(234d) Dynamics of Semiflexible Colloidal Particle Chains Under Rotating Magnetic Fields

Several naturally occurring and practically useful phenomena, such as flagellar propulsion and fluid manipulation via artificial cilia, are products of the unique dynamics of semi-flexible filaments as they respond to external forces in a fluid environment. In order to harness these phenomena and design optimal synthetic systems, we must be able to predict the eventual dynamics of fiber as a function of the applied driving forces and material properties. However, in the intermediate semi-flexible regime, where many fibers of interest, such as microtubules, carbon nanotubes, and artificial cilia reside, there appear to be deviations from the scalings expected of rigid and highly flexible fibers. We investigate these dynamics via a tunable experimental model, consisting of chains of linked, paramagnetic colloidal particles. When these chains are driven by an external, rotating magnetic field, rich dynamical regimes are observed, including non-reciprocal, wagging orbits and potentially bifurcating regimes. Using a combination of experimental filaments, numerical simulations, and theoretical calculations, we classify and predict these dynamics as a function of the dimensionless Mason and magnetoelastic numbers of the system.