Prefilled Syringe Breakaway Force for Reliable Needle Insertion
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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 for users and may not ensure sufficient needle insertion and triggering, especially with prefilled syringes that need gentle handling.
Innovation Solution
A jet injector with a prefilled syringe and a retractable needle guard mechanism, featuring a lock ring or interference component that provides a breakaway force resistance, allowing controlled needle insertion and triggering, and using a spring to maintain injecting pressure between 80 and 1000 p.s.i. for effective medicament delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant force is required to trigger needle guard retraction, then sufficient needle insertion and triggering can be ensured, but the operation becomes challenging for users and may damage the syringe
Solution Approach 1:
The force requirement is segmented into two distinct phases: a high breakaway force phase for initial needle guard release and needle insertion, and a low sustaining force phase for the actual jet injection triggering. This is achieved through the friction fit between the syringe outer surface and housing inner surface, which provides initial resistance then allows smooth movement.
Solution Approach 2:
The friction fit mechanism dynamically adapts the force resistance during operation. Initially, the friction between the syringe outer surface and housing inner surface provides high breakaway force for reliable needle insertion. Once the needle guard is retracted and needle is inserted, the friction allows the plunger to move freely for jet injection without requiring significant additional force.
2Stability of the object's composition
If the syringe is supported during jet injection, then the syringe remains stable, but the distal portion may not be positioned correctly for effective injection
Solution Approach 1:
Different portions of the syringe receive different support characteristics. The proximal portion is supported by the syringe support to maintain stability, while the distal portion including the needle tip remains unsupported to allow precise positioning and effective jet injection. This localized differentiation of support quality resolves the contradiction between overall stability and injection precision.
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 reliable and gentle medicament injection with minimal risk of syringe damage, preventing backflow, and achieving efficient distribution of the medicament without forming a bolus, even with short needles.
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. In one embodiment, the energy source comprises a spring.
Implementation Method 2
an interference component adjacent to the retractable guard that interferes with the movement of the retractable guard when the retractable component is moved at least partially from the protecting position toward the injecting position
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.