Split Needle Shield Safety Mechanism for Pre-filled Syringes
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Solution Overview
Problem
Existing safety devices for pre-filled syringes do not adequately prevent accidental needle stick injuries after injection, as they often require additional user interaction to activate safety features, and manufacturing complexities arise from single-direction spring mechanisms.
Innovation Solution
A safety device with a split needle shield system, where a first needle shield moves proximally to release a second needle shield, which is biased to move distally and lock into position, covering the injection needle, using a torsion spring that relaxes once to ensure needle safety without additional user interaction, made from inexpensive plastics materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single needle shield is used that moves in one direction, then the device structure is simpler, but it cannot provide adequate needle safety after injection
Solution Approach 1:
The needle shield is divided into two separate shields: a first needle shield that moves proximally during injection and a second needle shield that moves distally after injection to cover the needle. This segmentation allows each shield to perform its specific function independently, providing comprehensive needle safety while keeping individual shield structures simple.
2Ease of operation
If a spring mechanism is used to automate shield movement, then user interaction is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of using a spring to push the shield forward during injection, the invention uses a spring to push the shield backward (distally) after injection. This inversion of the typical spring mechanism direction simplifies the manufacturing process and reduces costs while still achieving automated shield movement for safety coverage.
Solution Approach 2:
The second needle shield is automatically moved by the spring mechanism after the injection is completed, without requiring additional user interaction. The system self-activates the safety feature by utilizing the natural recoil or release mechanism built into the device structure.
3Ease of operation
If separate power sources are provided for each shield, then each shield can be precisely controlled, but the device becomes more complex and expensive
Solution Approach 1:
The invention merges the control mechanism into a single integrated system where one power source or actuation mechanism controls both the first and second needle shields. The shields are coordinated through mechanical linkages or sequential activation, eliminating the need for separate power sources and reducing overall device complexity.
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
The device effectively prevents accidental needle stick injuries by automatically activating safety features after use, reducing manufacturing costs and complexity, and is intuitive to use, ensuring needle safety without requiring separate power sources for each shield.
Implementation Method 1
using a torsion spring that relaxes once to ensure needle safety without additional user interaction
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
According to the invention, a safety device(1) for a pre-filled syringe(2) comprises - a support body(1.3) adapted to mount the pre-filled syringe(2), - a first needle shield(1.1) slidably arranged with respect to the support body(1.3) and - a second needle shield(1.2) slidably arranged with respect to the support body(1.4) and releasably retained in a retracted position(PR). A proximal movement of the first needle shield(1.1) with respect to the support body(1.3) releases the retention of the second needle shield(1.2) in the retracted position(PR), so that the second needle shield(1.2) is allowed to slide in the distal direction towards an advanced position(PA).