Auto-Injector Needle Shroud for Bruising and Needle-Stick Prevention
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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 accidental needle sticks, particularly for users with dexterity issues or inexperience.
Innovation Solution
An auto-injector design featuring a rotating collar to dampen pressure on the skin, a sliding needle shroud with a rotating collar to prevent bruising, and a lateral release element to prevent accidental activation, along with safety mechanisms to ensure proper placement and needle safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-driven auto-injector is used to eliminate manual pressing, then injection reliability is improved, but injection force becomes too high causing hand trembling and discomfort
Solution Approach 1:
The injection process is divided into multiple phases: needle insertion phase with high force, medication delivery phase with reduced force, and needle retraction phase. The spring mechanism is designed to provide different force levels at different stages, segmenting the overall injection process to avoid continuous high force application that causes hand trembling.
Solution Approach 2:
The spring is pre-compressed to store energy before injection. The needle insertion is achieved through the pre-stored spring energy, eliminating the need for manual pressing during insertion. This preliminary energy storage allows the system to deliver the required injection force without requiring continuous user input, thereby preventing hand trembling.
2Reliability
If the button/plunger extension is increased to ensure full injection, then injection completeness is improved, but device complexity and user convenience deteriorate
Solution Approach 1:
The auto-injector mechanism automatically tracks and executes the complete injection process without requiring user intervention. The spring-driven plunger automatically advances the medication until the syringe is empty, and then automatically retracts the needle. This self-service mechanism ensures complete injection delivery while eliminating the need for users to monitor or manually extend the plunger.
Solution Approach 2:
The device incorporates feedback mechanisms that monitor injection progress and automatically adjust the plunger position to ensure complete medication delivery. The system detects when the medication is fully administered and automatically stops the injection process, preventing both incomplete injection and unnecessary extended plunger movement.
3Device complexity
If manual button pressing is used to control injection, then device complexity is reduced, but dosing accuracy and reliability deteriorate
Solution Approach 1:
The manual control element (button/plunger) is extracted from the system and replaced with an automatic spring-driven mechanism. This removes the source of user error while maintaining a relatively simple mechanical structure. The spring mechanism is designed to deliver precise dosing through controlled expansion, eliminating the need for users to manually control the injection rate and volume.
Solution Approach 2:
The system changes the control parameter from manual user input to pre-calibrated spring mechanical energy. The spring is designed with specific tension and expansion characteristics that correspond to the required injection dose. This parameter change from human-controlled variable force to mechanically-controlled consistent force improves dosing accuracy while keeping the device structure relatively simple.
4Ease of operation
If the needle remains exposed after injection for easy removal, then ease of operation is improved, but safety deteriorates due to accidental needle sticks
Solution Approach 1:
The needle protection function is merged with the needle removal mechanism. After injection, the spring-driven mechanism automatically advances a protective shield over the needle, and the same mechanical motion that provides protection also facilitates easy removal by disengaging the needle from the tissue. This merging of functions eliminates the need for separate manual needle covering steps while maintaining ease of operation.
Solution Approach 2:
The protective shield is preliminarily positioned within the device housing before injection. After the injection is complete, the automatic mechanism activates the shield to cover the needle, preliminarily protecting the user before removal. This preliminary protective action occurs automatically as part of the injection sequence, ensuring safety without requiring additional user steps.
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 accidental needle sticks while ensuring complete dose delivery and user safety through intuitive operation and compact design.
Implementation Method 1
The rotating collar creates friction to slow down a proximal movement of the needle shroud that rests on the skin of the patient during the injection.
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).