Autoinjector Controlled Needle Retraction
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Solution Overview
Problem
Existing autoinjector devices with automatic needle retraction can cause medicament to escape from the injection site, especially when injecting adrenaline, as the needle retracts quickly before the medicament has dispersed, leading to inefficiencies and regulatory challenges associated with custom medicament chambers.
Innovation Solution
An autoinjector design that allows controlled retraction of the needle by moving the outer housing axially, using a rotating sleeve to switch between positions that prevent or allow rearward movement of the syringe, enabling manual control over needle retraction and integration with a standard syringe presentation, reducing complexity and regulatory burdens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If automatic needle retraction is implemented, then device complexity is reduced and ease of operation is improved, but medicament may escape from the injection site causing loss of substance
Solution Approach 1:
The device transitions from fully automatic retraction to a dynamic system where the outer housing can move axially to selectively enable or disable retraction. The engagement means selectively engage with the syringe support means to prevent or allow rearward movement based on the axial position of the outer housing, allowing the system to adapt to different operational requirements.
Solution Approach 2:
The engagement means act as an intermediary mechanism between the syringe support means and the biasing means. This intermediary selectively transmits or blocks the biasing force depending on the axial position of the outer housing, enabling controlled retraction timing to prevent medicament escape while maintaining ease of operation.
2Volume of moving object
If custom medicament chamber is designed, then device compactness is improved, but regulatory control complexity increases
Solution Approach 1:
The device is designed to accommodate standard pre-filled syringes with universal dimensions and configurations. The syringe support means and engagement means are configured to work with standard syringe presentations, eliminating the need for custom medicament chambers while maintaining device functionality and reducing regulatory complexity.
3Reliability
If needle retraction is delayed or controlled, then medicament dispersion is improved, but device complexity increases
Solution Approach 1:
The biasing means provides self-service automatic retraction force that acts on the syringe support means when engagement is released. The system uses the stored mechanical energy in the biasing means to automatically retract the needle without requiring additional power sources or complex control systems, maintaining reliability while minimizing device complexity.
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
Facilitates controlled needle retraction, preventing medicament loss and allowing for the use of standard pre-filled syringes, enhancing user control and operational reliability while minimizing regulatory hurdles.
Implementation Method 1
biasing means capable of biasing said syringe support means so that said needle is normally inside said housing
Implementation Method 2
engagement means selectively moveable by a user from a first position in which rearward movement of the syringe along said axial path is substantially prevented
Data Source
AI summary
An autoinjector including: a housing, in which can be mounted a syringe (28) having a plunger, a barrel and needle (19) at one end thereof through which medicament can be delivered to an injection site,—a syringe support means (30) capable of causing said syringe to move 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; and engagement means (180) selectively moveable by a user from a first position in which rearward movement of the syringe along said axial path is substantially prevented when said syringe is in an extended position where at least part of said needle is out of the housing, 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; wherein said housing includes an outer housing (16) and said autoinjector further comprises a sleeve (18) intermediate the syringe support means and said outer housing that is capable of moving the engagement means between said first and second positions by rotating said sleeve about a longitudinal axis of said autoinjector between a first rotational position and a second rotational position; and wherein the sleeve is moveable between said first and second rotational positions by moving said outer housing with respect to the sleeve in a substantially axial direction.