Search Results (64)

This paper presents a symmetry-driven broadband circularly polarized magnetoelectric dipole antenna with bandpass filtering response, where the principle of symmetry is strategically employed to enhance both radiation and filtering performance. The antenna’s circular polarization is achieved through a symmetrical arrangement of two orthogonally placed metallic ME dipoles combined with a phase delay line, creating balanced current distributions for optimal CP characteristics. The design further incorporates symmetrical parasitic elements—a pair of identical inverted L-shaped metallic structures placed perpendicular to the ground plane at −45° relative to the ME dipoles—which introduce an additional CP resonance through their mirror-symmetric configuration, thereby significantly broadening the axial ratio bandwidth. The filtering functionality is realized through a combination of symmetrical modifications: grid slots etched in the metallic ground plane and an open-circuited stub loaded on the microstrip feed line work in tandem to create two radiation nulls in the upper stopband, while the inherent symmetrical properties of the ME dipoles naturally produce a radiation null in the lower stopband. This comprehensive symmetry-based approach results in a well-balanced bandpass filtering response across a wide operating bandwidth. Experimental validation through prototype measurement confirms the effectiveness of the symmetric design with compact dimensions of 0.96${\lambda }_0$ × 0.55${\lambda }_0$ × 0.17${\lambda }_0$ (${\lambda }_0$ is the wavelength at the lowest operating frequency), demonstrating an impedance bandwidth of 66.4% (2.87–5.05 GHz), an AR bandwidth of 31.9% (3.32–4.58 GHz), an average passband gain of 5.5 dBi, and out-of-band suppression levels of 11.5 dB and 26.8 dB at the lower and upper stopbands, respectively, along with good filtering performance characterized by a gain-suppression index (GSI) of 0.93 and radiation skirt index (RSI) of 0.58. The proposed antenna is suitable for satellite communication terminals requiring wide AR bandwidth and strong interference rejection in L/S-bands. Full article

This study presents the fabrication and characterization of hybrid magneto-responsive composites (hMRCs), composed of recyclable components: magnetite microparticles (MMPs) as fillers, lard as a natural binding matrix, and cotton fabric for structural reinforcement. MMPs are obtained by in-house plasma-synthesis, a sustainable, efficient, and highly tunable method for producing high-performance MMPs. hMRCs are integrated into flat capacitors, and their electrical capacitance (C), resistance (R), dielectric permittivity (${ϵ}^{\prime }$), and electrical conductivity ($\sigma$) are investigated under a static magnetic field, uniform force field, and an alternating electric field. The experimental results reveal that the electrical properties of hMRCs are dependent on the volume fractions of MMPs and microfibers in the fabric, as well as the applied magnetic flux density (B) and compression forces (F). C shows an increase with both B and F, while R decreases due to improved conductive pathways formed by alignment of MMPs. $\sigma$ is found to be highly tunable, with increases of up to 300% under combined field effects. In the same conditions, C increases up to 75%, and R decreases up to 80%. Thus, by employing plasma-synthesized MMPs, and commercially available recyclable lard and cotton fabrics, this study demonstrates an eco-friendly, low-cost approach to designing multifunctional smart materials. The tunable electrical properties of hMRCs open new possibilities for adaptive sensors, energy storage devices, and magnetoelectric transducers. Full article

Two-layered structures consisting of piezopolymer and magnetic elastomer were investigated as magnetoelectric material. Three types of magnetic elastomer based on cobalt ferrite (CoFe₂O₄) and Ni- or Zn-substituted CoFe₂O₄ nanoparticles were used as magnetically sensitive layers. Cobalt ferrite nanoparticles are considered one of the most promising metal-oxide nanomaterials because of their favorable magnetic properties, such as high saturation magnetization and magnetic anisotropy. The substitution of Co²⁺ in cobalt ferrite with other transition metals allows for additional tailoring of these properties. The modified magnetic behavior of the substituted CoFe₂O₄ nanoparticles directly influenced the magnetic properties of magnetic elastomers and, consequently, the magnetoelectric response of composite structures. In this case, the resonant frequency of the magnetoelectric effect remained largely independent of the type of magnetic nanoparticles in the magnetic elastomer layer but its magnitude increased upon Zn substitution up to ~107 mV·cm⁻¹·Oe⁻¹. These findings highlight the potential of chemically engineered magnetic properties of CoFe₂O₄ nanoparticles for manufacturing magnetoelectric composites to expand their applications in energy harvesting and sensors. Full article

