MEMS Magnetometer Gradiometer Arrays for Magnetic Interference Rejection

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Solution Overview

Problem

Existing magnetic sensors are limited by their sensitivity to all forms of magnetic interference, such as the Earth's magnetic field and expansive electromagnetic infrastructure, which hinders the detection of sensitive magnetic fields, particularly in applications like cardiac imaging.

Innovation Solution

The technology enables the measurement of sensitive magnetic fields at a single point with a single sensor, achieving increased immunity to magnetic interference by directly detecting spatial derivatives of the magnetic field, thereby enhancing sensitivity to objects in close proximity while reducing sensitivity to distant sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing magnetic sensors are used to detect magnetic fields, then they can measure magnetic intensity, but they are sensitive to all forms of interference such as the Earth's magnetic field and electromagnetic infrastructure

Engineering Contradiction:

Improvemagnetic field detection accuracyVSAvoidmagnetic interference sensitivity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The sensor is divided into multiple sensing elements arranged in specific geometric patterns (e.g., gradiometer configurations with multiple magnetometers at different positions). By segmenting the sensing function across multiple elements and combining their outputs through differential measurements, the system can isolate local magnetic field variations from distant interference sources.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensor design emphasizes local field detection by configuring sensing elements to measure spatial derivatives of the magnetic field. This local quality approach makes the sensor respond primarily to magnetic sources in immediate proximity while being inherently less sensitive to distant sources, effectively filtering out far-field interference.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If large instruments with magnetic shielding are used, then immunity to magnetic interference is improved, but device size and complexity increase

Engineering Contradiction:

Improvemagnetic interference immunityVSAvoidinstrument size and shielding requirements

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces mechanical magnetic shielding structures with a computational approach using arrays of magnetometers that measure spatial derivatives. Instead of physically blocking magnetic fields with shielded rooms or ferromagnetic materials, the system uses mathematical processing of differential measurements from multiple sensors to achieve interference rejection, eliminating the need for bulky shielding infrastructure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The sensor array design serves multiple functions simultaneously: it measures magnetic field gradients, rejects distant interference sources, and can operate in unshielded environments. This multi-functionality allows a single device to replace what would traditionally require separate components (multiple individual sensors plus shielding infrastructure).

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If spatial derivatives of the magnetic field are detected, then sensitivity to objects in close proximity is enhanced, but sensitivity to distant sources is reduced

Engineering Contradiction:

Improveproximity detection sensitivityVSAvoiddistant source detection capability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The sensor measures spatial derivatives (gradients) of the magnetic field rather than absolute field intensity. This parameter transformation changes the sensitivity characteristics: first derivatives enhance sensitivity to nearby sources while suppressing distant sources, and second derivatives provide even stronger localization. The mathematical relationship between field derivatives and source distance inherently provides distance-dependent sensitivity.

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

This approach allows for miniaturized magnetic sensing in portable and wearable equipment, effectively overcoming the limitations of traditional sensors and enabling more accurate and efficient detection of magnetic fields in noisy environments.

Implementation Method 1

a sensor becomes more sensitive to objects in close proximity, and far less sensitive to sources that are farther away

Methodology Applied

Scientific EffectMagnetic field gradient detection: Magnetic Field

Data Source

PatentUS12270868B2MEMS magnetometer and gradiometer arrays and patterns

Publication Date: 2025.04.08 TRUSTEES OF BOSTON UNIV

AI summary

A system and method of measuring a magnetic field from a source. A plurality of sensors each include a plurality of sensing elements. A first sensing element is configured to detect an intensity of the magnetic field and a second sensing element is configured to directly measure a gradient of the magnetic field. A positioned is determined, with respect to the source, where a magnitude of the magnetic field in a first direction is greatest. An orientation of the sensors is determined in a three-dimensional pattern by arranging the sensors to emphasize sensing the magnetic field in the first direction. The sensors are oriented and positioned according to the position and orientation determined. The magnetic field is measured, in the first direction, using the sensors.