Jet Injector Guard Retraction for Gentle Prefilled Syringe Handling
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Solution Overview
Problem
Certain jet injection devices require significant force to trigger the needle guard retraction and injection, which can be challenging to manage, especially with prefilled syringes that need gentle handling to avoid damage.
Innovation Solution
A jet injector with a prefilled syringe and a retractable needle guard mechanism that includes an interference component, such as a lock ring, to provide a breakaway force resistance before allowing needle insertion and triggering, using a spring for injecting pressure between 80 and 1000 p.s.i., with a needle penetration depth of 0.5 to 15 mm below the skin surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant force is applied to trigger needle guard retraction and injection, then the injection can be initiated, but the prefilled syringe may be damaged
Solution Approach 1:
The device segments the force application into two distinct phases: a breakaway phase that requires high force to overcome the lock ring engagement, and a retraction phase that requires minimal force. The lock ring with engagement portions creates a mechanical segmentation that separates the triggering function from the retraction function, allowing the syringe to remain intact during high-force triggering while enabling gentle retraction afterward.
Solution Approach 2:
The lock ring is pre-configured with engagement portions that must be overcome before needle guard retraction can begin. This preliminary breakaway action prepares the mechanism for subsequent gentle retraction, ensuring that the syringe is properly positioned and secured before the injection sequence begins, thereby preventing damage during the high-force triggering phase.
2Ease of operation
If the needle guard is retracted significantly to allow needle insertion and triggering, then injection can proceed, but control over insertion depth becomes difficult
Solution Approach 1:
The lock ring provides localized engagement at specific portions along the needle guard, creating discrete control points for insertion depth. The engagement portions are positioned to provide tactile feedback and mechanical stops at predetermined depths, allowing precise control of needle insertion while maintaining ease of operation through the simple retraction motion.
Solution Approach 2:
The lock ring engagement portions provide tactile feedback to the user during needle guard retraction, indicating when specific insertion depths are reached. This mechanical feedback system allows the user to control insertion depth precisely by feeling the engagement portions, combining ease of operation with precision control.
3Strength
If a lock ring with engagement portions is used to provide breakaway force resistance, then gentle syringe handling is enabled, but the device complexity increases
Solution Approach 1:
The lock ring serves multiple functions: it provides breakaway force resistance to protect the syringe during triggering, controls needle insertion depth through engagement portions, and enables gentle retraction once activated. By combining these functions into a single component, the device complexity is minimized while achieving comprehensive syringe protection and control.
Solution Approach 2:
The lock ring merges the breakaway mechanism, depth control features, and retraction assistance into a single integrated component. This consolidation reduces the number of separate parts needed in the needle guard mechanism, thereby protecting the syringe without significantly increasing 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
Ensures gentle and reliable jet injection with minimal syringe damage, preventing medicament leakback and allowing for precise needle insertion depths, enhancing medicament distribution without forming a bolus at the injection site.
Implementation Method 1
an energy source configured for biasing the plunger with a force selected to produce an injecting pressure on the medicament in the fluid chamber to jet inject the medicament from the fluid chamber through the needle to the injection site
Implementation Method 2
the injecting pressure remains between about 80 p.s.i. and about 1000 p.s.i. during injection of the medicament
Data Source
AI summary
A jet injector that includes a prefilled syringe. The syringe includes a fluid chamber that contains a medicament. The syringe also has an injection-assisting needle, and a plunger is movable within the fluid chamber. A housing is configured for allowing insertion of the needle to a penetration depth. The housing includes a retractable guard and an interference component, e.g., a lock ring, adjacent to the retractable guard that interferes with the movement of the retractable guard. An energy source is configured for biasing the plunger to produce an injecting pressure to jet inject the medicament from the fluid chamber through the needle to an injection site.