Microfluidic Plasma Separation Cartridge for Fingerstick Assays
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Solution Overview
Problem
Existing methods for extracting plasma from whole human blood for colorimetric assays are inefficient, often requiring larger blood samples and separate devices, with no commercial products capable of extracting plasma from a small drop of blood, such as from a fingerstick.
Innovation Solution
A microfluidic method and cartridge system that separates plasma from small blood samples using a plasma filter and capillary channels, mixes it with a diluent and reagent, and performs colorimetric chemistry tests using light transmission or reflection, allowing for precise quantification and sequential filling of cuvettes to avoid cross-contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If centrifugation is used to separate plasma from whole blood, then plasma separation is achieved, but the blood sample volume required increases to 100 μL
Solution Approach 1:
The plasma separation filter is integrated within the microfluidic cartridge, nesting the separation function inside the testing device. This eliminates the need for external centrifugation equipment and enables plasma separation from small blood samples (20-30 μL) within the cartridge itself, resolving the contradiction between reducing sample volume and maintaining separation capability.
Solution Approach 2:
The patent replaces the mechanical centrifugation system with a microfluidic filter-based separation system. The filter uses capillary action and pressure differential to separate plasma from whole blood, eliminating the need for centrifugation machinery while achieving the same separation goal with much smaller sample volumes.
2Device complexity
If separate devices are used for plasma separation and colorimetric assay, then each function is optimized, but the overall system complexity increases
Solution Approach 1:
The patent combines plasma separation, sample mixing, and colorimetric assay functions into a single integrated microfluidic cartridge. The cartridge contains the separation filter, mixing chambers with reagents, and cuvettes for optical measurement, all connected through microfluidic channels. This merging reduces system complexity and enables point-of-care testing while maintaining functional optimization through careful design of each integrated component.
3Loss of substance
If larger blood samples are used for plasma extraction, then sufficient plasma is obtained for assay, but sample waste increases
Solution Approach 1:
The microfluidic cartridge is designed to efficiently extract and process plasma from small blood samples (20-30 μL) through integrated capillary channels and filters. The system self-regulates the plasma extraction process, obtaining sufficient plasma for the assay while minimizing blood sample waste, eliminating the need for larger 100 μL samples required by centrifugation methods.
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
Enables the efficient separation and quantification of plasma from small blood samples, facilitating accurate colorimetric assays without the need for excessive blood volume, while ensuring the integrity of the testing process through fluidic isolation and precise reagent mixing.
Implementation Method 1
A microfluidic method is used to separate a desired amount of plasma (a sample) from small amounts of whole human blood
Implementation Method 2
capillary channels, mixes it with a diluent and reagent
Implementation Method 3
performs colorimetric chemistry tests using light transmission or reflection
Implementation Method 4
performs colorimetric chemistry tests using light transmission or reflection
Implementation Method 5
mixes it with a diluent and reagent
Data Source
AI summary
A device includes a plasma separation membrane, a capillary channel positioned adjacent the plasma separation membrane to receive plasma from blood placed on the plasma separation membrane, at least one cuvette coupled to the capillary channel, a gas permeable membrane, and a distribution channel coupled to the capillary channel to provide plasma to the cuvette, wherein the cuvette is configured to hold an amount of plasma with reagent suitable for colorimetric assay by a tester to hold the device. Variations include the use of a quantitation channel to provide a selected amount of plasma and a mixing channel to mix plasma with a diluent.