Production of Highly Monodisperse Millimeter‐Sized Double‐Emulsion Droplets in a Coaxial Capillary Device

Abstract

An innovative coaxial capillary device with a size-comparable outlet channel was designed to meet the challenges for controllable production of highly monodisperse millimeter-sized double-emulsion droplets by one-step dripping. The technique of two angled junctions, coaxial capillaries, and compound channel geometry was introduced to convert the millifluidics to microfluidic hydrodynamic features. The relevant nondimensional numbers for a typically regular dripping in this kind of millifluidic flows were similar to those in common microfluidic devices. Effects of the rival forces due to the fluid factors on droplet formation were clarified to explain the dynamic behaviors of double-emulsion formation and to establish the mechanism of droplet breakup. The results helped to understand the coaxial flow pattern for obtaining a more precise droplet size control and to develop high-throughput setups for chemistry, physics, and biology.

An improvement of microfluidic‐assisted internal gelation in the preparation of millimeter‐sized ceramic microspheres

“…In traditional microfluidics, the microchannel size was a few hundred microns and interfacial tension and viscous force dominated. The effect of gravity and inertial force was relatively small and ignored 17,18 . In contrast, the inner diameter of PTFE tubing in this work was 3 mm.…”

“…The effect of gravity and inertial force was relatively small and ignored. 17,18 In contrast, the inner diameter of PTFE tubing in this work was 3 mm. A large sol droplet was generated in the wider microchannel, thereby amplifying the influence of gravity.…”

Generation of liquid metal double emulsion droplets using gravity-induced microfluidics

“…The inertial force ( F inertial ), interfacial tension force ( F σ ) and drag force ( F drag ) are regarded as the parallel forces, while buoyancy force ( F b ) is the vertical force. 74,78 The balance of the holding and detaching forces determines the formation of the double emulsion droplets. Assuming the equilibrium shape of the double emulsion droplet to be spherical, the main forces acting on the double emulsion droplet during its detachment are schematically shown in Fig.…”

“…1(b). 74,76,77 In the le half of Fig. 1(b), the inner droplet and the generating shell droplet are analyzed as a whole, subjected to F b , F s , F inertial and F drag , while F b is negligible owing to the small density difference of different uids.…”

“…The interfacial tension force (F s ) keeps the droplet attached to the dispersed phase, dened as the holding force. [72][73][74] The magnitude of all forces may be calculated from the following equations: 74,75…”