Medicament Delivery Device Interlock Mechanism
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Solution Overview
Problem
Medicament delivery devices lack effective mechanisms to prevent premature actuation, ensure safe handling, and provide clear status indication, particularly for single-use devices, leading to potential misuse and increased manufacturing costs due to complexity.
Innovation Solution
A medicament delivery device with a drive mechanism, actuation member, and interlock mechanism that prevents premature actuation and indicates usage, featuring a push button and latching projections/surfaces to securely lock the actuation member in the second position after dose delivery, ensuring clear indication of use and safe disposal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a push button is positioned at the distal end for easy operation, then ease of operation is improved, but the device can be accidentally actuated during handling before proper positioning
Solution Approach 1:
The patent applies preliminary anti-action by introducing an interlock mechanism that preemptively prevents premature actuation. The interlock member is positioned to block the push button before actuation can occur, and only releases when proper positioning conditions are met (needle inserted into hub). This preemptive blocking mechanism prevents the harmful effect of accidental activation while preserving ease of operation once properly positioned.
2Reliability
If complex mechanisms are added to prevent misuse and provide status indication, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated interlock mechanism. This mechanism simultaneously: (1) prevents premature actuation by blocking the push button, (2) provides status indication through its positional state (locked vs. released), and (3) ensures proper positioning before use. By combining these functions into one mechanism rather than separate components, the patent achieves improved reliability without proportionally increasing device complexity.
Solution Approach 2:
The interlock member serves multiple functions: it acts as a physical blocker to prevent premature actuation, a status indicator showing whether the device is ready for use, and a positioning verification mechanism. This multi-functionality allows a single component to address multiple reliability concerns, reducing the need for additional separate mechanisms.
3Ease of operation
If the actuation member can be returned to initial position after use, then ease of operation for multiple doses is improved, but single-use devices may be misused by returning the button
Solution Approach 1:
The patent applies preliminary action by designing the interlock mechanism to be released only after the actuation sequence is complete. The interlock member is positioned to block the push button during storage and before use, then releases automatically when the needle is inserted into the hub (preparing for actuation). After actuation, the mechanism remains in a state that prevents returning the button to its initial position, thereby preventing reuse while maintaining ease of operation for the intended single use.
4Loss of information
If mechanisms are added to provide clear status indication, then loss of information is reduced, but device complexity increases
Solution Approach 1:
The interlock mechanism serves as a self-service status indicator. Its physical position (locked blocking the button vs. released allowing actuation) automatically communicates the device status without requiring separate indicators, displays, or additional components. The mechanism's own state provides the information, eliminating the need for dedicated status indication systems and thereby reducing device complexity while preventing information loss.
Data Source
AI summary
A medicament delivery device includes a housing adapted to receive a medicament container; an actuation member movable from a first position to a second position, such that the medicament is allowed to be expelled through the delivery member; and an interlock member movable between a locking position and a releasing position. The device has an indicator to show that it has been used provided by the actuation member's being retained in its second position. The actuation member includes at least one latching projection, and the drive mechanism includes corresponding latching surfaces, against which the latching projections latch when the actuation member is in its second position.