Thin-Film-Based SAW Magnetic Field Sensors

In this work, the first surface acoustic-wave-based magnetic field sensor using thin-film AlScN as piezoelectric material deposited on a silicon substrate is presented. The fabrication is based on standard semiconductor technology. The acoustically active area consists of an AlScN layer that can be excited with interdigital transducers, a smoothing SiO2 layer, and a magnetostrictive FeCoSiB film. The detection limit of this sensor is 2.4 nT/Hz at 10 Hz and 72 pT/Hz at 10 kHz at an input power of 20 dBm. The dynamic range was found to span from about ±1.7 mT to the corresponding limit of detection, leading to an interval of about 8 orders of magnitude. Fabrication, achieved sensitivity, and noise floor of the sensors are presented.

Recent Progress in Devices Based on Magnetoelectric Composite Thin Films

The strain-driven interfacial coupling between the ferromagnetic and ferroelectric constituents of magnetoelectric (ME) composites makes them potential candidates for novel multifunctional devices. ME composites in the form of thin-film heterostructures show promising applications in miniaturized ME devices. This article reports the recent advancement in ME thin-film devices, such as highly sensitive magnetic field sensors, ME antennas, integrated tunable ME inductors, and ME band-pass filters, is discussed. (Pb1−xZrx)TiO3 (PZT), Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), Aluminium nitride (AlN), and Al1−xScxN are the most commonly used piezoelectric constituents, whereas FeGa, FeGaB, FeCo, FeCoB, and Metglas (FeCoSiB alloy) are the most commonly used magnetostrictive constituents in the thin film ME devices. The ME field sensors offer a limit of detection in the fT/Hz1/2 range at the mechanical resonance frequency. However, below resonance, different frequency conversion techniques with AC magnetic or electric fields or the delta-E effect are used. Noise floors of 1–100 pT/Hz1/2 at 1 Hz were obtained. Acoustically actuated nanomechanical ME antennas operating at a very-high frequency as well as ultra-high frequency (0.1–3 GHz) range, were introduced. The ME antennas were successfully miniaturized by a few orders smaller in size compared to the state-of-the-art conventional antennas. The designed antennas exhibit potential application in biomedical devices and wearable antennas. Integrated tunable inductors and band-pass filters tuned by electric and magnetic field with a wide operating frequency range are also discussed along with miniaturized ME energy harvesters.

Towards Fabrication of Planar Magnetoelectric Devices: Coil-Free Excitation of Ferromagnet-Piezoelectric Heterostructures

Magnetoelectric (ME) effects in composite ferromagnet-piezoelectric (FM/PE) heterostructures realize the mutual transformation of alternating magnetic and electric fields, and are used to create magnetic field sensors, actuators, inductors, gyrators, and transformers. The ME effect in composite structures is excited by an alternating magnetic field, which is created using volumetric electromagnetic coils. The coil increases the size, limits the operating frequencies, and complicates the manufacture of devices. In this work, we propose to excite the ME effect in composite heterostructures using a new coil-free excitation system, similar to a “magnetic capacitor”. The system consists of parallel electrodes integrated into the heterostructure, through which an alternating current flows. Modeling and measurements have shown that the excitation magnetic field is localized mainly between the electrodes of the magnetic capacitor and has a fairly uniform spatial distribution. Monolithic FM/PE heterostructures of various designs with FM layers of amorphous Metglas alloy or nickel-zinc ferrite and PE layers of lead zirconate titanate piezoceramic were fabricated and investigated. The magnitude of the ME effect in such structures is comparable to the magnitude of the ME effect in structures excited by volumetric coils. However, the low impedance of the coil-free excitation system makes it possible to increase the operating frequency, reducing the size of ME devices and the power consumption. The use of coil-free excitation opens up the possibility of creating planar ME devices, and accelerates their integration into modern electronics and microsystem technology.

