Needle Safety Arrangement with Cam De-latching Mechanism
Solution Overview
Problem
Current injection devices, both manual and auto-injectors, face challenges such as user discomfort due to injection force and hand trembling, risk of incomplete doses, and inadequate needle safety after use.
Innovation Solution
A needle safety arrangement featuring a slidable needle sheath biased in the proximal direction, a sheath linkage with a cam mechanism for de-latching and covering the needle, and a syringe carrier that allows joint axial translation and rotation, ensuring the needle is safely retracted and protected after use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual device uses a button/plunger that must be continuously pressed by the user, then the user can control the injection process, but the user experiences high injection forces and must maintain continuous pressure to prevent underdosing
Solution Approach 1:
The device uses a spring mechanism that automatically provides the injection force without requiring continuous user pressure. The spring is compressed during the loading phase and then automatically expands to deliver the injection, making the system self-powered and eliminating the need for sustained user effort during the actual injection.
Solution Approach 2:
The spring is pre-compressed during the loading phase before injection is needed. This preliminary compression stores the energy required for injection, so that when the user activates the device, the spring automatically delivers the injection force without requiring the user to continuously apply pressure during the injection itself.
2Reliability
If the button/plunger extension is made great to ensure full dose delivery, then the user can reach the end position, but the extended button causes hand trembling and discomfort
Solution Approach 1:
The spring mechanism automatically handles the needle retraction and dose delivery without requiring the user to manually extend a long button. The system self-manages the injection process, eliminating the need for extended user manipulation that causes trembling and discomfort.
Solution Approach 2:
The manual button extension mechanism is replaced with an automatic spring-driven system. The spring provides the mechanical force to advance the needle and deliver the dose, substituting the user's manual extension action with an automated mechanical system that eliminates hand trembling.
3Ease of operation
If the needle is left exposed after injection, then the user can easily access it, but the user is at risk of needle stick injuries
Solution Approach 1:
The needle automatically retracts into the syringe barrel using spring force after the injection is complete. The system self-performs the safety function of needle retraction without requiring user intervention, thereby eliminating needle stick risks while maintaining ease of operation.
Solution Approach 2:
The spring mechanism is pre-positioned to automatically retract the needle after injection. This preliminary setup ensures that the needle retraction occurs automatically as part of the injection sequence, eliminating the need for manual needle handling and reducing injury risks.
4Ease of operation
If the syringe carrier allows joint axial translation and rotation, then the needle can be properly inserted and retracted, but the device complexity increases
Solution Approach 1:
The syringe carrier combines multiple functions (axial translation for needle insertion, rotation for needle orientation, and retraction) into a single integrated component. By merging these functions into one carrier structure rather than separate mechanisms, the design achieves proper needle handling while minimizing overall device complexity.
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
The solution reduces user discomfort by requiring two actions for needle insertion, minimizing the risk of incomplete doses and ensuring safe needle protection after use, thus enhancing the safety and efficacy of injection devices.
Implementation Method 1
The syringe carrier exhibits at least one cam on its circumference. The cam is arranged to de-latch the needle sheath from the sheath linkage on rotation of the syringe carrier
Data Source
AI summary
The invention refers to a needle safety arrangement for protecting a hollow injection needle of a syringe after an injection, the needle safety arrangement comprising:a needle sheath having essentially the shape of a hollow cylinder arranged to surround the needle, the needle sheath slidable in longitudinal direction with respect to the syringe and biased in proximal direction (P),a sheath linkage, slidable in longitudinal direction,a syringe carrier for holding the syringe, the syringe and syringe carrier arranged for joint axial translation and rotation relative to the needle sheath,wherein the sheath linkage comprises means for restricting translation in proximal direction (P) with respect to the syringe by abutting against the syringe carrier, wherein in an initial state the sheath linkage is abutted against the syringe carrier and latched to the needle sheath for joint axial translation, wherein the syringe carrier exhibits at least one cam on its circumference, wherein the cam is arranged to de-latch the needle sheath from the sheath linkage on rotation of the syringe carrier so as to release the needle sheath for being translated in proximal direction (P) and cover the needle.