The advantages of miniaturized systems and the laminar flow regime that is present in microfluidic channels have opened a new range of applications in which the use of multiple streams with different reagents is exploited. However, further development of these microdevices needs deeper understanding on the phenomena involved in order to efficiently design such microsystems. In this work, we report the analysis of the solute mass transport performance in Y-Y-shaped microchannels as a function of the coupled influence of both the flow patterns and mass transport kinetics. With this objective, the influence of the following operation variables has been analyzed, the ratio between the residence and diffusion times (γ) and the volumetric ratio between the fluid phases (α), that was determined for three different geometric configurations. The performance of the devices was presented as the solute separation factor in the donor fluid and the concentration factor in the receiving phase. Results showed that the ratio α greatly impacts the solute concentration value reported in both phases for the same γ value, which in turn influences the solute mass flow at the channel outlets. Both the flow patterns and the concentration gradients developed inside the systems were numerically studied by using Computational Fluid Dynamics (CFD) techniques and experimentally analyzed by fluorescence microscopy with fluorescein employed as model solute. This study represents a thorough analysis of the phenomena that determine the performance of the separation of solutes between homogeneous flowing fluids in microdevices where the fluid dynamics are coupled with mass transfer phenomena and facilitates its extension to the general case where separation is enhanced by chemical reactions.

微型化系统的优势和微流控通道中存在的层流态势开辟了新的应用范围，其中利用了多种使用不同试剂的物流。但是，这些微型设备的进一步开发需要对所涉及的现象有更深入的了解，以便有效地设计此类微型系统。在这项工作中，我们报告了YY形微通道中溶质的传质性能分析，该分析是流型和传质动力学的耦合影响的函数。为此目的，分析了以下操作变量的影响：停留时间和扩散时间之间的比率（γ）和流体相之间的体积比率（α），这是针对三种不同的几何构型确定的。装置的性能表示为供体流体中的溶质分离因子，而接收阶段则为浓度因子。结果表明，对于相同的γ值，比率α会极大影响两相中报告的溶质浓度值，进而影响通道出口处的溶质质量流量。使用计算流体动力学（CFD）技术对系统内部形成的流动模式和浓度梯度进行了数值研究，并使用荧光素作为模型溶质，通过荧光显微镜进行了实验分析。