Improving device design in insulator-based electrokinetic tertiary separations

•A methodology for designing iEK systems for separating tertiary samples is presented.•The methodology is designed for complex samples, illusterating versatility.•Microchannels with varied shapes and arrangements of insulating posts were explored.•COMSOL model predicted the retention time of particles to identify the best designs.•Experimentally tested channel designs separated tertiary mixtures efficiently. This study presents a methodology for designing effective insulator-based electrokinetic (iEK) systems for separating tertiary microparticle samples, which can be extended to more complex samples. First, 144 distinct iEK microchannel designs were built considering different shapes and arrangements of the insulating posts. Second, a mathematical model was developed with COMSOL software to predict the retention time of each particle type in the microchannel, this allowed identifying the best channel designs for two distinct types of separations: charge-based and sized-based. Third, the experimental charge-based and size-based separations of the tertiary microparticle mixtures were performed employing the improved designs identified with COMSOL modeling. The experimental results demonstrated successful separation in terms of separation resolution and good agreement with COMSOL predictions. The findings from this study show that the proposed method for device design, which combines mathematical modeling with varying post shape and post arrangement is an effective approach for identifying iEK systems capable of separating complex microparticle samples. [Display omitted]