Buoyant magnetic milliswimmers reveal design rules for optimizing microswimmer performance
Buoyant magnetic milliswimmers reveal design rules for optimizing microswimmer performance
复制标题
浮力磁性微型游泳器揭示了优化微型游泳器性能的设计规则
DOI：
10.1039/d3nr02846a
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发表时间：
2023
期刊：
影响因子：
6.7
通讯作者：
Taylor, Rebecca E.
中科院分区：
文献类型：
--
作者：
Benjaminson, Emma;Imamura, Taryn;Lorenz, Aria;Bergbreiter, Sarah;Travers, Matthew;Taylor, Rebecca E.
磁致动游泳微型机器人是一种新兴的工具，导航和操纵材料在有限的空间。最近的工作表明，有可能在微米和纳米尺度上使用聚合物微球，磁性颗粒和DNA纳米技术建立这样的系统。然而，虽然这些材料能够以前所未有的能力小规模构建，但此类系统通常表现出由材料变化和组装过程本身引起的显著多分散性。这种可变性使得很难预测，更不用说优化，从设计参数，如链接形状或纵横比的方向或幅度的微型游泳器速度。为了将游泳者的设计问题与其物理尺寸的变化隔离开来，我们提出了一种新的实验平台，使用双光子聚合来构建具有完全可定制的形状和集成的柔性连接器的双链接，浮力milliswimmer（游泳者是欠驱动的，能够实现不对称的周期运动和净平移）。我们的方法使我们能够控制游泳方向和游泳运动员的表现的可重复性。这些研究提供了地面实况数据，揭示了一阶和二阶模型目前都没有捕捉到milliswimmer性能的关键特征。因此，我们使用我们的实验平台来制定调整游泳速度的设计指南，我们确定了以下三种提高速度的方法：（1）针对固定的纵横比调谐致动频率，（2）在给定期望的操作频率范围的情况下调节纵横比，以及（3）使用我们测试的值中的较弱的连接件刚度值，同时仍然保持链路之间的鲁棒连接。我们还发现，实验中，球形的两个链接的游泳者与不同的链接直径实现净速度与游泳者与圆柱形链接，但两个链接的球形游泳者相同的直径不。
Magnetically-actuated swimming microrobots are an emerging tool for navigating and manipulating materials in confined spaces. Recent work has demonstrated that it is possible to build such systems at the micro and nanoscales using polymer microspheres, magnetic particles and DNA nanotechnology. However, while these materials enable an unprecedented ability to build at small scales, such systems often demonstrate significant polydispersity resulting from both the material variations and the assembly process itself. This variability makes it difficult to predict, let alone optimize, the direction or magnitude of microswimmer velocity from design parameters such as link shape or aspect ratio. To isolate questions of a swimmer's design from variations in its physical dimensions, we present a novel experimental platform using two-photon polymerization to build a two-link, buoyant milliswimmer with a fully customizable shape and integrated flexible linker (the swimmer is underactuated, enabling asymmetric cyclic motion and net translation). Our approach enables us to control both swimming direction and repeatability of swimmer performance. These studies provide ground truth data revealing that neither the first order nor second order models currently capture the key features of milliswimmer performance. We therefore use our experimental platform to develop design guidelines for tuning the swimming speeds, and we identify the following three approaches for increasing speed: (1) tuning the actuation frequency for a fixed aspect ratio, (2) adjusting the aspect ratio given a desired range of operating frequencies, and (3) using the weaker value of linker stiffness from among the values that we tested, while still maintaining a robust connection between the links. We also find experimentally that spherical two-link swimmers with dissimilar link diameters achieve net velocities comparable to swimmers with cylindrical links, but that two-link spherical swimmers of equal diameter do not.