Monodisperse Multiple Emulsions Research Articles

Rapid and Highly Controlled Generation of Monodisperse Multiple Emulsions via a One-Step Hybrid Microfluidic Device

Multiple Emulsions (MEs) contain a drop laden with many micro-droplets. A single-step microfluidic-based synthesis process of MEs is presented to provide a rapid and controlled generation of monodisperse MEs. The design relies on the interaction of three immiscible fluids with each other in subsequent droplet formation steps to generate monodisperse ME constructs. The design is within a microchannel consists of two compartments of cross-junction and T-junction. The high shear stress at the cross-junction creates a stagnation point that splits the first immiscible phase to four jet streams each of which are sprayed to micrometer droplets surrounded by the second phase. The resulted structure is then supported by the third phase at the T-junction to generate and transport MEs. The ME formation within microfluidics is numerically simulated and the effects of several key parameters on properties of MEs are investigated. The dimensionless modeling of ME formation enables to change only one parameter at the time and analyze the sensitivity of the system to each parameter. The results demonstrate the capability of highly controlled and high-throughput MEs formation in a one-step synthesis process. The consecutive MEs are monodisperse in size which open avenues for the generation of controlled MEs for different applications.

Reply to the ‘Comment on “Wetting-induced formation of controllable monodisperse multiple emulsions in microfluidics”’ by J. Guzowski and P. Garstecki, Lab Chip, 2014, 14, DOI: 10.1039/C3LC51229K

Reply to the ‘Comment on “Wetting-induced formation of controllable monodisperse multiple emulsions in microfluidics”’ by J. Guzowski and P. Garstecki, Lab Chip, 2014, 14, DOI: 10.1039/C3LC51229K

Comment on “Wetting-induced formation of controllable monodisperse multiple emulsions in microfluidics” by N.-N. Deng, W. Wang, X.-J. Ju, R. Xie, D. A. Weitz and L.-Y. Chu, Lab Chip, 2013,13, 4047

Comment on “Wetting-induced formation of controllable monodisperse multiple emulsions in microfluidics” by N.-N. Deng, W. Wang, X.-J. Ju, R. Xie, D. A. Weitz and L.-Y. Chu, Lab Chip, 2013,<b>13</b>, 4047

Simple and inexpensive microfluidic devices for the generation of monodisperse multiple emulsions

Droplet-based microfluidic devices have become a preferred versatile platform for various fields in physics, chemistry and biology. Polydimethylsiloxane soft lithography, the mainstay for fabricating microfluidic devices, usually requires the usage of expensive apparatus and a complex manufacturing procedure. Here, we report the design and fabrication of simple and inexpensive microfluidic devices based on microscope glass slides and pulled glass capillaries, for generating monodisperse multiple emulsions. The advantages of our method lie in a simple manufacturing procedure, inexpensive processing equipment and flexibility in the surface modification of the designed microfluidic devices. Different types of devices have been designed and tested and the experimental results demonstrated their robustness for preparing monodisperse single, double, triple and multi-component emulsions.

Wetting-induced formation of controllable monodisperse multiple emulsions in microfluidics

Multiple emulsions, which are widely applied in a myriad of fields because of their unique ability to encapsulate and protect active ingredients, are typically produced by sequential drop-formations and drop-encapsulations using shear-induced emulsification. Here we report a qualitatively novel method of creating highly controlled multiple emulsions from lower-order emulsions. By carefully controlling the interfacial energies, we adjust the spreading coefficients between different phases to cause drops of one fluid to completely engulf other drops of immiscible fluids; as a result multiple emulsions are directly formed by simply putting preformed lower-order emulsion drops together. Our approach has highly controllable flexibility. We demonstrate this in preparation of both double and triple emulsions with a controlled number of inner drops and precisely adjusted shell thicknesses including ultra-thin shells. Moreover, this controllable drop-engulfing-drop approach has a high potential in further investigations and applications of microfluidics. Importantly, this innovative approach opens a window to exploit new phenomena occurring in fluids at the microscale level, which is of great significance for developing novel microfluidics.

미세채널에서 수력학적 조절을 통한 단분산성 다중 액적 생성

This study reports the microfluidic preparation of monodisperse multiple emulsions using hydrodynamic control. To generate multiple emulsions, we fabricate a microfluidic capillary device based on co-flowing stream with- out any surface modification of microchannels. Based on the system, we can successfully generate multiple emulsions (W/O/W) using water containing 0.5 wt% Tween 20, n-hexadecane with 5 wt% Span 80, and 10 wt% poly (vinyl alco- hol) (PVA) aqueous solution, respectively. Furthermore, we control the number of inner droplets by modulation of flow rate of inner fluid at fixed flow rate of middle and outer fluid. The multiple emulsions having precisely controlled inner droplets' size and number can be applicable for multiple chemical reactions as an isolated microreactor.

Controllable Monodisperse Multiple Emulsions

Tropfen in Tropfen in Tropfen: Mit einer Mikrofluidtechnik werden hochkontrollierte Mehrfachemulsionen erzeugt (siehe Bild). Das hohe Maß an Kontrolle und Skalierbarkeit ermöglicht einen flexiblen Zugang zu Designeremulsionen und Mikrokapseln mit Multiphasenstrukturen. Die breite Anwendbarkeit der Methode sollte zur Erzeugung neuartiger Materialien mit komplexen inneren Strukturen führen.

Controllable Monodisperse Multiple Emulsions

Controllable Monodisperse Multiple Emulsions

Preparation of monodisperse multiple emulsions at high production rates by multi-stage premix membrane emulsification

Multiple W/O/W emulsions have been prepared by multi-stage (repeated) premix membrane emulsification using Shirasu-porous glass (SPG) membrane with a mean pore size of 10.7 μm. A coarse emulsion containing droplets with a mean particle size of about 100 μm was homogenized 5–6 times through the same membrane at a constant pressure difference of 20–300 kPa to achieve additional droplet homogenization and size reduction. The optimum conditions with regard to particle size uniformity were three homogenization cycles at a pressure difference of 100 kPa, under which the mean size of outer W/O particles was 9 μm and the span of particle size distribution was as low as 0.28. The optimum pressure difference in a single-stage process was higher, but the particle size distribution of prepared emulsions was broader than in a multi-stage process at smaller pressures. The transmembrane flux was in the range of 1.8–37 m 3 m −2 h −1 and increased with increasing pressure difference and decreasing the content of W/O particles. The mean size of W/O particles in each cycle was remarkably constant over a wide range of their concentration of 1–60 vol.%.