Magnetic microrollers as a platform for active transport

CBET-1706562PI：Donev，Aleksandar颗粒在粘性液体中的悬浮液在流动中通常表现出不寻常的行为。该奖项将研究在外加磁场中旋转的磁性颗粒的悬浮。颗粒的旋转会在周围的液体中产生流动。研究人员发现，悬浮液中的不稳定会导致颗粒形成松散堆积的聚集体，在磁场的引导下，颗粒可以从悬浮液的其余部分移开。聚集体在移动时保持不变，即使聚集体中的粒子不相互接触。这导致了一种有趣的通过液体传输颗粒的新方法，这种方法可以应用于微流控或芯片实验室系统，在这些系统中，设备的小尺寸往往会限制颗粒相的传输。该奖项将支持研究集合体的产生、运动以及集合体与其在流动中遇到的障碍的相互作用的实验研究。这些实验将得到数值研究的补充，这些研究将有助于解释数据和探索聚集形成和运动的机制。靠近壁面的磁性微粒器的模型系统将被用于探索一种新的主动运输平台。数值模拟将被用来确定预期形成微团聚体的条件。实验将验证聚集体的形成，并展示不同颗粒形状对聚集体形成和传输的影响。为了模拟结构化环境中的流动，将在周期、准周期、自相似和无序图案的图案柱阵列中研究微滚柱的传输。将研究使用微滚轴系统运输胶体货物的可能性。微型滚筒系统的实验和模拟形成了视觉上吸引人的演示，将用于纽约地区中小学生的动手活动。

CBET - 1706562PI: Donev, AleksandarSuspensions of particles in a viscous liquid often exhibit unusual behavior in flow. This award will study suspensions of magnetic particles that rotate in an applied magnetic field. The rotation of the particles induces a flow in the surrounding liquid. The investigators have found that an instability in the suspension leads to the formations of loosely-packed aggregates of the particles, which can move away from the rest of the suspension under guidance from the magnetic field. The aggregates stay intact as they move, even though the particles inside an aggregate do not touch each other. This leads to an interesting new way to transport particles through a liquid that could be applied in microfluidic or lab-on-a-chip systems where the small dimensions of the device often limit transport of particulate phases. This award will support experimental studies to study the generation of the aggregates, their motion, and the interactions of the aggregates with obstacles they encounter in the flow. The experiments will be complemented by numerical studies that will help interpret data and explore the mechanisms of aggregate formation and motion.A model system of magnetic microllers near a wall will be used to explore a new platform for active transport. Numerical simulations will be used to identify conditions under which microroller aggregates are expected to form. Experiments will validate the formation of the aggregates and demonstrate effects of different particle shape on aggregation formation and transport. To simulate flow in a structured environment, microroller transport will be studied in an array of patterned posts in periodic, quasi-periodic, self-similar and disordered patterns. The potential for using the microroller system for transporting colloidal cargos will be investigated. The experiments and simulations of the microroller system form visually appealing demonstrations that will be used in hands on activities for elementary and high school students in the New York area.