Magnetic Resonance Sensor Shielding Against RFI Interference
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Solution Overview
Problem
Magnetic Resonance (MR) sensors face interference from Radio Frequency Interference (RFI) due to both electric and magnetic coupling, which is challenging to mitigate using conventional electromagnetic shielding, especially in portable or bulk material applications where shielding is impractical.
Innovation Solution
An apparatus comprising a magnetic resonance sensor and a shield member electrically isolated from it, with a magnetic resonator positioned to compensate for magnetic coupling, and an isolation circuit to reduce electrical energy coupling, utilizing a dished-shaped shield and a circular or multi-turn resonator configuration to enhance signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electromagnetic shielding is used to prevent RFI interference, then the MR sensor is protected from extraneous signals, but the device becomes impractical for portable applications and bulk material detection on conveyors
Solution Approach 1:
The shielding function is segmented into multiple discrete components: a shield member positioned behind the sensor, a magnetic resonator for active compensation, and an isolation circuit. This segmentation allows the shielding functionality to be integrated into portable devices without requiring a complete enclosed shielded room, thus maintaining protection while enabling portability and bulk material detection.
2Object-affected harmful factors
If a shield member is positioned behind the magnetic resonance sensor to block magnetic coupling, then interference from distant transmitters and power mains is reduced, but the device complexity increases
Solution Approach 1:
A magnetic resonator is introduced as an intermediary component positioned between the shield member and the MR sensor. This resonator actively compensates for magnetic coupling interference by resonating at the interference frequency and canceling the unwanted signals, providing enhanced protection without requiring a complex enclosed shielded structure.
Solution Approach 2:
The shield member is designed with specific geometric parameters (dished-shaped configuration, optimized depth and curvature) to enhance its magnetic shielding effectiveness. By optimizing these geometric parameters, the shield provides superior interference rejection with a simpler structure compared to traditional enclosed shielding.
3Object-affected harmful factors
If the shield member is electrically isolated from the magnetic resonance sensor, then electric coupling interference is reduced, but the magnetic shielding effectiveness may be compromised
Solution Approach 1:
The magnetic resonator serves as an intermediary that magnetically couples the shield member to the MR sensor without requiring direct electrical contact. This allows the shield to effectively block magnetic fields while remaining electrically isolated, thus reducing electric coupling interference while maintaining magnetic shielding effectiveness through the resonator's magnetic coupling mechanism.
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
Effectively shields MR sensors from unwanted magnetic and electric couplings, allowing for reliable detection of magnetic resonance signals even in environments with significant RFI, such as near human limbs or power transmission mains, while maintaining efficiency in signal transmission and reception.
Implementation Method 1
the shield member being positioned relative to the magnetic resonance sensor such that when the magnetic resonance sensor faces the target, the shield member is behind the magnetic resonance sensor to shield the magnetic resonance sensor from magnetically coupling with sources other than the magnetic resonance signals
Implementation Method 2
a magnetic resonator electrically isolated from the shield member and the magnetic resonance sensor, the magnetic resonator being adapted to resonate and scatter the magnetic field towards the target to at least partially compensate for magnetic coupling of sources other than the target with the magnetic resonance sensor
Implementation Method 3
an isolation circuit arranged between the magnetic resonance sensor and the output to transfer electrical energy from the magnetic resonance sensor to the output while reducing electrical energy electrically coupled to the magnetic resonance sensor from transferring to the output
Data Source
AI summary
An apparatus for detecting magnetic resonance signals from a target, comprises a magnetic resonance sensor for responding to magnetic resonance signals from a target, and a shield member electrically isolated from the magnetic resonance sensor, the shield member being positioned relative to the magnetic resonance sensor such that when the magnetic resonance sensor faces the target, the shield member is behind the magnetic resonance sensor to at least partially shield the magnetic resonance sensor from magnetically coupling with sources other than the magnetic resonance signals.