“…[14][15][16]22,23,[27][28][29] However, it is in stark contrast to flow-focusing drop-making geometries where the drop size is strongly flow-rate dependent, resulting in broader size distributions, as variations in the flow rate of individual drop makers are inevitable. 10,[30][31][32][33] This broadening is exacerbated if any of the channels clog during the operation.…”
Monodisperse drops with diameters between 20 μm and 200 μm can be used to produce particles or capsules for many applications such as for cosmetics, food, and biotechnology. Drops composed of low viscosity fluids can be conveniently made using microfluidic devices. However, the throughput of microfluidic devices is limited and scale-up, achieved by increasing the number of devices run in parallel, can compromise the narrow drop-size distribution. In this paper, we present a microfluidic device, the millipede device, which forms drops through a static instability such that the fluid volume that is pinched off is the same every time a drop forms. As a result, the drops are highly monodisperse because their size is solely determined by the device geometry. This makes the operation of the device very robust. Therefore, the device can be scaled to a large number of nozzles operating simultaneously on the same chip; we demonstrate the operation of more than 500 nozzles on a single chip that produces up to 150 mL h of highly monodisperse drops.
“…[14][15][16]22,23,[27][28][29] However, it is in stark contrast to flow-focusing drop-making geometries where the drop size is strongly flow-rate dependent, resulting in broader size distributions, as variations in the flow rate of individual drop makers are inevitable. 10,[30][31][32][33] This broadening is exacerbated if any of the channels clog during the operation.…”
Monodisperse drops with diameters between 20 μm and 200 μm can be used to produce particles or capsules for many applications such as for cosmetics, food, and biotechnology. Drops composed of low viscosity fluids can be conveniently made using microfluidic devices. However, the throughput of microfluidic devices is limited and scale-up, achieved by increasing the number of devices run in parallel, can compromise the narrow drop-size distribution. In this paper, we present a microfluidic device, the millipede device, which forms drops through a static instability such that the fluid volume that is pinched off is the same every time a drop forms. As a result, the drops are highly monodisperse because their size is solely determined by the device geometry. This makes the operation of the device very robust. Therefore, the device can be scaled to a large number of nozzles operating simultaneously on the same chip; we demonstrate the operation of more than 500 nozzles on a single chip that produces up to 150 mL h of highly monodisperse drops.
“…In the CCME, the detachment time and size of the emulsion are mainly determined by the forces on the droplet. The droplet that forms at the pore before detachment is subject to the following forces, 29,32,[38][39][40][41][42] as illustrated in Figure 1B.…”
Continuous ceramic membrane emulsification is a promising and scalable technique to prepare water‐in‐heavy oil (W/O) emulsions. The droplet size of W/O emulsions is comprehensively influenced by phase parameters, operational parameters, and membrane parameters, which collectively impact the forces acting on water droplets. In this work, a droplet size prediction model involving multiple factors is established. The forces are analyzed by considering the influence of transmembrane pressure and the viscosity ratio between the dispersed and continuous phases, which are not well considered by current researchers. Additionally, the effects of pore size, crossflow velocity, temperature, and transmembrane pressure were experimentally verified. The experimental results show a high degree of agreement with the predictions. Also, based on the relaxation time difference in oil and water, magnetic resonance imaging was used for the first time to assess the stability of W/O emulsions which was found to be stable for 4 months.
“…Pore-scale phenomena in oil recovery and CO 2 storage, 1,2 separation in membranes, 3 manipulation of minute amounts of liquids on patterned surfaces, 4 and nanofluidics-based medical diagnostics 5 are examples of nanoscale flow and transport processes. Oil recovery and CO 2 storage in rock formations highlight the often multiphase character (gas-liquid mixtures or systems with multiple immiscible liquids-oil, water, pressurized CO 2 ) of many such systems.…”
in Wiley Online Library (wileyonlinelibrary.com) Through molecular dynamics, the sliding motion of a liquid drop embedded in another liquid over a substrate as a result of a shear flow is studied. The two immiscible Lennard-Jones liquids have the same density and viscosity. The system is isothermal. Viscosity, surface tension, and static contact angles follow from calibration simulations. Sliding speeds and drop deformations (in terms of dynamic contact angles) are determined as a function of the shear rate. The latter is nondimensionalized as a capillary number (Ca) that has been varied in the range 0.02-0.64. For Ca up to 0.32, sliding speeds are approximately linear in Ca. For larger Ca, very strong droplet deformations are observed.
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