Electromagnetic Interference Research Articles

Multifactor evaluation method of smart meter

As an important terminal of smart grid, smart meter has the functions of equipment health monitoring and power metering. However, it is difficult to quantify the impact of factors such as ex-factory parameters, historical failure rates, electromagnetic interference when conducting an operational condition assessment. Therefore, in view of the large number of influencing factors and the difficulty in quantifying the degree of influence, an improved multifactor evaluation model for the operating status of smart meters is constructed. Firstly, a multifactor index system for evaluating the operating state of smart meters is constructed by analyzing the working mechanism and operating characteristics of smart meters. Then, an improved combinatorial weighting method is proposed by combining the subjective weight and the objective weight. The combinatorial weighting method is used to estimate the weight of factors in the health status evaluation of smart meters, and the improved multifactor evaluation method is presented to evaluate the health status of smart meters. Finally, an example is given to verify and analyze the proposed method. Compared with the other three methods, this method can provide effective evaluation results, and help guide targeted maintenance or replacement to improve the efficiency of smart meter detection.

Impact of Data Corruption and Operating Temperature on Performance of Model-Based SoC Estimation

Electric vehicles (EVs) are becoming popular around the world. Making a lithium battery (LIB) pack with a robust battery management system (BMS) for an EV to operate under different complex environments is both a challenge and a requirement for engineers. A BMS can intelligently manage LIB systems by estimating the battery state of charge (SoC). Due to the nonlinear characteristics of LIB, influenced by factors such as the harsh environment and data corruption caused by electromagnetic interference (EMI) inside electric vehicles, SoC estimation should consider available capacity, model parameters, operating temperature and reductions in data sampling time. The widely used model-based algorithms, such as the extended Kalman filter (EKF) have limitations. Therefore, a detailed review of the balance between temperature, data sampling time, and different model-based algorithms is necessary. Firstly, a state of charge—open-circuit voltage (SoC-OCV) curve of LIB is obtained by the polynomial curve fitting (PCF) method. Secondly, a first-order RC (1-RC) equivalent circuit model (ECM) is applied to identify the battery parameters using a forgetting factor-based recursive least squares algorithm (FF-RLS), ensuring accurate internal battery parameters for the next step of SoC estimation. Thirdly, different model-based algorithms are utilized to estimate the SoC of LIB under various operating temperatures and data sampling times. Finally, the experimental data by dynamic stress test (DST) is collected at temperatures of 10 °C, 25 °C, and 40 °C, respectively, to verify and analyze the impact of operating temperature and data sampling time to provide a practical reference for the SoC estimation.

All Inorganic Scintillating Fiber for Thermal Neutron Detection

AbstractThermal neutron detection with scintillating fibers has excellent scientific and technological potential for remote and spatially resolved detection. However, most fibers are polymers, and developing all‐inorganic scintillating fibers remains a significant challenge. Herein, all‐inorganic scintillating fibers and prototype neutron detection devices are successfully constructed for neutron detection. The scintillating fibers with a perfect waveguide configuration and tunable size have been fabricated through the melt‐in‐tube method. The interactions between the thermal neutron and scintillating fiber have been theoretically analyzed. The dependence of the neutron absorption ability on the core diameter, cladding thickness, and 6Li abundance has been investigated. Guided by the above experimental and theoretical results, the configuration of the scintillating fiber and the corresponding neutron detection prototype device has been built. Its practical application for neutron detection has been demonstrated, and importantly, the single thermal neutron event can be successfully monitored. The device shows great promise for neutron detection applications in special scenarios such as tiny space and electromagnetic interference environments.

