Filter Plunger Air Cushion for Uniform Plasma Separation
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Solution Overview
Problem
Existing plasma separation devices, such as the 'Mini-UniPrep' and EP 0 292 329 A2, face issues with reproducible and uniform pressure application, leading to potential bursting of red blood cells and contamination of the plasma fraction due to pressure peaks.
Innovation Solution
The proposed solution involves a filter plunger with a grip element and a filtrate collector vessel that tapers to contact the filter element, forming an annular chamber with a sealing element to create a controlled air cushion, allowing gradual and uniform pressure application through flow connections between the chamber and the filter element, preventing haemolysis and enabling reproducible plasma extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a filtration plunger is pushed into the sample container to separate plasma from whole blood, then plasma extraction is achieved, but pressure peaks occur that cause bursting of red blood cells and contamination of plasma
Solution Approach 1:
The patent introduces an air cushion as an intermediary between the plunger and the blood sample. This air layer acts as a buffer that distributes pressure uniformly across the filter element, preventing direct pressure transmission that would cause red blood cell bursting. The air cushion mediates the force application, transforming concentrated pressure into distributed pressure.
Solution Approach 2:
The invention pre-establishes an air cushion before filtration begins. By trapping air in the annular chamber before the plunger contacts the blood sample, the system prepares a protective buffer in advance. This beforehand cushioning prevents harmful pressure peaks from developing during the filtration process, ensuring gentle and uniform pressure application throughout.
2Speed
If pressure is applied to force fluid through the filter media, then filtration speed increases, but red blood cells burst due to excessive pressure
Solution Approach 1:
The air cushion serves as a pressure-distributing intermediary that enables fast filtration without harmful pressure concentrations. It allows the system to achieve high filtration speeds by providing a large, uniform pressure front that moves quickly through the filter while maintaining pressure below the haemolysis threshold through even distribution.
Solution Approach 2:
The invention changes the pressure distribution parameter from concentrated to uniform by introducing the air cushion. This parameter transformation allows the system to maintain high overall pressure for fast filtration while keeping local pressure at any point below the critical threshold that causes red blood cell bursting.
3Productivity
If the plunger is pushed to the bottom of the container to complete filtration, then all sample is processed, but uncontrolled pressure is applied to the filter
Solution Approach 1:
By establishing the air cushion before filtration begins, the system ensures that even when the plunger reaches the bottom of the container, the pressure is always mediated through the air layer. This beforehand cushioning guarantees reproducible and controlled pressure application throughout the entire filtration process, preventing uncontrolled pressure spikes.
Solution Approach 2:
The invention uses pneumatic principles by employing compressed air as the driving force for filtration. The air cushion provides a compliant, gas-based pressure transmission system that is inherently more controllable and reproducible than direct mechanical contact, allowing complete sample processing with consistent pressure application.
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 design ensures reproducible and uniform pressure application, preventing red blood cell bursting and contamination, while allowing efficient extraction of plasma from small whole blood samples with easy handling, ensuring high-quality plasma samples.
Implementation Method 1
an air cushion, acting on the sample fluid, is formed upon introduction of the filter plunger into the sample container
Implementation Method 2
a filter element at its front end and will receive in its interior the filtrate obtained
Data Source
Figure 1~2
Figure 3~7
AI summary
The invention relates to a separation device for separating a filtrate from a sample fluid, especially for extracting plasma (42) from whole blood (41), comprising a sample container (25) for receiving the sample fluid and a filter plunger (26) to be introduced under seal into the sample container (25), which filter plunger has a filter element (24) at its front end and a grip element (27) on the opposite end and will receive in its interior the filtrate obtained. After insertion of the filter plunger (26) into the sample container (25) an annular chamber (34) is formed between the inner wall of the sample container (25) and the outer wall of the filter plunger (26), which is sealed against the exterior by a sealing lip (32) and in which an air cushion is formed upon introduction of the filter plunger (26) into the sample container (25), which acts on the sample fluid. A flow connection is provided between the annular chamber (34) and the front side of the filter element (24) after insertion of the filter plunger (26) is terminated.