Needle-Shroud Decoupling for Drug Delivery Feedback
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Solution Overview
Problem
Existing injection devices, both manual and autoinjectors, face challenges such as the need for manual force application, potential premature dose interruption, difficulty in aligning and maintaining stability during injection, and dexterity requirements, which can be problematic for elderly or children, and the desire for ensuring a full medicament dose is administered.
Innovation Solution
A drug delivery device with a feedback mechanism comprising a collar and needle shroud that decouples during the injection process, providing audible and tactile feedback when the full dose is delivered, and a plunger release mechanism to ensure complete delivery, along with a shroud lock mechanism for safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual plunger is used to drive medicament through a needle, then the device structure is simple, but the injection requires continuous manual force which may be too high for elderly or children and may be released prematurely
Solution Approach 1:
The device uses a spring mechanism that automatically provides the force needed to push the plunger, eliminating the need for manual force application. The spring is pre-loaded and releases automatically when the device is activated, performing the injection service without requiring the user to exert force.
Solution Approach 2:
The spring is pre-compressed during device assembly or activation, storing energy in advance. This preliminary action ensures that when the injection is triggered, the stored energy is immediately released to drive the plunger, eliminating the need for real-time manual force application.
2Extent of automation
If a conventional autoinjector is used with spring activation, then automated injection is achieved, but there is no feedback mechanism to confirm full dose delivery
Solution Approach 1:
The device incorporates a feedback mechanism where the needle shroud is coupled to the plunger rod and moves with it during injection. When the plunger reaches its distal position indicating full dose delivery, the needle shroud also reaches a corresponding position that can be visually observed or tactily felt, providing feedback to the user that the injection is complete.
Solution Approach 2:
The needle shroud acts as an intermediary element that translates the plunger's movement into a user-perceptible signal. By coupling the needle shroud to the plunger rod, the system uses the shroud's position as an intermediate indicator to communicate injection progress and completion status to the user.
3Reliability
If the plunger is continuously pressed during injection, then medicament delivery is maintained, but premature release stops the injection and may not deliver intended dose
Solution Approach 1:
The spring mechanism automatically maintains continuous force on the plunger throughout the injection process, eliminating the need for the user to continuously press or hold the plunger. The system self-regulates the force application, ensuring reliable dose delivery without requiring ongoing user intervention.
Solution Approach 2:
The device transitions from a static manual pressing requirement to a dynamic automated spring-driven system. The spring provides continuously varying force as the plunger moves, automatically adapting to the injection process requirements without needing manual adjustment or continuous user input.
4Manufacturing precision
If alignment and stability during injection is required, then injection accuracy is improved, but dexterity is required which some patients may not have
Solution Approach 1:
The device is designed to be self-aligning through its activation mechanism. When the activation button is pressed, it automatically triggers the spring release and plunger movement in a predetermined sequence, eliminating the need for the user to manually align or stabilize the device during injection. The system performs the alignment and stabilization functions automatically.
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
The device ensures complete delivery of the medicament dose with user-friendly operation, reducing the risk of premature dose interruption and enhancing safety by providing clear feedback and secure needle retraction.
Implementation Method 1
a control spring biasing the collar in a distal direction
Implementation Method 2
providing audible and tactile feedback when the full dose is delivered
Data Source
AI summary
A drug delivery device includes a case adapted to hold a medicament container, a plunger disposed within the case and slidable from a proximal position into a distal position for delivering a medicament from the medicament container, at least one feedback mechanism that is in operative connection with the plunger. The feedback mechanism comprises a collar, a control spring biasing the collar in a distal direction, a needle shroud, operatively axially abutting the collar in a first coupled state and prevented from axially decoupling the collar by the plunger in its proximal position The plunger, when approaching the distal position during movement from the proximal position towards the distal position, is adapted to allow axial decoupling of the needle shroud from the collar, allowing for a limited axial movement of the collar relative to the needle shroud until the collar axially abuts the needle shroud in a second coupled state.