A super-stretchable conductive film with strain-insensitive conductivity for stretchable EMI shielding materials and wearable capacitive strain sensors

Strain-insensitive conductive films as stretchable electromagnetic interference (EMI) shielding materials and stretchable electrodes are highly desired in wearable electronics. However, fabricating super strain-insensitive conductive films under a tensile strain higher than 400 % is still a great challenge. Herein, a super-stretchable conductive film based on the crumple-structured Ti3C2Tx nanosheets-single walled carbon nanotubes/stretchable substrate double-layers is designed for the stretchable EMI shielding materials and electrodes. The resulting film exhibits a strain-insensitive electrical conductivity as high as 3.01 × 103 S/m even at a strain up to 500 %, which endows the film with a high and stable electromagnetic interference shielding efficiency (EMI SE) value of ∼45 dB. More interestingly, the EMI SE value of the film remains nearly constant even after 2000 cycles of 500 % tensile strain, indicating the excellent long-term service stability as a stretchable EMI shielding material. Moreover, a capacitive strain sensor with extra-wide sensing range, ultra-high stability, and excellent durability is successfully achieved by employing the as-prepared films as stretchable electrodes. This work proposes a convenient strategy of strain-insensitive conductive film aiming to design stretchable EMI shielding materials and electrodes for wearable electronics.

Optimization of Construction of the Balance Mechanism Axial Superconducting Antenna: Research of Methods Stabilizing the Degree of its Balance

Introduction. There are three main means of supression of electromagnetic interference that can reveal at the operation of SQUID magnetometers – spatial and frequency signal selection and digital processing. The spatial signal selection is the most effective means that allows to significantly improve the signal/interference ratio directly in the receiving superconducting antenna. To optimize the design of the balancing system of the receiving gradiometric antenna is an important task in the conditions of existence of high electromagnetic interference in the contemporary city. The purpose of the work is to justify and develop a new design of the balancing mechanism of superconducting gradiometric antenna of the SQUID magnetometer for operation in conditions of a high level electromagnetic interference. To develop an algorithm for balancing the antenna of such a SQUID magnetometer. Results. The paper considers the main implementations of gradiometric antennas and their balancing methods. As the main factor affecting the normal operation of the balancing system of the gradiometric antenna of the SQUID magnetometer over a long period of time (the time between refueling the cryostat with liquid helium), the decrease in the level of liquid helium in the cryostat was emphasized. Such a decrease in level leads to the deformation of individual elements of the balancing system. As an counteraction to this, it is proposed to place the mechanism for moving the gradiometer balancing elements directly in the antenna housing. In it the all parts of the mechanism are located below the level of liquid helium during the entire time the magnetometer is operating. The analysis of the resistance to temperature and mechanical effects of individual elements of the balancing system was carried out. The approach to choosing the optimal size of the balancing element is substantiated, this size influences at the degree of the balance of antenna. The output of the magnetometer on the field of Helmholtz coils during the movement of balancing elements of different sizes along the axis of the axial gradiometer was obtained experimentally. Experimental results were obtained for a superconducting antenna – the second-order gradiometer, with a diameter of 20 mm and base of 60 mm. Conclusions. The approach proposed by the authors to increase the efficiency of electromagnetic interference filtering with the help of superconducting gradiometric antennas made it possible to develop a new design of their balancing mechanism. Its advantage is the resistance to mechanical stresses of individual elements of the system, which arises as a result of the existence of significant temperature gradients during the evaporation of liquid helium. The proposed algorithm for balancing of the superconducting gradiometer can be applied to balance superconducting gradiometric antennas of any configuration and size. Keywords: superconductivity, SQUID-magnetometer, antenna balance, optimization.

