Autoinjector User-Controlled Needle Retraction
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Solution Overview
Problem
Existing autoinjectors automatically retract the needle after medicament delivery, which may lead to medicament siphoning back or escape through the puncture hole, and lack user control over the needle's dwell time, which is crucial for certain medications like adrenaline.
Innovation Solution
The autoinjector design includes a releasable latch and a retraction ring mechanism that allows the user to control the needle's retraction by changing the axial position of the syringe holder, enabling user-selective retraction initiation and extended dwell time by altering the forward force applied to the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the needle automatically retracts after medicament delivery, then the device complexity is reduced and ease of operation is improved, but medicament loss occurs through siphoning back or escape, and user control over dwell time is lost
Solution Approach 1:
The patent implements a dynamic retraction system where the needle can transition between automatic and manual retraction modes. The blocking means (latch mechanism) allows the system to switch from an automatic retraction state to a controlled state where the user can prevent retraction until the desired dwell time is achieved, thereby preventing medicament loss while maintaining ease of operation.
Solution Approach 2:
The patent changes the operational parameter of needle retraction from a fixed automatic process to a variable process. By introducing the blocking means, the dwell time parameter can be adjusted by the user based on the specific medicament requirements, allowing optimization between automatic convenience and medicament retention.
2Ease of operation
If the needle automatically retracts after medicament delivery, then the ease of operation is improved, but user control over needle dwell time is lost, which is crucial for certain medications
Solution Approach 1:
The system dynamically adapts its retraction behavior based on user input. The blocking means enables the needle to remain in the extended position for a customized duration, allowing the device to accommodate different medicament requirements while maintaining the simplicity of automatic retraction when standard protocols are followed.
Solution Approach 2:
The patent creates a universal retraction system that can serve multiple functions: automatic retraction for standard medications and controlled retraction for medications requiring extended dwell time. The blocking means acts as a multi-functional element that enables both operational modes within a single device architecture.
3Adaptability or versatility
If a releasable latch mechanism is added to control needle retraction, then user control over dwell time is improved and medicament loss is prevented, but device complexity increases
Solution Approach 1:
The blocking means is designed as a self-service mechanism that utilizes the user's natural interaction with the device. The latch engages and disengages through user-induced movements during normal operation, eliminating the need for separate controls or complex actuation mechanisms. This reduces the effective complexity added to the device while maintaining user control capability.
Solution Approach 2:
The patent merges the blocking means with existing device components, integrating the latch mechanism into the housing and syringe holder assembly. By combining multiple functions into unified components, the patent minimizes the increase in device complexity while achieving the desired user control over needle retraction timing.
4Loss of substance
If the blocking means prevents rearward movement of the syringe, then needle dwell time is extended and medicament loss is prevented, but the device requires additional user actions to initiate retraction
Solution Approach 1:
The blocking means is designed to be released through natural user actions during the injection process, such as removing the device from the injection site or manipulating the housing. This self-service approach minimizes the additional user actions required while ensuring that medicament loss is prevented through controlled retraction timing.
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
This design provides the user with control over the needle's dwell time, preventing medicament loss and allowing for safe and controlled needle retraction, enhancing the administration process for medications requiring specific delivery conditions.
Implementation Method 1
spring biased in a forward direction
Data Source
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AI summary
An autoinjector including a housing, in which can be mounted a syringe having a plunger, a barrel and needle at one end thereof through which medicament can be delivered to an injection site; a syringe support means capable of causing said syringe to move therewith along an axial path with respect to said housing; biasing means capable of biasing said syringe support means so that said needle is normally inside said housing, blocking means selectively moveable by a user from a first position in which rearward movement of the syringe along said axial path is substantially prevented, to a second position in which rearward movement of the syringe along said axial path relative to said housing is possible and said biasing means causes said needle to retract inside said housing.