Retractable Syringe Needle Aperture Design
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Solution Overview
Problem
Retractable syringes often suffer from 'dead volume' issues and visible fluid bubbles, leading to inefficient fluid delivery and inaccurate dose control, which is particularly problematic in mass-produced prefilled syringes containing expensive pharmaceuticals or vaccines.
Innovation Solution
The design incorporates a retractable needle with an aperture positioned between the plunger-engaging member and the elongate portion, minimizing 'dead space' and eliminating visual bubbles, thereby enhancing fluid delivery efficiency and dose accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retractable needle is positioned with the cannula end in the barrel, then the needle can be retracted for safety, but dead volume is created and fluid delivery efficiency is reduced
Solution Approach 1:
The patent introduces a transverse aperture through the needle body, creating a new dimensional pathway for fluid flow. This allows fluid to bypass the dead volume region and flow directly from the barrel through the aperture to the cannula, resolving the contradiction between safety (retraction) and productivity (delivery efficiency) by adding a dimensional shortcut to the fluid path.
2Volume of moving object
If the cannula end is positioned in the barrel, then the needle assembly is compact, but visible bubbles are created and dose control accuracy is reduced
Solution Approach 1:
The patent extracts the bubble formation problem from the visible region by creating a transverse aperture that positions the fluid flow path away from the user's line of sight. The aperture acts as a hidden transfer point that removes the harmful visual distraction while maintaining the compact needle assembly volume.
3Reliability
If a complicated needle assembly is used for retraction, then safety features are enhanced, but device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The needle body is designed to perform multiple functions: it serves as the structural framework, the fluid conduit, the mounting surface for the aperture, and the interface for both the cannula and plunger-engaging member. This multi-functionality reduces the number of separate components needed, thereby reducing device complexity while maintaining safety features.
Data Source
AI summary
A retractable needle is provided for a syringe comprising a barrel and a plunger that comprises a portion capable of engaging the retractable needle for retraction. The retractable needle comprises a cannula, a needle body having a plunger-engaging member, at least one aperture and an elongate portion which houses the cannula, the cannula comprising an end which is in fluid communication with the at least one aperture, wherein the at least one aperture is located between the plunger-engaging member and the elongate portion. The positioning of the at least one aperture distal to the plunger-engaging member maximizes the efficiency of fluid delivery.