Coaxial Sampling Needle Structure for Complete Blood Tube Retrieval
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Solution Overview
Problem
Existing blood collection tubes (BCTs) face issues with needle bending and off-axis insertion due to manufacturing and assembly tolerances, leading to incomplete sample retrieval and potential contamination, especially when accessing both liquid and gas phases within the BCT.
Innovation Solution
A sampling device with a coaxial needle configuration, featuring a first needle and a second needle supported by a needle tip support that can open or retract, and optionally a needle middle support, to center and stabilize the needle during insertion, preventing bending and ensuring complete sample retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a long needle (>100 mm) is used to access the bottom of the elongated BCT, then the needle can reach both liquid and gas phases, but the needle may bend or deform due to insertion force and friction
Solution Approach 1:
The needle is divided into multiple sections: a first needle portion with larger outer diameter for structural strength, and a second needle portion with smaller outer diameter for sample access. This segmentation allows the needle to maintain rigidity while reaching the bottom of the BCT.
Solution Approach 2:
The second needle portion is arranged coaxially inside the first needle portion, creating a nested structure. This allows the longer needle to access the bottom of the BCT while the outer needle provides structural support and prevents bending during insertion.
2Strength
If the needle outer diameter is increased to prevent bending, then needle strength improves, but insertion force increases due to higher surface friction
Solution Approach 1:
The needle structure is segmented into an outer needle with larger diameter for strength and an inner needle with smaller diameter for insertion. This allows the system to benefit from both high strength and low insertion force.
Solution Approach 2:
Different parts of the needle system have different diameters optimized for their specific functions: the outer needle has larger diameter for structural integrity, while the inner needle has smaller diameter for easy insertion through the septum.
3Object-affected harmful factors
If a blunt or square tip is used to prevent cutting septum material, then septum damage is reduced, but insertion force increases
Solution Approach 1:
The needle tip is segmented into a blunt outer needle that prevents septum damage and a sharper inner needle that can still penetrate effectively. This allows the system to reduce harmful effects while maintaining insertion capability.
4Ease of manufacture
If the needle tip is not centered during insertion, then manufacturing tolerances are accommodated, but the needle may insert off-axis leading to incomplete sample retrieval
Solution Approach 1:
The coaxial nested structure of the two needles provides inherent centering. The outer needle guides and centers the inner needle, ensuring accurate positioning even when accommodating manufacturing tolerances in the BCT insertion.
Data Source
AI summary
According to an example aspect, there is provided a sampling device for transferring a fluidic sample from a sampling container comprising a closed lid, the sampling device comprising: a receptacle body extending along an axis, a first needle and a second needle arranged at least partially inside the receptacle body and extending along the axis, which second needle is arranged coaxially with the first needle and partially inside the first needle, and a needle tip support arranged inside the receptacle body for supporting a tip of the second needle, which needle tip support is configured to open or retract, when a force in a direction of the axis is applied to the tip of the second needle.