Topological transport of magnetic colloids on non-periodic patterns

非周期图案上磁性胶体的拓扑输运

• 批准号: 531559581
• 负责人: Professor Dr. Thomas Martin Fischer
• 金额: --
• 依托单位: Lehrstuhl für Experimentalphysik V
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/531559581?language=en
• 关键词: Topological; transport; magnetic; colloids; non

This project aims at understanding and controlling the transport of magnetic colloidal particles above non-periodic magnetic patterns. We have ample experience studying transport in periodic patterns. There, the colloidal particles are located above the periodic pattern and are driven by an external magnetic field. The external magnetic field is uniform in space and its orientation changes in time. We perform closed loops of the orientation of the field, such that the orientation returns to the initial value after completion of one loop. Loops that wind around special orientations are topologically nontrivial and induce transport of the colloidal particles. Once the loop returns to its initial position, the particle has been transported by one unit cell of the pattern. The transport is topologically protected since it depends only on a set of topological invariants: the winding numbers of the loop around the special orientations. Due to the topological protection, the transport is robust against perturbations. This allow us to e.g. transport simultaneously a collection of different particles (e.g. colloidal rods of different lengths) along different directions. However, due to the periodicity of the pattern, we have no control over the relative position of the particles above the pattern. That is, two identical particles are transported along the same direction independently of their position above the pattern. In this combined theoretical and experimental proposal, we will study transport in non-periodic patterns. We will create patterns in which the local symmetry, the orientation, and the size of the lattice vectors depend on the space coordinates. By doing so, we will be able to control the direction and the speed of the transport as a function of the position of the particle above the pattern. We will design patterns and modulation loops that can transport identical particles along different trajectories, depending on the position of the particles above the pattern. We will also be able to transport colloidal particles from an initially unknown position to a well defined location above the pattern. From such location it will be possible to induce an arbitrarily complex trajectory on the colloidal particle. The complexity of the transport will be encoded in both the pattern and the modulation loop. For example, we will design patterns with cloaked regions that the particles will automatically avoid during their trajectories. Such cloaked regions could be used as structural elements in lab-on-a-chip devices.

本项目旨在了解和控制磁性胶体粒子在非周期磁模式上的输运。我们有研究周期性输运的丰富经验。在那里，胶体颗粒位于周期图案上方，并由外部磁场驱动。外磁场在空间上是均匀的，其方向随时间而变化。我们对字段的方向执行闭合循环，使方向在完成一个循环后返回到初始值。缠绕在特殊方向上的环在拓扑上是非平凡的，并诱导胶体粒子的输运。一旦循环回到它的初始位置，粒子就被图案的一个单元格传送了。传输在拓扑上是受保护的，因为它只依赖于一组拓扑不变量：特殊方向周围环路的圈数。由于拓扑保护，传输对微扰具有鲁棒性。这允许我们沿不同方向同时传输不同的粒子（如不同长度的胶体棒）。然而，由于图案的周期性，我们无法控制图案上方粒子的相对位置。也就是说，两个相同的粒子沿着相同的方向传输，与它们在图案上方的位置无关。在这个结合理论和实验的建议中，我们将研究非周期模式的输运。我们将创建图形，其中局部对称性、方向和晶格向量的大小取决于空间坐标。通过这样做，我们将能够将传输的方向和速度作为粒子在图案上方位置的函数来控制。我们将设计模式和调制回路，可以沿着不同的轨迹传输相同的粒子，这取决于粒子在模式上方的位置。我们还将能够将胶体颗粒从最初未知的位置运输到图案上方的明确位置。从这样的位置，将有可能在胶体粒子上诱导出任意复杂的轨迹。传输的复杂性将在模式和调制环路中编码。例如，我们将设计带有隐藏区域的图案，粒子将在其轨迹中自动避开这些区域。这种隐形区域可以用作芯片实验室设备的结构元件。