In this work, a tachometer based on a Metglas/PZT/Metglas magnetoelectric (ME) composite was developed to achieve high-precision rotational speed measurement over a wide temperature range (−70 °C to 160 °C). The tachometer converts external magnetic signals into electrical signals through the ME effect and operates stably in extreme temperature environments. COMSOL Multiphysics software was used for simulation analysis to investigate the ME response characteristics of the composite in such environments. To evaluate the properties of the ME composite under different conditions, its response characteristics at various frequencies, DC bias, and temperatures were systematically investigated. A permanent magnet and a DC motor were used to simulate gear rotation, and the voltage output was analyzed by adjusting the position between the sensor and the DC motor. The results show that the measured values of the ME tachometer closely match the set values, and the tachometer demonstrates high measurement accuracy within the range of 480 to 1260 revolutions per minute (rpm). Additionally, the properties of the ME composite at different temperatures were examined. In the temperature range from −70 °C to 160 °C, the ME coefficients exhibit good regularity and stability, with the measured trend closely matching the simulation results, ensuring the reliability and accuracy of the ME tachometer. To verify its practicality, the measurement capability of the ME tachometer was comprehensively tested under extreme temperature conditions. The results show that in high-temperature environments, the tachometer can accurately measure speed while maintaining a high signal-to-noise ratio (SNR), demonstrating excellent anti-interference ability. The proposed ME tachometer shows promising application potential in extreme temperature conditions, particularly in complex industrial environments that require high reliability and precision. Full article

Dental inflammatory diseases remain a challenging clinical issue, whose causes and development are still not fully understood. During dental caries, bacteria penetrate the tooth pulp, causing pulpitis. To prevent pulp necrosis, it is crucial to promote tissue repair by recruiting immune cells, such as macrophages, able to secrete signal molecules for the pulp microenvironment and thus to recruit dental pulp stem cells (DPSCs) in the damaged site. To date, root canal therapy is the standard for dental caries, but alternative regenerative treatments are gaining attention. Complex Multifrequency Magnetoelectric Fields (CMFs) represent an interesting tool due to their potential anti-inflammatory activity. Against this background, the present work aims at investigating whether the CMF treatment might restore redox balance in a co-culture model of DPSCs and inflamed macrophages mimicking an inflammatory condition, like pulpitis. Results show that superoxide anion levels and markers related to the polarization of macrophages are modulated by the CMF treatment. In parallel, the use of CMFs discloses an impact on the odontogenic commitment of DPSCs, their immunophenotype being considerably modified. In conclusion, CMFs, by modulating the odontogenic commitment and the anti-inflammatory response of DPSCs, might represent a suitable therapeutic tool against pulpitis and, in general, towards dental inflammatory diseases. Full article

This study introduces an innovative energy harvesting system designed for industrial applications such as fluid pipelines, air conditioning ducts, sewer systems, and subsea oil pipelines. The system integrates magneto-electric flow coupling and utilizes a dynamic vibration absorber (DVA) to mitigate the vibrations induced by fluid flow while simultaneously harvesting energy through magnetic dipole–dipole interactions in a vibration energy harvester (VEH). The theoretical models, based on Hamilton’s Principle and the Biot–Savart Law, were validated through comprehensive experiments. The results indicate the superior performance of the small-magnet system over the large-magnet system in both damping and power generation. The study analyzed the frequency response and energy conversion efficiency across different parameters, including the DVA mass, spring constant, and placement location. The experimental findings demonstrated significant vibration reduction and increased voltage output, validating the theoretical model. This research offers new avenues for energy harvesting systems in pipeline infrastructures, potentially enhancing energy efficiency and structural integrity. Full article

The magnetoelectric (ME) antennas rely on the mechanical movement of magnetic dipoles, making it possible to break the constraints on physical dimensions decided by the wavelength of the electromagnetic wavelength. The ME antennas achieve super-low frequency (SLF) communications with a smaller size to provide a novel solution for long-range, underwater, and underground communications; navigation over the horizon; and geological exploring. As a result, further theoretical research and optimization of ME antennas have been an open challenge for decades. Here, we report on minitype arrays of acoustically actuated ME antenna and their more rigorous equivalent circuits. These arrays of ME antenna adjust amplitude-frequency response through the mechanical regulation method. The mechanical parameters of ME antennas in the arrays result in regulating amplitude-frequency response, such as working frequency, fractional bandwidth, and intensity of magnetic induction. Our work provides a more accurate theoretical model and diverse array form over state-of-the-art ME antenna arrays. The frequency, fractional bandwidth, and magnetic induction strength of the ME antenna arrays were achieved to be adjustable in the ranges of 84 to 181 Hz, 3.9% to 8.3%, and two to four times, respectively. In addition, we have calculated the attenuation characteristics of ME antennas and their minitype arrays in seawater. The results show that the ME antenna array described in this manuscript is able to enhance the radiation intensity and information-loading capability, which has a positive potential for application in SLF communication systems. Full article

