LBJ Coil Surgical Marker for Orientation-Independent Localization

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Solution Overview

Problem

Existing surgical markers for lesion localization are too large, require reconfiguration during deployment, and provide non-uniform magnetic responses based on orientation, making them fragile and difficult to deploy accurately.

Innovation Solution

A magnetic marker comprising a coil or helix of LBJ material with overlapping loops, allowing for a uniform harmonic response regardless of orientation, deployable without reconfiguration, and coated or housed for robustness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a straight piece of LBJ wire is used as a marker, then the marker can be deployed through a narrow gauge needle, but the marker produces a non-uniform magnetic response that varies with orientation relative to the detection probe

Engineering Contradiction:

Improvemarker sizeVSAvoidlocalization accuracy

Core Design Contradiction:

Length of moving objectVSMeasurement precision

Solution Approach 1:

The patent transforms the straight wire configuration into a coiled configuration. The coil geometry creates a magnetic response that is substantially uniform regardless of the orientation of the marker relative to the detection probe, eliminating the directional dependence problem while maintaining the ability to be deployed through narrow gauge needles.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Measurement precision

If the LBJ material is made into a coil with overlapping loops, then the magnetic response becomes uniform regardless of orientation, but the marker size increases

Engineering Contradiction:

Improvelocalization accuracyVSAvoidmarker size

Core Design Contradiction:

Measurement precisionVSLength of moving object

Solution Approach 1:

The patent implements overlapping loops where the coil is configured such that successive turns overlap with each other. This nesting approach creates the uniform magnetic response characteristic of a coil while minimizing the overall size of the marker, allowing it to remain suitable for deployment through narrow gauge needles.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If a longer LBJ wire is used to achieve sufficient magnetic signal, then the magnetic response strength increases, but the marker becomes too large for convenient clinical implantation

Engineering Contradiction:

Improvedetection signal strengthVSAvoidmarker size

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The coil configuration concentrates the magnetic material into a compact geometry that produces a strong magnetic response signal. The coiled structure with overlapping loops creates enhanced magnetic field interactions that improve detection signal strength while keeping the overall marker size small enough for clinical implantation.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The overlapping loops allow the magnetic material to be arranged in a space-efficient manner, maximizing the magnetic signal strength within a compact volume that can be implanted through narrow gauge needles.

Inventive Principle:

Principle #7Nested doll (Nesting)

4Length of moving object

If the marker is made fragile to achieve a compact size, then the marker can be deployed through narrow gauge needles, but the marker becomes vulnerable to damage during implantation and deployment

Engineering Contradiction:

Improvemarker sizeVSAvoidmarker robustness

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The patent combines the LBJ magnetic material with a protective coating or housing structure. This composite construction provides mechanical strength and protection during deployment through narrow gauge needles while maintaining the compact size and uniform magnetic response characteristics of the coiled configuration.

Inventive Principle:

Principle #40Composite materials

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 marker provides a uniform magnetic response for precise localization, enabling accurate detection and deployment, overcoming the limitations of prior art markers in size, fragility, and orientation-dependent signals.

Implementation Method 1

at least one piece of magnetic material that exhibits a large Barkhausen jump (LBJ) in its magnetisation curve

Methodology Applied

Scientific EffectBarkhausen jump: Barkhausen Effect

Implementation Method 2

A handheld probe generates an alternating field which excites a magnetically responsive marker, and detects the responding magnetic field

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP4574084A2Magnetic markers for surgical guidance

Publication Date: 2025.06.25 ENDOMAGNETICS LTD

Figure 1A~1B
Figure 2~3A
Figure 3B~3C

AI summary

An implantable magnetic marker comprising at least one piece of a large Barkhausen jump material (LBJ) containing at least one loop. The marker is deployed to mark a tissue site in the body for subsequent surgery, and a magnetic detection system with a handheld probe excites the marker above or below the switching field required for bistable switching of the marker causing a harmonic response to be generated in a bistable or sub-bistable mode that allows the marker to be detected and localised.