Coiling of semiflexible paramagnetic colloidal chains

Abstract

Semiflexible filaments deform into a variety of configurations that dictate different phenomena manifesting at low-Reynolds number. Harnessing the elasticity of these filaments to perform transport-related processes at the microfluidic scale...

Dynamic response of a ferromagnetic nanofilament under rotating fields: effects of flexibility, thermal fluctuations and hydrodynamics

“…7b, shape oscillations at field frequencies moderately above the critical value can be so large that the structure periodically changes between a rather extended and a very compact closed double loop “S” shapes, with an oscillation period significantly lower than the one of the field. This behavior resembles an extreme case of the ‘wagging’ oscillations reported in continuum models, 46 athermal MD simulations and experiments 15,66 of paramagnetic microparticle filaments, for the case in which the limit of ‘coiling’ of the free ends is reached. As the field frequency grows, the dynamics becomes too fast to allow large expansions and compactions of the filament structure, thus the range of the oscillations tends to shrink around moderately compact “S” shapes and their period tends to approach the one of the field, whereas the net rotation rate of the filament keeps decreasing.…”

“…Shape oscillations of relatively stiff microparticle filaments under asynchronous regimes have been observed in experiments, continuum models and athermal computer simulations. 15,46,66 However, to the best of our knowledge, this is the first time that are reported for ferromagnetic nanoparticle filaments. Thus, here we check whether the change in scale and the exploration of a wider range of flexibilities brings in significant differences.…”