Auto-Injector Cap Mechanism for Controlled Needle Shield Release
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Solution Overview
Problem
Existing auto-injectors face challenges in ensuring safe and reliable needle protection mechanisms, particularly in preventing unintended needle exposure during and after use, especially when handled by untrained personnel or for self-administration.
Innovation Solution
A drug delivery device with a cap and needle shield mechanism that includes a removable rigid needle shield, a cap with an outer portion and retainer, and a needle cover that moves through specific positions to ensure safe needle handling, featuring a protrusion and retaining tab system to secure and unlock the needle shield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid needle shield is used to protect the needle, then needle protection is improved, but the device complexity increases due to additional retention and release mechanisms
Solution Approach 1:
The retainer is integrated with the cap assembly, combining the protective shield retention function with the existing cap structure. This merging reduces overall device complexity while maintaining reliable needle protection throughout the injection process.
Solution Approach 2:
The removal projection on the retainer automatically engages with the needle shield and passively releases it through axial movement of the cap, eliminating the need for complex active release mechanisms. The system serves itself through simple mechanical motion.
2Reliability
If a cap with retainer and removal projection is added to control needle shield release, then safety is improved, but the ease of operation deteriorates due to additional user actions required
Solution Approach 1:
The retainer is pre-configured with the removal projection positioned to engage the needle shield during storage and transport. This preliminary arrangement ensures automatic retention without user intervention, while allowing simple axial movement of the cap to trigger release when needed.
Solution Approach 2:
Instead of requiring the user to actively disengage a locking mechanism, the design inverts the approach by having the cap's axial movement naturally drive the removal projection to release the needle shield. The simple action of removing or moving the cap accomplishes the complex task of shield release.
3Ease of operation
If the needle shield is automatically removed upon cap removal, then the ease of operation is improved, but the reliability deteriorates due to potential unintended needle exposure
Solution Approach 1:
The retainer is designed with dynamic characteristics, allowing it to remain engaged with the needle shield during normal cap removal operations while requiring a more deliberate axial movement for actual shield release. This dynamic behavior ensures automatic convenience while preventing unintended exposure through controlled engagement and disengagement thresholds.
Data Source
AI summary
A drug delivery device includes a housing, a syringe assembly including a barrel, a stopper, a cannula, and a rigid needle shield receiving at least a portion of the cannula, with at least a portion of the syringe assembly positioned within the housing, a drive assembly, with a portion of the drive assembly positioned within the housing, a cap secured to the housing, with the cap including an outer portion defining an interior space and a retainer comprising a body with a removal projection configured to remove the rigid needle shield upon axial movement of the outer portion of the cap away from the housing, and a needle cover having a pre-use position, an actuation position, and a post-use position. The outer portion receives a portion of the needle cover, with the outer portion configured to prevent movement of the needle cover from the pre-use position to the actuation position.