Practical twin-field quantum key distribution parameter optimization based on quantum annealing algorithm

Abstract Twin-field quantum key distribution (TF-QKD) is widely studied since it can surpass the key capacity of repeaterless QKD, whereas electromagnetic interference (EMI) is one of the main challenges in its practical applications. This study is based on the Faraday–Michelson TF-QKD. Analyze the effect of EMI on the rotation angle of the Faraday mirror causing an additional quantum bit error rate (QBER). Moreover, the quantum annealing algorithm (QA) based on quantum tunneling mechanism is applied to the optimization of practical TF-QKD. Mapping the secure key rate of TF-QKD into the evaluation function of QA and the transverse magnetic field is introduced to construct the kinetic energy term, which can realize the quantum tunneling effect. Meanwhile, the QA is improved in terms of chaotic optimization to obtain the dynamic initial value of the algorithm, the design of a perturbation method to skip the locally optimal solution, and the use of suitable temperature and magnetic field decay functions. Optimizing TF-QKD with QA, the standard deviation of QBER fluctuation caused by EMI is reduced to 0.206, the mean square error of the signal-state pulse intensity is only 3.38 × 10 − 4 , and the optimization accuracy of the secure key rate can reach 99.8 % . Additionally, this optimization method shortens the runtime and reduces computational resource consumption, making it highly efficient for practical implementations.

Ultra-Wideband Common-Mode Rejection Structure with Autonomous Phase Balancing for Ultra-High-Speed Digital Transmission.

For ultra-high-speed digital transmission, required by 5G/6G communications, ultra-wideband common-mode rejection (CMR) structures with autonomous phase-balancing capability are proposed. Common-mode noise, caused by phase and amplitude unbalances, is one of the most undesired disturbances affecting modern digital circuits. According to the circuit design guides with a typically used differential line (DL) for high-speed digital transmission, common-mode rejection is achieved using CMR filters, and the unbalanced phase, caused by a length difference between the two signal lines of a DL, is compensated by inserting an additional delay line. However, due to nonlinear phase interactions between the two DLs and unbalanced electromagnetic (EM) interferences, the conventional compensation method is frequency-limited at around 10 GHz. To significantly enhance the common-mode rejection level and extend the phase recovery bandwidth, the proposed CMR structure utilizes a planar balanced line (BL), such as a coplanar stripline (CPS) or a parallel stripline (PSL), along with additional conductor strips arranged laterally near the BL. To demonstrate the performance of the proposed BL-based CMR structures, various types of CMR structures are fabricated, and the measurement results are compared with the 3D EM simulation results. As a result, it is proven that the proposed BL-based CMR structures have the capability to reject the common-mode noise with suppression levels of more than 10 dB and to simultaneously recover the phase balance from near DC to over 40 GHz.

Study on the weakening of stator cogging torque of modular motors by gap offsets

Two schemes have been developed to reduce the cogging torque generated by the gap between the stator modules of the modular permanent magnet synchronous motor. These schemes involve shifting the gap position to change the phase of the cogging torque, thereby eliminating some of its components and reducing its magnitude. Finite element simulation was used to verify the cogging torque of E and C type modular motors using two different schemes. The effect of the offset gap on electromagnetic performance and motor vibration noise was also analysed. The results indicate that both schemes weaken the cogging torque without significantly affecting the electromagnetic performance of the motor or increasing vibration noise.

Structural, Morphology and Electromagnetic Interference Shielding Studies of Multifunctional Hybrids of Low-Density Polyethene with Graphene, Carbon Nanotube and Magnetite

ABSTRACT In this study, we investigate the EMI SE (Electromagnetic interference shielding effectiveness) of novel multifunctional polymer hybrids in the X-band and Ku-band frequencies. Magnetite nanoparticles were synthesized via wet chemical reduction and nanographene was synthesized through chemical exfoliation combined with microwave treatment. Nine different composites were prepared with varying weight ratios of graphene and magnetite. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed their structural and morphological properties. SEM analysis revealed magnetite particle sizes ranging from 10.05 nm to 29.8 nm. Vibrating Sample Magnetometer (VSM) analysis indicated that the magnetite nanoparticles exhibit super paramagnetic behavior with a magnetic anisotropy constant (K) of approximately 63.9375 × 106 J/m3. Impedance analysis, permittivity and permeability measurements showed frequency-dependent behaviors, with interfacial polarization effects due to magnetite agglomeration. The highest conductivity, observed in the 50:5:37.5:7.5 hybrid, peaked at 8 S/cm at lower frequencies. The 50:5:37.5:7.5 hybrid demonstrated the highest EMI SE of 50.08 dB (99.999019% suppression) in the X-band, which is suitable for advanced EMI-shielding applications.

