Gradiometer Sensor Unit for Contactless Brain-Wave Magnetic Field Detection
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Solution Overview
Problem
Existing methods for monitoring mental or physical states, such as fatigue, in users are either invasive, require continuous visual field, or are not practical for everyday use.
Innovation Solution
A sensor unit comprising gradiometer units arranged around a user's head, using magnetometers with spin resonance effects, and optionally nitrogen vacancy center magnetometers or vapor cell magnetometers, to detect brain current-induced magnetic fields without the need for shielding or direct contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EEG electrodes with contact gel are used to measure brain activity, then measurement reliability is improved, but ease of operation deteriorates due to invasive application requirements
Solution Approach 1:
The patent replaces the mechanical contact-based EEG electrode system with a contactless magnetic field sensing system using magnetometers. This substitution eliminates the need for physical contact and gel application while maintaining measurement capability through detection of magnetic fields generated by brain currents.
Solution Approach 2:
The patent changes the measurement parameter from electrical potential (EEG) to magnetic field strength. By measuring the magnetic fields generated by brain currents instead of electrical potentials, the system achieves reliable brain activity measurement without requiring skin contact or gel application.
2Ease of operation
If magnetometers are used to detect brain current-induced magnetic fields, then ease of operation is improved by eliminating contact requirements, but measurement precision deteriorates due to background magnetic fields
Solution Approach 1:
The patent divides the magnetic field measurement into two components: background magnetic field and brain current-induced magnetic field. By using multiple magnetometers arranged in specific configurations, the system separately measures and processes these components to isolate the brain activity signal from the background interference.
Solution Approach 2:
The patent converts the harmful effect of background magnetic fields into a beneficial measurement approach by using gradiometer configurations. The background field, which was previously a source of interference, becomes part of the measurement that can be mathematically differentiated from the brain-induced fields through gradient calculations.
3Measurement precision
If magnetic field shielding is implemented to improve measurement precision, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the physical magnetic field shielding system with a computational approach using multiple magnetometers and signal processing algorithms. Instead of physically blocking magnetic fields, the system uses mathematical methods to differentiate and isolate brain-induced fields from background fields.
Solution Approach 2:
The patent introduces signal processing algorithms and computational methods as intermediaries between the magnetometers and the final measurement results. These computational intermediaries process the raw magnetic field data to extract brain activity signals without requiring physical shielding.
4Measurement precision
If gradiometer units with multiple magnetometers are used, then measurement precision is improved by eliminating background fields, but device complexity increases
Solution Approach 1:
The patent designs the magnetometer system to serve multiple functions: measuring background magnetic fields, detecting brain current-induced fields, and providing spatial information through gradient calculations. This multi-functionality justifies the use of multiple magnetometers without proportionally increasing overall system complexity.
Solution Approach 2:
The patent implements a nested structure where gradiometer units (comprising multiple magnetometers) are arranged around the head, with each unit containing smaller-scale sensor arrangements. This nested configuration allows systematic measurement at different spatial scales while maintaining manageable system complexity.
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
Enables contactless, non-invasive measurement of brain activity suitable for everyday use, effectively detecting mental or physical states like fatigue by eliminating background magnetic fields and providing high sensitivity.
Implementation Method 1
Each magnetometer has a sensor medium and is configured to detect a magnetic field strength at a measurement location by reading a spin resonance in the sensor medium dependent on the magnetic field strength
Implementation Method 2
at least one of the magnetometers may comprise a nitrogen vacancy center magnetometer, wherein the sensor medium comprises a diamond crystal or a portion of a diamond crystal with nitrogen vacancy centers
Implementation Method 3
wherein the sensor unit further comprises at least one microwave source for generating a resonant field in the sensor medium
Implementation Method 4
at least one of the magnetometers may comprise a vapor cell magnetometer, wherein the sensor medium comprises an atomic spin-polarizable vapor in a cell
Data Source
AI summary
A sensor unit for detecting brain current-induced magnetic fields in an unshielded environment has a plurality of gradiometer units configured for arrangement around a head of a user. Each gradiometer unit has two magnetometers which are arranged at a fixed distance from each other. Each magnetometer has a sensor medium and is configured to detect a magnetic field strength at a measurement location by reading a spin resonance in the sensor medium depending on the magnetic field strength. The sensor unit further includes at least one excitation light source for radiating light into the sensor media of the magnetometer. The sensor unit further incudes at least one signal processing unit for determining a magnetic field gradient at a gradiometer unit as a difference of the output signals of the two magnetometers of the gradiometer unit and for detecting a time course of the magnetic field gradient.