Syringe Needle Retraction Mechanism With Bendable Plunger Flanges
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Solution Overview
Problem
Existing safety syringes often have complex mechanisms that are difficult to operate, with uncertain and/or incomplete retraction mechanisms, leading to confusion in use, and/or unclear operation, and often lack the ability to ensure the needle is retracted correctly, and can result in needlestick injuries and re-use, while also compromising liquid and air-tightness and volumetric accuracy.
Innovation Solution
A syringe with a needle retraction mechanism that is intuitively operable, automatically engaging upon emptying, using bendable flanges on the plunger to allow one-fluid motion operation, ensuring complete retraction without additional steps, and maintaining volumetric accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-loaded needle retraction mechanism is used, then needle safety is improved, but device complexity increases
Solution Approach 1:
The needle is nested within the syringe body housing, which serves as the retraction mechanism. The needle can be extended from and retracted into the housing, eliminating the need for separate complex retraction components while maintaining safety functionality.
Solution Approach 2:
The traditional spring-loaded retraction mechanism is extracted and replaced with a simpler fixed housing structure. The needle is directly mounted to move between extended and retracted positions within the housing, removing unnecessary mechanical complexity while preserving the safety function.
2Ease of operation
If the needle is fixed in the extended position, then ease of use is improved, but safety risk increases due to accidental sticks
Solution Approach 1:
The needle is designed to be dynamically positioned rather than fixed. It can be easily extended to the working position and automatically retracts to a safe position when not in use, providing both ease of operation and safety through its ability to change position as needed.
Solution Approach 2:
The needle is pre-positioned in a retracted safe state within the housing. When needed, it is easily extended to the working position. This preliminary safe positioning prevents accidental sticks while maintaining ease of use when the needle is actually needed.
3Ease of operation
If the needle can be easily removed and reattached, then ease of operation is improved, but alignment precision deteriorates
Solution Approach 1:
The needle and syringe body are merged into a single integrated assembly where the needle is permanently mounted to the plunger assembly. This eliminates the need for removal and reattachment, ensuring consistent alignment precision while maintaining ease of operation as a single unit.
Solution Approach 2:
The integrated needle-syringe assembly serves multiple functions: the needle provides injection capability, the plunger assembly provides injection and retraction functions, and the housing provides containment and safety functions. This multi-functional integration eliminates alignment issues while maintaining operational ease.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~3
AI summary
The present invention relates to a syringe with an improved needle retraction mechanism, comprising: (a)a cylindrical barrel, (b) a needle holder, (c) a hollow plunger, (d) a rod, (e) an extractor element, and (f) a recovery tension or compression spring, the extractor element being movably displaceable from an advanced position to a retracted position, said extractor element having a male protrusion to engage the internal cavity of the needle holder to join the extractor element to the needle holder, and hooking means defining a connection between the plunger and the extractor element, and wherein the axial hole of the plunger is defined by a plurality of bendable flanges which are configured to slide over the needle holder, said bendable flanges thereby bending outwardly and expanding the axial hole of the plunger, and whereby the extractor element is disconnected from said plunger and is retracted towards its retracted position. The present invention also relates to a syringe kit wherein the syringe is provided with an improved needle retraction mechanism as described herein.