U-Shaped Flow Path Asymmetry for Plasma Collection
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Solution Overview
Problem
In blood cell separation by centrifugation using a U-shaped flow path, only half of the purified plasma is typically used for analysis, as equal amounts are separated on both sides, limiting the collection of target liquid components.
Innovation Solution
A sample separation device with a U-shaped flow path where the cross-sectional area of the right side is larger, allowing gravity and capillary forces to act oppositely and reducing capillary force action after separation, enabling more plasma collection by orienting the sample introduction and extraction openings in the same direction and using a diameter change portion to balance capillary and gravitational forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a U-shaped flow path is used for centrifugation, then blood cells are separated from plasma, but only half of the plasma can be collected for analysis
Solution Approach 1:
The flow path is designed with asymmetric cross-sectional areas where the first flow path has a larger cross-sectional area than the second flow path. This asymmetry causes the liquid surface to be higher in the first flow path after centrifugation, enabling collection of plasma from both sides of the U-shaped structure and increasing the total plasma yield from approximately 50% to nearly 100% of the separated plasma.
2Ease of operation
If capillary force acts on the sample after separation, then the sample moves in the flow path, but blood cells may mix with plasma
Solution Approach 1:
The flow path cross-sectional area is varied at different locations to control capillary force distribution. The liquid surface defining portion has a smaller cross-sectional area that creates sufficient capillary force to move the liquid sample, while the plasma collection portion has a larger cross-sectional area that reduces capillary force to prevent blood cell mixing. This localized variation in geometric properties enables controlled sample movement while maintaining separation integrity.
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 configuration allows for the easy collection of target liquid components post-centrifugation while minimizing blood cell mixing and increasing the usable plasma amount for analysis.
Implementation Method 1
the first separating portion is configured so that gravity and a capillary force generated in a direction opposite to the gravity act on the sample after separation
Implementation Method 2
the first separating portion is configured so that gravity and a capillary force generated in a direction opposite to the gravity act on the sample after separation
Implementation Method 3
a method of centrifuging a blood collection tube containing several mL of blood is mainly used. Since the specific gravity of blood cells is higher than the specific gravity of plasma/serum, blood cells are separated at the bottom and plasma/serum is separated at the top
Data Source
AI summary
A sample separation device to introduce a sample to be separated to an inside of the sample separation device, centrifuge the sample, and collect a desired liquid after separation, includes: a sample introducing portion introducing the sample into the sample separation device; a liquid surface defining portion connected to the sample introducing portion; a first separating portion connected to the liquid surface defining portion; a second separating portion connected to the first separating portion; a third separating portion connected to the second separating portion; and a liquid extracting portion including the third separating portion and connected to the third separating portion, in which a tubular flow path is formed by at least the first separating portion and the second separating portion, in which an opening of the sample introducing portion and an opening of the liquid extracting portion are oriented in the same direction.