Dual-Layer Magnetic Shielding for Accurate Magnetometer Sensing
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Solution Overview
Problem
Existing magnetic field probes, such as atomic magnetometers, face challenges in accurately detecting small magnetic fields due to interference from stray and environmental magnetic fields, leading to errors and false readings, particularly in applications requiring ultra-sensitivity like brain activity measurement and low-field NMR imaging.
Innovation Solution
A magnetic shield apparatus comprising an outer and inner shield made of high-permeability materials, with the inner shield's open end facing the outer shield and the outer shield partially closed, allowing samples to be inserted without fully opening the enclosure, and incorporating a compensation coil to reduce stray fields, ensuring the sensor detects only the magnetic fields from the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fully enclosed magnetic shield is used, then shielding effectiveness against environmental fields is improved, but access to the sensor and sample insertion becomes difficult
Solution Approach 1:
The magnetic shield is divided into multiple segments along its cylindrical structure, allowing the segments to be separated or moved apart. This enables access to the sensor and sample insertion without completely disassembling the shield, thus maintaining shielding effectiveness while improving ease of operation.
Solution Approach 2:
The shield incorporates movable or adjustable components that allow dynamic opening and closing of access points. The shield can be configured in different states (fully closed, partially open, fully open) depending on whether shielding or access is needed, resolving the contradiction between static shielding effectiveness and dynamic operational requirements.
2Object-affected harmful factors
If high-permeability materials are used for the shield, then shielding effectiveness is improved, but the shield becomes more susceptible to saturation from strong magnetic fields
Solution Approach 1:
The magnetic shield uses composite material construction, combining high-permeability materials for shielding effectiveness with low-permeability or non-magnetic materials in strategic locations to prevent saturation. This composite approach allows the shield to maintain high shielding performance while being more resistant to magnetic saturation from strong external fields.
Solution Approach 2:
Different regions of the shield have different material properties tailored to their specific functions. High-permeability materials are used where maximum shielding is needed, while materials with different properties are used in areas prone to high field strengths to prevent saturation, optimizing both shielding effectiveness and saturation resistance.
3Object-affected harmful factors
If the shield is fully enclosed, then environmental field rejection is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The shield is constructed from segmented components rather than a single complex enclosure, simplifying manufacturing and assembly. The segments can be produced separately using standard fabrication processes and then assembled to form the complete shield, reducing overall device complexity while maintaining effective environmental field rejection.
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 shield effectively isolates the sensor from environmental fields, enabling accurate detection of sample-generated magnetic fields with minimal distortion, facilitating applications like brain current measurement and low-field NMR imaging without the need for full enclosure opening.
Implementation Method 1
the outer shield and the inner shield each comprise a surface of a magnetically permeable material of permeability greater than 100
Implementation Method 2
incorporating a compensation coil to reduce stray fields
Data Source
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AI summary
A magnetic shield apparatus for shielding magnetic field probes. The shield apparatus comprises an outer shield, and an inner shield contained within the outer shield. A magnetic field sensor is housed in the inner shield, and the outer shield and the inner shield comprise a magnetically permeable material, enclosing a volume and having at least a first end that is open.