摘要
This paper adopts a physical model and a numerical simulation approach to study electrokinetic focusing injection on microfluidic chips. The model reflects the principal material transport mechanisms such as electrokinetic migration, ionic concentration, fluid flow, and diffusion. The current study also involves the design and testing of various injection systems used to deliver a sample plug. A novel double-cross injection system has been developed which uses electrokinetic focusing to achieve variable-volume injection of the sample plug. The injection technique uses a unique sequence of loading steps with different electric potential distributions and potential magnitudes within the various channels to effectuate a virtual valve. The proposed design combines several functions of traditional sample plug injection systems on a single microfluidic chip.