http://orcid.org/0000-0001-9062-5554
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Abstract
The aim of this study was to stably produce monodisperse food-grade oil-in-water (O/W) emulsions using an asymmetric straight-through microchannel (MC) array that is microfabricated on an aluminum chip. Circular MCs of the inlet side were fabricated using a microdrilling process, while microslots of the outlet side were fabricated by electric discharge machining. We used refined soybean oil as the dispersed phase and a Milli-Q water solution containing 1 wt% Tween 20 as the continuous phase. An aluminum MC array with a circular MC diameter (dMC) of 116.9 μm produced monodisperse O/W emulsion droplets with an average diameter (dav) of about 300 μm and coefficients of variation (CVs) below 4%, whereas an aluminum MC array with 82.1 μm diameter stably generated monodisperse O/W emulsion droplets with dav of about 150 μm and CVs below 4%. The dav of the produced oil droplets was affected by the dimensions of asymmetric straight-through MCs. Monodisperse O/W emulsions were successfully generated below the critical dispersed-phase flow rate, with little variation in dav and CV values. The force balance during droplet generation was also analyzed for discussing the results for the effect of the dispersed-phase flow rate.