Evolution of MEG: A first MEG‐feasible fluxgate magnetometer

Abstract

In the current article, we present the first solid-state sensor feasible for magnetoencephalography (MEG) that works at room temperature. The sensor is a fluxgate magnetometer based on yttrium-iron garnet films (YIGM). In this feasibility study, we prove the concept of usage of the YIGM in terms of MEG by registering a simple brain induced field-the human alpha rhythm. All the experiments and results are validated with usage of another kind of high-sensitive magnetometers-optically pumped magnetometer, which currently appears to be well-established in terms of MEG.

On-scalp Yttrium-Iron Garnet sensor arrays for brain source localization: Cramér-Rao bound analysis

“…Uniform sensor arrays. Another type of sensor layout used in this study was originally created for our implementation of the OPM-MEG system [5]. In this layout, the sensors are evenly distributed over the measurement area (head surface).…”

“…Parameters of all sensors used in this study (from left to right): instrumental noise σ, distance to scalp d, number of integration points N i , base of gradiometer and the size of the sensitive element, adopted from [6] Sensor type Sensor signal modelling. The YIGM sensor is a solid-state magnetometer based on thin films of yttrium-iron garnet and is currently under development at the Russian Quantum Center [5,22]. The films are arranged to form a square plate 38×38 mm 2 .…”

“…However, recent technological advances in the field of low-frequency magnetometry -Optically Pumped Magnetometers (OPM) -could increase the availability of MEG [3,4]. In parallel to OPM a new solid-state magnetometer based on Yttrium-Iron Garnet films (YIGM) is designed and tested for brain signal recording [5,6]. Both, OPM and YIGM-based MEG systems are promising not only in terms of reliability and durability but also as sensors that can register various components of MEG signals which may bring a reasonable advantage [7].…”

How to build a magnetometer with thermal atomic vapor: a tutorial

“…Monitoring the transmission of the laser, used for optical pumping, also allows us to measure the M z component. While the absorptive Lorentzian line shape is perfectly suited for the optimization of the magnetometer (sections 5.3 and 5.4), it does not give us a signal proportional to the magnetic field, as was derived in equation (15). To obtain such a signal requires generating the derivative of the absorptive Lorentzian.…”

Ferrimagnetic Oscillator Magnetometer

“…Consequently, magnetic sensors employing spin-wave interferometry in ferrimagnetic films [34,35] or ferrimagnetic resonance (FMR) in spheres [36][37][38] or films [39][40][41][42] have been investigated, including demonstrations with pT/ √ Hz-level sensitivity. Using ferrimagnetic materials, classical sensors such as fluxgates [43][44][45] and Faradayrotation-based devices [46,47] have achieved sensitivities down to 40 fT/ √ Hz and 10 pT/ √ Hz, respectively. Additionally, ferrimagnetic materials have long found commercial use in tunable microwave filters [48,49] and oscillators [50][51][52].…”