Wireless optically pumped magnetometer MEG

The current magnetoencephalography (MEG) systems, which rely on cables for control and signal transmission, do not fully realize the potential of wearable optically pumped magnetometers (OPM). This study presents a significant advancement in wireless OPM-MEG by reducing magnetization in the electronics and developing a tailored wireless communication protocol. Our protocol effectively eliminates electromagnetic interference, particularly in the critical frequency bands of MEG signals, and accurately synchronizes the acquisition and stimulation channels with the host computer's clock. We have successfully achieved single-channel wireless OPM-MEG measurement and demonstrated its reliability by replicating three well-established experiments: The alpha rhythm, auditory evoked field, and steady-state visual evoked field in the human brain. Our prototype wireless OPM-MEG system not only streamlines the measurement process but also represents a major step forward in the development of wearable OPM-MEG applications in both neuroscience and clinical research.

Multi-dimensional, multi-interface Fe3C/carbon sheets/carbon tubes nanoarchitecture towards high-performance microwave absorption

The serious problem of electromagnetic (EM) interference brings growing demand for developing high-performance electromagnetic shielding materials. In this study, three-dimensional (3D) Fe3C/carbon/carbon tubes (Fe3C/C/CT) absorber with multi-heterointerface was prepared by a facile self-propagating followed by chemical vapor deposition (CVD) strategy. Initially, Fe3O4 nanoparticles were anchored onto carbon nanosheets through the self-propagating process. After different etching times with diluted acid, CTs with diverse dimensions and quantities were catalyzed by the modified Fe3O4 catalysts during the CVD approach and grown from the carbon sheets. Such a special nanoarchitecture, which consists of carbon sheets and carbon tubes, acts as the source of dielectric loss. Meanwhile, Fe3C nanoparticles provide magnetic loss, and the abundant interfaces facilitate synergistic electromagnetic loss. Moreover, large numbers of heterointerfaces from the unique multidimensional nanoarchitecture significantly enhance the impedance matching and produce abundant dipole polarization. Ultimately, with etching time of 30 min, the Fe3C/C/CT-30 achieves excellent electromagnetic wave (EMW) absorption property with a minimum reflection loss of −46.4 dB at 10.56 GHz with a thickness of 3.0 mm. When the thickness is 3.57 mm, the effective absorption bandwidth (EAB) can extend up to 4.48 GHz. Moreover, the practical application of the absorbers was evaluated using radar cross-section (RCS) simulation, indicating that Fe3C/C/CT-30 achieves a maximum RCS reduction value of 58 dBm2. The multi-dimensional and multi-heterointerface absorber presented in this work might offer valuable insights for optimizing electromagnetic absorbers.

Enhanced Oxidation‐Resistant and Conductivity in MXene Films with Seamless Heterostructure

AbstractMXene‐based films have garnered significant attention for their remarkable electrical and mechanical properties. Nevertheless, the practical application of MXene is impeded by its intrinsic instability caused by spontaneous oxidation. The traditional anti‐oxidative strategies frequently lead to a compromise in stability, electrical conductivity, and mechanical properties. In this study, a novel approach is proposed involving metal nano‐armoring, wherein a copper layer with nano thickness is deposited onto MXene film surfaces to establish a uniform and seamless heterogeneous interface (MXene@Cu). The precise tunability and uniformity of this heterostructure are consistently demonstrated through both theoretical calculations and experimental results. The MXene@Cu films exhibit exceptional electrical conductivity of 1.17 × 106 S m−1, electromagnetic interference shielding effectiveness of 77.1 dB, and tensile strength of 43.4 MPa. More importantly, this heterostructure significantly improves MXene's stability against oxidation. After exposure to air for 30 days, the resultant MXene@Cu films exhibit a remarkable conductivity retention of 72.0%, significantly exceeding that of pristine MXene films (44.3%). This scalable synthesis approach holds significant promise for electronic device applications, particularly in electromagnetic shielding and thermal management.

