Collaborative Research: Shepherding Biomedical Microswimmers Using Magnetic Fields

生物医学微型机器人有可能被功能化，在体内进行治疗，如化疗和热疗，这些治疗的目标是在一个小区域内，以避免对周围健康组织的损害，并避免副作用。这些“微型机器人”很可能是没有计算智能的微型结构，它们在患者体内由体外产生的磁场控制。到目前为止，关于磁性微型机器人的大部分工作都集中在微型游泳者身上，这种微型游泳者使用螺旋螺旋桨，通过一种受细菌启发的方法游泳。然而，到目前为止，有希望的实验室结果利用了少量的微泳者，并依赖于相机等成像技术来跟踪单个微游者，这在医学应用中是不现实的。该奖项支持基础研究，以便在没有足够分辨率的医学图像来跟踪单个微泳者的情况下，能够以复杂的方式控制成群的微泳者。这一奖项的结果将是使微创生物医学微型机器人更接近临床现实的知识。该奖项还将为研究生和本科生提供研究机会，并将扩大未被充分代表的群体在工程教育中的参与。这项研究将检验这样一个猜想，即在没有个体本地化的情况下，磁力微泳者在旋转磁偶极子磁场中的内在动力学使其有可能引导一群微泳者。借用“牧羊人”一词是因为牧羊人的意图是执行与放羊时相同类型的任务。其目标是开发基本的操作基元，例如“将聚集的蜂群移动到一个位置”、“分散蜂群”、“将蜂群聚集在一起”和“将蜂群分成较小的蜂群并将它们移动到不同的位置”。具体任务包括：对单个游泳者的动态进行建模；描述假定相同且不相互作用的游泳者的牧羊人控制基元；表征利用群体内种群变化的牧羊人控制基元；对游泳者之间的磁力和流体动力相互作用进行建模；以及综合上述效应的相对贡献，以使复杂的牧羊人动作能够与实际的磁性微泳者群进行。

Biomedical microrobots have the potential to be functionalized to perform therapies in the body, such as chemotherapy and hyperthermia, which are targeted in a small region to avoid damage to healthy surrounding tissue and to avoid side-effects. These "microrobots" are likely to be microstructures with no computational intelligence on board, which are controlled within the patient's body by magnetic fields generated outside the body. Much of the work on magnetic microrobots to date has focused on microswimmers that use a helical propeller to swim using a method inspired by bacteria. However, promising laboratory results to date have utilized small numbers of microswimmers and have relied on imaging techniques such as cameras to track individual microswimmers, which is not practical for medical applications. This award supports fundamental research to enable swarms of microswimmers to be controlled in a complex fashion, in the absence of medical images with enough resolution to track individual microswimmers. The outcome of this award will be knowledge that will bring minimally invasive biomedical microrobots one step closer to clinical reality. The award will also provide research opportunities for graduate and undergraduate students, and will broaden participation of underrepresented groups in engineering education.This research will test the conjecture that the inherent dynamics of magnetic microswimmers in rotating magnetic dipole fields make it possible to shepherd a swarm of microswimmers in the absence of localization of individuals. The term "shepherding" is borrowed because the intent is to perform the same type of tasks that would be done when herding sheep. The goal is to develop basic manipulation primitives such as "move the aggregate swarm to a location,"spread out the swarm," "gather the swarm together," and "split the swarm into smaller swarms and move them to separate locations." Specific tasks include: modeling the dynamics of single swimmers; characterizing shepherding control primitives assuming identical and non-interacting swimmers; characterizing shepherding control primitives that take advantage of population variation within a swarm; modeling magnetic and hydrodynamic interactions between swimmers; and synthesizing the relative contribution of the above effects to enable complex shepherding maneuvers with actual swarms of magnetic microswimmers.