Heterogeneously flagellated microswimmer behavior in viscous fluids

Louis William Rogowski; Micah Oxner; Jiannan Tang; Min Jun Kim

doi:10.1063/1.5137743

Heterogeneously flagellated microswimmer behavior in viscous fluids

Biomicrofluidics. 2020 Apr 20;14(2):024112. doi: 10.1063/1.5137743. eCollection 2020 Mar.

Authors

Louis William Rogowski¹, Micah Oxner¹, Jiannan Tang¹, Min Jun Kim¹

Affiliation

¹ Department of Mechanical Engineering, Southern Methodist University, 3101 Dyer Street, Suite 200, Dallas, Texas 75206, USA.

Abstract

An analysis of heterogeneously flagellated microswimmers inside viscous fluids is presented. Flagella harvested from Salmonella typhimurium were isolated, repolymerized, and functionalized to have biotin at their ends, allowing for chemical attachment along the surfaces of avidin-coated microparticles. Assembled microswimmers were rotated under incremental magnetic field frequencies, in saline and methylcellulose solutions, to baseline their velocity responses. A mean square displacement analysis revealed that rotating microswimmers exhibited anomalous diffusive behavior at small time scales in each fluid and had increased diffusivity compared with the non-rotating cases. Flagellated microswimmers had decreased diffusivity when compared with non-flagellated microparticles in Brownian conditions. Microswimmers were demonstrated to perform selected trajectories under proportional feedback control with reasonable accuracy. Finally, microswimmer propulsion was shown to be heavily influenced by the handedness of the rotating magnetic fields, with frequency induced reversals of swimming direction observed under clockwise rotation; this effect was determined to be the result of flagellar bundling and unbundling.