Drug Delivery Plunger Rod Spacing and Feedback Mechanism
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Solution Overview
Problem
Conventional drug delivery devices face challenges in ensuring accurate and reliable medicament delivery due to manufacturing and transport tolerances, which can lead to premature drug emission or device damage during storage and use.
Innovation Solution
The design incorporates a plunger rod initially spaced from the stopper to accommodate manufacturing and transport variations, with a feedback mechanism providing audible and tactile feedback upon completion of medicament delivery, ensuring precise delivery and minimizing device damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plunger rod is positioned close to the stopper to ensure complete medicament delivery, then delivery completeness is improved, but manufacturing and transport tolerances cause premature drug emission or device damage
Solution Approach 1:
The feedback mechanism is activated in advance when the plunger rod reaches a predetermined position relative to the stopper, before complete medicament delivery is finished. This preliminary activation provides early warning to the user, allowing them to remove the device before tolerances cause premature drug emission or device damage during transport or storage.
Solution Approach 2:
The device incorporates a feedback mechanism that provides audible and/or tactile signals to the user when the plunger rod reaches a predetermined position. This feedback loop allows the user to monitor the delivery process and take appropriate action, resolving the contradiction between ensuring complete delivery and preventing tolerance-related failures.
2Reliability
If the plunger rod is spaced from the stopper to accommodate tolerances, then premature drug emission is prevented, but medicament delivery completeness may be compromised
Solution Approach 1:
The feedback mechanism monitors the plunger rod position and provides signals to the user at predetermined intervals during the delivery process. This allows the device to maintain the beneficial spacing for tolerance accommodation while ensuring the user is informed of delivery progress, maintaining both reliability and productivity.
Solution Approach 2:
The feedback mechanism provides preliminary warnings at predetermined positions before the plunger rod reaches the stopper. This allows users to plan for complete delivery while the device maintains safe spacing, resolving the contradiction between device stability and delivery efficiency.
3Loss of information
If a feedback mechanism is added to indicate delivery completion, then user awareness of delivery status is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism that uses the existing relative motion between the plunger rod and stopper to trigger audible and/or tactile signals at predetermined positions. By leveraging the natural movement already present in the device, the feedback system adds minimal complexity while effectively communicating delivery status to the user.
Solution Approach 2:
The feedback mechanism utilizes the inherent relative movement between existing components (plunger rod and stopper) to activate the feedback signals. This self-service approach means the device's own operational movement triggers the feedback, reducing the need for additional complex actuation mechanisms and minimizing overall device complexity.
Data Source
AI summary
The invention relates to a drug delivery device (1000) comprising a housing (100) configured to receive a medicament container (8) with a stopper (82) proximally sealing the medicament container. Furthermore, the drug delivery device comprises a plunger rod (1) arranged axially movable with respect to the housing and/or the medicament container and a feedback mechanism operatively coupled to the plunger rod. The drug delivery device has an initial state in which the plunger rod is in a start position. The drug delivery device is configured such that, in the initial state and when the medicament container is received in the housing, the plunger rod is axially spaced from the stopper. Furthermore, the drug delivery device is configured such that the plunger rod is axially movable from its start position in a distal direction into a feedback position. The movement of the plunger rod in the distal direction enables the plunger rod to interact with the stopper in order to push the stopper in the distal direction such that a medicament stored in the medicament container is delivered. The feedback mechanism is triggered when the plunger rod reaches the feedback position. Triggering of the feedback mechanism creates an audible and/or tactile feedback in order to indicate an end of the medicament delivery. The invention also relates to a plunger rod, a set of plunger rods, a set of drug delivery devices and a method for assembling a drug delivery device.