Cannula Protective Housing Lamella Retention
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Solution Overview
Problem
Existing cannula protective housings with hooks fail to reliably prevent the cannula from accidentally emerging, leading to potential puncture injuries and contamination, and require complex design and operator skill for secure closure.
Innovation Solution
A two-part protective housing design featuring a flexible inner housing with lamellae and a less elastic outer sleeve, where the outer housing applies a compressive force to maintain the funnel slot closed, preventing unwanted cannula egress through inclined contact surfaces and access openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hooks are used as retaining means in the protective housing, then the cannula can be restrained, but the cannula can still slide out laterally along the free hook ends, leading to unreliable retention
Solution Approach 1:
The protective housing is divided into two separate parts: an inner housing containing the retaining means (hooks) and an outer housing that provides structural support. This segmentation allows the inner housing to focus on retention functionality while the outer housing provides rigid support to prevent lateral sliding, thereby improving reliability without excessive complexity in either component
Solution Approach 2:
The solution moves from a single housing structure to a two-dimensional nested structure with inner and outer housings. The outer housing adds a new spatial dimension of support that prevents lateral movement along the hook ends, addressing the reliability issue by adding restraint in a different dimensional plane
2Reliability
If additional restraining means or hooks are added to the protective housing, then cannula retention may improve, but the housing requires additional openings and greater manufacturing effort
Solution Approach 1:
By segmenting the housing into inner and outer parts, the retaining means can be integrated into the inner housing structure during its molding process, while the outer housing is separately manufactured and then assembled. This reduces the manufacturing complexity compared to adding multiple openings and features to a single housing piece
Solution Approach 2:
The inner housing is nested within the outer housing, allowing the retaining means to be contained within the inner housing structure. This nesting approach simplifies manufacturing by allowing each housing to be produced separately with standard molding techniques, then assembled together, avoiding the need for complex integrated features in a single piece
3Ease of operation
If the protective housing is made flexible to allow cannula entry, then the cannula can easily enter, but the housing cannot reliably prevent the cannula from emerging again due to pressure forces
Solution Approach 1:
The housing is segmented into an inner flexible housing that allows easy cannula entry through deformation, and an outer less elastic housing that provides rigid support to prevent unwanted emergence. Each part performs its specialized function optimally without compromising the other
Solution Approach 2:
Different parts of the housing system have different elastic properties tailored to their specific functions: the inner housing is highly elastic at the entry region to facilitate easy cannula insertion, while the outer housing is less elastic to provide stable retention and prevent accidental emergence under pressure forces
4Ease of operation
If the funnel slot is made expandable to allow cannula entry, then the cannula can enter freely, but the slot can widen undesirably under external pressure, allowing cannula egress
Solution Approach 1:
The housing structure is segmented into an inner expandable housing that allows the funnel slot to expand for easy cannula entry, and an outer rigid housing that constrains the overall structure and prevents unwanted expansion under external pressure, thereby preventing cannula egress
Solution Approach 2:
The inner housing has localized elasticity at the funnel slot region to allow expansion during cannula entry, while the outer housing provides localized rigidity to prevent excessive expansion under pressure. This spatial differentiation of material properties enables both easy entry and reliable retention
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
Enhances user safety by securely retaining the cannula, preventing accidental egress and contamination, while simplifying the design and reducing the need for additional openings and operator skill.
Implementation Method 1
the inner housing is formed of an elastic, resilient material
Implementation Method 2
the outer housing applies a compressive force to maintain the funnel slot closed
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a cannula, preferably equipped with a cannula holder for, in particular a blood sampling device, which comprises a pivotable protective housing (102) for a free end of the cannula. Said protective housing (102) is closed on the periphery except for a cannula insertion opening (8) provided between opposing side walls. Said insertion opening is produced by at least one pair of lamella (8a, 8b), formed on the side walls, the lamella tapering towards one another in the manner of a funnel and forming an expandable funnel slot. The protective housing (102) comprises two housing parts which can be inserted into each other. The inner housing (2a) comprises the pair of lamella (8a, 8b) and an outer housing (11), which surrounds the inner housing (2a), is embodied as a sleeve that is less elastic than the inner housing (2a).