Flagellated and Ciliated Microswimmers

有鞭毛和纤毛的微型游泳者

• 批准号: 254575174
• 负责人: Dr. Jens Elgeti
• 金额: --
• 依托单位: Forschungszentrum Jülich
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/254575174?language=en
• 关键词: Flagellated; Ciliated; Microswimmers

Eukaryotic microswimmers often propel themselves with cilia, hair-like structures that perform a whip-like motion to propel fluid parallel to the cell surface, or with flagella, filament-like structures that display a snake-like motion. In fact, eukaryotic cilia and flagella have essentially the same underlying structure and active protein machinery. From unicellular Chlamydomonas to multicellular Volvox, microswimmers of many length scales use two to thousands of cilia to swim through the fluid. For flagellated microswimmers, sperm is a paradigmatic example.In the previous grant period, we have studied theoretically and numerically (“in silico'') the dynamics of sperm cells in strong confinement of structured, zigzag-shaped, microfluidic channels, as well as the dynamics of the flagellar beat of sperm tethered to a surface. The deflection angle of sperm swimming around corners in microchannels agrees well with experimental results. Furthermore, the simulations reveal an important role of the beat pattern. The analysis of the beat pattern of tethered sperm reveals a significant contribution of a second-harmonic frequency, which turns out to be important for steering. For multi-ciliated microswimmers, we find a complex dynamical behavior which is affected by the flow field around the body, and the cilia arrangement. In the next grant period, we plan to study theoretically and numerically the sperm motion in complex geometries and with different beat patterns. In particular, we will explore the consequences of a second harmonic frequency and the beat amplitude for the resulting motion in three dimensions, in chemical gradients, and in confined geometries.Furthermore, we plan to simulate multi-ciliated microswimmers, similar to Volvox algae. Recent experiments and preliminary simulation results indicate a strong dependence of metachronal coordination on mechanical anchoring of the cilia. Importantly, the swimming properties of a multi-ciliated microswimmer seem to strongly depend on its metachronal coordination. We will simulate multi-ciliated microswimmers with different types of cilia anchoring, and with both controlled and self-organized metachronal coordination. Key questions are the direction and persistence of swimming, but also pair- interactions and collective behavior of several such microswimmers.

真核微泳者通常用纤毛推动自己，毛发状结构执行鞭子状运动以推动流体平行于细胞表面，或者用鞭毛，表现出蛇状运动的顺从性结构。事实上，真核生物的纤毛和鞭毛具有基本相同的基本结构和活性蛋白质机制。从单细胞的披衣藻到多细胞的团藻，许多长度尺度的微泳者使用两到数千根纤毛在液体中游动。对于有鞭毛的微泳者，精子是一个典型的例子。在前一个资助期，我们已经研究了理论和数值（“在硅片”）的精子细胞的动力学结构化的强限制，橡皮囊形，微流体通道，以及精子的鞭毛节拍拴在一个表面的动力学。精子在微通道中绕角游动的偏转角度与实验结果吻合。此外，模拟揭示了节拍模式的重要作用。拴系精子的节拍模式的分析揭示了一个显着的二次谐波频率的贡献，这是很重要的转向。对于多纤毛微泳者，我们发现了一个复杂的动力学行为，它受到周围流场和纤毛排列的影响。在下一个资助期内，我们计划从理论和数值上研究精子在复杂几何形状和不同节拍模式下的运动。特别是，我们将探讨的后果，第二谐波频率和拍振幅的三维运动，在化学梯度，并在密闭的geometris.Further，我们计划模拟多纤毛microswimmers，类似团藻。最近的实验和初步的模拟结果表明，机械锚定的纤毛异时协调的强烈依赖。重要的是，多纤毛微泳者的游泳特性似乎强烈依赖于其异时协调。我们将模拟多纤毛microswimmer与不同类型的纤毛锚定，并与控制和自组织的异时协调。关键问题是游泳的方向和持续性，以及几个这样的微型游泳者的配对相互作用和集体行为。