Magnetic Shielding Device Active Gradient Control
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Solution Overview
Problem
Diagnostic imaging techniques, such as Magnetocardiogram (MCG) and Magnetoencephalogram (MEG), face challenges in measuring magnetic fields due to the need for high sensitivity and the interference from external magnetic fields, which are hundreds of thousands of times stronger than those generated by the body, requiring effective magnetic shielding.
Innovation Solution
A magnetic shielding device comprising a passive shield with an inner space, a first coil to cancel incoming magnetic fields, a first magnetic sensor to measure these fields, a second sensor positioned farther from the coil, and a controller to ensure the gradient between the measured fields is below a predetermined threshold, with additional coils and sensors to further refine the shielding within a target space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a passive shield is used to block external magnetic fields, then the magnetic field strength in the inner space is reduced, but the gradient of the magnetic field becomes significant causing measurement errors
Solution Approach 1:
The shielding system is segmented into multiple functional components: a passive shield for blocking external fields, and active coils (first coil, second coil) for compensating gradient effects. The control system segments the correction process by independently controlling different coils based on feedback from magnetic sensors positioned at specific locations.
Solution Approach 2:
The system implements feedback control by using magnetic sensors to continuously measure the magnetic field at the center and edges of the inner space, then feeding this information back to the control system which adjusts the coil currents accordingly to maintain field uniformity within the threshold.
2Volume of moving object
If the inner space volume is increased to accommodate measurement devices, then the shielding effectiveness decreases due to larger area exposed to external fields
Solution Approach 1:
The system addresses the volume-shielding effectiveness tradeoff by introducing a temporal dimension through active control. Rather than relying solely on passive geometric shielding, the system dynamically compensates for field variations using coils and feedback control, enabling larger inner spaces to maintain shielding effectiveness through active management of the magnetic field environment.
3Measurement precision
If active coils are added to cancel magnetic fields, then the gradient control improves, but the device complexity increases
Solution Approach 1:
The magnetic sensors serve multiple functions: they monitor the magnetic field for gradient compensation, verify shielding effectiveness, and provide feedback for control adjustments. The coils serve both to cancel external fields and to control field gradients, reducing the need for separate dedicated components for each function.
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 solution effectively reduces the gradient of magnetic fields within the shielding device's inner space, minimizing external magnetic field interference and enhancing the accuracy of magnetic field measurements, allowing for precise diagnostic imaging of sensitive organs like the heart and brain.
Implementation Method 1
a first coil that cancels a magnetic field entering in the inner space
Implementation Method 2
a first magnetic sensor that measures the magnetic field entering in the inner space; a second magnetic sensor located in a position farther from the first coil than the first magnetic sensor
Implementation Method 3
a passive shield having an inner space
Data Source
AI summary
A magnetic shielding device includes: a passive shield having an inner space; a first coil that cancels a magnetic field entering in the inner space; a first magnetic sensor that measures the magnetic field entering in the inner space; a second magnetic sensor located in a position farther from the first coil than the first magnetic sensor; and a controller that controls the first coil so that a gradient between a first magnetic field measured by the first magnetic sensor and a second magnetic field measured by the second magnetic sensor be less than a predetermined threshold.