Auto-Injector Cap Assembly for Controlled Needle Shielding
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Solution Overview
Problem
Existing auto-injectors face challenges in ensuring safe and reliable needle protection mechanisms, particularly in preventing unintended contact with the needle after use, especially when handled by untrained personnel or during accidental drops or impacts.
Innovation Solution
A drug delivery device with a cap and needle shield mechanism that allows for controlled actuation and automatic needle shielding, featuring a cap with an outer portion that moves axially to engage and disengage with the needle cover and retainer, ensuring safe handling and preventing unintended actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid needle shield is used to protect the needle after use, then needle protection is improved, but the device complexity increases due to additional components like cap, retainer, and needle cover
Solution Approach 1:
The patent combines multiple protective functions into an integrated cap assembly that includes the retainer and needle cover as unified components. The cap serves both as a protective shield for the needle and as a manual actuation mechanism, merging the functions of protection and control into a single integrated structure that reduces overall device complexity.
Solution Approach 2:
The cap assembly serves multiple functions: it protects the needle during storage and transport, provides a manual actuation interface for users, and automatically shields the needle after injection. This multi-functional design eliminates the need for separate components for each function, thereby reducing device complexity while maintaining reliable needle protection.
2Object-affected harmful factors
If automatic needle shielding is implemented, then user safety is improved, but the device complexity increases due to additional mechanisms
Solution Approach 1:
The needle shield is pre-positioned in a retracted state during device assembly, and the cap is pre-configured with engagement features that automatically activate the shielding function after injection. This preliminary arrangement allows the automatic safety mechanism to function without requiring complex real-time control systems, thereby enhancing user safety while minimizing added complexity.
Solution Approach 2:
The device automatically shields the needle through the mechanical interaction between the cap, retainer, and needle cover components during the injection process. The system self-activates the safety mechanism without requiring external control or additional power sources, providing enhanced user safety through a passive, self-regulating design that avoids increasing device complexity.
3Reliability
If the cap is designed to prevent unintended contact with the needle, then reliability is improved, but the ease of operation decreases due to restricted needle cover movement
Solution Approach 1:
The cap and needle cover are designed with dynamic engagement features that adapt their interaction based on the device state. During normal operation, the engagement features allow smooth movement for intended actions, while automatically engaging to prevent unintended contact. This dynamic behavior maintains ease of operation for legitimate uses while ensuring reliability by blocking accidental activation.
Solution Approach 2:
The retainer acts as an intermediary component between the cap and the needle cover, mediating their interaction. It provides controlled engagement that prevents direct restrictive contact between the cap and needle cover, allowing the needle cover to move freely during intended operations while still preventing unintended contact. This intermediary mechanism preserves ease of operation while maintaining reliability.
4Reliability
If the outer portion of the cap is designed to engage the needle cover, then needle protection is improved, but the device complexity increases due to additional engagement features
Solution Approach 1:
The engagement features are nested within the existing cap and needle cover structures rather than being added as separate external components. The outer portion of the cap contains engagement features that interface with corresponding features on the needle cover, creating a nested arrangement where protective functions are integrated into the existing form factor. This nesting approach provides reliable needle protection without significantly increasing overall device complexity.
Data Source
AI summary
A drug delivery device (10) includes a housing (26), a syringe assembly (16) including a barrel (52), a stopper (54), a cannula (56), and a rigid needle shield (58) receiving at least a portion of the cannula, with at least a portion of the syringe assembly positioned within the housing, a drive assembly (40), with at least a portion of the drive assembly positioned within the housing, a cap (18) secured to the housing, with the cap including an outer portion (20) defining an interior space and a retainer (160) comprising a body with a removal projection (164) 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 (22) 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.