Microfluidic Droplet Injection Using Electric-Field Interface Disruption
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Solution Overview
Problem
Existing methods for combining fluids in microfluidic systems face challenges in controlling the coalescence of droplets, particularly due to surface tension and droplet size differences, making it difficult to fuse or coalesce fluids that are unable to do so naturally.
Innovation Solution
A microfluidic system with intersecting channels and electrodes is used to apply an electric field at the interface between fluids, allowing controlled injection of one fluid into droplets in another channel by disrupting the fluid interface, enabling the fusion or coalescence of fluids that would otherwise not combine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If droplets are brought into contact to combine fluids, then fluid combination is achieved, but control of coalescence is difficult due to surface tension and droplet size differences
Solution Approach 1:
The patent replaces mechanical contact-based coalescence with an electric field-based system. Electodes apply electrical forces to disrupt the fluid interface and control droplet fusion, eliminating the reliance on surface tension and physical contact that cause control difficulties in conventional mechanical systems.
Solution Approach 2:
The patent changes the physical state of the fluid interface by applying an electric field, which alters the interfacial tension and allows controlled disruption. This parameter change enables precise control over when and how droplets coalesce, overcoming the natural resistance caused by surface tension differences.
2Ease of operation
If electric field is applied to disrupt fluid interface, then controlled fluid injection is achieved, but system complexity increases with electrodes and electric field control
Solution Approach 1:
The electric field system serves multiple functions: it disrupts the fluid interface to enable injection, controls the timing of coalescence, and regulates the amount of fluid transferred. This multi-functionality reduces the need for separate mechanical components, offsetting the added electrical system complexity with operational simplification.
Solution Approach 2:
The electric field acts as an intermediary between the control system and the fluid interface. Rather than direct mechanical manipulation, the electric field mediates the interaction, providing precise control over fluid injection and coalescence while isolating the control mechanism from the fluid handling complexity.
3Quantity of substance
If droplets of different sizes are used, then fluid volume flexibility is improved, but coalescence control becomes more difficult
Solution Approach 1:
By replacing mechanical contact-based coalescence with electric field control, the system can handle droplets of varying sizes without the control difficulties that arise from size mismatches. The electric field can be adjusted to account for different droplet dimensions, maintaining ease of operation across a range of fluid volumes.
Solution Approach 2:
The electric field parameters can be dynamically adjusted based on droplet size and desired outcome. This dynamic control allows the system to adapt to different droplet configurations, maintaining ease of operation whether combining small or large droplets, thereby preserving both volume flexibility and operational simplicity.
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 method allows for precise control of fluid exchange between channels, enabling the fusion of droplets that cannot coalesce naturally, facilitating efficient fluid mixing and manipulation in microfluidic systems.
Implementation Method 1
applying an electric field to the interface to urge the second fluid to enter the droplets in the first microfluidic channel
Data Source
Figure 1~2C
Figure 3
Figure 4A
AI summary
The present invention generally relates to systems and methods for the control of fluids and, in some cases, to systems and methods for flowing a fluid into and/or out of other fluids. As examples, fluid may be injected into a droplet contained within a fluidic channel, or a fluid may be injected into a fluidic channel to create a droplet. In some embodiments, electrodes may be used to apply an electric field to one or more fluidic channels, e.g., proximate an intersection of at least two fluidic channels. For instance, a first fluid may be urged into and/or out of a second fluid, facilitated by the electric field. The electric field, in some cases, may disrupt an interface between a first fluid and at least one other fluid. Properties such as the volume, flow rate, etc. of a first fluid being urged into and/or out of a second fluid can be controlled by controlling various properties of the fluid and/or a fluidic droplet, for example curvature of the fluidic droplet, and/or controlling the applied electric field.