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We propose a novel microfluidic “opposed-flow” geometry in which the continuous fluid phase is fed into a junction in a direction opposite to 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 μm. By contrast, the conventional “coflowing” junction leads to a first order jetting transition, in which the jet disappears at a finite radius of several μm, 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.
Original languageEnglish
Pages (from-to)8344-8351
Number of pages8
JournalSoft Matter
Issue number41
Early online date8 Oct 2018
Publication statusPublished - 7 Nov 2018


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