Gradiometric Coil for Resonant Fluid Sensor Crosstalk
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Solution Overview
Problem
Existing fluid properties sensors with magnetic transducers face challenges in sensitivity due to interference from strong AC magnetic fields, eddy currents in conductive materials, and unwanted voltages induced by excitation coils, limiting their ability to measure small amplitudes and operate over a large range of fluid properties, especially in environments with substantial magnetic fields.
Innovation Solution
The use of a gradiometric coil structure, composed of two windings wound in opposite directions and connected in series, which cancels out induced voltages in uniform magnetic fields and reduces interference from eddy currents and unwanted voltages, enhancing the system's sensitivity and reducing crosstalk between excitation and sensing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coil is used for both excitation and sensing, then the device structure is simple, but strong AC magnetic fields and eddy currents induce unwanted voltages that overwhelm the sensing signal
Solution Approach 1:
The single coil is segmented into two separate coils: an excitation coil for driving the resonator and a sensing coil for detecting vibrations. This segmentation allows each coil to perform its specific function independently, preventing the excitation coil's strong AC magnetic fields from inducing unwanted voltages in the sensing coil, thereby improving sensing signal accuracy while maintaining reasonable structural complexity
Solution Approach 2:
A magnetic coupling mechanism serves as an intermediary between the excitation coil and the resonator, and between the resonator and the sensing coil. This intermediary allows energy and signal transmission without direct electrical connection, enabling the excitation and sensing functions to operate independently and preventing interference between them
2Measurement precision
If the sensing coil is placed close to the resonator to maximize sensitivity, then small amplitude vibrations can be detected, but eddy currents in nearby conductive materials generate interference signals
Solution Approach 1:
The sensing coil is extracted from the immediate vicinity of conductive materials that generate eddy currents. By positioning the sensing coil at an optimized distance from the resonator while maintaining separation from conductive interference sources, the system achieves high sensitivity to small vibration amplitudes without being overwhelmed by eddy current-induced interference signals
Solution Approach 2:
The system utilizes the magnetic field coupling between coils in a controlled manner to achieve sensitive detection, while the geometric arrangement and magnetic shielding convert potentially harmful eddy current effects into negligible interference. The magnetic coupling mechanism allows the system to benefit from close proximity for sensitivity while minimizing harmful effects through proper design
3Measurement precision
If permanent magnets are used in the transducer, then the magnetic field is strong and sensing is effective, but magnetic particles from the fluid adhere to the sensor surface and distort readings
Solution Approach 1:
The permanent magnets are extracted from the fluid-contact environment and placed in a protected location. The magnetic field is maintained through magnetic coupling mechanisms that allow field transmission without direct contact between the magnets and the fluid, preventing magnetic particles from adhering to the sensor surface while maintaining effective sensing
Solution Approach 2:
Magnetic coupling mechanisms serve as intermediaries that transmit the magnetic field from the permanent magnets to the sensing coils without requiring the magnets to be in direct contact with the fluid. This intermediary approach maintains the strength of the magnetic field for effective sensing while preventing contamination from magnetic particles in the fluid
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 gradiometric coil configuration significantly improves the sensitivity and accuracy of fluid properties measurement by minimizing interference from external magnetic fields and eddy currents, allowing for precise measurement of small amplitudes and operation over a wide range of fluid properties, even in challenging environments.
Implementation Method 1
an excitation coil and an excitation coil driving electrical network... The excitation coil is positioned so that a varying magnetic field produced by the excitation coil will drive the resonator
Implementation Method 2
an electromagnetic sensing assembly, including a gradiometric sense coil is positioned so that a magnetic field originating due to movement of the resonator... will create a time-varying magnetic field gradient across the sense coil
Data Source
AI summary
A fluid properties measurement device, including a magnetically excited and sensed resonator and a resonator electromagnetic excitation assembly, including an excitation coil driven by an electrical network, electrically connected to the excitation coil. The excitation coil is positioned so that a varying magnetic field produced by the excitation coil will drive the resonator in a pattern of resonating movement that has predetermined characteristics. Also, an electromagnetic sensing assembly, including a gradiometric sense coil is positioned so that an electromagnetic field originating due to movement of the resonator in a pattern having the predetermined characteristics, will create a time-varying gradient across the sense coil. Finally, a signal sensing electrical network is electrically connected to the sense coil.