Actuated Post Arrays for Integrated Studies of Pumping, Mixing and Free Swimmers

了解流动是如何由微致动器产生和控制的，对于基础流体物理学、微流体技术和微机器人具有重要意义。由纤毛产生的微观流动是生物学的核心；例子包括肺粘膜纤毛清除，受精卵沿输卵管到子宫的纤毛运输，以及细菌和原生动物的推进。作为微流体技术开发的这些结构的工程模拟为混合器，泵和血液凝固诊断中的微流体流变传感器的微尺度运输提供了独特的解决方案。在这个项目中，光刻成型的仿生纤毛表面将用于研究泵送和混合的基本问题。吸取的经验教训将用于设计和控制纤毛游泳者，即仿生草履虫。本项目有三个主要目标：低雷诺数流体的泵送、混合和游动。从泵送开始，该项目将研究执行器阵列产生流动的方式。使用设计的阵列和驱动策略，该项目将使用类似驱动器几何形状的阵列，并比较不同策略在打破运动时间对称性方面的效用。使用相同的阵列，该项目将在执行器（对，阵列等）之间产生协调的时间不对称节拍，单个执行器中的时间不对称节拍，以及时间不对称扩展到数十个执行器的超时向波。将研究这些流动的性质，以了解长距离流体运动的长度尺度和混合，其中一部分可能发生在短长度尺度上。接下来，该项目将使用阵列来专注于混合。在低雷诺数的微流体系统中，流体不能支持湍流，因此混合是扩散受限的。该项目将确定提供高混合的加热执行器的参数。最后，该项目将制造不受束缚的自由游泳者。控制表面附着结构定向流产生的设计规则直接转移到游泳体设计中。这样，该项目将完全关闭流体泵送和游泳者推进之间的循环。总的来说，该研究项目将为更好的生物医学诊断设计驱动表面，并为未来的植入式治疗策略设计微型机器人。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

An understanding of how flows are produced and controlled by microactuators is of significant interest for fundamental fluids physics, for microfluidics technologies and for microrobotics. Microscopic flows generated by cilia are central to biology; examples include muco-ciliary clearance in the lung, ciliary transport of the fertilized ovum along the fallopian tube to the uterus, and the propulsion of bacteria and protozoa. Engineered mimics of these structures developed as microfluidic technologies offer unique solutions for transport at the microscale for mixers, pumps and as microfluidic rheological sensors in blood clotting diagnostics. In this project, photolithographically molded biomimetic ciliated surfaces will be used to investigate fundamental questions pumping and mixing. The lessons learned will be used to design and control ciliated swimmers, i.e. biomimetic paramecia.This project has three goals focused on pumping, mixing, and swimming in low Reynolds number fluid. Starting with pumping, the project will study the ways in which arrays of actuators can generate flows. Using designed arrays and actuation strategies, the project will use arrays of similar actuator geometry and compare the utility of different strategies for breaking time symmetry of motion. Using the same arrays, the project will generate coordinated time-asymmetric beats between actuators (pairs, arrays, etc.), time asymmetric beats in single actuators, and metachronal waves where the time-asymmetry extends over tens of actuators. The nature of these flows will be studied to understand the length scale of long-range fluid motions and for mixing, which in part may occur on short length scales. Next, the project will use the arrays to focus on mixing. In the low Reynolds number of microfluidics systems, fluids cannot support turbulence and therefore mixing is diffusion limited. The project will identify the parameters of beating actuators that provide high mixing. Finally, the project will fabricate free swimmers that will be untethered. The design rules that govern the generation of directed flow for surface attached structures directly transfer to swimmer design. In this way, the project will completely close the loop between fluid pumping and swimmer propulsion. In total, the research program will design actuating surfaces for better biomedical diagnostics and design micro-robotics for future implantable treatment strategies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.