Autoinjector End-of-Dose Visual Indicator Mechanism
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Solution Overview
Problem
Users of autoinjectors may struggle to determine when a full dose of medicine has been administered, leading to premature removal of the device and potential loss of medication, due to the lack of clear visual, audible, and tactile indications.
Innovation Solution
An autoinjector design featuring a retraction assembly with an opaque and transparent or translucent section, where an end-of-dose visual indicator moves into the transparent section upon completion of the injection, providing a clear visual cue that the full dose has been delivered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If no visual indication is provided to signal injection completion, then the device structure remains simple, but users cannot determine when the full dose has been administered, leading to premature removal and medication loss
Solution Approach 1:
The patent employs color changes in the visual indicator to signal injection completion. The indicator transitions from a first color (e.g., red) during injection to a second color (e.g., green) when the full dose has been administered, providing clear visual feedback to users without requiring complex electronic systems.
Solution Approach 2:
The visual indicator is extracted as a separate, simple component within the retraction assembly rather than being integrated into the main injection mechanism. This allows the indicator functionality to be added with minimal impact on the overall device structure and manufacturing complexity.
2Reliability
If users are instructed to hold the injector at the injection site longer than necessary, then injection completion is ensured, but user discomfort and distress increase due to prolonged needle presence
Solution Approach 1:
The patent implements visual feedback through the indicator that transitions to a completion color, allowing users to stop holding the injector at the precise moment injection is complete. This eliminates the need for conservative time-based instructions that cause unnecessary discomfort.
Solution Approach 2:
The indicator is pre-configured to automatically change color at the exact moment the full dose is administered, providing advance visual confirmation before the user would otherwise need to remove the device based on time estimates.
3Loss of information
If a complex injection indication mechanism with multiple signaling elements is implemented, then injection progress can be indicated, but device complexity increases significantly
Solution Approach 1:
The patent extracts only the essential visual indication function from complex multi-sensory indication systems found in prior art. By using a single visual indicator within the retraction assembly rather than combining tactile, audio, and visual elements, the device provides sufficient information with minimal added complexity.
Solution Approach 2:
Instead of using complex mechanisms to actively display injection progress, the patent uses a passive indicator that simply changes appearance when the injection is complete, inverting the approach from active monitoring to passive confirmation.
Data Source
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AI summary
An autoinjector that automatically retracts a needle contained therein includes an injection assembly, having a plunger and a movable piston coupled to the plunger, a retraction assembly coupled to the injection assembly, and an end-of-dose visual indicator disposed within the retraction assembly. The retraction assembly includes an opaque section, a transparent or translucent section coupled to the opaque section, and a drug container having a hypodermic needle. The end-of-dose visual indicator is disposed within the retraction assembly such that the indicator moves upwardly from the opaque section of the retraction assembly to the transparent or translucent section of the retraction assembly upon full administration of a drug solution or medicine contained within the drug container. The end-of-dose visual indicator may be configured according to many preferred embodiments, among which may include a hollow cylinder, a split indicator ring, a co-extruded ring, and a multi-faceted polygonal cylinder.