Ultrathin carbon doped hexagonal boron nitride films for electromagnetic interference shielding in the terahertz region

We have investigated the electromagnetic interference (EMI) shielding efficiency of carbon-doped hexagonal boron nitride (hBN) films in 0.3–1.8 THz regions using transmission-based terahertz time-domain spectroscopy (THz TDS). The hBN films were synthesized on Copper foils by atmospheric pressure chemical vapor deposition (APCVD) utilizing ammonia borane (AB) powder as a precursor. Carbon doping of BN films was achieved by using the intrinsic carbon dissolved in the Copper substrate. The EMI shielding efficiencies and the optical, dielectric, and electrical properties of the films were determined using THz TDS. The Absorbance is much greater than the Reflectance indicating that absorption is the dominant mechanism of shielding in these films. These carbon-doped hBN films show a high EMI shielding effectiveness, with 99.99 % EM radiation blocked. A maximum value of 30 dB and 55 dB at 1.72 THz were observed for films with 4.5 nm and 6.5 nm thicknesses. This is equivalent to shielding efficiency per unit thickness of 6667 dB/µm and 8460 dB/µm, which is among the highest reported for 2D materials.

WIRELESS CHARGING TECHNOLOGY FOR ELECTRIC VEHICLES: CURRENT TRENDS AND ENGINEERING CHALLENGES

Wireless charging technology (WCT) for electric vehicles (EVs) has gained significant attention as a promising alternative to traditional plug-in charging systems due to its convenience and efficiency. This paper systematically reviews 100 peer-reviewed studies on the advancements in WCT, focusing on wireless power transfer (WPT) methods such as inductive and resonant coupling, and the critical engineering challenges that limit widespread adoption. Key issues identified include power transfer efficiency, misalignment between the vehicle and charging pad, and electromagnetic interference (EMI). Additionally, this review explores the infrastructure and scalability challenges of implementing WCT in urban environments and highways, including the potential of dynamic wireless charging systems, which allow EVs to charge while in motion. Despite recent innovations, such as adaptive control systems and advanced coil designs, gaps remain in the research on long-term feasibility and standardization. This study emphasizes the need for interdisciplinary collaboration across technical, economic, and policy domains to support the large-scale commercialization of WCT.

Interfacial enhancement enables highly conductive reduced graphene oxide-based yarns for efficient electromagnetic interference shielding and thermal regulation

Although the coating of conductive graphene onto commercial yarns is promising for scalable production, the resulting conductive yarns are susceptible to the coating detachment, causing reduced conductivity and poor stability. Herein, we propose a scalable and cost-effective interfacial enhancement strategy for fabricating highly conductive yarns with satisfactory mechanical properties by modifying polyamide yarns with polyethyleneimine to enhance their interaction with graphene oxide (GO) sheets and subsequently reducing the GO component with hydroiodic acid. Because the enhanced interfacial interactions of the polyethyleneimine-modified polyamide yarns with the GO sheets improve the loading of GO and the coating stability, the resultant yarns can withstand bending, embroidering, sewing and weaving, maintaining an extraordinary conductivity of 4.7 × 103 S m−1 after 10000-cycle bending. The conductive textiles woven by the yarns reach an excellent electromagnetic interference (EMI) shielding effectiveness of 66.7 dB at the thickness of 0.615 mm along with superior hydrophobicity, satisfactory air permeability, and high electrothermal and solar-thermal energy conversion performances. The EMI shielding effectiveness of the textile is well maintained even after 5000-cycle bending, demonstrating its satisfactory stability. This work demonstrates an interfacial enhancement strategy for the large-scale fabrication of multifunctional yarns that hold great promise for EMI shielding, personal thermal regulation, and deicing applications.

