Simulation studies on picolitre volume droplets generation and trapping in T-junction microchannels

Abstract

In this paper, we present simulation studies on the formation of water microdroplets in mineral oil in a T-junction Microfluidics device. We have studied the droplet generation in two different regimes, viz., squeezing and squeezing to dripping transition regime. The effect of fluid flow rates, and surfactant concentration on the droplet generation has been investigated. It is seen that a rise in the concentration of surfactant by 4%, increases the frequency of droplet generation by 16% at the higher capillary number (C a = 0.02), whereas, there is only a marginal or no change in the case of squeezing regime (C a = 0.0028-0.008). We have also studied the trapping of the generated microdroplets in microwells. It is observed that the trapping of the droplet is highly influenced by the viscous drag force, droplet length, the surface energy of the droplet, droplet speed, depth of the Well for trapping and alignment of the two plates constituting the device. Our studies reveal that the droplets travelling faster than a critical trapping velocity do not get trapped in the Well. Addition of a surfactant to the mineral oil is seen to lead to a significant reduction in the critical velocity for the droplet trapping. Trapping of droplets travelling at velocities close to the critical velocity for trapping depends strongly on the alignment of the two plats of the Slip-Chip device.

Hydrodynamics of Liquid-Liquid Flows in Micro Channels and Its Influence on Transport Properties: A Review

“…A detailed review on the VOF methods is published by Rider and Kothe, [60]. This method is capable of handling problems with significant interface topology change and does not suffer from mass (or volume) losses.…”

Splitting of droplet with different sizes inside a symmetric T-junction microchannel using an electric field

“…The ability to control the droplet size and sort them introduces many advantages such as cost reduction, higher efficiency, and improved safety in such systems. Aspects of droplet behavior such as coalescence 4 , trapping 5 , deformation 6 , fission 7 , 8 , formation 9 – 18 , and breakup 19 – 31 were explored by researches in several geometries in a microfluidic network involving flow-focusing 9 , 14 , 17 , cross junction 12 , T-junction 10 , 11 , 18 , Co-flowing 7 , 13 , etc. The main approach to tune the size of droplets are T- and Y-junctions 19 – 31 .…”