Droplet generation at Hele-Shaw microfluidic T-junction

Abstract

We proposed the combined numerical and experimental study of the dynamics of droplets generation at shallow microfluidic T-junction, where the flow is strongly confined in the vertical direction. The numerical simulation is performed by employing quasi-2D Hele-Shaw approximation with an interface capturing procedure based on coupled Level-Set and Volume-of-Fluid methods. We investigate the effect of the capillary number, Ca, the channel geometry (cross section aspect ratio, χ), and the flow rate (disperse-to-continuous phases) ratio, Γ, on the dynamics of the droplet breakup. Depending on Ca, three distinct flow regimes are identified: squeezing, tearing and jetting. In the squeezing regime at low Ca, the size of the generated droplets depends on χ and Γ, while it is almost insensitive to Ca in agreement to previous studies. In the tearing regime at moderate Ca, the droplet size decreases as ∼Ca−1/3, while it is only a weak function of χ and Γ. Finally, in the jetting regime, the steady co-flow of both phases takes place at high enough Ca. The numerical predictions based on the Hele-Shaw flow approximation are in excellent agreement with our in-house experimental results, demonstrating that the proposed approach can be effectively used for computationally inexpensive and adequately accurate modeling of biphasic flows in shallow microfluidic devices.

Accounting for corner flow unifies the understanding of droplet formation in microfluidic channels

“…A striking example is the flow of a single droplet through a microchannel 5–8 for which the most basic question how the speed of the droplet depends on flow conditions, fluid properties, and the level of confinement still lacks a full answer. The generation of droplets in microchannels 9,10 using T-junctions 11–19 , flow-focusing 20–22 , co-flow 23 , step emulsification 24–29 and parallel devices 30–32 , opened the new discipline of droplet microfluidics 33,34 that revolutionized analytical methods in biology 35 and medicine with digital assays 36 , single cell sequencing 37 , or systems for research on biological evolution 38 . Droplet microfluidic systems are also used to create new materials for pharmaceutical 39–41 , cosmetics 42 and food 43 industries.…”

CO2 Laser Fabrication of PMMA Microfluidic Double T-Junction Device with Modified Inlet-Angle for Cost-Effective PCR Application

“…Droplet formation using microfluidic channel for dynamic continuous-flow-based PCR device has been done using three methods as follows: (1) co-flowing dripping streams, (2) cross-flowing dripping streams and (3) flow focusing dripping streams [14,15]. Although the effect of shear forces, interfacial forces and channel dimensions on droplet generation have already been widely studied, emulsification using cross-flow microfluidics devices is considered quite new, [16,17,18].…”

Droplet‐based microreactor for the production of micro/nano‐materials

“…In lithographically fabricated poly(dimethylsiloxane) (PDMS) devices, there are various channel geometries that can be applied to the droplet breakup, including T‐junction , co‐flow , and flow‐focusing , as shown in Fig. 2A.…”