Chung Seok, Yun Hoyoung, Kamm Roger D
Department of Mechanical Engineering, Massachusetts Institute of Technology Cambridge, MA 02139, USA.
Small. 2009 Mar;5(5):609-13. doi: 10.1002/smll.200800748.
To generate flow in microchannels, various actuation schemes such as electrokinetic, pressure-driven, and capillary-driven flow have been suggested. Capillary-driven flow is widely used in plastic disposable diagnostic platforms due to its simplicity and because it requires no external power. However, plastics such as poly(methyl methacrylate) (PMMA), generally used in microfluidics, are hydrophobic, which inhibits capillary force generation and requires surface enhancement that deteriorates with age. It is shown that the microchannels made of PMMA lose their acquired hydrophilicity by oxygen plasma treatment in long-term storage and tend to generate slow capillary flow exhibiting large variability. To promote consistency and drive flow in the microchannel, nanointerstices (NI) are introduced at the side wall of the microchannel, which results in capillary flow that is less dependent on surface characteristics. The results show that NI flow generation can be a useful alternative technique to create long-term predictable flow in commercialized products with microchannels.
为了在微通道中产生流动，人们提出了各种驱动方案，如电动驱动、压力驱动和毛细管驱动流动。毛细管驱动流动因其简单性且无需外部动力而被广泛应用于塑料一次性诊断平台。然而，微流控中常用的诸如聚甲基丙烯酸甲酯（PMMA）之类的塑料具有疏水性，这会抑制毛细管力的产生，并且需要进行表面增强处理，而这种处理会随着时间的推移而变差。研究表明，由PMMA制成的微通道在长期储存过程中会因氧等离子体处理而失去其获得的亲水性，并倾向于产生表现出较大变异性的缓慢毛细管流动。为了促进微通道中流动的一致性并驱动流动，在微通道的侧壁引入了纳米间隙（NI），这导致毛细管流动对表面特性的依赖性降低。结果表明，NI流动产生可以成为一种有用的替代技术，以便在具有微通道的商业化产品中创建长期可预测的流动。
