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Magnetoelectric Sensor Systems and Applications

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (11 December 2021) | Viewed by 36448

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Institute for Electrical Engineering and Information Engineering, Faculty of Engineering, Kiel University, D-24143 Kiel, Germany
Interests: signal processing; biomedical applications; real-time systems

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Guest Editor
Inorganic Functional Materials, Institute for Materials Science, University of Kiel, D-24143 Kiel, Germany
Interests: magnetoelectric materials; magnetoelectric sensor concepts

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Guest Editor
Electrical and Computer Engineering Department, Northeastern University, Boston, MA, USA
Interests: magnetoelectric materials; magnetoelectric sensor concepts; magnetoelectric antennas
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Faculty of Engineering Kiel University, D-24143 Kiel, Germany
Interests: magnetoelectric materials; magnetoelectric sensor concepts; low- noise and low-power design; biomedical signal acquisition
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Well-established magnetic sensors such as superconducting quantum interference devices (SQUIDs) or optically pumped magnetometers (OPMs) have several advantages if magnetometers are used either in addition or sometimes instead of electric measurements. Application examples include spatially and temporally high-resolution medical analysis such as combined electro- and magnetoencephalography (EEG/MEG), electro- and magnetocardiography (ECG/MCG), or structural material analysis. The drawbacks of current magnetic sensor technologies are mainly their high cost and their limited robustness against environmental influences. External magnetic fields, such as the magnetic field of the earth or the fields created by power supplies, saturate sensor principles and expensive magnetic shielding and sometimes expensive cooling are required. The magnetoelectric (ME) sensor principle is relatively new and has the potential to overcome these limitations at a very low cost. Recent advances, in terms of magnetic layer optimization, low-noise readout, and dedicated signal processing for new read-out principles, might enhance the sensitivity of magnetoelectric sensor principles and bring them very close to that of OPMs or SQUIDs without robustness problems.

This Special Issue will report the latest research on magnetoelectric sensor systems and corresponding applications. The bandwidth of contributions can range from advances in material science and improved understanding of the magnetic processes that are involved in magnetoelectric layers, low-noise amplification circuits, and specially tailored readout schemes for ME sensors, but also application examples from biomedical or other fields.

Prof. Dr. Gerhard Schmidt
Prof. Dr. Eckhard Quandt
Prof. Dr. Nian X. Sun
Prof. Dr. Andreas Bahr
Guest Editors

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Keywords

  • magnetoelectric sensors
  • magnetic sensor concepts
  • sensor system development
  • biomedical applications

Published Papers (12 papers)

