Metachronal coordination at the mesoscale

In nature, metachronal coordination is an efficient strategy for fluid
pumping and self-propulsion. Yet, mimetic systems for this type of organization
are scarce. Recently, metachronal motion was observed in a bead-based
magnetocapillary mesoswimmer, but the mechanism of such device's behavior
remained unclear. Here, we combine theory and experiments to explain two
swimming regimes that we identify by modulation of the driving frequency. In
the linear, low-frequency regime, the swimmer motion originates from individual
bead rotations. However, the high-frequency, metachronal regime is dominated by
deformations of the device near a mechanical resonance, which highlights the
role of bead inertia for optimized self-propulsion.