Sorting Rotating Micromachines by Variations in Their Magnetic Properties

Abstract

For the promising class of micromachines that respond to a rotating magnetic field with linear motion, control of large groups has been largely limited to aggregate movement. Unfortunately, techniques to differentiate micromachines do not scale well to large groups, and are not practical for application $i\phantom{\rule{0}{0ex}}n$ $v\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}v\phantom{\rule{0}{0ex}}o$. This work presents an open-loop control scheme to sort magnetic micromachines, requiring neither localization of individuals nor a structured environment, and for which sorting time is independent of group size. This work is a step toward enabling magnetic microswimmers to be used in medical applications.