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Research

28 pages, 2715 KiB  
Article
Quantitative Evaluation for Magnetoelectric Sensor Systems in Biomagnetic Diagnostics
by Eric Elzenheimer, Christin Bald, Erik Engelhardt, Johannes Hoffmann, Patrick Hayes, Johan Arbustini, Andreas Bahr, Eckhard Quandt, Michael Höft and Gerhard Schmidt
Sensors 2022, 22(3), 1018; https://0-doi-org.brum.beds.ac.uk/10.3390/s22031018 - 28 Jan 2022
Cited by 25 | Viewed by 3360
Abstract
Dedicated research is currently being conducted on novel thin film magnetoelectric (ME) sensor concepts for medical applications. These concepts enable a contactless magnetic signal acquisition in the presence of large interference fields such as the magnetic field of the Earth and are operational [...] Read more.
Dedicated research is currently being conducted on novel thin film magnetoelectric (ME) sensor concepts for medical applications. These concepts enable a contactless magnetic signal acquisition in the presence of large interference fields such as the magnetic field of the Earth and are operational at room temperature. As more and more different ME sensor concepts are accessible to medical applications, the need for comparative quality metrics significantly arises. For a medical application, both the specification of the sensor itself and the specification of the readout scheme must be considered. Therefore, from a medical user’s perspective, a system consideration is better suited to specific quantitative measures that consider the sensor readout scheme as well. The corresponding sensor system evaluation should be performed in reproducible measurement conditions (e.g., magnetically, electrically and acoustically shielded environment). Within this contribution, an ME sensor system evaluation scheme will be described and discussed. The quantitative measures will be determined exemplarily for two ME sensors: a resonant ME sensor and an electrically modulated ME sensor. In addition, an application-related signal evaluation scheme will be introduced and exemplified for cardiovascular application. The utilized prototype signal is based on a magnetocardiogram (MCG), which was recorded with a superconducting quantum-interference device. As a potential figure of merit for a quantitative signal assessment, an application specific capacity (ASC) is introduced. In conclusion, this contribution highlights metrics for the quantitative characterization of ME sensor systems and their resulting output signals in biomagnetism. Finally, different ASC values and signal-to-noise ratios (SNRs) could be clearly presented for the resonant ME sensor (SNR: 90 dB, ASC: 9.8×107 dB Hz) and also the electrically modulated ME sensor (SNR: 11 dB, ASC: 23 dB Hz), showing that the electrically modulated ME sensor is better suited for a possible MCG application under ideal conditions. The presented approach is transferable to other magnetic sensors and applications. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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21 pages, 2400 KiB  
Article
Adaptive Model for Magnetic Particle Mapping Using Magnetoelectric Sensors
by Ron-Marco Friedrich and Franz Faupel
Sensors 2022, 22(3), 894; https://0-doi-org.brum.beds.ac.uk/10.3390/s22030894 - 24 Jan 2022
Cited by 1 | Viewed by 2956
Abstract
Imaging of magnetic nanoparticles (MNPs) is of great interest in the medical sciences. By using resonant magnetoelectric sensors, higher harmonic excitations of MNPs can be measured and mapped in space. The proper reconstruction of particle distribution via solving the inverse problem is paramount [...] Read more.
Imaging of magnetic nanoparticles (MNPs) is of great interest in the medical sciences. By using resonant magnetoelectric sensors, higher harmonic excitations of MNPs can be measured and mapped in space. The proper reconstruction of particle distribution via solving the inverse problem is paramount for any imaging technique. For this, the forward model needs to be modeled accurately. However, depending on the state of the magnetoelectric sensors, the projection axis for the magnetic field may vary and may not be known accurately beforehand. As a result, the projection axis used in the model may be inaccurate, which can result in inaccurate reconstructions and artifact formation. Here, we show an approach for mapping MNPs that includes sources of uncertainty to both select the correct particle distribution and the correct model simultaneously. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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17 pages, 5682 KiB  
Article
Sputter Deposited Magnetostrictive Layers for SAW Magnetic Field Sensors
by Lars Thormählen, Dennis Seidler, Viktor Schell, Frans Munnik, Jeffrey McCord and Dirk Meyners
Sensors 2021, 21(24), 8386; https://0-doi-org.brum.beds.ac.uk/10.3390/s21248386 - 15 Dec 2021
Cited by 3 | Viewed by 2639
Abstract
For the best possible limit of detection of any thin film-based magnetic field sensor, the functional magnetic film properties are an essential parameter. For sensors based on magnetostrictive layers, the chemical composition, morphology and intrinsic stresses of the layer have to be controlled [...] Read more.
