.*

Recently reported achiral microswimmers can be massively fabricated at low cost and are envisioned for used in future in vivo biomedical applications, such as drug delivery and minimally invasive surgeries. Towards this goal, we report on the propulsion of two-dimensional magnetic microswimmers, fabricated through photolithography, and actuated in dilute methylcellulose solutions. We observed that the microswimmers displayed increased swimming speeds in certain polymer concentrations. Furthermore, we observed that the reduction rate of achiral microswimmers' precession angle increases with the concentration of the polymer weight percent. Upon understanding the underlying principles, more effective control strategies can be implemented on achiral microswimmers to perform biomedical tasks. These observations suggest that achiral microswimmers have similar speed enhancement to those well known to exist for chiral simmers in complex media.