Contact Trigger Release Needle Guard for Prefilled Syringes
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Solution Overview
Problem
Conventional passive anti-needle stick safety devices for prefilled syringes rely on syringe and stopper tolerances, which can interfere with injection force, obscure syringe contents, and impede inspection and handling processes, and are not independent of geometrical tolerances.
Innovation Solution
A contact trigger release needle guard with a lock collar and device shield biased by a spring, which moves relative to the lock collar, attaching to the syringe neck and step down area to automatically shield the needle without relying on syringe tolerances, and optionally providing tactile and audible feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional passive anti-needle stick safety devices are mounted to the syringe barrel, then needle stick protection is provided, but the devices obscure syringe contents and interfere with inspection processes
Solution Approach 1:
The safety device is segmented into separate functional components: a collar that attaches to the syringe neck and a shield that covers the needle. This segmentation allows the shield to be positioned distally without obscuring the syringe barrel contents, while still providing effective needle protection.
Solution Approach 2:
The safety device transitions from mounting on the syringe barrel (one dimension) to mounting on the syringe neck and extending distally (another dimension). This dimensional change allows the shield to cover the needle without interfering with optical inspection systems that examine the syringe barrel contents.
2Ease of operation
If conventional safety devices are positioned under the syringe finger flange, then the safety mechanism can be triggered, but the devices become dependent on syringe and stopper tolerances
Solution Approach 1:
The safety device triggering mechanism is extracted from its conventional position under the finger flange and relocated to the syringe neck area. The collar engages with the syringe neck and bulbus, independent of the stopper and finger flange tolerances, thereby eliminating dependence on tight geometrical tolerances while maintaining reliable triggering.
3Reliability
If safety devices are applied post-filling to the syringe barrel, then needle protection is achieved, but the devices interfere with handling equipment and packaging processes
Solution Approach 1:
The collar is designed to be pre-assembled on the syringe neck before filling, in a ready-to-fill state. This preliminary action allows the syringe to be handled and packaged using existing equipment without modification, while the safety shield is activated after filling to provide needle protection, thus maintaining productivity while achieving safety.
4Reliability
If the device shield is biased to move from exposed to covered position, then automatic needle shielding is achieved, but additional mechanical interference may occur during injection
Solution Approach 1:
The device shield is biased by a spring to automatically move from the exposed position to the covered position after needle insertion, without requiring additional user action. The spring mechanism provides the necessary force for automatic shielding, reducing the injection force requirement compared to manually activated devices while maintaining reliable automatic protection.
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
Enables safe needle shielding independent of syringe geometry, maintaining operational efficiency during injection and handling, while allowing clear inspection and packaging without additional mechanical interference.
Implementation Method 1
The device shield is biased relative to the lock collar by a spring
Data Source
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AI summary
A needle guard device mountable to a pre-filled syringe in its ready-to-fill state. The device includes a lock collar and a device shield biased to move relative to the lock collar. The lock collar interfaces with the syringe neck to attach the device to the syringe. With the removal of a needle shield assembly comprising rigid and soft needle shields, the lock collar and device shield are free to move proximally along the syringe neck and interact with a syringe step down area to activate the device. As the device moves proximally, retention arms of the device shield interact with the syringe step down, causing the arms to deflect radially outwards to disengage from the lock collar triggering the device shield to move from a first position to a second position.