Towards ultimate low frequency air-core magnetometer sensitivity

Abstract

Air-core magnetometers are amongst the most commonly used magnetic field detectors in biomedical instruments. They offer excellent sensitivity, low fabrication complexity and a robust, cost-effective solution. However, air-core magnetometers must be tailored to the specific application to achieve high sensitivity, which can be decisive in the accuracy of the diagnoses and the time required for the examination. Existing methods proposed for the design of air-core magnetometers are based on simplified models and simulations using a reduced number of variables, potentially leading to sensitivity that is suboptimal. To circumvent this we chose a method with fewer assumptions and a larger number of decision variables which employed a genetic algorithm, a global optimisation method. Experimental validation shows that the model is appropriate for the design of highly sensitive air-core magnetometers. Moreover, our results support the suitability of a genetic algorithm for optimization in this context. The new method described herein will be made publicly available via our website to facilitate the development of less costly biomedical instruments using air-core magnetometers with unprecedented sensitivity.

3D-Spatial encoding with permanent magnets for ultra-low field magnetic resonance imaging

“…1c), corresponding to a frequency spread of 43–430 Hz. This is comparable to B m and well within the bandwidth of our recently developed highly sensitive coil-based magnetometers 18 .…”

“…We chose optimized air-core magnetometers for ULF-MRI signal detection 18 . Signal detection with a single surface coil (diameter 120 mm) placed 3 mm away from the sample, and oriented perpendicular to B p , B m , and the sample surface was used in the simulation.…”

Biosensing Using Magnetic Particle Detection Techniques

“…Magnetic binding assays were also reported to detect BSA adsorption using magnetic markers and a magnetic permeability meter [ 246 ]. Another related technique involves the air-core magnetometer, which is commonly used in biomedical applications [ 18 ]. In the inductive coil magnetic resonance detection, the effect of MP shape on signal amplification has been evaluated based on the magnetic susceptibility of oriented nanostructures [ 247 ].…”

“…The last step in the design of a MP system is selecting an analytical technique to detect the magnetic signal. There are several types of magnetic detection techniques, including but not limited to spintronic sensors based on giant magnetoresistance (GMR), tunnel magnetoresistance (TMR), and planar Hall effect (PHE) sensors, superconducting quantum interference devices (SQUIDs), atomic magnetometers (AMs), nuclear magnetic resonance (NMR) systems, fluxgate sensors, Faraday induction coil sensors, diamond magnetometers, and domain walls-based sensors [ 3 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. These techniques have been used to measure the magnetic response in the form of susceptibility, relaxation, remanence, MP-induced proton NMR, and even frequency mixing [ 17 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ].…”

Design of a Matching Network for a High-Sensitivity Broadband Magnetic Resonance Sounding Coil Sensor

“…Coil sensors are widely used in biomedical and geological survey instruments because of their excellent sensitivity, low fabrication complexity, robustness and low cost [ 13 , 14 , 15 , 16 ]. To optimize the coil sensor designs and improve the sensitivity, numerical methods have been developed [ 17 , 18 , 19 ].…”