The electrokinetic molecular concentration (EMC) effect at the micro–nanofluidic interface, which enables million-fold preconcentration of biomolecules, is one of the most compelling yet least understood nanofluidic phenomena. Despite the tremendous interests in EMC and the substantial efforts devoted, the detailed mechanism of EMC remains an enigma so far owing to its high complexity, which gives rise to the significant scientific controversies outstanding for over a decade and leaves the precise engineering of EMC devices infeasible. We report a series of experimental and theoretical new findings that decipher the mechanism of EMC. We demonstrate the first elucidation of two separate operating regimes of EMC, and establish the first theoretical model that analytically yet concisely describes the system. We further unveil the dramatically different scaling behaviors of EMC in the two regimes, thereby clarifying the long-lasting controversies. We believe this work represents important progress towards the scientific understanding of EMC and related nano-electrokinetic systems, and would enable the rational design and optimization of EMC devices for a variety of applications.

中文翻译：

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微纳流界面上基于极化的极化离子电动势分子浓度的解析：理论极限和尺度定律†

在微纳米流体界面上的电动分子浓度（EMC）效应使生物分子能够进行百万倍的预浓缩，是最引人注目的但鲜为人知的纳米流体现象之一。尽管对EMC有着极大的兴趣并付出了巨大的努力，但由于EMC的详细机制具有很高的复杂性，至今仍是一个谜，这引起了十多年未解决的重大科学争议，并且使EMC设备的精确工程设计不可行。 。我们报告了一系列实验和理论上的新发现，这些新发现破译了EMC的机理。我们展示了对EMC的两个独立运行机制的首次阐明，并建立了第一个理论模型，该模型在分析上却简洁地描述了该系统。我们进一步揭示了在两种情况下EMC的缩放行为截然不同，从而阐明了长期存在的争议。我们相信这项工作代表了在科学理解EMC和相关的纳米电动系统方面的重要进展，并且将使合理设计和优化EMC器件用于各种应用成为可能。