Autoinjector Retracting Needle Skin Sensor Trigger
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Solution Overview
Problem
Current needle safety mechanisms for small drug delivery devices with long needles face challenges, such as premature needle withdrawal during drug delivery in retracting needle types and increased device size due to robustness requirements in extending cover types, which compromise portability and usability.
Innovation Solution
A needle safety mechanism activated by a skin sensor element, allowing controlled needle retraction after drug delivery, using a stored energy source that expands offset from the needle axis to maintain compactness and avoid additional user actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a retracting needle mechanism is used, then needle withdrawal is automatic, but the needle may withdraw before drug delivery is complete
Solution Approach 1:
The needle retraction mechanism is designed to be triggered by skin sensor detection of device removal, which occurs automatically after drug delivery. This preliminary sensing action ensures that retraction only occurs after delivery is complete, preventing premature withdrawal while maintaining automatic operation.
2Reliability
If the needle remains in place after drug delivery, then drug absorption is improved, but drug leakage may occur
Solution Approach 1:
The skin sensor provides feedback about device removal from the injection site. When the sensor detects that the device has been removed, it triggers the needle retraction mechanism. This feedback loop ensures the needle remains in place during the critical absorption period but retracts automatically once the device is removed, preventing both leakage and ensuring absorption.
3Object-affected harmful factors
If an extending cover mechanism is used, then the needle remains protected, but the device size increases
Solution Approach 1:
The needle protection function is extracted from a separate extending cover mechanism and integrated into the needle assembly itself through the retraction mechanism. By retracting the needle into the device body rather than extending a cover over it, the solution provides continuous protection without requiring additional space for cover extension, maintaining compact device dimensions.
4Object-affected harmful factors
If a robust extending needle cover is used, then needle safety is ensured, but portability is compromised
Solution Approach 1:
The protection function is extracted from a heavy, robust extending cover and implemented through a lightweight retraction mechanism that pulls the needle back into the device. This eliminates the need for oversized protective covers while maintaining needle safety, preserving device portability and user comfort.
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 timely needle retraction without compromising drug delivery and maintains device compactness, enhancing portability and usability of small drug delivery devices with long needles.
Implementation Method 1
a skin sensor element coupled to the housing and movable relative to the housing, wherein the skin sensor element is biased into a front position relative to the housing and is movable to a rear position relative to the housing when the skin sensor element is pressed against an injection site on a patient
Implementation Method 2
The autoinjector comprises a needle retraction mechanism configured to withdraw the hypodermic needle into the housing when the needle retraction mechanism is released; wherein the needle retraction mechanism is coupled to the skin sensor element
Data Source
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Figure 3
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AI summary
An automatic drug delivery device comprising: a housing (1); a skin sensor element (15) coupled to the housing, biased into a front position relative to the housing, and movable to a rear position relative to the housing when pressed against an injection site; a needle assembly comprising a hypodermic needle (11) extending outside of the housing in a needle insertion position; a drug delivery mechanism comprising a stored energy source within the housing, and a further stored energy source releasable to deliver a drug through the hypodermic needle; a needle retraction mechanism configured to withdraw the hypodermic needle into the housing when released; wherein the needle retraction mechanism is coupled to the skin sensor element such that when the skin sensor element is moved from the rear position towards the front position, and the needle is in the needle insertion position, the needle retraction mechanism is released.