Effects of viscosity, interfacial tension, and flow geometry on droplet formation in a microfluidic T-junction

Enhancing Throughput of Combinatorial Droplet Devices via Droplet Bifurcation, Parallelized Droplet Fusion, and Parallelized Detection

“…This variation could be caused by the PDMS membranes in our device, as the membranes can vary in thickness from the soft lithography fabrication process. Moreover, variations in reagent viscosity can also lead to variability in droplet sizes as well [40,41]. Based on visually observing the initial size of the reagent droplets, we subsequently shortened or lengthened the opening time for each reagent microvalve.…”

Numerical Investigation of the Drop Formation Mechanism and Study of the Droplet\'s Pressure Contour

“…Castrejón-Pita et al (2012) examined that the surface tension drives two contending forms, squeezing off and shortening, and the relative timescales of these, controlled by the harmony amongst slender and gooey powers, decide the ultimate result. Wehking et al (2014) studied the impact of interfacial tension between the two immiscible fluids, viscosity ratios, and channel geometries on droplet formation. According to them, the transition flow rate ratio (Q dispersed /Q continuous) for a given capillary number declines with declining aspect ratio for both DTJ-DC and DC-PF transitions.…”

Microfluidic methods to study emulsion formation

“…And in the jetting regime, droplet size suddenly decreases with increasing flow rate ratio (Chen et al 2012). The flow rate ratio influences the detachment point, which moves further away from the injection point going from dripping, to squeezing, to jetting (Chen et al 2012;Gupta et al 2009;Liu & Zhang 2009;Tan et al 2009;Tice et al 2004;Wehking et al 2013;Xu, Luo, et al 2006). As expected, the frequency of droplet production increased with the flow rate ratio ).…”

“…At increased continuous phase flow rate, the droplets become smaller due to increased shear on the emerging droplets (Fries & Rudolf von Rohr 2009;Yeom & Lee 2011a). When the capillary number and the flow rate ratio are kept constant, the normalised droplet size is dependent on the geometry and increases with decreasing continuous phase channel width (Fries & Rudolf von Rohr 2009;Garstecki et al 2006;Gupta & Kumar 2010a;Wehking et al 2013).…”

“…Droplets and bubbles formed in the squeezing or dripping regime decrease in size with decreasing the dispersed phase channel width (Christopher et al 2008;Fries & Rudolf von Rohr 2009;Yeom & Lee 2011a), further it was found that the effect of the dispersed phase channel width on droplet volume is larger at low capillary number (Christopher et al 2008). For the critical capillary numbers related to transitions between regimes; increasing the aspect ratio decreases Ca c for transition from dripping to jetting and to parallel flow (Chen et al 2012;Garstecki et al 2006), whereas the transition from squeezing to dripping is hardly affected (Wehking et al 2013). …”