When tiny soft ferromagnetic particles are placed along a liquid interface and exposed to a vertical magnetic field, the balance between capillary attraction and magnetic repulsion leads to self-organization into well-defined patterns. Here, we demonstrate experimentally that precessing magnetic fields induce metachronal waves on the periphery of these assemblies, similar to the ones observed in ciliates and some arthropods. The outermost layer of particles behaves like an array of cilia or legs whose sequential movement causes a net and controllable locomotion. This bioinspired many-particle swimming strategy is effective even at low Reynolds number, using only spatially uniform fields to generate the waves.

当微小的软铁磁颗粒沿着液体界面放置并暴露于垂直磁场时，毛细管吸引和磁斥力之间的平衡会导致自组织成明确定义的模式。在这里，我们通过实验证明，进动磁场在这些组件的外围感应出异时波，类似于在纤毛虫和某些节肢动物中观察到的。粒子的最外层的行为类似于纤毛或腿的排列，其连续运动会导致净的和可控制的运动。这种受生物启发的多粒子游泳策略即使在低雷诺数下也有效，仅使用空间均匀的场来产生波浪。