Needle-Free Injection Plunger Auto-Disable Mechanism
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Solution Overview
Problem
Needle-free injection devices face challenges in preventing reuse of nozzle assemblies, which can lead to improper use and hygiene issues, as existing solutions do not effectively restrict the reactivation of the plunger and ram after an injection.
Innovation Solution
The nozzle assembly incorporates a plunger with a frangible region and deformable extensions that break or deform upon use, preventing the plunger from being retracted back into the nozzle body, thereby auto-disabling the device and restricting reuse, combined with a drive assembly that ensures the plunger and ram cannot be coupled again after an injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plunger is designed to be reusable, then device complexity is reduced, but hygiene and safety are compromised due to potential contamination from previous use
Solution Approach 1:
The plunger is divided into two separate portions: a first portion that remains in the nozzle body and a second portion that is driven by the drive assembly. This segmentation allows the plunger to function as a disposable component while maintaining a simple overall device structure, as each portion can be independently manufactured and assembled.
Solution Approach 2:
The first portion of the plunger is received within the nozzle body, creating a nested configuration where the plunger portion is housed inside the nozzle assembly. This nesting arrangement ensures proper positioning and integration while maintaining a compact device structure.
2Reliability
If the plunger is made secure to prevent accidental dislodgement, then reliability improves, but ease of operation deteriorates due to difficulty in removal
Solution Approach 1:
The deformable extensions are pre-configured in a deformable state that allows easy insertion and coupling with the drive assembly. During the injection process, the extensions automatically deform to lock the plunger in place, providing secure retention without requiring additional user actions.
Solution Approach 2:
The extensions change their physical state from deformable to engaged during operation. Initially, the extensions are in a flexible state that allows easy coupling, but after deformation during injection, they assume a locked configuration that prevents accidental dislodgement, thus changing the retention parameter dynamically.
3Reliability
If auto-disable mechanism is implemented, then hygiene safety improves by preventing reuse, but device complexity increases due to additional components
Solution Approach 1:
The frangible region is pre-weakened during manufacturing to ensure it will break at a predetermined location during the injection process. This preliminary preparation allows the auto-disable mechanism to function automatically without requiring additional sensors or control systems, maintaining device simplicity.
Solution Approach 2:
The first portion of the plunger is designed as a disposable component that is destroyed during use through the frangible region breakage. This approach prevents reuse in a simple and reliable manner, as the broken plunger portion cannot be reattached, effectively disabling the nozzle assembly after a single use.
4Ease of operation
If the plunger extensions are deformable for easy coupling, then ease of operation improves, but reliability deteriorates due to potential improper engagement
Solution Approach 1:
The deformable extensions are pre-configured with specific geometric features and material properties that guide their deformation path during coupling. This preliminary design ensures that the extensions will deform in a controlled manner to achieve proper engagement, eliminating the need for complex alignment procedures.
Solution Approach 2:
The extensions undergo a controlled parameter change from a flexible, easy-to-couple state to a rigid, securely engaged state. The deformation process transforms the extensions' physical properties, ensuring that once coupled, they maintain reliable engagement without slipping or dislodging during operation.
Data Source
AI summary
A nozzle assembly for a needle-free injection device. The nozzle assembly includes a nozzle body including an injectate chamber and one or more outlet orifices and a plunger configured to move through the injectate chamber toward the one or more outlet orifices. In some embodiments, the plunger includes a first portion and a second portion removably joined by a frangible region. In some embodiments, the plunger includes extensions configured to couple the plunger to a drive assembly of a needle-free injection device.