Microfluidic Single Emulsion Device

Single emulsions are mixed systems consisting of two immiscible liquids in which the inner phase is homogeneously dispersed in the continuous phase in a droplet-wise manner. The single emulsion microfluidic method produces different microsized W/O or O/W emulsion droplets with the desired homogeneous size, shape and tailored structure by simply tuning the experimental parameters, such as pressure, flow rate and regimen, dimensionless parameters (e.g., Reynolds and capillary numbers), as well as taking advantage of the properties of the two fluid phases (interfacial tension and viscosity (1).

The RayDrop Single Emulsion Device, developed and manufactured by Secoya technologies, relies on the alignment of two glass capillaries inside a pressurised chamber. A 3D-printed micro-nozzle is additionally connected at the tip of the injection capillary, enforcing the dripping (fluids flow at low rates) of small droplets. This non-embedded design presents both the characteristics of a co-flow (axisymetric geometry) and a flow focusing (dramatic local accelerations of the continuous phase), and is thereby called non-embedded co-flow focusing (2). The nozzle and outlet capillary are aligned in the continuous phase chamber, the dispersed phase comes through the nozzle to create the microparticles into the continuous phase and exit by the outlet insert.

The technological breakthroughs of RayDrop Single Emulsion Device’s design is two-fold:

• Firstly, it enables the high-throughput generation of monodisperse droplets intrinsic to the dripping regime for a wide variety of fluids, due to the continuous phase not being confined before entering the extraction capillary, allowing for the flushing of viscous continuous phases. 
• Secondly, it benefits from specific fabrication techniques and materials compatible with a large-scale production of the device, while ensuring a  precise and reproducible alignment of the two capillaries in the chamber (2).