Open-Sided Microfluidic Channel for Uniform Plasma Separation
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Solution Overview
Problem
Existing microfluidic systems for separating blood plasma from blood often experience uneven filling of channels due to capillary forces, leading to inconsistent liquid fronts and difficulties in diagnostics, as well as issues with air entrapment and chemical dissolution.
Innovation Solution
A microfluidic apparatus with channels open on one or both sides, featuring a recess that acts as a lateral liquid stop to ensure uniform filling by capillary forces, preventing air entrapment and allowing direct examination of the sample liquid without side walls, and incorporating deflector elements to manage filling speeds and prevent lateral liquid advancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If closed channels are used for receiving and conveying blood plasma, then the structure is simple and complete, but the filling speed becomes uneven and air entrapment occurs
Solution Approach 1:
The channel is segmented into open sections and closed sections. The open sections allow for uniform capillary filling, while the closed sections provide structural completeness and contain the liquid front. This segmentation resolves the contradiction by combining the benefits of both open and closed channel designs.
Solution Approach 2:
The invention transitions from a fully closed two-dimensional channel cross-section to a three-dimensional structure with open sides. By opening the channel on one or more sides, capillary forces can act uniformly across the entire cross-section, enabling even filling speeds while maintaining structural integrity through the closed portions.
2Device complexity
If side walls are provided in the channel, then the channel structure is complete, but the liquid front advancement becomes uneven
Solution Approach 1:
The invention extracts (removes) the side walls from the channel structure in certain regions, creating open sides. This allows capillary forces to act uniformly on the liquid front across the entire width of the channel, eliminating the uneven advancement caused by side walls while maintaining enough structural enclosure to define the channel path.
3Reliability
If the channel is completely open on sides, then venting is improved and direct examination is enabled, but lateral liquid stop is lost
Solution Approach 1:
The invention introduces a lateral liquid stop structure as an intermediary element within the open channel. This stop structure prevents unwanted lateral liquid advancement while maintaining the open-sided design that enables efficient venting and direct optical examination of the liquid front.
4Device complexity
If inner edges are present at channel transitions, then the channel structure is well-defined, but capillary forces become excessively high
Solution Approach 1:
The invention replaces sharp inner edges at channel transitions with rounded or curved surfaces. This curvature eliminates the high capillary forces that would otherwise occur at sharp edges, while still maintaining a well-defined channel structure and transition zones between different channel sections.
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
The apparatus achieves rapid, uniform, and optimized filling of channels, reducing air entrapment and enabling direct examination of the sample liquid, thereby enhancing diagnostic capabilities and ensuring consistent sample availability for analysis.
Implementation Method 1
The channel (3) is designed to be filled with the sample liquid (2) rapidly and uniformly by means of capillary forces
Implementation Method 2
The laterally open construction of the channel ensures an improved, particularly optimum venting when the channel is filled with sample liquid
Data Source
AI summary
The invention relates to an apparatus for separating blood and at the same time an apparatus (1) for absorbing blood (19) and separating components such as blood plasma, as a sample liquid (2), having a feed device (13) for receiving the blood (2), a separating device (15) for separating blood components as the sample liquid (2), a channel (3) which takes up the sample liquid (2) preferably exclusively by capillary forces and a fill device for filling the channel (3) with sample liquid (2) in an inlet or feed region (18) of the channel (3), wherein the separating device (15), particularly a membrane, is domed, more particularly convexly shaped and projects with the apex of the convex shape into the filling device in the direction of filling.