Auto-Injector Rotating Collar for Skin-Pressure Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing injection devices, both manual and auto-injectors, pose challenges such as the risk of underdosing, high injection forces, hand trembling, and potential needle stick injuries due to improper use, especially for users with dexterity issues or inexperience.
Innovation Solution
An auto-injector design featuring a rotating collar that dampens the pressure exerted on the skin during injection, a lateral release element to prevent accidental activation, and safety mechanisms to ensure proper placement and needle safety, utilizing a single drive means for multiple functions like needle insertion, medicament expulsion, and needle retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single drive means is used for multiple functions (needle insertion, medicament expulsion, needle retraction), then device complexity is reduced and cost is lowered, but the drive means must exert high forces for all functions which may cause skin bruising
Solution Approach 1:
A rotating collar is introduced as an intermediary component between the drive means and the needle assembly. The collar rotates during needle insertion and medicament expulsion, absorbing excess drive force through rotational friction. This mediates the high force from the single drive means, preventing skin bruising while maintaining the simplified single-drive architecture
Solution Approach 2:
The drive means parameters are optimized to provide controlled force delivery. The spring constant and pre-compression of the spring are calibrated to deliver sufficient force for all functions while the rotating collar dissipates excess energy. The plunger surface area is also optimized to distribute force evenly, reducing pressure on the skin
2Manufacturing precision
If the button/plunger extension is made long to ensure full injection, then dosing accuracy is improved, but the button extension becomes difficult to reach and causes hand trembling
Solution Approach 1:
The device performs the injection function automatically without requiring the user to manually extend a long plunger. The auto-injector mechanism self-activates upon application to the skin, eliminating the need for users to reach and press a distant button, thus solving both the dosing accuracy and ease of operation contradiction
3Device complexity
If manual injection is used to reduce device complexity, then device complexity is reduced, but the user must continuously press the plunger which may lead to underdosing
Solution Approach 1:
The auto-injector is designed to self-activate and complete the full injection cycle automatically. Once applied to the skin, the spring-driven mechanism automatically drives the plunger to its full extension, ensuring complete dosing without requiring continuous user pressure. This maintains simplicity while ensuring reliable dosing
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
Reduces the risk of bruising and needle stick injuries while ensuring accurate dosing and safe operation, particularly suitable for self-administration by users with limited dexterity, and allowing for a compact, cost-effective, single-use device.
Implementation Method 1
a rotating collar rotatably arranged within the housing. The needle shroud in the safe position surrounds the injection needle after the injection has been carried out. The rotating collar engages the needle shroud in a manner that forces the rotating collar to rotate within the housing when the needle shroud is translated in the proximal direction
Data Source
AI summary
According to the invention, an auto-injector for administering a dose of a liquid medicament (M) comprises of a substantially cylindrical housing arranged to contain a pre-filled syringe filled with the medicament (M), a needle shroud slidably arranged with respect to the housing and adapted to rest on the skin of a patient receiving an injection, a releasable drive means arranged within the housing that is capable of, upon release, translating the needle shroud in a proximal direction (P) towards a safe position (PS) and a rotating collar rotatably arranged within the housing. The needle shroud in the safe position (PS) surrounds the injection needle after the injection has been carried out. The rotating collar engages the needle shroud in a manner that forces the rotating collar to rotate within the housing when the needle shroud is translated in the proximal direction (P).