Microscale propulsion and pumping in complex fluids

仿生合成游泳微生物（微游泳者）的发展为需要非常小尺度的广泛潜在应用打开了大门。这些微型游泳者可用于进行内部手术或人体药物输送，用作自主漫游化学传感器，甚至用于微型组装。锚定的微型游泳者可以充当微型泵，模仿自然界中的纤毛，这是一种在细胞尺度上进行运输和混合的非常有效的方法。设计这些合成微型游泳器和微型泵的一个困难在于，如此小尺度的流体物理学与日常可观察到的现象有着根本的不同，而且往往很不直观。在这些尺度上，粘性力占主导地位，惯性可以忽略不计，因此熟悉的运动和抽水方法可能完全无效。在设计这些用于工业或生物应用的微型装置时，一个特别的挑战是相关流体通常是非牛顿流体。尽管在制造这些仿生装置方面取得了创新的实验进展，但科学必须取得进步，才能正确地表征它们在复杂系统和流体中的力学特性。如果这些设备要从简单的概念验证发展到工业和商业可行性，开发这种理解是至关重要的，并且对于医疗保健中的应用至关重要。本文建议在复杂流体和系统中开发合成微游泳者和微泵的力学研究计划，包括流体可能包含微观结构的情况，以及许多游泳者的相互作用（集体运动）可能至关重要的情况。

The development of biomimetic synthetic swimming microorganisms (micro-swimmers), opens the door to a wide spectrum of potential applications where very small scales are required. These micro-swimmers could be used to perform internal surgery or drug delivery in the human body, used as autonomous roving chemical sensors or even for microscale assembly. An anchored micro-swimmer can act as a microscale pump, mimicking cilia found in nature, a very effective method for transport and mixing at the cellular scale. A difficulty in the design of these synthetic micro-swimmers and micro-pumps is that the physics of fluids at such small scales is fundamentally different than that of everyday observable phenomena and often quite unintuitive. At these scales viscous forces are dominant and inertia is negligible hence familiar methods of locomotion and pumping can be completely ineffective. A particular challenge in the design of these micro-devices for use in industrial or biological applications is that the relevant fluids are often non-Newtonian. Despite the innovative experimental strides being made in fabricating these biomimetic devices, scientific progress must be made to properly characterize their mechanics in complex systems and fluids. Developing this understanding is critical if these devices are to progress from simply a proof-of-concept to industrial and commercial viability, and it is vital for applications in healthcare. It is proposed here to develop a research program on the mechanics of synthetic micro-swimmers and micro-pumps in complex fluids and systems, including scenarios where the fluid may contain microstructure, and where the interaction of many swimmers (collective motion) may be crucial.