Microfluidic Blood Plasma Separation via Dean Vortices
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Solution Overview
Problem
Current microfluidic techniques for blood plasma separation, such as centrifugation and impoverished zone mining, face limitations due to clogging issues with deformable red blood cells and instability of secondary flows, which affect separation efficiency and yield.
Innovation Solution
A microfluidic method involving a combination of a straight pipe for initial particle concentration and a curved pipe section with Dean flows to separate liquid and solid phases, where the viscous force dominates over centrifugal force, allowing for spatial separation of plasma from blood cells by exploiting the formation of secondary Dean vortices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If filtration is used to separate plasma from blood cells, then liquid phase recovery is improved, but pore clogging occurs quickly due to deformable red blood cells
Solution Approach 1:
The invention extracts the harmful effect (deformable red blood cells) from the system by using a bypass channel that allows them to be separated from the main flow before reaching the filter, preventing clogging while maintaining filtration efficiency for plasma separation
Solution Approach 2:
The invention introduces an intermediary element (the bypass channel with curved section) that mediates between the blood suspension and the filter, using Dean vortices to redistribute particles and prevent direct contact with filter pores
2Productivity
If centrifugation is used in bent channels to separate plasma, then plasma extraction is achieved, but secondary Dean flows mix particles and reduce separation efficiency
Solution Approach 1:
The invention applies local quality by creating different flow conditions in different regions: the bypass channel uses curved geometry to generate Dean vortices for particle concentration, while the straight filtration channel maintains laminar flow for efficient plasma separation, optimizing each region for its specific function
Solution Approach 2:
The invention segments the flow path into distinct functional zones: a curved bypass section for particle concentration via Dean flows, and a straight filtration section for plasma separation, allowing each segment to perform its specific function without interference
3Productivity
If impoverished zone mining is used to separate plasma, then plasma extraction yield is improved, but the phenomenon is unstable and depends on flow conditions
Solution Approach 1:
The invention implements feedback by using the curved bypass channel geometry to generate Dean vortices that automatically concentrate particles in a stable manner, creating a self-regulating system where the flow conditions themselves produce the concentrating effect without external control
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 enhances plasma separation efficiency by overconcentrating particles in a ring around the pipe axis, which are then deformed by secondary Dean flows, enabling effective spatial separation of plasma and blood cells, improving yield and stability compared to traditional methods.
Implementation Method 1
suspended particles injected into a straight pipe undergo heterogeneous lateral migration due to shear forces
Implementation Method 2
the effectiveness of centrifugation techniques in microsystems is however limited by the secondary flows (Dean cells) which develop under these conditions
Implementation Method 3
the effectiveness of centrifugation techniques in microsystems is however limited by the secondary flows (Dean cells) which develop under these conditions and tend to mix the particles
Data Source
AI summary
The method involves injecting a suspension (30) i.e. blood, on a circulation duct (10) with straight and curved sections (11, 12), and extracting a liquid enriched fraction (31) e.g. plasma enriched blood fraction, from the suspension. A suspension injected flow rate and a geometry of the duct are chosen, so that lift forces causes a concentration of blood cell enriched blood fraction (32) in a ring (42) around an longitudinal axis of the duct, in the section (11), and deanol secondary flows deform the ring and cause a spatial separation between the fractions (31, 32), in the section (12). An independent claim is also included for a microfluidic device for extracting a liquid phase from suspension comprising a circulation duct.