For the application of high-frequency current detection in power systems, such as very fast transient current, lightning current, partial discharge pulse current, etc., current sensors with a quick response are indispensable. Here, we propose a high-frequency magnetoelectric current sensor, which consists of a PZT piezoelectric ceramic and Metglas amorphous alloy. The proposed sensor is designed to work under d₁₅ thickness-shear mode, with the resonant frequency around 1.029 MHz. Furthermore, the proposed sensor is fabricated as a high-frequency magnetoelectric current sensor. A comparative experiment is carried out between the tunnel magnetoresistance sensor and the magnetoelectric sensor, in the aspect of high-frequency current detection up to 3 MHz. Our experimental results demonstrate that the d₁₅ thickness-shear mode magnetoelectric sensor has great potential for high-frequency current detection in smart grids. Full article

Based on the proposed microscopic model, we investigate the multiferroic characteristics of VOX₂ (X = Cl, Br, I) monolayers using a Green’s function method. The dependence of the microscopic parameters of the ferroelectric system (pseudo-spin arrangement and flipping rate) on the magnitude and sign of the exchange magnetic interaction along the b-axis and the value of the Dzyaloshinskii–Moria vector have been investigated and qualitatively explained. The possibility of observing a spin-reorientation transition with a change in the character of spin ordering from antiferromagnetic to ferromagnetic is investigated. It is found that the antisymmetric magnetoelectric interaction may be responsible for the spin-reorientation transition without a change in the ordering of magnetic moments. Changing the sign of the exchange magnetic interaction along the b-axis leads to ferromagnetic ordering without observing a spin-reorientation transition. The dependence of isotropic and antisymmetric magnetic interactions on the microscopic parameters of the ferroelectric system is qualitatively explained. A mechanism for the occurrence of the spin-reorientation transition is presented based on the proposed microscopic model. The obtained results qualitatively coincide with Density Functional Theory calculations. Full article

Magnetoelectric (ME) magnetic field sensors are novel sensing devices of great interest in the field of biomagnetic measurements. We investigate the influence of magnetic crosstalk and the linearity of the response of ME sensors in different array and excitation configurations. To achieve this aim, we introduce a combined multiscale 3D finite-element method (FEM) model consisting of an array of 15 ME sensors and an MRI-based human head model with three approximated compartments of biological tissues for skin, skull, and white matter. A linearized material model at the small-signal working point is assumed. We apply homogeneous magnetic fields and perform inhomogeneous magnetic field excitation for the ME sensors by placing an electric point dipole source inside the head. Our findings indicate significant magnetic crosstalk between adjacent sensors leading down to a 15.6% lower magnetic response at a close distance of 5 mm and an increasing sensor response with diminishing crosstalk effects at increasing distances up to 5 cm. The outermost sensors in the array exhibit significantly less crosstalk than the sensors located in the center of the array, and the vertically adjacent sensors exhibit a stronger crosstalk effect than the horizontally adjacent ones. Furthermore, we calculate the ratio between the electric and magnetic sensor responses as the sensitivity value and find near-constant sensitivities for each sensor, confirming a linear relationship despite magnetic crosstalk and the potential to simulate excitation sources and sensor responses independently. Full article

A mesoscopic model for a polymer-based magnetoelectric (ME) composite film is developed. The film is assumed to consist of a piezoelectric polymer matrix of the PVDF type filled with CFO-like single-domain nanoparticles. The model is treated numerically and enables one to obtain in detail the intrinsic distributions of mechanical stress, polarization and electric potential and helps to understand the influence of the main configurational parameters, viz., the poling direction and the orientational order of the particle magnetic anisotropy axes on the electric response of the film. As the model is fairly simple—it uses the RVE-like (Representative Volume Element) approach with a single-particle cell—the results obtained are rather of qualitative than quantitative nature. However, the general conclusions seem to be independent of the particularities of the model. Namely, the presented results establish that the customary ME effect in composite films always comprises at least two contributions of different origins, viz., the magnetostrictive and the magnetoactive (magnetorotational) ones. The relative proportion between those contributions is quite movable depending on the striction coefficient of the particles and the stiffness of the polymer matrix. This points out the necessity to explicitly take into account the magnetoactive contribution when modeling the ME response of composite films and when interpreting the measurements on those objects. Full article

