Needle Assembly Shielding Mechanism for Injection Safety
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Solution Overview
Problem
Existing needle assemblies for injection devices often fail to adequately shield needles after use, leading to risks of needle stick injury, cross-infection, and tissue damage, and may be complex and costly to manufacture, with users unable to visually confirm needle insertion.
Innovation Solution
A needle assembly with a slideable shield and actuator portion that moves between a first position exposing the needle and a second position retracting it, featuring latching elements and engagement features for secure locking, providing a tactile and audible indication of shield engagement, and an ergonomic actuator surface for easy operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a removable or detachable shield is mounted on the forward end of a needle assembly, then the needle can be covered after use to prevent needle stick injury, but the shield can easily get lost or damaged during the injection process
Solution Approach 1:
The shield is integrated with the needle assembly through a ratchet mechanism that combines the shield, ratchet arm, and needle hub into a unified structure. The ratchet arm is fixed to the shield and engages with ratchet teeth on the needle hub, creating a combined assembly that cannot be easily separated, thus preventing loss or damage during injection.
Solution Approach 2:
The ratchet mechanism provides dynamic functionality where the shield can be easily pushed forward to cover the needle after use, and the ratchet arm automatically engages with the ratchet teeth to lock it in place. The mechanism allows unidirectional movement (pushing forward) while preventing reverse movement, providing both ease of operation and secure retention.
2Object-affected harmful factors
If a shield arrangement is biased towards a position in which the needle is covered, then the needle is automatically shielded after use, but the arrangement adds significant complexity and cost to the needle assembly
Solution Approach 1:
The shield is designed to be manually pushable in a forward direction to cover the needle, with a ratchet mechanism that automatically engages to lock the shield in place. This dynamic design allows easy one-handed operation while maintaining structural simplicity, avoiding complex spring-loaded or motorized biasing mechanisms.
Solution Approach 2:
The ratchet arm acts as an intermediary element between the shield and the needle hub. It translates the simple pushing motion of the shield into a secure locking engagement with the ratchet teeth, providing automatic retention without requiring complex mechanisms. The ratchet arm serves as a mechanical mediator that simplifies the overall system.
3Object-affected harmful factors
If the shield automatically moves back into a shielding position as the needle is removed from the skin, then needle safety is improved, but the user is generally unable to see the needle during insertion
Solution Approach 1:
The shield is designed to be manually movable between an extended position (allowing needle visibility during insertion) and a retracted position (providing safety after use). The ratchet mechanism allows the shield to be pushed forward to cover the needle, but does not prevent manual retraction, giving the user control over needle visibility when needed while ensuring safety when the shield is in the forward position.
Data Source
AI summary
A needle assembly (1) for mounting on an injection device is disclosed comprising: a main body (10) which is removably attached to an injection device in use; a needle (90) secured in the main body and having a forward portion which projects forwardly from the main body. The needle assembly further includes a shield (50) which is slideably mounted within the main body (10) and an actuator portion (70) which extends outside the main body and is configured for pushing the shield (50) forward manually in use. The shield (50) is slideably moveable between a first position in which the forward portion of the needle (90) projects forwardly of a shield cavity (64), and a second position in which said forward portion of the needle is located within the shield cavity (64). The shield (50) and main body (10) are provided with cooperating features comprising at least one latching element (66) provided on one of the shield (50) or the main body (10) and at least one corresponding engagement feature (44) provided on the other of the shield (50) and the main body. The latching element (66) moves into a latched position as the shield (50) moves into the second position to hold the shield in its second position.