Magnetic microrollers as a platform for active transport

CBET - 1706562PI：Donev，Aleksandar 粘性液体中的颗粒悬浮液通常在流动中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悬浮液。 颗粒的旋转引起周围液体的流动。 研究人员发现，悬浮液中的不稳定性会导致形成松散堆积的颗粒聚集体，这些颗粒可以在磁场的引导下远离悬浮液的其余部分。 即使聚集体内部的颗粒不相互接触，聚集体在移动时仍保持完整。 这带来了一种通过液体传输颗粒的有趣新方法，该方法可应用于微流体或芯片实验室系统，在这些系统中，设备的小尺寸通常限制颗粒相的传输。 该奖项将支持实验研究，以研究聚集体的生成、它们的运动以及聚集体与它们在流动中遇到的障碍物的相互作用。 这些实验将得到数值研究的补充，这将有助于解释数据并探索聚集体形成和运动的机制。靠近墙壁的磁性微球模型系统将用于探索主动运输的新平台。 数值模拟将用于确定微辊聚集体预期形成的条件。 实验将验证聚集体的形成，并证明不同颗粒形状对聚集体形成和运输的影响。 为了模拟结构化环境中的流动，将在周期性、准周期性、自相似和无序模式的图案化柱阵列中研究微滚子传输。 将研究使用微滚轮系统运输胶体货物的潜力。 微滚轮系统的实验和模拟形成了具有视觉吸引力的演示，将用于纽约地区中小学生的实践活动。

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.