Sample Tube Sealing Cap with Segmented Cavity to Limit Liquid Transfer
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Solution Overview
Problem
Existing sealing caps for blood collection tubes allow a significant amount of liquid to flow into the sample tube during centrifugation, contaminating the sample and potentially falsifying analysis results due to coagulation and hemolysis, and also risk contamination during transport.
Innovation Solution
The cavity of the sealing cap is divided into two sub-areas, with only the smaller sub-area above the opening allowing liquid to flow into the sample tube, reducing the volume of liquid that enters the sample tube and maintaining the desired ratio of liquid to preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cavity of the sealing cap is designed with a larger volume to accommodate more liquid, then the sampling capacity is improved, but during centrifugation a larger amount of liquid flows into the sample tube causing contamination and falsifying analysis results
Solution Approach 1:
The cavity is divided into two separate sub-areas (first sub-area and second sub-area) by a separating wall. The first sub-area stores the majority of the liquid sample, while the second sub-area positioned above the opening contains only a small residual amount of liquid. This segmentation prevents excessive liquid from entering the sample tube during centrifugation, thus avoiding contamination while maintaining adequate sampling capacity.
2Reliability
If the non-return valve is designed to remain closed during transport, then sample contamination is prevented, but during centrifugation the valve opens allowing liquid to flow into the sample tube
Solution Approach 1:
The cavity design creates a local quality difference between the first sub-area (larger volume, below opening level) and the second sub-area (smaller volume, above opening level). This spatial differentiation ensures that even when the non-return valve opens during centrifugation, only the minimal liquid in the second sub-area can enter the sample tube, while the majority of liquid remains in the first sub-area and does not contaminate the sample.
3Object-affected harmful factors
If the cavity volume is reduced to minimize liquid flow during centrifugation, then sample contamination is reduced, but the sampling capacity is diminished
Solution Approach 1:
The solution addresses the volume contradiction by introducing a spatial dimension - the separating wall creates vertical stratification of the cavity space. The first sub-area utilizes the lower volume space for bulk liquid storage, while the second sub-area occupies the upper space above the opening level. This dimensional arrangement allows the cavity to maintain large total volume for sampling capacity while ensuring minimal liquid (only in the second sub-area) can potentially contaminate the sample during centrifugation.
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 minimizes the volume of liquid entering the sample tube, ensuring accurate analysis results by maintaining the integrity of the sample and preventing contamination, thus ensuring the quality of subsequent analysis.
Implementation Method 1
Due to the typical preparation of a sample in a centrifuge, a tensile force is exerted in the axial direction on the installed non-return valve, causing it to open. The relatively large amount of liquid contained in the cavity of the sealing cap enters the sample tube
Data Source
AI summary
A sealing cap seals a sample tube for receiving a liquid, in particular blood. The sealing cap includes a cavity delimited by a membrane and a base having an opening that can be sealed by a non-return valve. In order to reduce the volume of liquid which, during centrifugation of the sample tube sealed by the sealing cap, flows out of the sealing cap through the then open opening into the sample tube, the cavity of the sealing cap has a separating wall that divides the cavity into a first and a second sub-area. Only the second sub-area is above the opening, also meaning that only the volume of liquid in the second sub-area can flow into the sample tube.