Collaborative Research: Precise and Dexterous Single-Particle Manipulation Using Non-uniform AC Magnetic Fields

液体环境中生物细胞和胶体等单个微粒的高精度操纵是单细胞分析等应用中的关键过程。已经开发了无数种方法来实现这种操作。然而，在实际应用中，很少有人能同时满足所有的要求，如高精度、健壮性、能够沿任意路径移动粒子、低成本和良好的生物兼容性。最近，主要研究人员发现了一种新的粒子操纵方法，即利用非均匀交变磁场驱动各向异性磁团簇，并进一步将其应用于操纵非磁性粒子。与其他磁力操纵方法不同的是，这种方法只需要低频、弱磁场，功率低两个数量级就可以达到相同的过渡速度，整个设置非常划算。然而，这种方法的基本机制尚不清楚，精确控制团簇运动的参数也是未知的。该项目旨在解决这一挑战，从而创造一种精确、灵巧、低成本和生物兼容的操纵单个颗粒的方法。该项目有可能实现更好的单细胞分析，并使研究和教育界更容易进行这种分析，从而产生巨大的科学和社会影响。该项目包括涉及不同种族背景的本科生和地区K-12学生的教育项目。该项目的发现将向技术人员和普通读者传播。该项目的目标是通过两个具体目标来理解、完善和应用新发现的磁粒子驱动方法：(1)了解使用非均匀交变磁场驱动单个磁粒子的过程；(2)通过驱动单个磁粒子来研究非磁性粒子的操纵。这些目标将通过将磁性颗粒的制备、液体中颗粒动力学的实验表征和多物理模拟相结合来实现。这些跨学科的活动将受益于佐治亚大学和弗吉尼亚理工大学的两个研究小组的协同合作，这两个研究小组在材料合成、仪器以及低雷诺数流动中粒子输运的实验和计算研究方面具有丰富的合作历史和专业知识。该项目的结果将为有效设计操纵单个粒子和细胞的系统提供理论基础和实践指导。该项目还将在液体环境中磁性颗粒的动力学和低雷诺数流动中颗粒的流体动力驱动方面创造新的知识，从而同时为磁驱动、流体动力学、颗粒组装和生物技术领域做出贡献。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

High-precision manipulation of single micro-particles such as biological cells and colloids in the liquid environment is a critical process in applications such as single-cell analysis. A myriad of methods has been developed to achieve such manipulation. However, few of them can simultaneously meet all the requirements in practical applications, e.g., high precision, robustness, ability to move particles along arbitrary paths, low cost, and good biocompatibility. Recently the principal investigators discovered a new kind of particle manipulation method, i.e., using non-uniform alternating magnetic fields to actuate an anisotropic magnetic cluster and further applying the actuated cluster to manipulate nonmagnetic particles. Unlike other magnetic manipulation methods, this method requires only low-frequency, weak magnetic fields, and two orders of magnitude less power to achieve the same transitional speed, and the entire setup is extremely cost-effective. However, the fundamental mechanisms underlying this method are not clear and the parameters to precisely control the cluster motion are unknown. This project seeks to resolve this challenge and thus to create a precise, dexterous, low-cost, and biocompatible method for manipulating single particles. The project can potentially enable better single-cell analysis and make such analysis more accessible to research and educational communities, thereby creating great scientific and societal impact. The project includes education programs involving undergraduate students with diverse ethnical backgrounds and regional K-12 students. Discoveries from the project will be disseminated to technical as well as general audiences.The objective of this project is to understand, prefect, and apply the newly discovered magnetic particle actuation method through two specific aims: (1) to understand the actuation of single magnetic particles using non-uniform alternating magnetic fields; (2) to investigate nonmagnetic particle manipulation through the actuation of single magnetic particles. These aims will be achieved by integrating magnetic particle fabrication, experimental characterization of particulate dynamics in liquids, and multiphysics simulations. These interdisciplinary activities will benefit from the synergistic collaboration of the two research teams at University of Georgia and Virginia Tech, which have a fruitful history of collaboration and demonstrated expertise in material synthesis, instrumentation, and experimental and computational studies of particle transport in low-Reynolds number flows. The results from this project will provide both the theoretical basis and practical guidelines for the effective design of systems to manipulate single particles and cells. This project will also create new knowledge on the dynamics of magnetic particles in liquid environments and hydrodynamic actuation of particles in low-Reynolds number flows, thereby simultaneously contributing to the fields of magnetic actuation, fluid dynamics, particle assembly, and biotechnology.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.