Injection Device Locking Actuator for Safety and Site Selection
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Solution Overview
Problem
Existing medical injection devices with needle shields often lock in a way that prevents users from changing pricking sites after initial use, leading to the device being discarded with unused substance, as the locking mechanism does not allow further movement of the needle shield from the safety position back to the retracted position.
Innovation Solution
An injection device with a locking actuator that moves from a non-actuating to an actuating position when the plunger rod reaches a threshold, allowing the needle shield to be locked in a safety position after use while still enabling multiple pricking sites by maintaining an open mode until the plunger rod reaches its final position, allowing the needle shield to move freely between retracted and safety positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the needle shield is locked in the safety position after injection, then user safety is improved, but the ability to change pricking sites is lost
Solution Approach 1:
The locking unit is designed to dynamically change its state from open to closed based on the plunger rod position. During injection (plunger rod moving), the locking unit remains open allowing needle shield movement for site changes. After injection (plunger rod stationary at final position), the locking unit closes to lock the needle shield in the safety position, thus adapting the system's constraint level based on operational phase.
Solution Approach 2:
The system changes the parameter of locking unit state (open/closed) based on the plunger rod position parameter. When the plunger rod reaches its final position indicator, this parameter change triggers the locking unit to transition from open to closed state, thereby controlling needle shield mobility according to the injection phase.
2Adaptability or versatility
If the needle shield can move freely between retracted and safety positions, then the ability to change pricking sites is improved, but user safety is reduced due to risk of accidental injury
Solution Approach 1:
The locking unit provides dynamic constraint control on the needle shield. During the injection phase, it remains open to allow movement. After injection detection, it transitions to closed state to provide static protection, thus adapting the level of constraint based on operational needs.
Solution Approach 2:
The system uses plunger rod position as a control parameter to change the locking unit state. When the plunger rod reaches its final position indicator, this parameter change automatically triggers the locking transition, ensuring the needle shield becomes locked only after injection is complete.
3Reliability
If the locking unit is activated early, then user safety is improved, but the device cannot be used for multiple pricking sites
Solution Approach 1:
The system incorporates feedback from the plunger rod position (specifically when it reaches the final position indicator) to control the locking unit activation. This feedback mechanism ensures the locking unit is activated only after injection completion is detected, preventing premature locking that would waste the device while ensuring safety activation when needed.
Solution Approach 2:
The locking unit is prepared to activate but remains inoperative during injection. The system preliminarily sets up the locking capability but delays its activation until the plunger rod reaches the final position indicator, ensuring the device remains usable for multiple sites throughout the injection process before safety locking engages.
4Object-affected harmful factors
If the needle shield is locked immediately after first use, then accidental injuries are prevented, but the substance cannot be fully administered
Solution Approach 1:
The system uses feedback from the plunger rod reaching its final position indicator to determine when to activate the locking unit. This ensures the needle shield remains unlocked throughout the entire injection process, allowing complete substance administration, and only locks afterward to prevent accidental injuries, thus eliminating the contradiction between safety and substance utilization.
Solution Approach 2:
The locking capability is preliminarily available but delayed in activation. The system prepares the locking mechanism in advance but ensures it activates only after the plunger rod reaches the final position indicator, guaranteeing both complete substance administration and subsequent safety protection against accidental injuries.
Data Source
AI summary
An injection device for injecting a substance into a body, including a syringe having: a needle, a barrel, a stopper, a plunger rod, moveable from an initial position to a final position, a needle shield, moveable at least from a retracted position to a safety position, a locking unit, arranged to lock the needle shield into the safety position, a locking actuator moveable at least: from a non-actuating position, into which the locking unit is in an open mode, to an actuating position, into which the locking actuator is arranged to put the locking unit in closed mode so that the needle shield can be locked into the safety position.