Magnetometer Research Articles

The Adsorption Behavior of Gas Molecules on Mn/N- and Mn-Doped Graphene.

By using density functional theory (DFT), the adsorption behavior of gas molecules on defective graphene doped with manganese and nitrogen were investigated. The geometric structure, electronic structure, and magnetic properties of two substrates were calculated and the sensing mechanism was also analyzed. The results indicate that the MnSV-GP and MnN3-GP have stronger structural stability, in which Mn atoms and their coordination atoms will become the adsorption point for five gas molecules (CH2O, CO, N2O, SO2, and NH3), respectively. Moreover, at room temperature (298 K), the recovery time of the MnSV-GP sensor for N2O gas molecules is approximately 1.1 s. Therefore, it can be concluded that the MnSV-GP matrix as a magnetic gas sensor has a promising potential for detecting N2O. These results also provide a new pathway for the potential application of Mn-doped graphene in the field of gas sensors.

Controlled Synthesis of 2D Ferromagnetic/Antiferromagnetic Cr7Te8/MnTe Vertical Heterostructures for High-Tunable Coercivity.

Two-dimensional ferromagnetic/antiferromagnetic (2D-FM/AFM) heterostructures are of great significance to realize the application of spintronic devices such as miniaturization, low power consumption, and high-density information storage. However, traditional mechanical stacking can easily damage the crystal quality or cause chemical contamination residues for 2D materials, which can result in weak interface coupling and difficulty in device regulation. Chemical vapor deposition (CVD) is an effective way to achieve a high-quality heterostructure interface. Herein, high-quality interface 2D-FM/AFM Cr7Te8/MnTe vertical heterostructures were successfully synthesized via a one-pot CVD method. Moreover, the atomic-scale structural scanning transmission electron microscope (STEM) characterization shows that the interface of the vertical heterostructure is clear and flat without an excess interface layer. Compared to the parent Cr7Te8, the coercivity (HC) of the high-quality interface Cr7Te8/MnTe heterostructure is significantly reduced as the thickness of MnTe increases, with a maximum decrease of 74.5% when the thickness of the MnTe nanosheet is around 30 nm. Additionally, the HC of the Cr7Te8/MnTe heterostructure can also be regulated by applying a gate voltage, and the HC increases or decreases with increasing positive or negative gate voltages. Thus, the effective regulation of HC is essential to improving the performance of advanced spintronic devices (e.g., MRAM and magnetic sensors). Our work will provide ideas for spin controlling and device application of 2D-FM/AFM heterostructures.

Artificial design of anisotropic magnetoelectric effect in Sr2IrO4/SrTiO3 superlattices

Magnetoelectric response in thin films is highly desirable for high-throughput and high-density microelectronic applications, like magnetic sensors. To sensitively detect the direction of magnetic field, the anisotropic magnetoelectric effect is required. Here, we artificially design an anisotropic magnetoelectric response in Sr2IrO4/SrTiO3 superlattices, where a strong (negligible) magnetoelectric response for magnetic fields along the z-direction (xy-plane) of Sr2IrO4/SrTiO3 interface was observed. A combination of perturbative calculations with numerical results and density functional theory calculations reveals that only the effective z-component Zeeman field within the Sr2IrO4 layers can change the electron occupation of the neighboring SrTiO3 layers, which is proportional to the polarization. Via controlling the periodicity of the superlattices, we can further control the anisotropy of magnetoelectric responses. This atomic-scale design of 3d/5d superlattices paves an alternative way toward controllable magnetoelectric effects with thin film integrations.

An ultrathin, rapidly fabricated, flexible giant magnetoresistive electronic skin

In recent years, there has been a significant increase in the prevalence of electronic wearables, among which flexible magnetoelectronic skin has emerged as a key component. This technology is part of the rapidly progressing field of flexible wearable electronics, which has facilitated a new human perceptual development known as the magnetic sense. However, the magnetoelectronic skin is limited due to its low sensitivity and substantial field limitations as a wearable electronic device for sensing minor magnetic fields. Additionally, achieving efficient and non-destructive delamination in flexible magnetic sensors remains a significant challenge, hindering their development. In this study, we demonstrate a novel magnetoelectronic touchless interactive device that utilizes a flexible giant magnetoresistive sensor array. The flexible magnetic sensor array was developed through an electrochemical delamination process, and the resultant ultra-thin flexible electronic system possessed both ultra-thin and non-destructive characteristics. The flexible magnetic sensor is capable of achieving a bending angle of up to 90 degrees, maintaining its performance integrity even after multiple repetitive bending cycles. Our study also provides demonstrations of non-contact interaction and pressure sensing. This research is anticipated to significantly contribute to the advancement of high-performance flexible magnetic sensors and catalyze the development of more sophisticated magnetic electronic skins.

