Injection Device Plunger Stops for Accurate Microdose Delivery
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Solution Overview
Problem
Existing injection devices struggle to accurately administer micro doses of injection solutions, particularly for medical treatments requiring precise dosages that differ from the syringe's filling volume, and there is a need for a reliable system to transfer injection solutions from syringes to injection devices.
Innovation Solution
An injection device with a plunger stop mechanism and a plunger releasing mechanism that allows for accurate administration of micro doses, combined with a system for transferring injection solutions from a syringe to the device using Luer tapers and a filling adapter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the injection device uses a standard syringe for administering injection solution, then the device is simple and easy to manufacture, but it cannot accurately administer micro doses that differ from the syringe's filling volume
Solution Approach 1:
The injection device divides the syringe into two independent parts: a removable plunger assembly and a stationary barrel with dose marking scale. This segmentation allows the plunger to be transferred between syringes while maintaining accurate dosing capability through the permanent markings on the barrel, resolving the contradiction between dosing precision and device simplicity.
Solution Approach 2:
The dose marking scale on the barrel acts as an intermediary reference system that enables accurate dosing measurement without requiring complex injection mechanisms. The scale provides visual feedback and measurement reference, allowing users to precisely control the injection volume through simple plunger displacement while maintaining device simplicity.
2Reliability
If the injection device is designed for single use only, then sterilization and reliability are improved, but cost increases and device reuse is not possible
Solution Approach 1:
The device separates the plunger (which contacts the injection solution) from the barrel (which contains the dose markings). The plunger can be sterilized and reused, while the barrel serves as a permanent reference tool. This segmentation enables both sterilization assurance and device reuse, as critical components can be properly sterilized and the dosing reference remains valid across multiple uses.
Solution Approach 2:
The design allows the plunger to be disposable while the barrel is reusable, or both to be reusable after proper sterilization. This flexible approach enables single-use configurations for maximum reliability when needed, while also permitting reuse when appropriate, optimizing both sterilization assurance and adaptability to different usage requirements.
3Measurement precision
If the injection device includes a plunger stop mechanism for accurate dosing, then dosing precision is improved, but the device complexity and difficulty of operation increase
Solution Approach 1:
The plunger stop mechanism automatically engages with the dose marking scale without requiring additional user actions. As the user pushes the plunger, the stop mechanism self-activates when reaching the marked dose level, providing accurate dosing control while maintaining operational simplicity. The system serves itself by using the visible markings to automatically limit plunger travel.
4Adaptability or versatility
If the injection device allows plunger removal and reuse, then adaptability and cost-effectiveness are improved, but reliability and sterility maintenance become more difficult
Solution Approach 1:
The removable plunger design separates the sterilizable component from the dosing reference component. The plunger can be easily removed, sterilized using standard autoclaving or chemical sterilization methods, and reused. The barrel with dose markings remains stationary and serves as a permanent reference, maintaining reliability while enabling plunger reuse flexibility.
Data Source
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AI summary
An injection device (10) comprises an injection solution receptacle (30) and a plunger (70) at least a portion of which is slidably received in the injection solution receptacle (30), wherein the plunger (70) is displaceable relative to the injection solution receptacle (30). A dosing element (144) is attached to the plunger and a housing element is rotatable relative to the plunger. The housing element comprises a first dosing surface that is adapted to abut against the dosing element to stop a displacement of the plunger (70) relative to the injection solution receptacle (30) in the distal direction at a first dosing position (PI) and a second dosing surface that is adapted to abut against the dosing element to stop a displacement of the plunger (70) relative to the injection solution receptacle (30) from the first dosing position (PI) in the distal direction at a second dosing position (P2). The second dosing surface is offset from the first dosing surface in a circumferential direction relative to a longitudinal axis of the plunger. A limiting mechanism comprising a first limiting element attached to the housing element and a second limiting element that abuts the first limiting element when rotation of the housing element relative to the plunger aligns the dosing element with the second dosing surface.