We present a microfluidic method leading to accurate measurements of the mutual diffusion coefficient of a liquid binary mixture over the whole solute concentration range in a single experiment. This method fully exploits solvent pervaporation through a poly(dimethylsiloxane) (PDMS) membrane to obtain a steady concentration gradient within a microfluidic channel. Our method is applicable for solutes which cannot permeate through PDMS, and requires the activity and the density over the full concentration range as input parameters. We demonstrate the accuracy of our methodology by measuring the mutual diffusion coefficient of the water (1) + glycerol (2) mixture, from measurements of the concentration gradient using Raman confocal spectroscopy and the pervaporation-induced flow using particle tracking velocimetry. © 2017 American Institute of Chemical Engineers AIChE J, 2017

中文翻译：

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稳定的微流体测量液体二元混合物的相互扩散系数

我们提出了一种微流控方法，可在单个实验中精确测量整个二元溶质浓度范围内液体二元混合物的相互扩散系数。该方法充分利用了通过聚二甲基硅氧烷（PDMS）膜进行的溶剂渗透蒸发，从而在微流体通道内获得稳定的浓度梯度。我们的方法适用于不能透过PDMS的溶质，并且需要在整个浓度范围内的活度和密度作为输入参数。我们通过测量水（1）+甘油（2）混合物的相互扩散系数，使用拉曼共聚焦光谱法测量浓度梯度和使用粒子跟踪测速法测量蒸发引起的流量来证明方法的准确性。AIChE的Ĵ，2017年