The separation of nanoparticles has drawn critical attention in various microfluidic applications including chemical analysis, diagnostics and environmental monitoring. Thus, a number of nanoparticle separation methods have been extensively proposed. However, most of the conventional methods require complicated structured devices, expensive manufacturing processes, and external power sources. While a spontaneous diffusiophoretic separation device based on an ion exchange mechanism could overcome such drawbacks, the recovery of separated particles and the inevitable development of an acidic environment due to the release of H⁺ from the cation exchange membrane limit its practical applicability. Therefore, in this work, we present a simple but robust nanoparticle separation method based on spontaneously induced diffusiophoresis, which is operated in a continuous manner to overcome the limitations of conventional methods. First, we confirmed that the particle exclusion distance followed the previously developed scaling law of diffusiophoresis. Consequently, we demonstrated the separation of nanoparticles of 40 nm, 200 nm and 2 μm diameter by utilizing the fact that the exclusion distances of various particles were proportional to their diffusiophoretic mobility. Furthermore, the use of Tris buffer increased the diffusiophoretic migration of nanoparticles due to the enhanced concentration gradient, and enabled the produced solution to be compatible with pH-sensitive bio-samples. Therefore, we expect this continuous and spontaneous diffusiophoretic separation platform to be useful in practical applications for analyzing various nano-meter scale bio-particles.

中文翻译：

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通过扩散电泳连续和自发地分离纳米颗粒。

纳米颗粒的分离在各种微流体应用中引起了极大的关注，包括化学分析，诊断和环境监测。因此，已经广泛提出了许多纳米颗粒分离方法。然而，大多数常规方法需要复杂的结构化装置，昂贵的制造工艺和外部电源。尽管基于离子交换机制的自发发散电泳分离设备可以克服这些缺点，但由于H ⁺的释放，分离出的颗粒会得到回收，并不可避免地导致酸性环境的发展。阳离子交换膜的应用限制了它的实际适用性。因此，在这项工作中，我们提出了一种基于自发诱导扩散电泳的简单而稳健的纳米颗粒分离方法，该方法以连续的方式运行以克服常规方法的局限性。首先，我们确认了粒子的排他距离遵循了先前开发的扩散电泳的定律。因此，我们利用各种颗粒的排斥距离与它们的扩散电泳迁移率成正比这一事实，证明了直径40 nm，200 nm和2μm纳米颗粒的分离。此外，由于浓度梯度增加，Tris缓冲液的使用增加了纳米粒子的扩散电泳迁移，使所生产的溶液与pH敏感的生物样品兼容。因此，我们希望该连续且自发的发散电泳分离平台在实际应用中可用于分析各种纳米级生物颗粒。