Harnessing nonlinear electrokinetic effects for microparticle identification and separation in microfluidic devices

便携式实验室，也被称为芯片实验室系统，能够在一个设备中执行多种分析，可以很容易地放在你的手中。微流体技术是一种对非常小体积液体的控制技术，它使芯片实验室设备成为可能。小型化支持可移植性和可访问性，并缩短了分析时间。要使便携式微流体装置工作，必须在装置中实施分离和分析方法。尽管用于分析纳米级颗粒（如蛋白质分子）的高效和稳健的分离技术已成功地用于微流控装置，但用于分离和分析更大的微米级颗粒（如微生物）的类似技术还不可用。该项目将研究电场或电动力学的使用，用于分离和分析微流体装置内微米大小的颗粒。通过分析微粒的迁移，可以识别微粒类型并分离微粒混合物。最近的报道表明，第二类电泳的非线性电动力学（EK）现象是影响绝缘子基EK （iEK）体系中微珠和微生物电迁移的主要因素。这些发现揭示了微尺度电动力学领域的重大变化，彻底改变了整个研究领域；多年来，人们认为介电现象是这些体系的主导效应。本项目的重点是利用这一新知识来理解线性和非线性EK效应下的粒子电迁移，并将非线性EK现象与色谱理论原理相结合，开发一种新的分离技术。通过数学建模和实验，建立了非线性电动色谱新技术的理论和基本方程。这些方程将微粒的不同EK迁移率与分离性能参数（如颗粒保留时间和分离分辨率）联系起来。该项目将通过开发一种利用非线性EK效应的新技术，推动微尺度电动力学的发展。本项目将为本科生和研究生提供研究机会，并将通过“工程中的女性”项目协助为女学生提供研究机会。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。

Portable laboratories, also known as lab-on-a-chip systems, are capable of performing multiple analyses in a device that will easily fit in your hand. Microfluidics, which is the manipulation of very small volumes of liquid, is what makes lab-on-a-chip devices possible. Miniaturization enables portability and accessibility and shortens analysis time. For portable microfluidic devices to work, separation and analytical methods must be implemented in the devices. Although efficient and robust separation techniques for analyzing nano-sized particles, such as protein molecules, have been successfully used in microfluidic devices, similar techniques for the separation and analysis of larger micron-sized particles, such as microorganisms, are not available. This project will investigate the use of electric fields, or electrokinetics, for separating and analyzing micron-sized particles inside a microfluidic device. By analyzing this migration of particles, it is possible to identify the microparticle type and to separate mixtures of microparticles. Recent reports have revealed that the nonlinear electrokinetic (EK) phenomenon of electrophoresis of the second kind is a dominant effect on the electromigration of beads and microorganisms in insulator-based EK (iEK) systems. These findings unveiled a major change in the field of microscale electrokinetics that revolutionized this entire research area; for many years it was believed that the phenomenon of dielectrophoresis was the dominant effect in these systems. This project focuses on using this new knowledge to understand particle electromigration under linear and nonlinear EK effects and develop a new separation technique that combines nonlinear EK phenomena with the principles of chromatographic theory. By using mathematical modeling and experimentation, the theory and basic equations of the new technique of nonlinear electrokinetic chromatography will be developed. These equations will relate the distinct EK mobilities of the microparticles to separation performance parameters such as particle retention time and separation resolution. The project will advance the state of the art in microscale electrokinetics by developing a new technique that exploits nonlinear EK effects. The present project will provide a research opportunity for undergraduate and graduate students, and will also assist in providing research opportunities for female students through the Women in Engineering programs.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.