Magnetic Marker Geometry and Materials for Needle-Delivered Localization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magnetic medical markers face challenges in providing a uniform magnetic response due to their geometry and size constraints, which limits their detectability and localization accuracy, especially when deployed through narrow needles for surgical procedures.
Innovation Solution
The development of magnetic markers with non-spherical configurations and specific material compositions that alter their magnetic susceptibility anisotropy ratio, such as using superparamagnetic iron oxide nanoparticles or magnetically soft materials, to achieve a more uniform magnetic response across different orientations and improve detectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If magnetic markers are constrained to small diameter (less than 1.5 mm) for delivery through narrow needles, then patient discomfort is minimized and delivery is facilitated, but the magnetic response strength is limited and localization accuracy deteriorates
Solution Approach 1:
The marker uses a composite structure with a ferromagnetic core material (such as iron, nickel, cobalt, or their alloys) providing strong magnetic response, combined with a biocompatible coating layer (such as silicone, titanium, or polymer coatings) for safety and delivery. This composite approach allows the marker to maintain small diameter for easy delivery while achieving sufficient magnetic response strength for accurate localization.
2Quantity of substance
If marker volume is maximized to achieve effective magnetic response, then magnetic signal strength is improved, but the marker requires significant length greater than diameter (aspect ratio greater than 5), resulting in non-uniform magnetic response
Solution Approach 1:
The marker employs a spherical or near-spherical geometry instead of elongated shapes. This spherical form factor provides uniform magnetic response in all directions (isotropic magnetic properties), eliminating the directional dependence that plagues elongated markers. The sphere maximizes volume for a given diameter constraint while maintaining uniform magnetic susceptibility regardless of orientation relative to the detection probe.
3Ease of manufacture
If conventional magnetic marker materials and geometries are used, then manufacturing is relatively simple, but the magnetic response is anisotropic with much stronger signal when marker major axis is in line with probe and weaker signal when transverse
Solution Approach 1:
The marker incorporates localized high-permeability ferromagnetic material concentrated in a spherical core, with the magnetic properties optimized at the local level. The ferromagnetic core material provides high magnetic susceptibility locally, while the spherical geometry ensures this local quality translates to uniform global magnetic response. The biocompatible coating provides different local properties for safety and delivery, creating a multi-functional composite structure.
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
These markers provide a more uniform and intense magnetic signal, enhancing localization accuracy and visibility under various imaging modalities, while maintaining a compact size for efficient delivery through small needles, thus improving surgical precision and reducing the need for excessive marker material.
Implementation Method 1
magnetic markers for surgical use... magnetic markers with a more uniform magnetic response... superparamagnetic iron oxide nanoparticles or magnetically soft materials
Implementation Method 2
superparamagnetic iron oxide nanoparticles
Implementation Method 3
alter their magnetic susceptibility anisotropy ratio... achieve a more uniform magnetic response across different orientations
Data Source
AI summary
A magnetic marker for marking a site in tissue in the body. In one embodiment, the marker comprises a magnetic metallic glass. In another embodiment, the marker is in a non-spherical configuration having an anisotropy ratio less than 9. In yet another embodiment, the marker is in a non-spherical configuration having an anisotropy ratio less than 6. In yet another embodiment, the marker is in a non-spherical configuration having an anisotropy ratio less than 3.