Cenev Zoran, Würger Alois, Zhou Quan
Department of Electrical Engineering and Automation, Aalto University, 02150 Espoo, Finland.
Department of Applied Physics, Aalto University, 02150 Espoo, Finland.
Phys Rev E. 2021 Jan;103(1):L010601. doi: 10.1103/PhysRevE.103.L010601.
Understanding the motion of particles on an air-liquid interface can impact a wide range of scientific fields and applications. Diamagnetic particles floating on an air-paramagnetic-liquid interface are previously known to have a repulsive motion from a magnet. Here, we show a motion mechanism where the diamagnetic particles floating on the air-paramagnetic-liquid interface are attracted and eventually trapped at an off-center distance from the magnet. The behavior of magnetic particles has been also studied and the motion mechanisms are theorized in a unified framework, revealing that the motion of particles on an air-paramagnetic-liquid interface is governed not only by magnetic energy, but as an interplay of the curvature of the interface deformation created by the nonuniform magnetic field, the gravitational potential, and the magnetic energy from the particle and the liquid. The attractive motion mechanism has been applied in directed self-assembly and robotic particle guiding.
了解气液界面上粒子的运动可以影响广泛的科学领域和应用。先前已知漂浮在气-顺磁-液界面上的抗磁性粒子会受到磁铁的排斥作用。在此，我们展示了一种运动机制，即漂浮在气-顺磁-液界面上的抗磁性粒子会被吸引，并最终被困在距磁铁一定偏心距离处。我们还研究了磁性粒子的行为，并在一个统一的框架中对运动机制进行了理论化，结果表明，气-顺磁-液界面上粒子的运动不仅受磁能支配，还受非均匀磁场产生的界面变形曲率、引力势以及粒子和液体的磁能之间相互作用的影响。这种吸引运动机制已应用于定向自组装和机器人粒子引导。
