Autoinjector Key Deformation for Injection Completion Feedback
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Solution Overview
Problem
Current autoinjectors face challenges in preventing accidental triggering, ensuring reliable and safe use, particularly for elderly or disabled users, and in providing clear indications for the completion of injections, especially when dealing with viscous fluids or large volumes, which can lead to incomplete delivery and safety risks.
Innovation Solution
The autoinjector design incorporates a movable element with deformable lugs and an audible/tactile indication system, including a key with a rod part and head part that deforms to signal injection completion, along with a control sleeve and central piece connected by a foldable/wearable connection, ensuring secure locking and user feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism is added to prevent accidental activation, then safety is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is segmented into a cover portion and a body portion with separate locking elements (balls and grooves). The cover can be removed to unlock the device, while the body contains the injection mechanism. This segmentation allows independent control of access and activation, improving safety without requiring a completely complex integrated system.
Solution Approach 2:
The cover acts as an intermediary element between the user and the injection mechanism. It provides a simple interface (removal action) that triggers the locking/unlocking sequence through the balls and grooves system. This intermediary simplifies the user interaction while maintaining reliable locking through the mechanical intermediary elements.
2Reliability
If the locking mechanism is made more reliable to prevent accidental triggering, then safety is improved, but ease of operation deteriorates
Solution Approach 1:
The locking mechanism is self-service in that the cover removal automatically triggers the unlocking sequence through the mechanical interaction of balls and grooves. The device itself performs the unlocking action without requiring additional user manipulation or complex control systems. This maintains reliability while preserving ease of operation for the intended user.
Solution Approach 2:
The locking elements (balls) are preliminarily positioned in grooves that prevent activation. When the cover is removed, the balls are preliminarily guided into positions that allow the plunger to be pushed. This preliminary arrangement ensures safety during storage while enabling easy activation when needed.
3Reliability
If the injection time is extended to ensure complete fluid delivery, then reliability of fluid delivery is improved, but loss of time increases
Solution Approach 1:
The device provides tactile feedback through the plunger movement and visual feedback through the transparent reservoir. The user can observe the fluid level decreasing and feel the plunger movement, providing real-time feedback on injection progress. This allows the user to know when the injection is complete without requiring extended time or complex timing mechanisms.
Solution Approach 2:
The mechanical spring-driven plunger system replaces complex electronic pumping or timing systems. The spring provides continuous force to push the plunger, ensuring complete fluid delivery through simple mechanical means. This substitution maintains reliability of fluid delivery while minimizing time loss by eliminating the need for electronic control systems.
4Reliability
If the needle safety device is made more secure to prevent detachment, then safety is improved, but ease of operation deteriorates
Solution Approach 1:
The needle safety device is merged with the cover assembly. The cover not only provides the locking function but also houses the needle protection mechanism. When the cover is removed for activation, the needle is exposed; when the cover is replaced, the needle is automatically protected. This merging eliminates the need for separate needle safety operations, maintaining safety while preserving ease of operation.
Data Source
Figure 1
Figure 2a~2f
Figure 3a~3c
AI summary
Autoinjector having a pre-filled syringe, a piston rod (1005), an injection spring (1008), a movable element (1004; 1006), an acoustic and/or tactile indicating device (1500) having a key (1121), said key having a shaft part (1120), which extends inside the piston rod (1005), and a head part (1122), said movable element having at least one deformable tab (1510; 1520), said piston rod (1005) exerting traction on said head part (1122) via said shaft part (1121) of said key (1120) at the end of injection, thereby permitting a radial deformation of said at least one deformable tab and an axial movement of said movable element under the effect of said injection spring (1008), said movement generating an acoustic and/or tactile indication for the user.