Shape Memory Alloy Cannula for Snag-Free Biopsy Marker Deployment
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Solution Overview
Problem
Current marker delivery devices for breast biopsies face challenges in accurately deploying markers through both end-deploy and side-deploy needles, as they often require different introducers and can be difficult to use due to snagging issues, limiting precise relocation of biopsy sites.
Innovation Solution
A marker delivery device with a shape memory alloy inner cannula that can transition from a straight to an arcuate shape, allowing smooth deployment through a side aperture of a biopsy needle without snagging, and a design that accommodates both end-deploy and side-deploy configurations using a single device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If side-deploy marker delivery devices are used to deploy markers through the lateral aperture of the biopsy needle, then the marker can be deployed directly through the needle that took the biopsy sample, but the marker or push rod can snag on the lateral aperture making withdrawal difficult
Solution Approach 1:
The inner cannula is formed from a shape memory alloy and configured to have a curved or arcuate shape that complements the lateral aperture geometry. This curved configuration allows the inner cannula to smoothly navigate through the lateral aperture without sharp edges or angles that could cause snagging, enabling reliable marker deployment and device withdrawal.
Solution Approach 2:
The shape memory alloy inner cannula changes its physical parameters (shape, flexibility) in response to temperature changes. When cooled, it becomes more flexible and can be inserted in a straight configuration; when warmed to body temperature, it transitions to its predetermined curved configuration that prevents snagging on the lateral aperture.
2Measurement precision
If end-deploy marker delivery devices are used to deploy markers through the distal end of the needle, then a different introducer is required, but this makes it more difficult to accurately deploy the marker in the exact biopsy location
Solution Approach 1:
The marker delivery device is designed with a universal inner cannula system that can accommodate both end-deploy and side-deploy needle configurations. The inner cannula can be oriented and positioned to work with either needle type, eliminating the need for different introducers while maintaining accurate marker placement at the biopsy site.
Solution Approach 2:
The inner cannula is designed to be dynamically adjustable in orientation and position within the outer cannula. It can be rotated or repositioned to align with either the distal end or lateral aperture of the biopsy needle, providing versatility for different deployment configurations without requiring separate devices.
3Device complexity
If a straight inner cannula is used for marker delivery, then the device structure is simple, but the marker delivery device cannot smoothly deploy through the lateral aperture without snagging
Solution Approach 1:
The inner cannula utilizes shape memory alloy properties to change its physical configuration based on temperature. During insertion, it maintains a simple straight configuration; once deployed, it transitions to a curved configuration that enables smooth passage through the lateral aperture. This dynamic parameter change allows the device to maintain structural simplicity while achieving operational smoothness.
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
Enables precise and accurate deployment of markers directly through the biopsy needle, reducing the complexity of using different introducers and minimizing the risk of snagging, thereby facilitating easier relocation of biopsy sites during subsequent surgeries.
Implementation Method 1
A marker delivery device with a shape memory alloy inner cannula that can transition from a straight to an arcuate shape
Data Source
AI summary
A marker delivery device includes an outer cannula, an inner cannula assembly, and a push rod. The outer cannula defines a longitudinal axis and includes an outer lumen. The outer lumen extends distally along the longitudinal axis from a handle to an open outer cannula distal end. The inner cannula assembly includes an inner cannula and a grip. The inner cannula is disposed within the outer lumen and extends distally along the longitudinal axis from the grip to an open distal end. The inner cannula has a resilient portion located proximate the open distal end. The resilient portion is configured to move between a stressed configuration when engaged with the outer cannula and a relaxed configuration when disengaged with the outer cannula. The push rod is disposed within an inner lumen of the inner cannula and is configured to deploy a marker through the open distal end.