Active colloidal clusters swimming through artificial constrictions

对智能微和纳米机器人领域的兴趣日益增长，导致了能够在液体环境中自推进的各种人工微和纳米电机的快速发展。在过去的几年中，已经开发了在尺寸、形状和能量转换途径方面的大量多样性的人工游泳者。人造游泳者也被证明可以拿起货物并移动到明确的地方。在这里，我们提出了一种方法，它将允许通过任意的外部收缩，通过确定和控制的游泳者的形状，通过外部施加的电位移动这样的游泳者。该方法是基于从磁帽粒子的集群。当这些粒子上下振荡时，簇内粒子之间的相互作用使整个簇运动起来。运动的方向和速度完全由外部磁场控制，外部磁场也用于定义簇的形状。我们将通过外部构建的电势来演示由这些簇组成的游泳者的运动，这些电势是使用微流体中已知的方法构建的。我们将展示如何通过狭窄的收缩来采用运动的集群。这种运动与运载货物的可能性相结合，将为在生物系统中使用人工游泳者的可能性提供重要的见解。在这种情况下，特别重要的是，在不输入可能有害的燃料的情况下驱动集群。目前的建议的目标是证明集群的能力，在各种外部潜力，并优化这种运动的效率和速度。

Growing interest to the field of intelligent micro- and nanomachinery has resulted in enormously fast evolution of the wide class of artificial micro- and nano-motors, capable of self-propulsion in a liquid environment. A large diversity of artificial swimmers in terms of size, shape, and energy conversion pathway has been developed during the past years. It has also been proven that artificial swimmers can pick up cargo and move to well-defined places. Here we propose a method which will allow to move such swimmers through arbitrary external constrictions by determining and controlling the shape of the swimmers through externally applied potentials. The method is based on clusters built from magnetically capped particles. When these particles are oscillating up and down, the interaction between the particles inside the cluster set the whole cluster into motion. The direction and speed of motion is fully controlled by external magnetic fields, which are also used to define the shape of the clusters.We will demonstrate the motion of swimmers made of these clusters through externally built potentials, which are constructed using methods known in microfluidics. We will show how to adopt the clusters for motion through narrow constrictions. Such motion in combination with the possibility to carry cargo will deliver important insight into the possibility to use artificial swimmers in biological systems. In this context, it is especially important that the clusters are driven without the input of a possibly harmful fuel. The goal of the current proposal is to demonstrate the ability of the clusters to move in various external potentials and to optimize this motion in terms of efficiency and speed.