Development and optimization of microfabrication processes for capillary driven microfluidic valves

微流体毛细管系统自动化，小型化和加快实验室程序，而不需要任何主动机械元件，如外部泵或阀门。该技术使支持公司Sensoreal能够开发独立的、自供电的微流体盒，使用几滴血进行快速血液测试，测量多种蛋白质生物标志物。目前，由于毛细管微流体系统的层流行为，再水合试剂不能均匀地分布在感兴趣的储层上，因此有超过80%的样品和用于进行分析的试剂的浪费。此外，目前的问题使得微芯片的体积庞大（5厘米× 10厘米）。提出的研究项目计划通过引入用于干燥试剂（SRDR）缓释的毛细管阀来提高微流控毛细管系统的性能。然后，阀门系统可以集成到Sensoreal的毛细管电路中，使墨盒消耗更少的样品和试剂体积，并进一步缩小墨盒的占地面积。在这种情况下，我们的最终目标是开发和优化微制造工艺，包括等离子体合成、蚀刻和功能化工艺，以制造硅制成的SRDR阀。将特别关注等离子体蚀刻工艺的优化（气相比，温度），以尽量减少硅通道表面上任何疏水钝化层的形成，同时保持微流体侧壁轮廓尽可能垂直（各向异性蚀刻）。不同的技术将被用于进一步氧化微通道表面，以增强其亲水性，这是SRDR操作所需要的。这些技术包括基于等离子体的功能化和/或基于等离子体的薄膜沉积。如果成功，该解决方案将给Sensoreal更多的机会来增加他们的技术组合，并拥有未来的市场份额，特别是在价格敏感的国家。

Microfluidic capillary systems automate, miniaturize and expedite the laboratory procedures without any needfor active mechanical elements such as external pumps or valves. The technology has enabled Sensoreal, thesupporting company, to develop self-contained, and self-powered microfluidic cartridges that perform rapidblood tests to measure multiple protein biomarkers using a few drops of blood. Currently, due to the laminarflow behaviour of the capillary microfluidic systems, the rehydrated reagents do not uniformly spread acrossthe reservoirs of interest and as a result there is over 80% waste of the volume of the sample and the reagentused to perform the assay. Also the current issue makes the footprint of the microchips bulky (5 cm x 10 cm).The proposed research project plans to enhance the performance of the microfluidic capillary systems byintroducing a capillary valve for the slow release of the dry reagents (SRDR). The valving system could then beintegrated to the Sensoreal's capillary circuits for making cartridges consuming much less sample and reagentsvolume and could further miniaturize the footprint of the cartridges made.In this context, our ultimate goal is to develop and optimize microfabrication processes including plasmasynthesis, etching and functionalization processes to fabricate SRDR valves made in silicon. A particularattention will be paid to the optimization of the plasma etching processes (gaz ratio, temperature) to minimizethe formation of any hydrophobic passivation layer on the surface of the Si channels, while keeping themicrofluidic sidewall profiles as vertical as possible (anisotropic etching). Different techniques will be used tofurther oxidize the surface of the microchannel to enhance their hydrophilicity as required for the operation ofthe SRDR. These techniques will include plasma-based functionalization and/or plasma-based thin filmdeposition. If successful, the solution will give Sensoreal more opportunities to increase their technologyportfolio and have future market share especially in price sensitive countries.