On-Surface Synthesis of 2D Radical Frameworks

The design of atom thick two-dimensional (2D) frameworks by on-surface synthesis has recently contributed to the development of advanced materials with high control over their structural, electronic, optical and magnetic properties. Countless 2D frameworks, with a large variety of applications, can be synthesized made of purely organic molecules (covalent organic and supramolecular frameworks) or combining both metals and organic molecules (metalorganic frameworks). Here, we focus on the design and synthesis of radical 2D frameworks, composed of open-shell nanographenes equipped with azaindole units, on an Au(111) surface. Interestingly, the deposition of transition metal atoms on such frameworks allow the tuning of their magnetic properties, expanding their possible applications. The structural, electronic and magnetic characterization of the frameworks was performed by scanning tunneling microscopy/spectroscopy (STM/STS) and non-contact atomic force microscopy, and supported by density functional theory (DFT) calculations. Additionally, the magnetic characterization was complemented by nickelocene-functionalized tips investigations, which act as a magnetic sensor that unveils the magnetism of the frameworks at the single molecule level.

Electrochemical Quartz Crystal Microbalance Study on the Electrodeposition of Fe, Co and Fe-Co Alloys

Cobalt-iron alloys are interesting soft magnetic materials which are used for example in magnetic sensors and transducers. They can be obtained by different techniques such as PVD, magnetron sputtering, or casting. One easy and not very expensive way to produce these alloys is the electrochemical deposition technique, which was also chosen in this study.This contribution will describe the electrodeposition of Co, Fe and Fe-Co alloys (Fe70Co30) from an aqueous sulphate-based electrolyte containing boric acid as a buffer and sodium citrate and citric acid besides the metal sulphates. Potentiostatic step experiments and cyclic voltammetry were performed in parallel to electrochemical quartz crystal microbalance. Thus, we could identify the potential at which the deposition of the metals sets in, the mass of the deposited species as well as the current efficiency. We could also extract the partial current due to hydrogen evolution reaction and the partial current due to individual metal or their alloys from the total current density. The morphology and structure of the deposited films were investigated by means of SEM and XRD, respectively. The grain size of the deposits was calculated from the XRD data using Scherrer equation. Addition of citric acid to the electrolyte results in the smaller grain size of the deposited Fe-Co films.

The structural, electronic and magnetic properties of [formula omitted] anti-perovskite

A comprehensive exploration of the structural, electronic, and magnetic attributes of anti-perovskite Fe3ZnC carbides was carried out using Density Functional Theory (DFT) and Monte Carlo Simulation (MCS). These anti-perovskite materials possess a unique structure where cation and anion positions are interchanged within the perovskite framework. Our study involves a comparative analysis of the electronic band structures and density of states (DOS) for Fe3ZnC, considering prior theoretical and experimental research. Understanding these anti-perovskite materials' band structures and DOS is pivotal for their effective utilization in magnetic sensors and magnetic refrigeration applications. Our results indicate that Fe3ZnC displays ferromagnetic metallic behavior, particularly when applying the Generalized Gradient Approximation (GGA). Notably, there is a significant overlap between the valence (VB) and conduction (CB) bands. Furthermore, MCS predicts a second-order ferromagnetic-to-paramagnetic transition in the anti-perovskite Fe3ZnC compound, characterized by a notably high Curie temperature. These insights advance our understanding of these materials, paving the way for their effective utilization in magnetic technologies.

