Enhancing the species mixing in microfluidic applications is key to reducing analysis time and increasing device portability. The mixing in electroosmotic flow is usually diffusion-dominated. Recent numerical studies have indicated that the introduction of electrically charged surface heterogeneities may augment mixing efficiencies by creating localized regions of flow circulation. In this study, we experimentally visualized the effects of surface charge patterning and developed an optimized electrokinetic micromixer applicable to the low Reynolds number regime. Using the optimized micromixer, mixing efficiencies were improved between 22 and 68% for the applied potentials ranging from 70 to 555 V/cm when compared with the negatively charged homogeneous case. For producing a 95% mixture, this equates to a potential decrease in the required mixing channel length of up to 88% for flows with Peclet numbers between 190 and 1500.
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机译：在微流控应用中增强物质混合是减少分析时间和提高设备便携性的关键。电渗流中的混合通常以扩散为主。最近的数值研究表明，带电表面异质性的引入可通过创建局部流动环流来提高混合效率。在这项研究中，我们通过实验可视化了表面电荷构图的影响，并开发了适用于低雷诺数制度的优化电动微混合器。与带负电的均匀情况相比，使用优化的微混合器，在70至555 V / cm的施加电势下，混合效率提高了22％至68％。对于生产95％的混合物，这意味着对于Peclet数在190和1500之间的流，所需的混合通道长度可能最多减少88％。
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