Using Shape Diversity on the Way to Structure-Function Designs for Magnetic Micropropellers
Using Shape Diversity on the Way to Structure-Function Designs for Magnetic Micropropellers
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DOI：
10.1103/physrevapplied.11.034039
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发表时间：
2018-09
影响因子：
4.6
通讯作者：
Felix Bachmann Klaas Bente;Agnese Codutti;D. Faivre
中科院分区：
文献类型：
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作者：
Felix Bachmann Klaas Bente;Agnese Codutti;D. Faivre
近年来，在微尺度上模拟生物运动的合成微泳者得到了发展。均匀旋转磁场驱动螺旋磁性材料是微尺度上应用最广泛的推进技术之一，部分原因是驱动策略围绕着驱动磁场频率和螺旋桨速度之间的简单线性关系。然而，完全控制游泳运动员的运动仍然是一个挑战。提高微型推进器的可控性对于实现复杂的驱动方案至关重要，而复杂的驱动方案又与许多应用直接相关。然而，线性关系的简单性限制了群体控制的可能性和灵活性。使用随机形状的磁性微泳者的泳池，我们展示了形状的复杂性可以有利地转化为增强控制。特别是，分选微型推进器的定向反转是由激励场的频率控制的。这种方向性变化与磁力和流体动力之间的平衡有关。我们进一步展示了一个例子，这个行为如何实验地导致简单而有效地将个人游泳者从一个组中分类出来。这些螺旋桨仅通过频率改变方向的能力增加了控制的可能性，这是螺旋桨2设计的一个例子，在这种设计中，许多应用所需的复杂性直接嵌入到螺旋桨几何中，而不是外部因素，如驱动序列。
Synthetic microswimmers mimicking biological movements at the microscale have been developed in recent years. Actuating helical magnetic materials with a homogeneous rotating magnetic field is one of the most widespread techniques for propulsion at the microscale, partly because the actuation strategy revolves around a simple linear relationship between the actuating field frequency and the propeller velocity. However, the full control of the swimmers' motion has remained a challenge. Increasing the controllability of micropropellers is crucial to achieve complex actuation schemes that in turn are directly relevant for numerous applications. The simplicity of the linear relationship though limits the possibilities and flexibilities of swarm control. Using a pool of randomly-shaped magnetic microswimmers, we show that the complexity of shape can advantageously be translated into enhanced control. In particular, directional reversal of sorted micropropellers is controlled by the frequency of the actuating field. This directionality change is linked to the balance between magnetic and hydrodynamic forces. We further show an example how this behavior can experimentally lead to simple and effective sorting of individual swimmers from a group. The ability of these propellers to reverse swimming direction solely by frequency increases the control possibilities and is an example for propeller 2 designs, where the complexity needed for many applications is embedded directly in the propeller geometry rather than external factors such as actuation sequences.