We report the fabrication of permeable membranes for microfluidic dialysis applications in poly(dimethylsiloxane) (PDMS) channels. A maskless UV projection device was used to photo-pattern long hydrogel membranes (mm–cm) with a spatial resolution of a few microns in PDMS chips integrating also micro-valves. We show in particular that multi-layer soft lithography allows one to deplete oxygen from the PDMS walls using a nitrogen gas flow and therefore makes possible in situ UV-induced polymerization of hydrogels. We also report a simple surface modification of the PDMS channels leading to strongly anchored hydrogel membranes that can withstand trans-membrane pressure drops up to 1 bar without leakages. We then measured the Darcy permeability of these membranes and estimated their cut-off by measuring the kinetics of diffusion of macromolecules of different sizes through the membrane. Finally, we illustrate the opportunities offered by such microfluidic chips for dialysis applications by observing in real time the crystallization of a model protein in a chamber of a few nanoliters.

中文翻译：

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在PDMS芯片中使用光图案化水凝胶膜进行微流透析。

我们报告了在聚（二甲基硅氧烷）（PDMS）通道中用于微流体透析应用的渗透膜的制造。无掩膜紫外投影设备用于对长水凝胶膜（mm-cm）进行光图案化，同时在PDMS芯片中集成了微阀，其空间分辨率为几微米。我们特别表明，多层软光刻技术允许使用氮气流从PDMS壁中消耗氧气，因此可以在原位实现紫外线诱导的水凝胶聚合。我们还报告了PDMS通道的简单表面改性，导致牢固锚固的水凝胶膜可以承受跨膜压降高达1 bar而无泄漏。然后，我们测量了这些膜的达西渗透率，并通过测量不同大小的大分子通过该膜的扩散动力学来估计其截止值。最后，我们通过实时观察几纳升的腔室中模型蛋白质的结晶情况，说明了这种微流控芯片为透析应用提供的机会。