Numerical simulation of electrokinetic injection techniques in capillary electrophoresis microchips

The effective design and control of a capillary electrophoresis (CE) microchip requires a thorough understanding of the electrokinetic transport phenomena associated with its microfluidic injection system. The present study utilizes a numerical simulation approach to investigate these electrokinetic transport processes and to study the control parameters of the injection process. Injection systems with a variety of different configurations are designed and tested, including the cross‐form, T‐form, double‐T‐form, variable‐volume focused flow cross‐form, and variable‐volume triple‐T‐form configuration. Each injection system cycles through a predetermined series of steps in which the magnitudes and distributions of the applied electric field are precisely manipulated in order to effectuate a virtual valve. This study investigates the sample leakage effect associated with each of the injection configurations and applies the double‐L, pullback, and focusing injection techniques to minimize the sample leakage effect. The injection methods presented in this paper have the exciting potential for use in high‐quality, high‐throughput chemical analysis applications and throughout the micro‐total‐analysis systems field.