Improved Electromagnetic Interference Shielding Efficiency of PVDF/rGO/AgNW Composites via Low-Pressure Compression Molding and AgNW-Backfilling Strategy.

Silver nanowires (AgNWs) have excellent electrical conductivity and nano-sized effects and have been widely used as a high-performance electromagnetic shielding material. However, silver nanowires have poor mechanical properties and are prone to fracture during the preparation of composite materials. In this study, PVDF/rGO/AgNW composites with a segregated structure were prepared using low-pressure compression molding and the AgNW-backfilling process. The low-pressure compression of the composite significantly improves its electromagnetic shielding performance because the low-pressure process can maintain the AgNWs' integrity. The backfilled AgNWs played a vital role in increasing the path of electromagnetic wave propagation and the absorption of electromagnetic waves. The backfilled amount of AgNWs was only 1 wt%, which increased the composite material's conductivity by one order of magnitude. The total electromagnetic interference shielding (SET) of the composite materials increased by 23.3% from 24.88 dB to 30.67 dB. The absorption contribution (SEA/SET) increased from 84.2% to 92.8%, significantly improving the electromagnetic interference shielding and the absorption contribution of the AgNWs in the composites. This was attributed to the backfilling of the porous structure by the AgNWs, which promoted multiple reflections and enhanced the absorption contribution.

Electromagnetic interference shielding properties of foamed SiCnws/SiC composites reinforced by in-situ grown carbon nanofibers

Interwoven network structures composed of one-dimensional nanomaterials with excellent dielectric properties present promising potential for application in the field of electromagnetic interference (EMI) shielding. In this work, the disordered carbon nanofibers (CNFs) are in-situ grown on the interconnected silicon carbide nanowires (SiCnws) aerogel by chemical vapor infiltration (CVI), which is foamed by unidirectional freeze casting. Subsequently, the SiC interface is deposited to construct an engagement of CNFs and SiCnws. Arising from the penetrating structure, the average total EMI shielding efficiency (SET) of the SiCnws/CNFs/SiC composites increases from 28.9 dB to 42.8 dB in X band with just 2 mm thickness. Moreover, the maximum SET value of the composites can be up to 57.2 dB, indicating more than 99.999 % of microwaves will be shielded. The excellent EMI shielding performance can be attributed to integrating multiple loss mechanisms such as conductivity loss, interface polarization loss, and dipole polarization loss. The integrated lightweight composites provide a new design routine for electromagnetic shielding structure components.

Enhancing cardiovascular health monitoring: Simultaneous multi-artery cardiac markers recording with flexible and bio-compatible AlN piezoelectric sensors

Continuous monitoring of cardiovascular parameters like pulse wave velocity (PWV), blood pressure wave (BPW), stiffness index (SI), reflection index (RI), mean arterial pressure (MAP), and cardio-ankle vascular index (CAVI) has significant clinical importance for the early diagnosis of cardiovascular diseases (CVDs). Standard approaches, including echocardiography, impedance cardiography, or hemodynamic monitoring, are hindered by expensive and bulky apparatus and accessibility only in specialized facilities. Moreover, noninvasive techniques like sphygmomanometry, electrocardiography, and arterial tonometry often lack accuracy due to external electrical interferences, artifacts produced by unreliable electrode contacts, misreading from placement errors, or failure in detecting transient issues and trends. Here, we report a bio-compatible, flexible, noninvasive, low-cost piezoelectric sensor for continuous and real-time cardiovascular monitoring. The sensor, utilizing a thin aluminum nitride film on a flexible Kapton substrate, is used to extract heart rate, blood pressure waves, pulse wave velocities, and cardio-ankle vascular index from four arterial pulse sites: carotid, brachial, radial, and posterior tibial arteries. This simultaneous recording, for the first time in the same experiment, allows to provide a comprehensive cardiovascular patient's health profile. In a test with a 28-year-old male subject, the sensor yielded the SI = 7.1 ± 0.2 m/s, RI = 54.4 ± 0.5 %, MAP = 86.2 ± 1.5 mmHg, CAVI = 7.8 ± 0.2, and seven PWVs from the combination of the four different arterial positions, in good agreement with the typical values reported in the literature. These findings make the proposed technology a powerful tool to facilitate personalized medical diagnosis in preventing CVDs.

