Authors: R-J Yang, C-C Chang, S-B Huang and G-B Lee
Affilation: National Cheng Kung University, Taiwan
Pages: 612 - 615
Keywords: microfluidics, injection, focusing, switching
This paper presents an investigation on hydrodynamic/electrokinetic focusing and switching, which are crucial for microfluidic applications. The hydrodynamic/electrokinetic focusing phenomenon is first theoretically modeled by employing a potential flow theory, and this simple theoretical model is further applied to predict the width of the focused stream. Data predicted by the new theoretical model are in good agreement with experimental and numerical results as shown in Fig. 1. Hydrodynamic and electrokinetic switching is then systematically investigated experimentally and numerically. A simple control model for electrokinetically pre-focused micro flow switches is also proposed. Using this model, the sample flow can be pre-focused electrokinetically into a narrow stream and is then injected directly to desired outlet ports. Figure 2 shows the schematic design of a microfluidic chip and the experimental and numerical results are shown in Figure 3. This study provides a systematical study on analogy of hydrodynamic and electrokinetic focusing/switching and could provide a useful tool for analysis of flow control in microfluidic devices.