Vacuum-Loaded Microfluidic Chip Droplet Generation
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Solution Overview
Problem
Conventional microfluidic chips face challenges in forming consistently-sized droplets and maintaining pressure balance during sample loading, leading to potential leaks and increased costs due to the need for additional seals and oil for pressure equalization.
Innovation Solution
The microfluidic chips incorporate a network that allows for gas evacuation from the test volume before sample introduction, using a single port for both gas removal and liquid loading, and feature a droplet-generating region with a constriction and expansion section to form consistent droplets, eliminating the need for precise ramp angles and additional seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional pressure-based loading is used, then sample can be loaded into test volume, but positive pressure causes seal separation and leaks
Solution Approach 1:
The patent inverts the conventional pressure-based loading approach by using vacuum pressure to draw sample liquid into the test volume. Instead of pushing liquid in with positive pressure that causes seal separation, the system creates negative pressure that pulls liquid in through the inlet port, thereby maintaining seal integrity and preventing leaks.
2Stability of the object's composition
If additional seals are added to maintain pressure, then liquid position can be maintained, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for additional seals by using a single inlet port that serves dual purposes: it allows vacuum evacuation of gas from the test volume and subsequently allows liquid loading through the same port. This removes the complexity of multiple seals required in conventional designs to maintain pressure differentials.
3Stress or pressure
If pressure equalization port is added, then pressure balance can be achieved, but droplet loss and additional oil requirements occur
Solution Approach 1:
The patent makes the inlet port multi-functional, using it for both vacuum evacuation and liquid loading operations. This eliminates the need for a separate pressure equalization port that would otherwise be required to balance pressure during droplet formation, thereby preventing droplet loss through additional ports and eliminating the need for extra oil.
4Productivity
If ramp geometry is used for droplet formation, then droplets can be generated, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the droplet generation process into distinct functional zones: a constriction section that focuses and directs liquid flow, and an expansion region that allows droplet formation and release. This segmentation eliminates the need for precise ramp angles while maintaining controlled droplet generation through the geometric features of the constriction and expansion zones.
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 approach ensures consistent droplet formation and reduces manufacturing constraints, eliminates the need for additional seals and oil, and enhances safety by maintaining a negative pressure environment, thereby reducing costs and improving leak containment.
Implementation Method 1
Gas evacuation can occur while the liquid is disposed in the port by decreasing the pressure at the port (e.g., to below ambient pressure). The changes in pressure can be achieved using a vacuum chamber.
Implementation Method 2
at least one of the droplet-generating region(s) can include a constriction section and, optionally, an expansion region having a minimum cross-sectional area larger than that of the constriction section
Data Source
AI summary
A microfluidic chip that can have a body defining a microfluidic network including a test volume, one or more ports, and one or more channels in fluid communication between the port(s) and the test volume. Gas can be removed from the test volume before a sample liquid is introduced therein by reducing pressure at a first one of the port(s), optionally while the liquid is disposed in the port. Liquid in the first port can be introduced into the test volume by increasing pressure at the first port. The microfluidic network can define one or more droplet-generating regions in which at least one of the channel(s) defines a constriction and/or two or more of the channels connect at a junction. Liquid flowing from the first port can pass through at least one of the droplet-generating region(s) and to the test volume.