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

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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.