Uniform drop has been crucial academic and industrial building blocks for various applications such as food, cosmetics, home- and personal care, and more particularly for pharmaceutical applications in drug delivery or radiology. Most of the research firms in the fields of chemistry also demand high monodispersed drops with tunable size, because the uniformity of drop can have significant consequences for the responsive behavior and properties of the end product. Recent studies for the drop focus on microfluidic technique, but it faces challenges during the attempts to scale up the technology to mass production. The poduction rates of the technology are 1-10kHz, but the microfluidic devises are hindered in commercialization for reasons such as the presence of continuous phase flows, small cross-sctional area, and very small flow rates. As a result, microfluidic approaches fail to satisfy the productivity requirement of standard yield, ~ 1000 t/y. The formation processes of millimeter-sized drops were recently re-highlighted in a buoyancy-driven system that is feasible for both fundmental studies and industrial applications because there are fewer governing forces and variables affecting the drop formation than the microfluidic processes. In this study, we propose a strategy to produce milli-scale drop. Uniform drops are selectively generated with controlling flow rate, channel diameter, affinity of membrane to the drop and their range of the production rates was ~ 0.1-2.1 Hz. The pinch-off time and force dynamics for drop generation are different according to the affinity between drop and membrane surface. It appears as different initial contact angles (whether larger or smaller than 90o) and results in the different diameter and frequency of the drops in same channel diameter. These phenomena are investigated by our novel model. On hydrophobic membranes, the diameter range of the uniform drops is wider (from ca. 5.7 to 10.4 mm) than that on hydrophilic one (from ca. 3.8 to 7.0 mm). However, on the hydrophilic membranes, the smaller drops are fastly generated in terms of the production rate than those of the hydrophobic membrane.

Understanding uniform, fast and scalable buoyancy-driven macro-sized drop generations

2019 Spring National Meeting

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