Fixed-Dose Injection Device With Split-Dose Prevention
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Solution Overview
Problem
Existing fixed dose injection devices are complex, costly, and prone to user errors due to the need for manual dose adjustment or arming mechanisms, which can lead to split doses and device malfunction.
Innovation Solution
A drug delivery device with a split-dose-prevention mechanism, utilizing a drive tube guided by activation, drive, and stop-guide-ports, and a torsion spring to ensure a predefined fixed dose is delivered without interruption, featuring a connector and retention structure to prevent unintended movement during dosing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual dose adjustment or arming mechanisms are used in fixed dose injection devices, then the device can deliver fixed doses, but the device complexity increases and user errors occur
Solution Approach 1:
The drive tube is self-guided through activation, drive, and stop-guide-ports that are integrated into the housing assembly, eliminating the need for complex external guiding mechanisms. The system automatically guides itself through the dosing process without requiring manual intervention or complex arming mechanisms.
Solution Approach 2:
The guide structure is segmented into distinct functional portions (activation-guide-portion, drive-guide-portion, stop-guide-portion) that are integrated into the housing assembly, allowing each portion to perform its specific function while maintaining overall system simplicity.
2Ease of operation
If manual dose adjustment is required, then the device can be operated flexibly, but user errors leading to split doses increase
Solution Approach 1:
The connector automatically returns to the activated position after dose delivery through the return spring mechanism, eliminating the need for manual resetting. This self-resetting feature prevents user errors and ensures the device is always ready for the next fixed dose without requiring user intervention.
Solution Approach 2:
The device operates in periodic cycles of activation, dosing, and automatic return to the activated position. This periodic operation ensures that each dose is delivered completely and the device is automatically prepared for the next dose, preventing split doses through automated cyclic operation.
3Device complexity
If a torsion spring is used to expel the fixed dose, then the dosing mechanism is simplified, but the risk of unintended connector movement during dosing increases
Solution Approach 1:
The retention structure prevents unintended movement of the connector in the opposite direction during dosing by applying a counteracting constraint. This preliminary prevention measure ensures that the connector remains properly positioned throughout the dosing process, maintaining dosing integrity while allowing the simple torsion spring mechanism to operate.
4Device complexity
If the connector can move freely during activation, then the activation mechanism is simpler, but split doses or device malfunction may occur
Solution Approach 1:
The retention structure preemptively prevents unintended connector movement during the dosing phase by constraining motion in the opposite direction. This ensures that the simple activation mechanism operates reliably without causing split doses or device malfunction.
Solution Approach 2:
The connector is dynamically constrained only during the critical dosing phase through the retention structure, while maintaining freedom of movement during activation and return phases. This dynamic constraint approach ensures reliability when needed without unnecessarily complicating the mechanism.
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 reliable delivery of a predefined fixed dose, simplifying the user experience and reducing device complexity while preventing split doses and ensuring complete dose delivery.
Implementation Method 1
the expelling of the fixed doses is driven by a torsion spring
Data Source
Figure 1A
Figure 1B~1F
Figure 2A~2D
AI summary
A drug delivery device (100, 200) for delivering a fixed dose, comprising a drive mecha- nism comprising a drive spring (108, 208), and an activation mechanism comprising a connector (170, 270) adapted for activating the drive mechanism, wherein the drug de- livery device further comprises a split-dose-prevention mechanism adapted for limiting the axial movement of the connector during dosing. The split dose prevention mechanism comprises: (i) a split-dose-prevention structure (184, 284.1, 284.2) provided on the drive tube (180, 280) and extending in a circumferential direction, and (ii) a retention portion (178.3, 278.2) provided on the connector. For the drive tube being arranged in the intermediate position, the split-dose-prevention structure (184, 284.1, 284.2) and the retention portion are arranged with a transverse overlap, whereby movement of the connector in the second axial direction is limited by the split-dose prevention structure. For the drive tube being arranged in the stop position, the split-dose-prevention structure (184, 284.1, 284.2) and the retention portion are arranged with a transverse clearance and/or an axial gap, whereby the return spring (107, 207) can move the connector in the second axial direction, in response to releasing the applied force in the first direction on the connector.