The Detector Control System for the magnetic field sensors in New Small Wheel phase I upgrade of ATLAS detector

In conjunction with the High Luminosity upgrade of the Large Hadron Collider accelerator at CERN, the ATLAS detector is also undergoing an upgrade to handle the significantly higher data rates. The muon end-cap system upgrade in ATLAS, lies with the replacement of the Small Wheel. The New Small Wheel (NSW) is expected to combine high tracking precision with upgraded information for the Level-1 trigger. To accomplish this, small Thin Gap Chamber (sTGC) and MicroMegas detector technologies are being deployed. Due to their installation location in ATLAS, the effects of Barrel Toroid and End-Cap Toroid magnets on NSW must be measured. For the final experiment at ATLAS, each sTGC large double wedge will be equipped with magnetic field Hall effect sensors to monitor the magnetic field near the NSW. The readout is done with an Embedded Local Monitor Board (ELMB) called MDT DCS Module (MDM). For the integration of this hardware in the experiment, first, a detector control system was developed to test the functionality of all sensors before their installation on the detectors. Subsequently, another detector control system was developed for the commissioning of the sensors. Finally, a detector control system based on the above two is under development for the expert panels of ATLAS experiment. In this paper, the sensor readout, the connectivity mapping and the detector control systems will be presented.

Application of magnetoelectric sensors in biomedicine

The prospects of applying highly sensitive magnetic field sensors based on the magnetoelectric effect in biomedicine are discussed in this paper. When developing highly sensitive magnetic field sensors, it is necessary to take into account the magnitude of the equivalent magnetic noise, as well as the mass and size dimensions and ease of use of the system that the sensor is included in. One of the most relevant areas discussed in the article is the application of magnetoelectric magnetic field sensors for magnetocardiography, magnetoencephalography, etc. These methods are non-invasive, have high sensitivity and are easy to use. They also have wide opportunities in detecting weak biomagnetic signals when examining the state of the human body and providing the necessary assistance.

Interface for indication and remote control of an unmanned vessel in automatic and manual modes

The article proposes a method for organizing the communication interface of an unmanned vessel and its operator. The interface contains manual controls for the course and speed of the vessel by regulating the angle of the rudder blade shift and the speed of rotation of the propeller shaft, an automatic system for keeping the vessel on a given trajectory for the purpose of navigating the vessel in automatic and manual modes. The interface comprises a system for obtaining filtration, storing the required kinematic and navigation data for identifying mathematical models of the vessel’s movement and the functioning of the autopilot. The interface allows adjusting the PID controller for automatic guidance of the vessel along the trajectory in real time to optimize automatic control, to correct the readings of the GPS and the Earth’s magnetic field sensors, to calibrate the Earth’s magnetic field sensor. The interface includes graphic and digital fields for displaying kinematic and navigation data on the vessel, autopilot and information on the operation of the operator-vessel complex. The interface allows the exchange of data between the operator and the vessel by means of a data transfer protocol via TCP-IP stack protocols on the radio frequencies of public Wi-Fi networks. The interface is created by means of appdesigner tools on the MATLAB platform.

Magnetoelectric Response of Laminated Cantilevers Comprising a Magnetoactive Elastomer and a Piezoelectric Polymer, in Pulsed Uniform Magnetic Fields

The voltage response to pulsed uniform magnetic fields and the accompanying bending deformations of laminated cantilever structures are investigated experimentally in detail. The structures comprise a magnetoactive elastomer (MAE) slab and a commercially available piezoelectric polymer multilayer. The magnetic field is applied vertically and the laminated structures are customarily fixed in the horizontal plane or, alternatively, slightly tilted upwards or downwards. Six different MAE compositions incorporating three concentrations of carbonyl iron particles (70 wt%, 75 wt% and 80 wt%) and two elastomer matrices of different stiffness are used. The dependences of the generated voltage and the cantilever’s deflection on the composition of the MAE layer and its thickness are obtained. The appearance of the voltage between the electrodes of a piezoelectric material upon application of a magnetic field is considered as a manifestation of the direct magnetoelectric (ME) effect in a composite laminated structure. The ME voltage response increases with the increasing total quantity of the soft-magnetic filler in the MAE layer. The relationship between the generated voltage and the cantilever’s deflection is established. The highest observed peak voltage around 5.5 V is about 8.5-fold higher than previously reported values. The quasi-static ME voltage coefficient for this type of ME heterostructures is about 50 V/A in the magnetic field of ≈100 kA/m, obtained for the first time. The results could be useful for the development of magnetic field sensors and energy harvesting devices relying on these novel polymer composites.