Needle Insertion Mechanism Backflow Prevention
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Solution Overview
Problem
Drug delivery devices often experience occlusions due to clots in the fluid path, which can prevent drug delivery when the pressure required to push the medication exceeds the drive force capability of the device, leading to delayed or incomplete administration of medication.
Innovation Solution
A multi-stage needle insertion mechanism with a backflow prevention mechanism, including a slide valve that selectively restricts and permits fluid flow, allowing for controlled insertion and retraction of the needle and cannula, and delayed drug delivery to prevent clot formation and ensure efficient medication administration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the device delivers medication immediately after needle insertion, then the delivery speed is improved, but the risk of clot formation increases due to backflow in non-primed fluid paths
Solution Approach 1:
The device performs preliminary actions by inserting the needle and cannula into the patient's tissue before delivering the medication. This allows the fluid path to be established and any air or backflow to be cleared before the actual drug delivery occurs, preventing clot formation while maintaining efficient delivery speed
Solution Approach 2:
The delivery process is segmented into distinct stages: needle insertion stage, delay stage (where the valve restricts flow), and medication delivery stage. This segmentation allows the device to control backflow during insertion while enabling rapid delivery when needed, resolving the contradiction between speed and clot prevention
2Device complexity
If the device operates without a backflow prevention mechanism, then the device complexity is reduced, but the reliability of medication delivery deteriorates due to occlusions from clots
Solution Approach 1:
A slide valve is introduced as an intermediary component between the reservoir and the needle/cannula assembly. This valve acts as a flow control mediator that can restrict or permit fluid flow based on the operational stage, preventing backflow and clot formation while maintaining reliable medication delivery without significantly increasing overall device complexity
Solution Approach 2:
The actuation assembly automatically transitions the valve between restricted and permitted states based on the operational phase, without requiring external control. The system self-regulates the fluid flow to prevent clots during needle insertion while enabling reliable delivery during the medication administration phase
Data Source
AI summary
A drug delivery device includes a housing, a container disposed in the housing, an activation mechanism, and a needle insertion mechanism (NIM). The container has an inner volume to contain a medicament which is urged out of the container by the activation mechanism. The needle insertion mechanism (NIM) is operably coupled with the activation mechanism and includes an actuation assembly adapted to insert a needle and a cannula to deliver the medicament from the container. The actuation assembly is movable between a storage state, a first operational state, a second operational state, and a third operational state to selectively position the needle and the cannula.