Magnetoresistance Sensor Circuit for Weak Magnetic Field Detection

Solution Overview

Problem

Existing magnetic field measurement systems, such as SQUID-based systems, are cumbersome and require constant cooling, making them impractical for accurate measurement of weak magnetic fields, especially in medical applications like magnetocardiography, and are not suitable for non-destructive detection of small magnetic materials or cracks in ferrous metals.

Innovation Solution

A magnetic sensor system comprising a high sensitivity magnetoresistance sensor with integrated electronic processing circuit, including multiple amplifier and filter stages, an analog-to-digital converter, and electromagnetic shielding, designed for ambient temperature operation without cooling, capable of measuring weak magnetic fields with high precision and minimal noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If SQUID-based measurement systems are used to measure weak magnetic fields, then measurement precision is improved, but device complexity and ease of operation deteriorate due to constant cooling requirements

Engineering Contradiction:

Improvemeasurement precisionVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical cooling system required by SQUID-based systems with a magnetoresistance sensor that operates at ambient temperature. This substitution eliminates the complex cooling infrastructure while maintaining the ability to measure weak magnetic fields with high precision through the inherent sensitivity of magnetoresistance materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating temperature parameter from cryogenic (required by SQUID) to ambient temperature (suitable for magnetoresistance sensors). This parameter change fundamentally simplifies the system while maintaining measurement capability, as magnetoresistance sensors can detect weak magnetic fields without requiring extreme temperature conditions.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If SQUID-based measurement systems are used to measure weak magnetic fields, then measurement precision is improved, but ease of operation deteriorates due to cooling requirements

Engineering Contradiction:

Improvemeasurement precisionVSAvoidease of operation

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the mechanical cooling system required by SQUID-based systems with a magnetoresistance sensor that operates at ambient temperature. This substitution eliminates the complex cooling infrastructure while maintaining the ability to measure weak magnetic fields with high precision through the inherent sensitivity of magnetoresistance materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If conventional measurement systems are used, then device size is reduced, but measurement precision deteriorates for weak magnetic fields

Engineering Contradiction:

Improvedevice sizeVSAvoidmeasurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the operating temperature parameter from cryogenic (required by SQUID) to ambient temperature (suitable for magnetoresistance sensors). This parameter change fundamentally simplifies the system while maintaining measurement capability, as magnetoresistance sensors can detect weak magnetic fields without requiring extreme temperature conditions.

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

The system effectively measures weak magnetic fields with high sensitivity and precision, comparable to SQUID-based systems, but without the need for cooling, enabling applications in magnetocardiography and non-destructive detection of magnetic materials, while being miniaturized and suitable for medical and industrial use.

Implementation Method 1

the magnetic sensor being a high sensitivity magnetoresistance sensor having high thermal stability

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Implementation Method 2

an electromagnetic shielding structure encasing the magnetic sensor and the electronic processing circuit, for example made of mu-metal and/or comprising a Faraday cage

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentUS12588848B2Devices and systems for measuring magnetic fields

Publication Date: 2026.03.31 EV TECHNOLOGIES

AI summary

The invention relates to a measurement device for measuring weak magnetic fields, such as fields in the sub-picotesla range (e.g. lower than a few nanotesla). The measurement device comprises ultrasensitive magnetic sensors (or arrays of ultrasensitive magnetic sensors) coupled to low-noise processing circuitry. The processing circuitry comprises a two-stage design including low-noise amplifiers and analog filters. The invention is suitable for magnetocardiovascular (MCV) applications thanks to its ability to measure very small magnetic fields with good accuracy and very little noise.