For the best possible limit of detection of any thin film-based magnetic field sensor, the functional magnetic film properties are an essential parameter. For sensors based on magnetostrictive layers, the chemical composition, morphology and intrinsic stresses of the layer have to be controlled during film deposition to further control magnetic influences such as crystallographic effects, pinning effects and stress anisotropies. For the application in magnetic surface acoustic wave sensors, the magnetostrictive layers are deposited on rotated piezoelectric single crystal substrates. The thermomechanical properties of quartz can lead to undesirable layer stresses and associated magnetic anisotropies if the temperature increases during deposition. With this in mind, we compare amorphous, magnetostrictive FeCoSiB films prepared by RF and DC magnetron sputter deposition. The chemical, structural and magnetic properties determined by elastic recoil detection, X-ray diffraction, and magneto-optical magnetometry and magnetic domain analysis are correlated with the resulting surface acoustic wave sensor properties such as phase noise level and limit of detection. To confirm the material properties, SAW sensors with magnetostrictive layers deposited with RF and DC deposition have been prepared and characterized, showing comparable detection limits below 200 pT/Hz1/2 at 10 Hz. The main benefit of the DC deposition is achieving higher deposition rates while maintaining similar low substrate temperatures. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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8 pages, 1617 KiB  
Communication
Thin-Film-Based SAW Magnetic Field Sensors
by Jana Marie Meyer, Viktor Schell, Jingxiang Su, Simon Fichtner, Erdem Yarar, Florian Niekiel, Thorsten Giese, Anne Kittmann, Lars Thormählen, Vadim Lebedev, Stefan Moench, Agnė Žukauskaitė, Eckhard Quandt and Fabian Lofink
Sensors 2021, 21(24), 8166; https://0-doi-org.brum.beds.ac.uk/10.3390/s21248166 - 07 Dec 2021
Cited by 12 | Viewed by 3820
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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16 pages, 1463 KiB  
Article
Active Magnetoelectric Motion Sensing: Examining Performance Metrics with an Experimental Setup
by Johannes Hoffmann, Eric Elzenheimer, Christin Bald, Clint Hansen, Walter Maetzler and Gerhard Schmidt
Sensors 2021, 21(23), 8000; https://0-doi-org.brum.beds.ac.uk/10.3390/s21238000 - 30 Nov 2021
Cited by 7 | Viewed by 2118
Abstract
Magnetoelectric (ME) sensors with a form factor of a few millimeters offer a comparatively low magnetic noise density of a few pT/Hz in a narrow frequency band near the first bending mode. While a high resonance frequency (kHz range) and limited [...] Read more.
Magnetoelectric (ME) sensors with a form factor of a few millimeters offer a comparatively low magnetic noise density of a few pT/Hz in a narrow frequency band near the first bending mode. While a high resonance frequency (kHz range) and limited bandwidth present a challenge to biomagnetic measurements, they can potentially be exploited in indirect sensing of non-magnetic quantities, where artificial magnetic sources are applicable. In this paper, we present the novel concept of an active magnetic motion sensing system optimized for ME sensors. Based on the signal chain, we investigated and quantified key drivers of the signal-to-noise ratio (SNR), which is closely related to sensor noise and bandwidth. These considerations were demonstrated by corresponding measurements in a simplified one-dimensional motion setup. Accordingly, we introduced a customized filter structure that enables a flexible bandwidth selection as well as a frequency-based separation of multiple artificial sources. Both design goals target the prospective application of ME sensors in medical movement analysis, where a multitude of distributed sensors and sources might be applied. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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18 pages, 2661 KiB  
Article
Modeling and Parallel Operation of Exchange-Biased Delta-E Effect Magnetometers for Sensor Arrays
by Benjamin Spetzler, Patrick Wiegand, Phillip Durdaut, Michael Höft, Andreas Bahr, Robert Rieger and Franz Faupel
Sensors 2021, 21(22), 7594; https://0-doi-org.brum.beds.ac.uk/10.3390/s21227594 - 16 Nov 2021
Cited by 3 | Viewed by 2054
Abstract
Recently, Delta-E effect magnetic field sensors based on exchange-biased magnetic multilayers have shown the potential of detecting low-frequency and small-amplitude magnetic fields. Their design is compatible with microelectromechanical system technology, potentially small, and therefore, suitable for arrays with a large number N of [...] Read more.
Recently, Delta-E effect magnetic field sensors based on exchange-biased magnetic multilayers have shown the potential of detecting low-frequency and small-amplitude magnetic fields. Their design is compatible with microelectromechanical system technology, potentially small, and therefore, suitable for arrays with a large number N of sensor elements. In this study, we explore the prospects and limitations for improving the detection limit by averaging the output of N sensor elements operated in parallel with a single oscillator and a single amplifier to avoid additional electronics and keep the setup compact. Measurements are performed on a two-element array of exchange-biased sensor elements to validate a signal and noise model. With the model, we estimate requirements and tolerances for sensor elements using larger N. It is found that the intrinsic noise of the sensor elements can be considered uncorrelated, and the signal amplitude is improved if the resonance frequencies differ by less than approximately half the bandwidth of the resonators. Under these conditions, the averaging results in a maximum improvement in the detection limit by a factor of N. A maximum N200 exists, which depends on the read-out electronics and the sensor intrinsic noise. Overall, the results indicate that significant improvement in the limit of detection is possible, and a model is presented for optimizing the design of delta-E effect sensor arrays in the future. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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13 pages, 2303 KiB  
