Syringe Passive Locking Mechanism Prevents Reuse
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Solution Overview
Problem
The reuse of hypodermic syringes without proper sterilization contributes to the spread of diseases, particularly among intravenous drug users, due to the high risk of contamination with viruses like AIDS and hepatitis, and existing solutions require active user intervention to disable the syringe.
Innovation Solution
A syringe assembly with a passive locking mechanism that prevents reuse by locking the plunger rod within the barrel after an injection cycle, utilizing a rib and protrusion system to restrict movement and include visual indicators to signify use or disability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive locking mechanism is implemented to prevent reuse, then reliability is improved, but device complexity increases
Solution Approach 1:
The protrusion on the plunger rod nests within the barrel, and the rib on the barrel engages with this protrusion to create the locking mechanism. The stopper nests within the barrel and works in conjunction with the plunger rod components. This nesting approach allows multiple functional elements to be integrated in a compact arrangement, achieving reliable passive locking without excessive complexity.
Solution Approach 2:
The locking mechanism is designed to activate automatically through the relative motion of the stopper and plunger rod during normal injection operation. The protrusion is positioned such that when the stopper reaches the distal end of the barrel, the plunger rod automatically engages with the rib to lock in place. This self-service mechanism eliminates the need for additional active disabling components, maintaining reliability while controlling complexity.
2Reliability
If the stopper and plunger rod are attached to prevent disassembly, then reliability is improved, but ease of operation worsens
Solution Approach 1:
The connection between the stopper and plunger rod is designed with differentiated properties: the stopper can move freely along the plunger rod during the injection stroke (ease of operation), but the overall assembly prevents disassembly of the syringe components (reliability). The relative motion capability is maintained locally where needed, while the integrated structure provides global prevention of disassembly.
3Loss of information
If visual indicators are added to indicate use or disability, then information completeness is improved, but device complexity increases
Solution Approach 1:
The syringe incorporates visual indicators that change appearance or position to indicate whether the syringe has been used or disabled. This may involve color-coded regions, visible markings, or positional indicators that become apparent through the locking mechanism's engagement. These indicators provide complete information about syringe status without requiring complex electronic or mechanical indicator systems.
Data Source
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AI summary
Syringe assemblies having a passive disabling system to prevent reuse are provided. According to one or more embodiments, the syringe assembly comprises a barrel, plunger rod and stopper wherein the plunger rod further comprises a flexible protrusion that locks the plunger rod within the barrel. Certain embodiments further include a frangible portion on the plunger rod that breaks when reuse is attempted. One or more embodiments include a plunger rod and stopper attachment that prevents disassembly of the syringe assembly prior to use. Syringe assemblies of one or more embodiments also include visual indicators or markers indicating whether a syringe assembly is used or the plunger rod is locked within the barrel.