Auto-injector Front-end Device with Opposite Screw Threads
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Solution Overview
Problem
Current auto-injector devices face challenges such as user error in administering complete doses, high injection forces, and discomfort due to manual operation, and there is a need for a more intuitive and safe method for self-administration of medicaments.
Innovation Solution
A reusable front-end device for an auto-injector with a support sleeve and outer sleeve featuring opposite screw threads for easy assembly, a syringe retainer for controlled needle exposure, and a needle shroud for skin contact detection, combined with a reusable back-end device for motor-driven injection, enhancing user safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual injection devices are used, then users can administer injections, but users must continuously press the plunger which causes hand shaking and discomfort
Solution Approach 1:
The injection device performs the injection action automatically without requiring continuous manual pressure from the user. The spring mechanism self-actuates to drive the plunger, eliminating hand shaking and discomfort associated with manual continuous pressing.
Solution Approach 2:
The injection process is divided into distinct phases: a rapid injection phase driven by spring energy release, followed by a controlled maintenance phase. This periodic action pattern eliminates the need for continuous manual pressure while ensuring complete dose delivery.
2Ease of operation
If manual injection devices are used, then users can administer injections, but users may stop pressing the plunger causing underdose
Solution Approach 1:
The device automatically completes the full injection sequence without requiring continuous user intervention. The spring mechanism ensures the plunger is driven to its full travel distance, guaranteeing complete dose delivery even if the user releases the device mid-injection.
Solution Approach 2:
The spring is pre-loaded with energy before use, and the device is designed to automatically execute the complete injection sequence upon activation. This preliminary preparation ensures that once triggered, the device will complete the full dose delivery without requiring ongoing user action.
3Ease of operation
If auto-injectors with spring energy are used, then injection forces are reduced, but device complexity increases
Solution Approach 1:
The device is divided into modular components: a reusable body housing containing the spring mechanism, and disposable cartridges containing the medicament and needle. This segmentation allows the complex spring mechanism to be reused while the potentially contaminated or single-use components are discarded, managing complexity through modularity.
Solution Approach 2:
Instead of having a simple disposable device, the invention inverts the approach by making the body with the complex spring mechanism reusable and the cartridges disposable. This reverses the traditional disposable model, placing complexity in the durable reusable portion rather than in single-use components.
4Ease of manufacture
If reusable front-end devices are used, then production costs are minimized, but assembly complexity increases
Solution Approach 1:
The needle and medicament are extracted into separate disposable cartridges that attach to the reusable body. This extraction simplifies the assembly process for the reusable portion while allowing the single-use components to be pre-assembled and sterilized separately, reducing overall manufacturing complexity despite the modular design.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4B
AI summary
The invention relates to a front-end device (1) of an auto-injector (A) for administering a dose of a liquid medicament, comprising -a support sleeve (1.2) with a first screw thread (1.2.1) adapted to engage a housing (2.1) of a back-end device(3) of the auto-injector (A) to attach the front- end device (1) to the back-end device (3) and -an outer sleeve (1.1) mounted onto a support sleeve (1.2) of the front-end device (1) by a second screw thread (1.2.3), wherein the front-end device (1) is adapted to receive a syringe (2) with an injection needle (2.2) and a barrel (2.3) containing the dose of the medicament and wherein the direction of rotation of the first screw thread (1.2.1) is opposite to the direction of rotation of the second screw thread (1.2.3).