Department of Physics, Zhejiang University, Zhejiang, 310027, China.
Soft Matter. 2018 Jun 27;14(25):5205-5212. doi: 10.1039/c8sm00249e.
Effective forces between two micro-wedges immersed in an active bath are investigated using Brownian dynamics simulations. Two anti-parallel and parallel wedge-like obstacles are considered respectively, and the effective forces between two wedges rely on the wedge-to-wedge distance, the apex angle of the wedge, as well as the particle density and aspect ratio. For two anti-parallel wedges, a transition from repulsion to attraction occurs by varying the apex angle, which is also sensitive to the particle density and aspect ratio. The optimal apex angle θr* (or θa*) and particle density ρ* are characterized by the saturated trapping of active particles inside a wedge. For two parallel wedges, the effective force also experiences a transition from repulsion to attraction as the wedge-to-wedge distance increases. These results originate from the collective trapping effect which is driven by the many-body dynamics of self-propelled particles in the confinement (near the boundary) of obstacles. Our results can provide insight into controlling the motion and assembly of microscopic objects through the suspension of active particles.
使用布朗动力学模拟研究了浸入主动浴中的两个微楔形物之间的有效力。分别考虑了两个反平行和平行的楔形障碍物，两个楔形物之间的有效力取决于楔形物之间的距离、楔形物的顶角以及粒子密度和纵横比。对于两个反平行的楔形物，通过改变顶角，从排斥到吸引的转变发生，这也对粒子密度和纵横比敏感。有效顶角θr*（或θa*）和最佳粒子密度ρ*由活性粒子在楔形物内的饱和捕获来表征。对于两个平行的楔形物，随着楔形物之间的距离增加，有效力也经历了从排斥到吸引的转变。这些结果源于由受限（靠近边界）障碍物中自推进粒子的多体动力学驱动的集体捕获效应。我们的结果可以为通过悬浮活性粒子来控制微观物体的运动和组装提供深入的了解。
