Enhancing magnetically driven microswimmer velocity via low Reynolds number hydrodynamic interactions

Abstract

The motion of comoving magnetic microswimmers is modeled by considering the inter-hydrodynamic interactions (HI) under low Reynolds number conditions. The microswimmer is a two-link design consisting of a magnetic head attached to a slender tail via a torsional spring, and it is driven by an external planar oscillatory magnetic field. The inter-HI considered are the head-head and tail-tail interactions. The propulsion velocity for the comoving mode is calculated and compared with that of an isolated mode. The comparative results show that the comoving mode velocity can be either similar or greater than the isolated mode, depending on the actuation frequency. The parametric dependency results show that the velocity generated in comoving mode depends on the average separation distance and length-to-width ratio of the tail. For proof of concept, a low-cost fabrication protocol is implemented to design a millimeter-sized magnetic flagellated swimmer. The experimental result shows that the comoving swimming mode generates larger velocity in comparison to isolated swimming.