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

了解微致动器如何产生和控制流动对于基础流体物理学、微流体技术和微机器人学具有重要意义。纤毛产生的微观流动是生物学的核心;例子包括肺中的粘膜纤毛清除，受精卵沿着输卵管沿着到子宫的纤毛运输，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物为混合器，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，仿生纤毛表面将被用于研究泵送和混合的基本问题。本计画的目标是在低雷诺数流体中进行泵送、混合及游动。从泵送开始，该项目将研究致动器阵列产生流动的方式。使用设计的阵列和驱动策略，该项目将使用类似的致动器几何形状的阵列，并比较不同策略的效用，打破运动的时间对称性。使用相同的阵列，该项目将在致动器（对，阵列等）之间产生协调的时间不对称节拍，单个致动器中的时间不对称节拍，以及时间不对称性在数十个致动器上延伸的异时波。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，这部分可能发生在短的长度尺度上。接下来，该项目将使用数组来专注于混合。在低雷诺数的微流体系统中，流体不能支持湍流，因此混合受到扩散限制。该项目将确定提供高混合的打浆致动器的参数。最后，该项目将制造自由游泳者，将不受束缚。控制表面附着结构产生定向流的设计规则直接转移到游泳者设计中。通过这种方式，该项目将完全关闭流体泵送和游泳者推进之间的回路。总的来说，该研究计划将设计驱动表面，以更好地进行生物医学诊断，并设计微型机器人，为未来的植入式治疗策略。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的知识价值和更广泛的影响审查标准的支持。

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.