Soft Robots: Computational Design, Fabrication, and Position Control of a Novel 3-DOF Soft Robot

This paper presents the computational design, fabrication, and control of a novel 3-degrees-of-freedom (DOF) soft parallel robot. The design is inspired by a delta robot structure. It is engineered to overcome the limitations of traditional soft serial robot arms, which are typically low in structural stiffness and blocking force. Soft robotic systems are becoming increasingly popular due to their inherent compliance match to that of human body, making them an efficient solution for applications requiring direct contact with humans. The proposed soft robot consists of three soft closed-loop kinematic chains, each of which includes a soft actuator and a compliant four-bar arm. The complex nonlinear dynamics of the soft robot are numerically modeled, and the model is validated experimentally using a 6-DOF electromagnetic position sensor. This research contributes to the growing body of literature in the field of soft robotics, providing insights into the computational design, fabrication, and control of soft parallel robots for use in a variety of complex applications.

Very High Temperature Hall Sensors in a Wafer‐Scale 4H‐SiC Technology

Abstract4H‐SiC is a key enabler for realizing integrated electronics operating in harsh environments, which exhibit very high temperatures. Through advances in 4H‐SiC process technology, different sensor and circuit types have been demonstrated to operate stable at temperatures as high as 800 °C, paving the way toward harsh‐environment immune smart sensors. In this work, for the first time the operation of ion‐implanted 4H‐SiC Hall sensors realized in a wafer scale Bipolar‐CMOS‐DMOS technology is demonstrated at a wide operation temperature range spanning room temperature up to 500 °C in addition to short‐term operation up to 600 °C. The temperature‐dependent sensor characteristics of 15–22 samples are evaluated in terms of sensitivity and noise. The small inter‐device variations reflect the stability of the used process for very high temperature Hall sensors. The noise‐limited detectivity is further evaluated, revealing a best value of 950 nT/ and a mean detectivity of 1 µT/ at 500 °C. This is the best value reported up to date for very high temperature Hall sensors, besides being the first demonstration of ion‐implanted wide‐bandgap Hall sensors. Overall, the results reflect the potential of the demonstrated Hall sensors for the next generation of integrated magnetic field sensors in harsh environments.

Scaling traffic variables from sensors sample to the entire city at high spatiotemporal resolution with machine learning: applications to the Paris megacity

Abstract Road transportation accounts for up to 35% of carbon dioxide and 49% of nitrogen oxides emissions in the Paris region. However, estimates of city traffic patterns are often incomplete and of coarse spatio-temporal resolution, even where extensive networks of sensors exist. This study uses a machine learning approach to analyze data from 2086 magnetic road sensors across Paris, generating a detailed dataset of hourly traffic flow and road occupancy covering 6846 road segments from 2018 to 2022. Our model captures flow and occupancy with a Symmetric Mean Absolute Percentage Error of 37% and 54% respectively, providing high-resolution insights into traffic patterns. These insights allow for the creation of a comprehensive map of hourly transportation patterns in Paris, offering a robust framework for assessing traffic variables for each significant road link in the city. The model's ability to incorporate an emission factor based on the mean speed of the vehicle fleet, derived from flow and occupancy data, holds promise for developing a detailed CO2 and pollutant inventory. This methodology is not limited to Paris; it can be applied to other urban centers with similar data availability, highlighting its potential as a versatile tool for sustainable urban monitoring.

Recognizing salat activity using deep learning models via smartwatch sensors

In this study, we focus on human activity recognition, particularly aiming to distinguish the activity of praying (salat) from other daily activities. To achieve this goal, we have created a new dataset named HAR-P (Human activity recognition for Praying), which includes eight different activities: walking, running, sitting, standing, walking upstairs, walking downstairs, typing with a keyboard, and praying (salat). The HAR-P dataset was collected from 50 male individuals, who wore smartwatches on their dominant wrists. We compare the activity classification performance using three state-of-the-art algorithms from the literature: Long Short-Term Memory, Convolutional Long Short-Term Memory, and Convolutional Neural Network—Long Short-Term Memory. To assess the influence of sensors, data from accelerometer, gyroscope, linear acceleration sensor, and magnetic field sensor were utilized. The impact of individual sensor data as well as combinations thereof was investigated. The highest classification accuracy within single sensor groups, reaching 95.7%, was achieved using the accelerometer data with the Convolutional Long Short-Term Memory method. Combining two sensor groups resulted in an increase in accuracy of up to 9%. The highest accuracy of 96.4% was obtained by utilizing three sensor groups together with the Convolutional Neural Network—Long Short-Term Memory method. Furthermore, the evaluation of sensor and model performance was conducted using the stratified k-fold cross-validation method with 5-folds. These findings contribute significantly to evaluating the performance of sensor combinations and different algorithms in activity classification. This study may provide an effective foundation for the automatic recognition and tracking of human activities and offer an applicable model, particularly for the recognition of religious practices such as praying.

