Marker Delivery Plunger Decoupling to Prevent Push Rod Shearing
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Solution Overview
Problem
Existing marker deployment systems require manual release of the plunger, which can lead to shearing of the push rod tip, leaving foreign objects in the body, and there is a need for markers that remain visible under ultrasound and distinguishable from microcalcifications.
Innovation Solution
A marker delivery device with an automatic plunger retraction mechanism and a biodegradable hydrogel marker that expands to center the marker in the biopsy cavity, ensuring visibility under ultrasound and minimizing migration, combined with a cannula design that aligns with biopsy needles for precise deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual plunger release is used in marker deployment, then the operator has control over marker delivery, but the push rod tip can be sheared leaving foreign objects in the body
Solution Approach 1:
The plunger is designed with a self-retracting mechanism that automatically returns to its initial position after marker deployment. The plunger includes a resilient member that biases it toward the retracted position, and a release mechanism that allows automatic resetting without manual intervention, thereby preventing push rod shearing and foreign object retention
Solution Approach 2:
The device prepares the plunger in advance by positioning it in a pre-loaded state before marker deployment. The resilient member is pre-compressed or pre-tensioned to provide the necessary force for automatic retraction, ensuring the plunger is ready to return to its safe position immediately after use
2Reliability
If a marker is deployed to mark biopsy site, then the biopsy site can be relocated, but the marker may migrate or become indistinguishable from microcalcifications
Solution Approach 1:
The marker incorporates radiopaque materials that appear distinct on imaging modalities such as X-ray and ultrasound. The marker may include specific density variations or contrast properties that make it visually distinguishable from surrounding tissue and microcalcifications, ensuring accurate identification and tracking of the biopsy site
Solution Approach 2:
The marker is designed with an asymmetric shape or unique geometric features that differentiate it from naturally occurring structures like microcalcifications. This asymmetric design ensures the marker can be easily distinguished from physiological structures during imaging and follow-up examinations
3Productivity
If the plunger remains pressed after marker deployment, then the marker is fully delivered, but the protruding plunger tip can be sheared against sharp edges
Solution Approach 1:
The plunger automatically detects when marker deployment is complete and initiates retraction without requiring operator intervention. Sensors or mechanical indicators trigger the resilient member to return the plunger to its retracted position, preventing the plunger tip from remaining exposed and vulnerable to shearing against sharp edges during device removal
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
The device ensures safe and precise marker deployment with automatic plunger retraction, maintaining marker visibility under ultrasound, and reduces the risk of foreign object retention, while allowing natural tissue growth and restoration.
Implementation Method 1
a biodegradable hydrogel marker that expands to center the marker in the biopsy cavity
Implementation Method 2
The tip of the push rod assembly may be severed on engagement against a sharp edge
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
A marker delivery device includes a handle, an elongate cannula, a push rod assembly, and a plunger. The handle includes a first bore disposed within a portion of the handle. The elongate cannula extends distally from the handle along a longitudinal axis. The push rod assembly includes a mating feature. The push rod assembly is disposed within the first bore and extends distally through the cannula. The plunger is disposed within the first bore proximally of the push rod assembly and includes an engagement feature. The engagement feature is removably coupled to the mating feature. The engagement feature is configured to de-couple from the mating feature when the plunger translates the push rod assembly distally.