Autoinjector Stall and Endpoint Detection via Encoder Feedback
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Solution Overview
Problem
Pre-filled hypodermic syringes pose challenges due to user aversion to exposed needles, mechanical complexities in injection processes, and issues with reliable drug delivery, including plunger stalling and inconsistent injection speeds, which affect the accuracy and safety of automated injection systems.
Innovation Solution
A drug delivery device with a motor-driven plunger system, encoder, and controller that ensures consistent injection speed by detecting plunger movement and adjusting the motor operation, along with a needle insertion mechanism for concealed needle operation and automatic retraction, addresses the mechanical and user-friendly design requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor-driven plunger system is used to automate injection, then injection consistency and reliability are improved, but device complexity increases due to additional components like encoders and controllers
Solution Approach 1:
The patent employs encoder feedback to monitor plunger position and injection speed, allowing the controller to adjust motor operation in real-time. This feedback mechanism ensures consistent injection delivery while managing system complexity through intelligent control algorithms that process encoder signals.
Solution Approach 2:
The patent replaces manual mechanical injection operations with an automated motor-driven system. The motor, encoder, and controller combination substitutes human manual plunger manipulation, providing precise control over injection speed and position while eliminating variability in manual operation.
2Object-affected harmful factors
If the needle is concealed during operation, then user safety and comfort are improved, but the complexity of the needle insertion and retraction mechanisms increases
Solution Approach 1:
The patent implements preliminary actions by automatically positioning and concealing the needle before injection, and automatically retracting it after injection. The system prepares the needle in a concealed state prior to use and ensures its automatic retraction following the injection process, eliminating the need for manual needle handling.
Solution Approach 2:
The needle insertion and retraction mechanisms operate autonomously without requiring user intervention. The motor-driven system automatically performs needle deployment into the concealed position and subsequent retraction, making the device self-servicing regarding needle management and eliminating exposure risks.
3Ease of operation
If the plunger is driven to a fixed end position, then injection completion is simplified, but plunger stalling and glass breaking risks increase
Solution Approach 1:
The encoder provides continuous feedback on plunger position and movement status. The controller monitors this feedback to detect plunger stalling conditions in real-time and can adjust motor torque or speed accordingly, preventing complete stalling and the associated risk of glass breakage while ensuring injection completion.
Solution Approach 2:
The patent employs dynamic control of the plunger drive system, adjusting motor parameters based on real-time plunger position and load conditions. This dynamic adjustment allows the system to adapt to varying resistance during injection, maintaining reliable operation throughout the plunger's travel to the end position.
Data Source
AI summary
An autoinjector drug delivery device configured with a stall and endpoint detection algorithm is described that allows for variations in the fill of the drug, barrel, plunger, and other components. The stall or end point detection can cause the autoinjector to stop an extrusion process.