Cutting-Edge Microwave Sensors for Vital Signs Detection and Precise Human Lung Water Level Measurement

In this article, a comprehensive review is presented of recent technological advancements utilizing electromagnetic sensors in the microwave range for detecting human vital signs and lung water levels. With the main objective of improving detection accuracy and system robustness, numerous advancements in front-end architecture, detection techniques, and system-level integration have been reported. The benefits of non-contact vital sign detection have garnered significant interest across a range of applications, including healthcare monitoring and search and rescue operations. Moreover, some integrated circuits and portable systems have lately been shown off. A comparative examination of various system architectures, baseband signal processing methods, system-level integration strategies, and possible applications are included in this article. Going forward, researchers will continue to focus on integrating radar chips to achieve compact form factors and employ advanced signal processing methods to further enhance detection accuracy.

Optimal configurations of an electromagnetic tracking system for 3D ultrasound imaging of pediatric hips – A phantom study

Tracking the position and orientation of a two-dimensional (2D) ultrasound scanner to reconstruct a 3D volume is common, and its accuracy is important. In this study, a specific miniaturized electromagnetic (EM) tracking system was selected and integrated with a 2D ultrasound scanner, which was aimed to capture hip displacement in children with cerebral palsy. The objective of this study was to determine the optimum configuration, including the distance between the EM source and sensor, to provide maximum accuracy. The scanning volume was aimed to be 320 mm × 320 mm × 76 mm. The accuracy of the EM tracking was evaluated by comparing its tracking with those from a motion capture camera system. A static experiment showed that a warm-up time of 20 min was needed. The EM system provided the highest precision of 0.07 mm and 0.01° when the distance between the EM source and sensor was 0.65 m. Within the testing volume, the maximum position and rotational errors were 2.31 mm and 1.48°, respectively. The maximum error of measuring hip displacement on the 3D hip phantom study was 4 %. Based on the test results, the tested EM system was suitable for 3D ultrasound imaging of pediatric hips to assess hip displacement when optimal configuration was used.

Influence of Mg+2 on the structure, microstructure, and magnetic interactions of zinc ferrite nanoparticles synthesized via co-precipitation route

Evolution of the structural, morphological and magnetic properties of Zn1-xMgxFe2O4 (X = 0.00, 0.10 and 0.20) nanoparticles are discussed in detail and relation between cation disorder and magnetic interactions are prospected. The synthesized samples sintered at 500 °C temperature under examination display cubic crystal structure possesses Fd-3m as space group. The average crystallite size and lattice parameter shows variation as revealed from scherrer equation with the addition of Mg dopant at zinc site. Rietveld refinement presented single phase formation. Raman spectroscopy was utilized to convey different Raman modes and their associated vibrations. Scanning electron microscopy was utilized to survey the morphological attributes. Magnetization studies reveal weak ferromagnetism at low temperature (5 K) due to cation disorder for all samples. Zero field cooled and field cooled curves from magnetization vs temperature reveal the blocking temperature and its dependence on cation disorder and particle size. These results provide information about the possible applications of zinc ferrite nanoparticles in magnetic sensors, nanomedicine, optoelectronics, and memory devices.

Investigating R&D Committee on Magnetic Sensor with Machine Learning

Investigating R&D Committee on Magnetic Sensor with Machine Learning

Preface to Special Issue on “New Developments on Techniques Using Magnetic Sensor and Machine Learning”

Preface to Special Issue on “New Developments on Techniques Using Magnetic Sensor and Machine Learning”

Exploring the effects of angle of incidence on stabbing resistance in advanced protective textiles: Novel experimental framework and analysis

Despite numerous research investigations to understand the influences of various structural parameters, to the authors' knowledge, no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles. Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested. Two samples, one composed of a single and the other of 4-panel layers, from each fabric type structure, were prepared, and tested against stabbing at [0°], [22.5°], and [45°] angle of incidence. A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized. The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch (HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively. A silicon compound was utilized to imprint the Back Face Signature (BFS) on the backing material after every specimen test. Each silicon print was then scanned, digitized, and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables, including Depth of Trauma (DOT), Depth of Penetration (DOP), and Length of Penetration (LOP). Besides, the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level. The results show stab angle of incidence greatly influences the stab response and performance of protective textiles. The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence, but also provide valuable information for protective textile manufacturer, armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing, testing, optimizing, and using protective textiles in various applications.

