Surgical Probe TMR Sensing for 3D Ferromagnetic Object Localization

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Solution Overview

Problem

Existing methods for detecting retained ferromagnetic foreign bodies during surgery are inadequate, particularly for small items like needles, and can lead to increased surgical costs, legal expenses, and patient morbidity due to the need for conversion to open surgery.

Innovation Solution

A system using tunneling magnetoresistance (TMR) sensors to detect ferromagnetic objects by passively sensing changes in the ambient magnetic field, providing a three-dimensional display to guide personnel to the object's location without generating electromagnetic fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If metal detectors relying on electrical conductivity are used to detect small retained objects, then electromagnetic field is generated, but detection precision deteriorates because small fragments produce undetectable eddy currents

Engineering Contradiction:

Improvedetection precisionVSAvoidelectromagnetic field generation

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electromagnetic detection methods with magnetic field-based detection using magnetoresistive sensors. Instead of generating electromagnetic fields to induce eddy currents, the system uses sensors that detect changes in ambient magnetic field caused by ferromagnetic objects, thereby avoiding electromagnetic field generation while maintaining detection capability for small objects

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from electrical conductivity (eddy currents) to magnetic susceptibility. By using magnetoresistive sensors that respond to magnetic field changes, the system can detect ferromagnetic objects regardless of their size, as even small fragments alter the ambient magnetic field

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If x-ray/fluoroscopy detection is used to detect retained foreign bodies, then detection capability is provided, but radiation exposure risk increases for patient and operating room team

Engineering Contradiction:

Improvedetection capabilityVSAvoidradiation exposure

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces x-ray detection with magnetic field-based detection using magnetoresistive sensors. This substitution eliminates ionizing radiation exposure while providing equivalent or superior detection capability for ferromagnetic objects, as the sensors directly detect magnetic field disturbances caused by retained foreign bodies

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Quantity of substance

If conventional metal detection methods are used, then detection of conductive metals is possible, but detection of small items deteriorates due to insufficient eddy current signal

Engineering Contradiction:

Improvedetection rangeVSAvoidsignal detectability

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent changes the detection principle from electromagnetic induction (eddy currents) to direct magnetic field sensing. Magnetoresistive sensors detect changes in ambient magnetic field caused by ferromagnetic objects, providing sufficient signal even for very small items like needles or suture fragments that would produce undetectable eddy currents

Inventive Principle:

Principle #35Parameter changes

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

Accurately locates ferromagnetic objects in the body, reducing the need for open surgery and associated costs, while being safe and cost-effective.

Implementation Method 1

A system using tunneling magnetoresistance (TMR) sensors to detect ferromagnetic objects by passively sensing changes in the ambient magnetic field

Methodology Applied

Scientific EffectTunneling magnetoresistance: Magnetoresistance

Implementation Method 2

detect ferromagnetic objects by passively sensing changes in the ambient magnetic field

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentUS12573113B2System and method for displaying the location of a ferromagnetic object in a living organism

Publication Date: 2026.03.10 MIKHAIL ALBERT A

AI summary

Described is a system and/or method for displaying the location of a ferromagnetic object in a living organism by using a surgical probe. The surgical probe has a shaft with three-dimensional magnetoresistance sensors located on a distal end configured for insertion into the living organism and three-dimensional magnetoresistance sensors located on a proximal end that stays outside of the living organism. The system comprises a display configured to show the relative location of a detected ferromagnetic object to the tip of the probe in a simulated three-dimensional view on a two-dimensional display.