Autoinjector Needle Shield Remover With Segmented Retainer
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Solution Overview
Problem
Existing autoinjectors face challenges in accurately and easily removing needle shields due to difficulties in achieving a secure grip, often requiring excess force or resulting in slippage.
Innovation Solution
A shield removal assembly for autoinjectors, comprising a retainer and a cap remover, is designed to provide a secure engagement mechanism. The retainer includes grasping features and radially-extending protrusions, while the cap remover has a flared distal end for ergonomic gripping, allowing for reliable positioning and easy removal of the needle shield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomeric needle shields are used, then sterility and safety are improved, but secure gripping and reliable removal become difficult
Solution Approach 1:
The shield removal assembly is divided into distinct functional components: a retainer with grasping features that engages the needle shield, and a cap remover that interfaces with the retainer. This segmentation allows each component to be optimized for its specific function - the retainer for secure engagement with the elastomeric shield, and the cap remover for easy user manipulation.
Solution Approach 2:
The retainer acts as an intermediary component between the user's grip (via the cap remover) and the needle shield. It provides a rigid structure with positive engagement features (grasping features and radially-extending protrusions) that bridge the gap between the user's manual grip and the elastomeric shield, enabling reliable removal without directly gripping the flexible shield material.
2Reliability
If firm grip between remover and needle shield is achieved, then removal reliability is improved, but excess force is required
Solution Approach 1:
The retainer is pre-positioned around the needle shield during assembly, with its grasping features already engaged with the shield's proximal end. The radially-extending protrusions are pre-aligned to engage with corresponding features on the shield. This preliminary positioning ensures that when the user activates the cap remover, the force is immediately transmitted through the pre-engaged retainer to the shield, eliminating the need for users to search for or apply force to difficult-to-reach areas.
Solution Approach 2:
The retainer replicates the engagement interface multiple times around the needle shield with its radially-extending protrusions, distributing the gripping force across multiple contact points. This multi-point engagement pattern copied around the circumference of the shield allows for reliable grip with reduced force per contact point, while the cumulative effect provides secure removal.
3Measurement precision
If accurate positioning of remover is required, then removal precision is improved, but device complexity increases
Solution Approach 1:
The retainer incorporates asymmetric features including radially-extending protrusions at specific angular positions and grasping features with predetermined orientations. These asymmetric elements provide unique geometric compatibility with corresponding features on the needle shield and syringe barrel, enabling accurate positioning through shape complementarity rather than complex adjustment mechanisms.
Solution Approach 2:
The retainer is designed with features that create equivalent engagement conditions at multiple locations: radially-extending protrusions that can engage with symmetric features on the shield, and a generally cylindrical body that provides uniform radial clearance. This equipotential design allows the retainer to be positioned accurately at any rotational orientation, simplifying the assembly process while maintaining precise positioning.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Provided herein is a shield removal assembly for an auto injector including a cap remover configured to be grasped by a user, a retainer received within the cap remover and having at least one grasping feature configured to engage a proximal edge of an auto injector needle shield. The shield removal assembly is configured such that the needle shield of the auto injector can be advanced through the shield removal assembly from a first position in which the at least one grasping feature is located proximally of the proximal edge of the needle shield to a second position in which the at least one grasping feature abuts the proximal edge of the needle shield.