Assessing the electromagnetic shielding effectiveness of coconut coir composites with varying iron particle concentrations

This study investigates the electromagnetic shielding effectiveness of Coconut Coir-based Porous Carbon (CCPC) composites with varying iron (Fe) particle concentrations, specifically focusing on four different weight ratios of CCPC/Fe-80, CCPC/Fe-60, CCPC/Fe-40, and CCPC/Fe-20. The novelty of this work lies in the use of sustainable coconut coir as a base material, emphasizing its eco-friendly and cost-effective attributes for Electromagnetic interference (EMI) shielding applications. The significance of varying iron particle concentrations is highlighted to optimize electromagnetic shielding effectiveness. Comprehensive analyses were conducted on these composites. X-Ray Diffraction (XRD) analysis confirmed the presence of crystalline Fe particles and amorphous carbon, with crystalline sizes determined via Williamson-Hall (W-H) plot, Scherrer Equation, and Strain Size Plot (SSP) ranging from 17.33 nm to 18.01 nm for the former. Raman spectroscopy revealed distinctive D and G bands, with intensity ratios indicating a slight increase in structural disorder with higher Fe content. UV-Visualization spectroscopy demonstrated distinct absorption peaks, with higher Fe content resulting in more pronounced absorbance and lower band gap energies. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses provided detailed insights into the material's microstructure and elemental composition, confirming the successful integration of Fe particles within the porous carbon matrix. Vector Network Analyzer (VNA) testing measured the reflection loss (RL), showing values in the range of −26.4 dB to −20.2 dB, for 2 mm thick samples, corresponding to electromagnetic wave attenuation of over 99%. These results underscore the potential of CCPC/Fe composites, particularly in applications requiring effective Electromagnetic (EM) wave attenuation. This research offers a sustainable and cost-effective solution, contributing significantly to the field of materials science by enhancing electromagnetic compatibility in various technological applications.

Fabrication of conductive polyimide/metal composite fibers for high temperature EMI shielding

Surface metallization of high-performance polymer fibers via electroless plating represents a significant advancement in producing lightweight, flexible and durable electromagnetic interference (EMI) shielding fabrics. The conventional process for metallization of polyimide (PI) fibers faces challenges, including complex procedures and insufficient interfacial adhesion between the metal layer and fiber matrix. Herein, carboxylate-containing PI (PIC) fibers were developed to mitigate the mechanical degradation caused by traditional alkaline etching. Conductive composite fibers (PIC/Cu) were successfully produced through a continuous electroless copper plating process. The robust PIC/Cu interfacial bonding achieved based on nanoscale mechanical interlocking through Ni nanoparticles imparts excellent flexibility and durability, evidenced by only a 4 % increase in electrical resistance after 5000 bending cycles. The dense, uniform copper layer provides high conductivity (1.3 × 104 S/cm), resulting in an optimal EMI shielding efficiency of 63.4 dB for the corresponding fabric. Moreover, PIC/Cu-Ni fibers prepared by further electroless plating of nickel layer on the surface of PIC/Cu fibers demonstrate remarkable electrical stability across temperatures ranging from 50 to 350°C, with only a 1.2 % reduction in conductivity after exposure to 350°C for 1 h. These findings advance the development of high-performance conductive PI fibers for applications in aerospace vehicles and high-temperature environments.