A multi-satellite survey scheme for addressing open questions on the Earth’s outer radiation belt dynamics

The Earth’s outer radiation belt is highly dynamic, containing relativistic electron fluxes that can increase by several orders of magnitude during magnetospheric disturbances. This greatly increases the likelihood of spacecraft malfunction or failure and significantly influences the solar-terrestrial system’s energy and mass coupling, highlighting the importance of fully understanding the mechanisms governing these dynamics from both theoretical and practical perspectives. Although many theories have been proposed, further research is essential to quantify the specific contributions of different dynamic mechanisms for improving space weather forecasting. To address this, observations of the outer radiation belt with high spatial–temporal resolution to distinguish the spatial and temporal variations are essential. We introduce a 10-CubeSat constellation survey scheme in the geosynchronous transfer orbit (GTO) to achieve this required observation. Three baseline instruments are proposed to be employed: the high energy electron detector (HEED), the search coil wave detector (SCWD), and the magnetometer (MAG). Two groups of physical processes will be investigated: wave-particle interactions involving charged particles interacting with whistler-mode waves, electromagnetic ion cyclotron (EMIC) waves, and ultra-low frequency (ULF) waves; and radial transport encompassing shock-induced injections, substorm injections, storm convection and magnetopause shadowing. The performance parameters of instruments and platform of the constellation are presented. Additionally, aligned with the concept of constellation survey, we outline the COSPAR-coordinated space program, COnstellation of Radiation BElt Survey (CORBES), which will provide a crucial scientific contribution in the absence of the Van Allen Probes. The program’s excellent observational capability enables a comprehensive understanding of the underlying physical mechanisms governing the outer radiation belt dynamics and improved space weather forecasting.

Settlement stability, electrical properties, and magnetoelectric properties of Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 multiferroic fluids modulating by particle sizes

Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 (MZFO-PZT) multiferroic fluids with different MZFO particle sizes were prepared, and magnetoelectric coupling effects were observed to be enhanced at room temperature. The X-ray diffraction analysis (XRD) indicates that the MZFO and PZT particles are in the pure phases. Scanning electron microscopy (SEM) images illustrate a decrease in MZFO particle size with increased ball milling time. As the MZFO particle sizes decrease, the settlement stability of multiferroic fluids becomes worse. The dielectric constant displays a nonlinear variation, exhibiting a maximum value of 4.52 at 140 Hz when the MZFO particle size is 0.55 μm. The residual polarization strength decreases and increases as particle size decreases, while the saturation polarization strength decreases gradually. The application of magnetic field results in a notable enhancement of the dielectric characteristics and ferroelectric properties, which indicates the presence of magnetodielectric and magnetoelectric coupling effects. The magnetoelectric coupling coefficient (αME) is 15.14 V/(cm·Oe) when the MZFO particle size is 0.61 μm. By modifying the strength of the applied magnetic field, the αME attains a maximum value of 114.43 V/(cm·Oe). This approach offers an effective strategy for optimizing the magnetoelectric coupling effect of multiferroic materials. Therefore, it is expected to be used in new magnetoelectric devices such as magnetoelectric random memories and magnetic field sensors.

Orientation of birds in radiofrequency fields in the absence of the Earth's magnetic field: a possible test for the radical pair mechanism of magnetoreception.

The magnetic compass sense of migratory songbirds is thought to derive from magnetically sensitive photochemical reactions in cryptochromes located in photoreceptor cells in the birds' retinas. More specifically, transient radical pairs formed by light-activation of these proteins have been proposed to account for the birds' ability to orient themselves using the Earth's magnetic field and for the observation that radiofrequency magnetic fields, superimposed on the Earth's magnetic field, can disrupt this ability. Here, by means of spin dynamics simulations, we show that it may be possible for the birds to orient in a monochromatic radiofrequency field in the absence of the Earth's magnetic field. If such a behavioural test were successful, it would provide powerful additional evidence for a radical pair mechanism of avian magnetoreception.