Resilient Snap Feature for Drug Delivery Device Empty Indication
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Solution Overview
Problem
Drug delivery devices lack a reliable mechanism to indicate when the maximum amount of medication has been dispensed, leading to uncertainty for users about when the device is empty.
Innovation Solution
Incorporating a resilient snap feature that engages with a piston rod, inhibiting further movement after the last dose is delivered, providing an audible click and visual indication of empty status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent locking mechanism is used to indicate maximum medication delivery, then reliability of empty indication is improved, but device complexity increases
Solution Approach 1:
The snap feature is designed as a resilient member that dynamically changes state between engaged and disengaged positions. It snaps into engagement with the piston rod at the maximum delivery position and can be reset when medication is replenished, providing reliable empty indication without permanent locking.
Solution Approach 2:
The snap feature utilizes elastic deformation as a parameter change mechanism. By preloading the resilient snap feature and allowing it to deflect when engaging the piston rod, the system creates a clear mechanical state change that reliably indicates maximum medication delivery without complex permanent locking structures.
2Reliability
If the snap feature is preloaded throughout use, then engagement reliability is improved, but force requirements increase
Solution Approach 1:
The snap feature is preloaded in advance during assembly to ensure reliable engagement. The resilient member is positioned and preloaded before the device is used, so that when the piston rod reaches the maximum delivery position, the snap feature is already prepared to snap into engagement without requiring excessive force during operation.
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
Ensures accurate notification to users when the device is empty, preventing further attempts to dispense medication and indicating the completion of the medication supply.
Implementation Method 1
the snap feature may be deflected in a radial outward direction due to the presence of the piston rod when the snap feature is not engaged with the piston rod
Implementation Method 2
the snap feature may deflect in a radial inward direction, thereby engaging with the piston rod
Data Source
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AI summary
An assembly (30) for a drug delivery device (1) is provided, wherein the assembly comprises an actuator (16) which is configured to perform a setting movement in order to set a dose and which is configured to perform a dispense movement in order to dispense a dose and a piston rod (10) which is configured to be moved in a distal direction in order to dispense a dose, and a snap feature (31) which is configured to snap into engagement with the piston rod (31). The snap feature (31) may be configured to inhibit a dispense movement of the actuator (16) and/or a setting movement of the actuator (16) when a maximum amount of medication has been delivered.