Article
Teaching Magnetoelectric Sensing to Secondary School Students—Considerations for Educational STEM Outreach
by Cara Broß, Carolin Enzingmüller, Ilka Parchmann and Gerhard Schmidt
Sensors 2021, 21(21), 7354; https://0-doi-org.brum.beds.ac.uk/10.3390/s21217354 - 05 Nov 2021
Viewed by 2126
Abstract
A major challenge in modern society is the need to increase awareness and excitement with regard to science, technology, engineering and mathematics (STEM) and related careers directly or among peers and parents in order to attract future generations of scientists and engineers. The [...] Read more.
A major challenge in modern society is the need to increase awareness and excitement with regard to science, technology, engineering and mathematics (STEM) and related careers directly or among peers and parents in order to attract future generations of scientists and engineers. The numbers of students aiming for an engineering degree are low compared to the options available and the workforce needed. This may, in part, be due to a traditional lack of instruction in this area in secondary school curricula. In this regard, STEM outreach programs can complement formal learning settings and help to promote engineering as well as science to school students. In a long-term outreach collaboration with scientists and engineers, we developed an outreach program in the field of magnetoelectric sensing that includes an out-of-school project day and various accompanying teaching materials. In this article, we motivate the relevance of the topic for educational outreach, share the rationales, objectives and aims, models and implementation strategies of our program and provide practical advice for those interested in outreach in the field of magnetoelectric sensing. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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19 pages, 8540 KiB  
Article
Magnetoelectric Response of Laminated Cantilevers Comprising a Magnetoactive Elastomer and a Piezoelectric Polymer, in Pulsed Uniform Magnetic Fields
by Gašper Glavan, Inna A. Belyaeva, Kevin Ruwisch, Joachim Wollschläger and Mikhail Shamonin
Sensors 2021, 21(19), 6390; https://0-doi-org.brum.beds.ac.uk/10.3390/s21196390 - 24 Sep 2021
Cited by 13 | Viewed by 2458
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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17 pages, 8862 KiB  
Article
Processing Chain for Localization of Magnetoelectric Sensors in Real Time
by Christin Bald and Gerhard Schmidt
Sensors 2021, 21(16), 5675; https://0-doi-org.brum.beds.ac.uk/10.3390/s21165675 - 23 Aug 2021
Cited by 5 | Viewed by 2400
Abstract
The knowledge of the exact position and orientation of a sensor with respect to a source (distribution) is essential for the correct solution of inverse problems. Especially when measuring with magnetic field sensors, the positions and orientations of the sensors are not always [...] Read more.
The knowledge of the exact position and orientation of a sensor with respect to a source (distribution) is essential for the correct solution of inverse problems. Especially when measuring with magnetic field sensors, the positions and orientations of the sensors are not always fixed during measurements. In this study, we present a processing chain for the localization of magnetic field sensors in real time. This includes preprocessing steps, such as equalizing and matched filtering, an iterative localization approach, and postprocessing steps for smoothing the localization outcomes over time. We show the efficiency of this localization pipeline using an exchange bias magnetoelectric sensor. For the proof of principle, the potential of the proposed algorithm performing the localization in the two-dimensional space is investigated. Nevertheless, the algorithm can be easily extended to the three-dimensional space. Using the proposed pipeline, we achieve average localization errors between 1.12 cm and 6.90 cm in a localization area of size 50cm×50cm. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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27 pages, 5847 KiB  
Article
Phase Noise of SAW Delay Line Magnetic Field Sensors
by Phillip Durdaut, Cai Müller, Anne Kittmann, Viktor Schell, Andreas Bahr, Eckhard Quandt, Reinhard Knöchel, Michael Höft and Jeffrey McCord
Sensors 2021, 21(16), 5631; https://0-doi-org.brum.beds.ac.uk/10.3390/s21165631 - 21 Aug 2021
Cited by 11 | Viewed by 3382
Abstract
Surface acoustic wave (SAW) sensors for the detection of magnetic fields are currently being studied scientifically in many ways, especially since both their sensitivity as well as their detectivity could be significantly improved by the utilization of shear horizontal surface acoustic waves, i.e., [...] Read more.
