Optimizing the microchannel geometry for effective control of analyte band dispersion

Abstract

Managing analyte band dispersion is a critical challenge in diagnostic systems, medical spectroscopy, chromatography, and drug delivery devices. Effective dispersion control ensures reliable measurements, enhanced resolution, heightened sensitivity, and improved system performance. This study emphasizes the importance of optimizing microchannel geometries, particularly curvature sections, to effectively control analyte band dispersion. To achieve this, four microchannel geometries, namely Type I to Type IV, each with distinct curvature differences, were analyzed to identify the optimal geometry with the lowest dispersion. Key parameters, including wall zeta potential, applied voltage, and the internal-to-external curvature radius ratio, were examined for their influence on dispersion. The finite element method was employed to solve the Laplace and Navier-Stokes equations for electric field and velocity distributions, while the unsteady-state diffusion-convection equation determined analyte concentration profiles. Results showed that dispersion reductions after optimization were 60 % for Type II, 48 % for Type III, and 32 % for Type IV microchannels, nevertheless for Type I microchannel dispersion remain constant after and before optimization about 70 %. Increasing the zeta potential from ζ = -0.1 V to ζ = -0.5 V led to a significant rise in dispersion from 25 % to 90 % post-optimization. Conversely, adjusting the curvature ratio R_r from 0.1 to 0.5 decreased dispersion from 42 % to 15 %. These findings underscore the importance of precise dispersion control in advancing analytical systems such as lab-on-disk and lab-on-chip technologies. This research provides valuable insights for optimizing microchannel designs to enhance the performance and reliability of various analytical and diagnostic applications.