Microfluidic Cross-Junction Emulsification Process
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Solution Overview
Problem
Existing methods for producing multiple emulsions, particularly double or triple emulsions, face challenges in achieving consistent droplet sizes and monodispersity, especially with high-viscosity oils, leading to instability and practical limitations in commercial applications.
Innovation Solution
A microfluidic process that involves a cross-junction geometry microchannel system with controlled flow rates and temperature optimization, allowing for the production of multiple emulsions with a coefficient of variation in droplet diameter of less than 5%, independent of the system used, by setting the ratio of dispersed phase flow rate to continuous phase flow rate within a specific operating window defined by fluid properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If two-step emulsification technique is used to produce multiple emulsions, then emulsion formation is achieved, but droplet size consistency and monodispersity deteriorate
Solution Approach 1:
The invention divides the emulsification process into two distinct microfluidic junctions: the first junction forms primary droplets (e.g., aqueous droplets in oil phase), and the second junction forms the multiple emulsion structure (e.g., encapsulating primary droplets in outer aqueous phase). This segmentation allows independent control of each emulsification step, achieving both emulsion formation and droplet size consistency with coefficient of variation less than 5%.
Solution Approach 2:
The invention introduces a transient intermediate state where primary droplets formed at the first junction are carried through a channel to the second junction before final emulsion formation. This intermediate transport phase allows precise control of droplet size and composition before the final encapsulation step, resolving the contradiction between forming stable multiple emulsions and maintaining monodispersity.
2Stability of the object's composition
If high-viscosity oils are used in multiple emulsions, then emulsion stability improves, but droplet size control and monodispersity deteriorate
Solution Approach 1:
The invention changes the physical parameters of the system by precisely controlling flow rates of dispersed and continuous phases through the microfluidic device. By adjusting the ratio of dispersed phase flow rate to continuous phase flow rate within a specific operating window, the system achieves droplet size consistency with coefficient of variation less than 5% even with high-viscosity oils, while maintaining emulsion stability.
Solution Approach 2:
The invention replaces traditional mechanical mixing methods with microfluidic flow control to achieve emulsification. The microfluidic junctions use controlled fluid flow rather than mechanical shear forces to form droplets, enabling precise droplet size control with high-viscosity oils that would be difficult to control using conventional mechanical emulsification methods.
3Productivity
If conventional emulsification methods are used, then emulsion production is achieved, but system dependence and reproducibility deteriorate
Solution Approach 1:
The invention creates a universal microfluidic platform that can produce multiple emulsions with consistent results across different systems. The process is defined by dimensionless numbers (Ohnesorge number, capillary number) and flow rate ratios rather than system-specific parameters, making the method transferable and reproducible across different microfluidic devices and laboratories while maintaining high productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process achieves highly monodisperse multiple emulsions with stable droplet sizes, enhancing the viability of these emulsions in industrial applications by ensuring consistent droplet formation and stability, regardless of the system used, without requiring changes in channel hydrophobicity or hydrophilicity and without the need for surfactants.
Implementation Method 1
Interfacial tension controlled W/O and O/W 2-phase flows in microchannel
Implementation Method 2
controlled flow rates and temperature optimization, allowing for the production of multiple emulsions with a coefficient of variation in droplet diameter of less than 5%
Data Source
Figure 1
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AI summary
A process for preparing an emulsion is disclosed comprising: injecting a first liquid as dispersed phase liquid through a central inlet of a microchannel (15) system with a cross junction geometry chip and injecting a second liquid as continuous phase liquid through the outer cross inlet (16), which continuous phase liquid does not instantly mix with said injected first liquid prior to the cross junction, wherein the flow rate Qc of the continuous phase in cubic meters per second is given by (I) where A is the exit area of the microchannel (17) in square meters, y the interfacial tension between the first liquid and the second liquid in Newtons per meter and µd the viscosity of the dispersed phase in Pascal-seconds, characterized in that f is in the range from 0.04 to 0.25.