Surface acoustic wave (SAW) sensors for the detection of magnetic fields are currently being studied scientifically in many ways, especially since both their sensitivity as well as their detectivity could be significantly improved by the utilization of shear horizontal surface acoustic waves, i.e., Love waves, instead of Rayleigh waves. By now, low-frequency limits of detection (LOD) below 100 pT/Hz can be achieved. However, the LOD can only be further improved by gaining a deep understanding of the existing sensor-intrinsic noise sources and their impact on the sensor’s overall performance. This paper reports on a comprehensive study of the inherent noise of SAW delay line magnetic field sensors. In addition to the noise, however, the sensitivity is of importance, since both quantities are equally important for the LOD. Following the necessary explanations of the electrical and magnetic sensor properties, a further focus is on the losses within the sensor, since these are closely linked to the noise. The considered parameters are in particular the ambient magnetic bias field and the input power of the sensor. Depending on the sensor’s operating point, various noise mechanisms contribute to f0 white phase noise, f1 flicker phase noise, and f2 random walk of phase. Flicker phase noise due to magnetic hysteresis losses, i.e. random fluctuations of the magnetization, is usually dominant under typical operating conditions. Noise characteristics are related to the overall magnetic and magnetic domain behavior. Both calculations and measurements show that the LOD cannot be further improved by increasing the sensitivity. Instead, the losses occurring in the magnetic material need to be decreased. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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14 pages, 1514 KiB  
Article
Investigation of Magnetoelectric Sensor Requirements for Deep Brain Stimulation Electrode Localization and Rotational Orientation Detection
by Mevlüt Yalaz, Günther Deuschl, Markus Butz, Alfons Schnitzler, Ann-Kristin Helmers and Michael Höft
Sensors 2021, 21(7), 2527; https://0-doi-org.brum.beds.ac.uk/10.3390/s21072527 - 04 Apr 2021
Cited by 6 | Viewed by 2876
Abstract
Correct position and orientation of a directional deep brain stimulation (DBS) electrode in the patient’s brain must be known to fully exploit its benefit in guiding stimulation programming. Magnetoelectric (ME) sensors can play a critical role here. The aim of this study was [...] Read more.
Correct position and orientation of a directional deep brain stimulation (DBS) electrode in the patient’s brain must be known to fully exploit its benefit in guiding stimulation programming. Magnetoelectric (ME) sensors can play a critical role here. The aim of this study was to determine the minimum required limit of detection (LOD) of a ME sensor that can be used for this application by measuring the magnetic field induced by DBS. For this experiment, a commercial DBS system was integrated into a head phantom and placed inside of a state-of-the-art Superconducting Quantum Interference Device (SQUID)-based magnetoencephalography system. Measurements were performed and analyzed with digital signal processing. Investigations have shown that the minimum required detection limit depends on various factors such as: measurement distance to electrode, bandwidth of magnetic sensor, stimulation amplitude, stimulation pulse width, and measurement duration. For a sensor that detects only a single DBS frequency (stimulation frequency or its harmonics), a LOD of at least 0.04 pT/Hz0.5 is required for 3 mA stimulation amplitude and 60 μμs pulse width. This LOD value increases by an order of magnitude to 0.4 pT/Hz0.5 for a 1 kHz, and by approximately two orders to 3 pT/Hz0.5 for a 10 kHz sensor bandwidth. By averaging, the LOD can be reduced by at least another 2 orders of magnitude with a measurement duration of a few minutes. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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18 pages, 2581 KiB  
Article
Magnetoelastic Coupling and Delta-E Effect in Magnetoelectric Torsion Mode Resonators
by Benjamin Spetzler, Elizaveta V. Golubeva, Ron-Marco Friedrich, Sebastian Zabel, Christine Kirchhof, Dirk Meyners, Jeffrey McCord and Franz Faupel
Sensors 2021, 21(6), 2022; https://0-doi-org.brum.beds.ac.uk/10.3390/s21062022 - 12 Mar 2021
Cited by 16 | Viewed by 2794
Abstract
Magnetoelectric resonators have been studied for the detection of small amplitude and low frequency magnetic fields via the delta-E effect, mainly in fundamental bending or bulk resonance modes. Here, we present an experimental and theoretical investigation of magnetoelectric thin-film cantilevers that can be [...] Read more.
Magnetoelectric resonators have been studied for the detection of small amplitude and low frequency magnetic fields via the delta-E effect, mainly in fundamental bending or bulk resonance modes. Here, we present an experimental and theoretical investigation of magnetoelectric thin-film cantilevers that can be operated in bending modes (BMs) and torsion modes (TMs) as a magnetic field sensor. A magnetoelastic macrospin model is combined with an electromechanical finite element model and a general description of the delta-E effect of all stiffness tensor components Cij is derived. Simulations confirm quantitatively that the delta-E effect of the C66 component has the promising potential of significantly increasing the magnetic sensitivity and the maximum normalized frequency change Δfr. However, the electrical excitation of TMs remains challenging and is found to significantly diminish the gain in sensitivity. Experiments reveal the dependency of the sensitivity and Δfr of TMs on the mode number, which differs fundamentally from BMs and is well explained by our model. Because the contribution of C11 to the TMs increases with the mode number, the first-order TM yields the highest magnetic sensitivity. Overall, general insights are gained for the design of high-sensitivity delta-E effect sensors, as well as for frequency tunable devices based on the delta-E effect. Full article
(This article belongs to the Special Issue Magnetoelectric Sensor Systems and Applications)
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