title: The synchronization of superparamagnetic beads driven by a micro-magnetic ratchet.
abstract: We present theoretical, numerical, and experimental analyses on the non-linear dynamic behavior of superparamagnetic beads exposed to a periodic array of micro-magnets and an external rotating field. The agreement between theoretical and experimental results revealed that non-linear magnetic forcing dynamics are responsible for transitions between phase-locked orbits, sub-harmonic orbits, and closed orbits, representing different mobility regimes of colloidal beads. These results suggest that the non-linear behavior can be exploited to construct a novel colloidal separation device that can achieve effectively infinite separation resolution for different types of beads, by exploiting minor differences in their bead's properties. We also identify a unique set of initial conditions, which we denote the "devil's gate" which can be used to expeditiously identify the full range of mobility for a given bead type.
authors.affiliation: Duke University, Department of Mechanical Engineering and Materials Science, Center for Biologically Inspired Materials and Material Systems (CBIMMS), Durham, NC 27708, USA. lu.gao@duke.edu
authors.forename: Lu
authors.initials: L
authors.lastname: Gao
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Gottron
authors.forename: Lawrence N
authors.initials: LN
authors.lastname: Virgin
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Yellen
mesh_terms: D000465:Algorithms; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D008280:Magnetics / Q000379:methods*; D008863:Microspheres; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D010316:Particle Size
chemical_list: D052203:Ferrosoferric Oxide