Search Results (5)

In hybrid active–passive magnetic shielding systems, active compensation coils are used to suppress residual magnetic fields inside the shield. However, due to the intrinsic hysteresis of high-permeability materials, the compensation fields inevitably magnetize the passive layers. This process introduces new and unpredictable remanent magnetization, paradoxically worsening the remanence stability during active compensation. This study systematically investigates and quantifies how the number of passive shielding layers affects remanence instability. A combined approach of theoretical analysis, finite-element simulations, and experimental validation is employed. The results reveal a key counter-intuitive finding: although adding more shielding layers enhances the static attenuation of external fields, it markedly amplifies the remanence instability induced by active compensation. Specifically, multi-layer shields exhibit larger remanence changes under identical compensation-field excitations. This finding reveals a previously overlooked performance trade-off and provides new design insights for ultra-high-precision shielding systems. These findings provide essential guidance for optimizing the design and operation of next-generation ultra-high-precision magnetic shielding devices and their applications in frontier areas such as fundamental physics and biomedicine. Full article

Josephson junctions (JJs) are superconductor-based devices used to build highly sensitive magnetic flux sensors called superconducting quantum interference devices (SQUIDs). These sensors may vary in design, being the radio frequency (RF) SQUID, direct current (DC) SQUID, and hybrid, such as D-SQUID. In addition, recently many of JJ’s applications were found in spiking models of neurons exhibiting nearly biological behavior. In this study, we propose and investigate a new circuit model of a sensory neuron based on DC SQUID as part of the circuit. The dependence of the dynamics of the designed model on the external magnetic flux is demonstrated. The design of the circuit and derivation of the corresponding differential equations that describe the dynamics of the system are given. Numerical simulation is used for experimental evaluation. The experimental results confirm the applicability and good performance of the proposed magnetic-flux-sensitive neuron concept: the considered device can encode the magnetic flux in the form of neuronal dynamics with the linear section. Furthermore, some complex behavior was discovered in the model, namely the intermittent chaotic spiking and plateau bursting. The proposed design can be efficiently applied to developing the interfaces between circuitry and spiking neural networks. However, it should be noted that the proposed neuron design shares the main limitation of all the superconductor-based technologies, i.e., the need for a cryogenic and shielding system. Full article

The development of new advanced functionalities, miniaturization, and the aim of obtaining optimized performance in electronic devices significantly impacts their electromagnetic compatibility (EMC). As electronic components become more densely packed on a printed circuit board (PCB), unintended coupling between components can cause electromagnetic interference (EMI). These requirements result in design restrictions that make using a board level shield (BLS) essential in reducing intra-system EMI in PCB designs. This contribution focuses on studying and characterizing a BLS solution based on combining a noise suppression sheet (NSS) with an aluminum layer to reduce intra-system EMI coupling. This hybrid solution has the advantage of providing a shielding option that does not require any electronic redesign. It does not need a footprint or a ground connection as it can be affixed over the EMI source. The solution is expected to provide higher attenuation levels than using only an NSS by combining the absorbing properties of the magnetic material and the loss mechanism of the metal. In order to verify the effectiveness of the hybrid BLS proposed solution, the magnetic near-field emissions of an EMI source are analyzed in this study. The experimental measurements and simulated results demonstrate a significant increase (51.6 dB at 1 GHz) in the shielding effectiveness (SE) provided by the proposed solution compared to a conventional NSS. Full article

A unique self-standing membrane composed of hierarchical thermoplastic polyurethane (TPU)/polyacrylonitrile (PAN) fibers is prepared by the electrospinning technique, followed by a simple dip-coating process. Fe₃O₄ nanoparticles are uniformly anchored on TPU/PAN fibers during the electrospinning process, enabling the membrane to achieve effective electromagnetic interference shielding (EMI SE) performance. Such a hybrid membrane has a high magnetization of 18.9 emu/g. When MXene (Ti₃C₂T_x) layers are further loaded on the TPU/PAN/Fe₃O₄NPs hybrid membrane, its EMI SE performance in the X band can exceed 30 dB due to the hydrogen bonds generated between the macromolecular chain of PAN and the functional group (T_x) on the surface of MXene. Simultaneously, the interfacial attraction between MXene and the TPU/PAN/Fe₃O₄NPs substrate is enhanced. The EMI SE mechanism of the hybrid membrane indicates that this film has great potential in the fields of wearable devices and flexible materials. Full article

We fabricate hybrid magnetoactive materials (hMAMs) based on cotton fibers, silicone oil, carbonyl iron and graphene nanoplatelets (nGr) at various mass concentrations ${\mathsf{\Phi }}_{\mathrm{nGr}}$. The obtained materials are used as dielectric materials for manufacturing plane electrical capacitors. The equivalent electrical capacitance $C_p$ and resistance $R_p$ are measured in an electric field of medium frequency f, without and respectively with a magnetic field of magnetic flux density B in the range from 0.1 T up to 0.5 T. The results are used to extract the components ${ϵ}_r^{\prime }$ and ${ϵ}_r^{″}$ of the complex relative permittivity ${ϵ}_r^{*}$, and to reveal the magnitude of the induced magnetoelectric couplings $k_x$ and magnetodielectric effects $MDE$. It is shown that ${ϵ}_r^{\prime }$, ${ϵ}_r^{″}$, $k_x$ and MDE are significantly influenced by $f,B$ and ${\mathsf{\Phi }}_{\mathrm{nGr}}$. We describe the underlying physical mechanisms in the framework of dipolar approximation and using elements of dielectric theory. The tunable magnetoelectric and magnetodielectric properties of hMAMs are useful for manufacturing electrical devices for electromagnetic shielding of living organisms. Full article