Measurements of electrophoretic mobility and size of a single particle using a novel microfluidic device based on electrophoresis

Description:
Characterization of a diverse range of particles, including biological, inorganic, and organic are essential in different fields. However, the heterogeneity of particles makes their characterization challenging. Electrophoretic mobility is a key parameter in particle characterization as it is dependent on particle’s physical properties, including size, shape, and the charge. Yet, accurate determination of electrophoretic mobility of a single particle in micro to nano sizes remains a difficult task. In this work, a simple microfluidic device with a single microchannel is used to measure the electrophoretic mobility and size of a single particle based on electrophoresis. A trajectory of every particle is analyzed using a particle tracking analysis (PTA) technique. Mean diameters of 0.53, 1, and 2 µm carboxyl functionalized polystyrene particles are used in this study and their electrophoretic mobilities and sizes are determined simultaneously. The dependence of the accuracy of the measured electrophoretic mobilities on the variation of the electric field within the channel, bulk flow velocity, and the center detection algorithm will be reported. Therefore, each factor is investigated further to improve the accuracy of the electrophoretic mobility measurements. For example, to improve the center detection of the particles, a good signal-to-noise (S/N) ratio is achieved with a high-powered illumination source and an optimal exposure time. Furthermore, a comparison between a simple theoretical model and the experimental trajectories shows a good agreement. This novel device is expected to improve the measurement of the electrophoretic mobility of individuals particles ranging from 10 µm to 100 nm in size.

Speaker: M. Hannah Choi - University of Pennsylvania
Hannah Choi is a PhD student at University of Pennsylvania in the Bioengineering department. She received her master’s and bachelor’s degree in Biomedical engineering at Saint Louis University. Her current research focuses on fabrication of microfluidic devices using various photolithography methods and utilizing these devices for particle characterization. Other research areas of interest include capillary electrophoresis and studying electrophoresis-based techniques.