Abstract

A number of methods for analyzing liquid media are based on carrying out specific reactions with the component to be determined. In microfluidic devices, due to the laminarity of the flow, it is difficult to organize uniform mixing of the reaction components, which deteriorates the reproducibility of the results of the reactions and the quality of the analysis. To improve the efficiency of passive mixing in microfluidic systems, you can use the input channel samples of variable geometry, in particular, with bends, or with a variable width. The mixing efficiency is directly related to the variability of reagent concentrations in the working area, and this characteristic is adequately evaluated through the dispersion of the concentration profile. To obtain an estimate of the dispersion of the concentration distribution, an analytical solution of the convective–diffusion equation using the method of moments is proposed. For this, the sample entry system—a straight section of constant width with an additional linearly expanding channel—is approximately replaced by an equivalent channel of constant width. Also, the values of convective velocity and diffusion coefficient are approximately replaced by averaged ones. The dispersion estimates obtained on the basis of an approximate analytical solution have an acceptable agreement with the results of numerical 2D modeling of convective mass transfer in COMSOL MULTYPHYSICS.

中文翻译：

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使用分析解决方案评估微流体系统中特定反应组分的浓度分布的变异性

摘要

用于分析液体介质的许多方法都是基于与待确定组分的特定反应。在微流体装置中，由于流动的层流性，难以组织反应组分的均匀混合，这降低了反应结果的可再现性和分析质量。为了提高微流体系统中被动混合的效率，您可以使用几何形状可变的输入通道样本，尤其是在弯曲或宽度可变的情况下。混合效率与工作区域中试剂浓度的可变性直接相关，并且可以通过浓度分布的分散性来充分评估此特性。为了估算浓度分布的离散度，提出了用矩量法求解对流扩散方程的解析解。为此，样品进入系统（一个恒定宽度的直段，带有一个额外的线性扩展通道）大约被一个恒定宽度的等效通道所代替。另外，对流速度和扩散系数的值大约被平均的值所代替。基于近似解析解获得的色散估计值与COMSOL MULTYPHYSICS中对流传质的二维二维数值模拟结果具有可接受的一致性。样品进入系统（一个恒定宽度的直段，带有一个额外的线性扩展通道）大约被一个恒定宽度的等效通道所代替。另外，对流速度和扩散系数的值大约被平均的值所代替。基于近似解析解获得的色散估计值与COMSOL MULTYPHYSICS中对流传质的二维二维数值模拟结果具有可接受的一致性。样品进入系统（一个恒定宽度的直段，带有一个额外的线性扩展通道）大约被一个恒定宽度的等效通道所代替。另外，对流速度和扩散系数的值大约被平均的值所代替。基于近似解析解获得的色散估计值与COMSOL MULTYPHYSICS中对流传质的二维二维数值模拟结果具有可接受的一致性。