Stability and dynamics of magnetocapillary interactions

Abstract

Recent experiments have shown that floating ferromagnetic beads, under the influence of an oscillating background magnetic field, can move along a liquid-air interface in a sustained periodic locomotion [Lumay et al., Soft Matter, 2013, 9, 2420]. Dynamic activity arises from a periodically induced dipole-dipole repulsion between the beads acting in concert with capillary attraction. We investigate analytically and numerically the stability and dynamics of this magnetocapillary swimming, and explore other related topics including the steady and periodic equilibrium configurations of two and three beads, and bead collisions. The swimming speed and system stability depend on a dimensionless measure of the relative repulsive and attractive forces which we term the magnetocapillary number. An oscillatory magnetic field may stabilize an otherwise unstable collinear configuration, and striking behaviors are observed in fast transitions to and from locomotory states, offering insight into the behavior and self-assembly of interface-bound micro-particles.

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Cited by in corpus (9)

• Realization of the Najafi-Golestanian microswimmer
• Remote control of self-assembled microswimmers
• Magnetocapillary self-assemblies: locomotion and micromanipulation along a liquid interface
• Surface microswimmers, harnessing the interface to self-propel
• Magnetically powered metachronal waves induce locomotion in self-assemblies
• Statics and dynamics of magnetocapillary bonds
• Optimal motion of triangular magnetocapillary swimmers
• Capillary assemblies in a rotating magnetic field
• Regimes of motion of magnetocapillary swimmers