Droplet-based microfluidic devices are now more than ever used for the synthesis of nanoparticles with low polydispersity and well-defined properties suitable for various industrial applications. Very small reaction volumes (microlitre to femtolitre) and short diffusion lengths, provide superior mixing efficiency and heat transport. Both play the dominant role in case of ultra-fast chemical reactions triggered upon reactant mixing, e.g. preparation of colloidal silver by reduction of silver salt. The high sensitivity of these systems to process variables makes otherwise more straightforward batch-wise production prone to suffer from inconsistency and poor reproducibility, which has an adverse effect on the reliability of production and further particle utilisation. This work presents a rigorous description of microfluidic droplet formation, reactant mixing, and nanoparticle synthesis using CFD simulations and experimental methods. The reaction mixture inside of droplets was homogenized in less than 40 milliseconds, which has been confirmed by simulations. Silver nanoparticles produced by droplet-based microfluidic chip showed superior to batch-wise preparation in terms of both particle uniformity and polydispersity.

中文翻译：

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使用基于液滴的微流控装置制备银纳米颗粒的控制因素。

现在，基于液滴的微流控设备比以往任何时候都多用于合成具有低多分散性和明确特性的纳米颗粒，适用于各种工业应用。反应体积非常小（微升至飞升），扩散长度短，可提供出色的混合效率和热传递。在反应物混合引发超快速化学反应的情况下，例如通过还原银盐制备胶体银，两者都起主要作用。这些系统对过程变量的高度敏感性使原本更直接的分批生产容易出现不一致和可重复性差的问题，这对生产的可靠性和进一步的颗粒利用具有不利影响。这项工作对微流体液滴的形成进行了严格的描述，使用CFD模拟和实验方法进行反应物混合和纳米颗粒合成。液滴内部的反应混合物在不到40毫秒的时间内被均质化，这已通过模拟得到了证实。基于液滴的微流控芯片生产的银纳米颗粒在颗粒均匀性和多分散性方面均优于分批制备。