Collaborative Research: Non-Antiperiodic Nonlinear Electrophoresis (NANEP): Towards Novel Separations of Anisotropic Particles Using Optimized Voltage Waveforms

The movement of electrically charged particles in a water solution containing dissolved salt under an applied voltage is called electrophoresis. Methods for sorting and separating small target particles, from polymers to microbes, often employ electrophoresis. Traditional electrophoretic techniques usually employ low voltages and, consequently, often struggle to separate particles that have similar electrical charges but different physical shapes. This project advances electrophoretic particle motion and separations under stronger voltages. By applying oscillating alternating current voltages of high amplitude and specific waveforms, particle movement can be driven based on subtle differences in physical shape and size, rather than just electrical charge. The project provides the scientific foundation for precise tools capable of isolating biological target particles, driving potential improvements in disease detection and biomanufacturing. Furthermore, the project supports STEM education by providing training and research mentorship for undergraduate and graduate students, thereby strengthening the future scientific workforce. Building upon a successful proof-of-concept for spherical particles, this research develops a comprehensive theoretical and experimental framework for the Non-Antiperiodic Nonlinear Electrophoresis (NANEP) electrokinetic transport of complex, non-spherical particles. The research involves three primary objectives. First, the project characterizes and predicts the NANEP movement of shape-anisotropic particles by employing advanced computational models to solve fully time-dependent, nonlinear electrokinetic equations and validating predictions through precision microfluidic experiments. Second, the project computationally and experimentally optimizes the applied electric field waveforms. By systematically varying frequency ratios and phase shifts, the conditions that maximize net particle drift and control movement direction are identified. Third, the project applies these fundamental findings to develop high-resolution separation technologies based on NANEP. The project demonstrates the selective fractionation of anisotropic synthetic particles and biological cells based on their unique NANEP migration profiles. This award translates a fundamental physical phenomenon into a robust analytical platform, offering a versatile, label-free method to separate complex mixtures that are indistinguishable using traditional linear transport methods. 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.