Needle Cover Rough Surface Reduces Pull-Out Force
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Solution Overview
Problem
Conventional needle covers for injection devices require a significant pull-out force for removal, which can be challenging for users with reduced strength, while also needing to maintain container closure integrity and prevent contamination and leakage over time.
Innovation Solution
A needle cover with a cavity having a surface roughness of 2 μm to 12 μm, featuring a first portion with a smooth surface and a second portion with randomly distributed reliefs, designed to reduce the pull-out force while ensuring sealing engagement with the injection device, thereby maintaining container closure integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a smooth surface is used on the needle cover, then the pull out force is high which prevents unintentional removal, but it becomes difficult for users with reduced strength to remove the needle cover
Solution Approach 1:
The needle cover incorporates a rough surface treatment applied locally to specific portions of the outer needle shield, rather than uniformly across the entire surface. This localized roughness creates specific friction zones that reduce pull-out force in controlled areas while maintaining structural integrity elsewhere, enabling easier removal for users with reduced strength without compromising overall retention.
Solution Approach 2:
The surface roughness parameter is modified within a specific range (2 μm to 12 μm) to optimize the balance between retention and removability. By controlling the roughness parameter within this range, the needle cover achieves reduced friction and pull-out force while maintaining sufficient engagement to prevent unintentional removal during normal handling.
2Ease of operation
If a rough surface is used to reduce pull out force, then users with reduced strength can remove the needle cover easily, but container closure integrity and sealing may be compromised
Solution Approach 1:
The rough surface treatment is applied selectively to specific portions of the outer needle shield, creating localized friction reduction zones. This ensures that the roughness affects primarily the removal characteristic while the sealed portions maintain their sealing function, preserving container closure integrity even after long storage periods.
Solution Approach 2:
The needle cover is divided into functional segments: portions requiring easy removal are treated with rough surface, while sealing portions maintain their sealing capability. This segmentation allows different regions to fulfill different functions - one optimized for user interaction and another for maintaining closure integrity.
3Ease of operation
If the needle cover is designed for easy removal with reduced pull out force, then usability is improved, but the risk of unintentional removal increases
Solution Approach 1:
The surface roughness is controlled within a specific range (2 μm to 12 μm) to achieve the optimal balance. This parameter control ensures sufficient friction reduction for easy removal by users with reduced strength, while maintaining enough engagement force to prevent unintentional removal during normal handling and transport.
Solution Approach 2:
The rough surface is applied to specific portions rather than the entire needle cover, creating controlled friction zones that facilitate intentional removal while leaving other areas with sufficient friction to prevent accidental disengagement during normal use.
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
The needle cover achieves a reduced pull-out force range of 7 N to 16 N, ensuring usability by users with varying strength levels while maintaining container closure integrity and preventing contamination and leakage, even after long storage periods.
Implementation Method 1
The inner surface of the needle cover body defining the second portion has a surface roughness extending in a range from 2 μm to 12 μm, inclusive
Data Source
AI summary
A needle cover for an injection device includes a needle cover body having a cavity therein. The cavity configured to receive a distal end of an injection device therein and having at least a portion configured such that, when the needle cover is disposed on an injection device, the portion at least partially engages with a distal end of the injection device. The inner surface defining the portions has a surface roughness extending in a range from 2 μm to 12 μm, inclusive. An injective device having such a needle cover and a method of forming the needle cover are also disclosed.