Designing And Preparation Of A Micro-fluidic Chip For Mixing And Preparing Micro-fluidic-columns

Micro-fluidic chip is the key technology of micro-fluidic analysis system. It is applied into the biology sciences, chemical and industry, environmental testing, etc. Mixing is an extremely important process of analysis and testing technology. The fluid in micro-channels has small Reynolds and is laminar flow, fluid mixing is limited in molecular diffusion, so that the mixing intensity is improved greatly. If the fluid mixed in the micro-channels is micro-liquid-columns, the mass transferring in the micro-liquid-columns will strengthen the mixing further. Micro-liquid-column is used to embed solid or liquid drug in order to achieve targeted drug delivery. And it is also used to synthesize the artificial antigen or cells to do immunological research. Micro-liquid-column is the core materials to synthesize the artificial microspheres, and micro-liquid-columns with micro-fluidic chips is one of the most effective ways.A kind of micro-fluidic chip used to mix reagents and prepare micro-liquid-columns is designed in this paper. The micro-fluidic chip is made of a T-shaped micro-channel and a Y-shaped micro-channel. The T-shaped micro-channel is used to prepare micro-liquid-columns. And the Y-shaped micro-channel is used tomix reagents.1. The effects of T-shaped micro-channel structure dimensions on the formation of micro-liquid-columns formed by vertical shear flow were studied via the method of CFD, then the T-shaped micro-channel structure dimensions was optimized. The conclusions of the CFD are given as follows.(1) the parameters affect the forming time of micro-liquid-columns, the order of importance is D2/D1,Z＜β, D1/W1, W2/W1;And for the length, the order is＜β, D2/D1, D1/W1, W2/W1.(2) For the shortest forming time, the optimized parameters of＜β,D2/D1,D1/W1and W2/W1are90°,1.00,1.00and1.60respectively.(3) To get the shortest micro-liquid columns, the optimizedparameters of＜β,D2/D1D1/W1and W2/W1are60°,1.00,1.00and1.60respectively.2. The effects of Y-shaped micro-channel structure dimensions on the mixing strength of reagents were studied via the method of CFD, then the Y-shaped micro-channel structure dimensions was optimized. The conclusions are given as follows.(1) when the fork angle (＜γ) of the Y-shaped micro-channel is60°, the part of the main channel volume reduction ratio (W4/W3) is3.0, the mixing strength of two reagents is the maximum.(2) The micro-structures’dimension at the bottom of Y-shaped micro-channelaffect the mixing strength of reagents, the order of importance is arrangement of micro-structures, shape, line spacing (d2), height (h), the geometry diameter of bottom surface (d1) and row spacing (d3).(3) The optimized parameters of the micro-structures is conical structure arranged in the form of any, the h and d1of each cone are10μm and20μm respectively, the d2and d3of neighboring cones are250μm and40μm respectively.3. The micro-fluidic chips were prepared by different methods, then were measured and compared.Results in this study provide the foundation for preparing micro-liquid-columns and mixing reagents by micro-fluidic chips, and it has reference value for design and select of micro-fluidic chips.