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arXiv · 1804.01471

Opposed flow focusing: evidence of a second order jetting transition

Jun Dong·Max Meissner·Jens Eggers·Annela M. Seddon·C. Patrick Royall
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Abstract

We propose a novel microfluidic "opposed-flow" geometry in which the continuous fluid phase is fed into a junction in a direction opposite the dispersed phase. This pulls out the dispersed phase into a micron-sized jet, which decays into micron-sized droplets. As the driving pressure is tuned to a critical value, the jet radius vanishes as a power law down to sizes below 1 $\mu$m. By contrast, the conventional "coflowing" junction leads to a first order jetting transition, in which the jet disappears at a finite radius of several $\mu$m, to give way to a "dripping" state, resulting in much larger droplets. We demonstrate the effectiveness of our method by producing the first microfluidic silicone oil emulsions with a sub micron particle radius, and utilize these droplets to produce colloidal clusters.

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Jun Dong, Max Meissner, Jens Eggers, Annela M. Seddon, C. Patrick Royall. 2018-04-04. Opposed flow focusing: evidence of a second order jetting transition. https://arxiv.org/abs/1804.01471

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