Bratsun Dmitry, Kostarev Konstantin, Mizev Alexey, Aland Sebastian, Mokbel Marcel, Schwarzenberger Karin, Eckert Kerstin
Department of Applied Physics, Perm National Research Polytechnic University, Perm 614990, Russia.
Institute of Continuous Media Mechanics, Perm 614013, Russia.
Micromachines (Basel). 2018 Nov 16;9(11):600. doi: 10.3390/mi9110600.
Continuous-flow microreactors are an important development in chemical engineering technology, since pharmaceutical production needs flexibility in reconfiguring the synthesis system rather than large volumes of product yield. Microreactors of this type have a special vessel, in which the convective vortices are organized to mix the reagents to increase the product output. We propose a new type of micromixer based on the intensive relaxation oscillations induced by a fundamental effect discovered recently. The mechanism of these oscillations was found to be a coupling of the solutal Marangoni effect, buoyancy and diffusion. The phenomenon can be observed in the vicinity of an air⁻liquid (or liquid⁻liquid) interface with inhomogeneous concentration of a surface-active solute. Important features of the oscillations are demonstrated experimentally and numerically. The periodicity of the oscillations is a result of the repeated regeneration of the Marangoni driving force. This feature is used in our design of a micromixer with a single air bubble inside the reaction zone. We show that the micromixer does not consume external energy and adapts to the medium state due to feedback. It switches on automatically each time when a concentration inhomogeneity in the reaction zone occurs, and stops mixing when the solution becomes sufficiently uniform.
连续流微反应器是化学工程技术的一项重要进展，因为药物生产需要在重新配置合成系统方面具有灵活性，而非大量的产品产量。这种类型的微反应器有一个特殊的容器，其中对流涡旋被组织起来以混合试剂，从而提高产品产量。我们基于最近发现的一种基本效应所引发的强烈弛豫振荡，提出了一种新型微混合器。发现这些振荡的机制是溶质马兰戈尼效应、浮力和扩散的耦合。在表面活性溶质浓度不均匀的气 - 液（或液 - 液）界面附近可以观察到这种现象。通过实验和数值模拟证明了振荡的重要特征。振荡的周期性是马兰戈尼驱动力反复再生的结果。这一特性被用于我们设计的在反应区内有单个气泡的微混合器。我们表明，该微混合器不消耗外部能量，并且由于反馈而适应介质状态。每当反应区内出现浓度不均匀时，它会自动开启，当溶液变得足够均匀时停止混合。