Recently, magnetoelectric (ME) antennas have become a hot topic in the field of antenna miniaturization in the very-low-frequency (VLF) band because their size can be reduced to one-ten-thousandth of the size of conventional electric antennas. However, they still suffer from narrow transmission/reception bandwidth and weak radiation intensity. To address these issues, VLF thin-film ME antennas with a microbridge structure are designed, and the method of array connection is used. Test results show that the detection limit of the ME antenna unit is 636 pT/√Hz at 23 kHz and the radiant magnetic field intensity at 0.12 m is 0.87 nT (input power of 10 mW). By series-connecting three ME antenna units with the same resonance frequency, the output response has been increased to 1.72 times and the EM wave radiation intensity is increased to 1.9 times compared to a single unit. By parallel-connecting two ME antenna units with different resonance frequencies, the output response bandwidth has been expanded to 1.56 times compared to a single unit, and the signal radiation bandwidth has been expanded to 1.47 times. This work provides a valuable reference for the future larger-scale arraying of ME antennas. Full article

Magnetoelectric (ME) magnetic field sensors utilize ME effects in ferroelectric ferromagnetic layered heterostructures to convert magnetic signals into electrical signals. However, the substrate clamping effect greatly limits the design and fabrication of ME composites with high ME coefficients. To reduce the clamping effect and improve the ME response, a flexible ME sensor based on PbZr_0.2Ti_0.8O₃ (PZT)/CoFe₂O₄ (CFO) ME bilayered heterostructure was deposited on mica substrates via van der Waals oxide heteroepitaxy. A saturated magnetization of 114.5 emu/cm³ was observed in the bilayers. The flexible sensor exhibited a strong ME coefficient of 6.12 V/cm·Oe. The local ME coupling has been confirmed by the evolution of the ferroelectric domain under applied magnetic fields. The flexible ME sensor possessed a stable response with high sensitivity to both AC and DC weak magnetic fields. A high linearity of 0.9988 and sensitivity of 72.65 mV/Oe of the ME sensor were obtained under flat states. The ME output and limit-of-detection under different bending states showed an inferior trend as the bending radius increased. A flexible proximity sensor has been demonstrated, indicating a promising avenue for wearable device applications and significantly broadening the potential application of the flexible ME magnetic field sensors. Full article

Recently, the realization of electromagnetic wave signal transmission and reception has been achieved through the utilization of the magnetoelectric effect, enabling the development of compact and portable low-frequency communication systems. In this paper, we present a miniaturized low-frequency communication system including a transmitter device and a receiver device, which operates at a frequency of 44.75 kHz, and the bandwidth is 1.1 kHz. The transmitter device employs a Terfenol-D (80 mm × 10 mm × 0.2 mm)/PZT (30 mm × 10 mm × 0.2 mm)/Terfenol-D glued composite heterojunction magnetoelectric antenna and the strongest radiation in the length direction, while the receiver device utilizes a manually crafted coil maximum size of 82 mm, yielding a minimum induced electromagnetic field of 1 pT at 44.75 kHz. With an input voltage of 150 V, the system effectively communicates over a distance of 16 m in air and achieves reception of electromagnetic wave signals within 1 m in simulated seawater with a salinity level of 35% at 25 °C. The miniaturized low-frequency communication system possesses wireless transmission capabilities, a compact size, and a rapid response, rendering it suitable for applications in mining communication, underwater communication, underwater wireless energy transmission, and underwater wireless sensor networks. Full article

The new xMnAs/(1 − x)PMN–PT (x = 0.2, 0.3) multicaloric composites, consisting of the modified PMN–PT-based relaxor-type ferroelectric ceramics and ferromagnetic compound of MnAs were fabricated, and their structure, magnetic, dielectric properties, and caloric effects were studied. Both components of the multicaloric composite have phase transition temperatures around 315 K, and large electrocaloric (~0.27 K at 20 kV/cm) and magnetocaloric (~13 K at 5 T) effects around this temperature were observed. As expected, composite samples exhibit a decrease in magnetocaloric effect (<1.4 K at 4 T) in comparison with an initial MnAs magnetic component (6.7 K at 4 T), but some interesting phenomena associated with magnetoelectric interaction between ferromagnetic and ferroelectric components were observed. Thus, a composite with x = 0.2 exhibits a double maximum in isothermal magnetic entropy changes, while a composite with x = 0.3 demonstrates behavior more similar to MnAs. Based on the results of experiments, the model of the multicaloric effect in an MnAs/PMN–PT composite was developed and different scenario observations of multicaloric response were modeled. In the framework of the proposed model, it was shown that boosting of caloric effect could be achieved by (1) compilation of ferromagnetic and ferroelectric components with large caloric effects in selected mass ratio and phase transition temperature; and (2) choosing of magnetic and electric field coapplying protocol. The 0.3MnAs/0.7PMN–PT composite was concluded to be the optimal multicaloric composite and a phase shift ∆φ = −π/4 between applied manetic fields can provide a synergetic caloric effect at a working point of 316 K. Full article