Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
Nano Lett. 2013 Sep 11;13(9):4263-8. doi: 10.1021/nl402031t. Epub 2013 Aug 19.
Controlling the motion of small objects in suspensions wirelessly is of fundamental interest and has potential applications in biomedicine for drug delivery and micromanipulation of small structures. Here we show that magnetic helical microstructures that propel themselves in the presence of rotating weak magnetic fields assemble into various configurations that exhibit locomotion and a change in swimming direction. The configuration is tuned dynamically, that is, assembly and disassembly occur, by the field input. We investigate a system that consists of two identical right-handed helices assembled at their center in order to model the motion of assembled swimmers. The swimming properties are dependent on both the component design and the assembly configuration. For particular designs and configurations, a reversal in swimming direction emerges, yet with other designs, a reversal in motion never appears. Understanding the locomotion of clustered chiral structures enables uni- and multidirectional navigation of this class of active suspensions.
无线控制悬浮液中小物体的运动具有重要意义，并且在生物医学领域具有药物输送和微小结构的微操作等潜在应用。在这里，我们展示了在旋转弱磁场存在下自行推进的磁性螺旋微结构会组装成各种表现出运动和游动方向变化的构型。通过磁场输入可以动态地调整构型，即发生组装和拆卸。我们研究了一个由两个相同的右手螺旋在其中心组装而成的系统，以模拟组装游泳者的运动。游动特性取决于组件设计和组装构型。对于特定的设计和构型，游动方向会发生反转，但对于其他设计，运动方向永远不会反转。了解聚集手性结构的游动性可以实现此类主动悬浮液的单方向和多方向导航。
