Electromagnetic Interference Shielding Research Articles

Flexible and Stretchable Hydrogel-based Composites using Ag Coated Hollow Glass Microspheres and Polypyrrole Nanotube Supported Ferroferric Oxide for Electromagnetic Interference Shielding

Flexible and Stretchable Hydrogel-based Composites using Ag Coated Hollow Glass Microspheres and Polypyrrole Nanotube Supported Ferroferric Oxide for Electromagnetic Interference Shielding

Liquid Metal Grid Patterned Thin Film Devices Toward Absorption-Dominant and Strain-Tunable Electromagnetic Interference Shielding

Multiple internal reflection-based absorption-dominant stretchable electromagnetic shielding thin film by incorporating liquid metal grid structure is developed.The device demonstrates high electromagnetic shielding effectiveness (SE) (SET of up to 75 dB) with low reflectance (SER of 1.5 dB at the resonant frequency).The shielding properties of the device can be tuned by adjusting the liquid metal patterned grid spaces upon strain.

Flexible multifunctional magnetic-conductive Janus nanocomposite films towards highly-efficient electromagnetic interference shielding and thermal management

The rapid development of aerospace, intelligent wearable electronics and 5G communications puts forward higher demands for electromagnetic interference (EMI) shielding materials. Herein, the flexible multifunctional magnetic-conductive Janus nanocomposite films with magnetic cobalt carbide nanowires/bacterial cellulose (Co@C NW/BC) blends as the upper side, and conductive Ti3C2Tx MXene as the bottom side are obtained via the layer-by-layer (LBL) vacuum assisted filtration-hot pressing method. The two magnetic and conductive sides endow the Janus nanocomposite films with distinctly different performances in EMI shielding and thermal management. When the electromagnetic waves are incident from Co@C NW/BC side, the films exhibit a high EMI shielding effectiveness (EMI SE) of 49.8 dB with an enhanced microwave absorption (SEA) of 33.9 dB at the ultralow thickness of 43 μm. Meanwhile, the Ti3C2Tx side exhibits improved electrical heating performances with a surface temperature of 120 °C at 6 V voltage, increased photothermal conversion temperature of 77.8 °C upon 2.0 kW/m2 light intensity, as well as excellent thermal stealth properties with a low radiation temperature of 88.4 °C on the 240 °C hot stage. Moreover, the Janus nanocomposite films show a high tensile strength of 80.0 MPa. The resultant Janus nanocomposite films possess great application prospects in highly-efficient EMI shielding and thermal management.

A flexible and breathable ammonium polyphosphate/chitosan/MWCNT doped PEDOT:PSS coating decorated carbon cloth for high-efficiency flame retardancy and electromagnetic interference shielding applications

There is an urgent need for versatile textiles for different applications due to the rapid development of flexible and wearable electronic devices. However, the poor breathability, high cost, and complex manufacturing processes are still urgent issues to be addressed. In this work, a breathable and flexible carbon cloth (CC) decorated multifunctional coatings (ACMPP) is developed through a facile and scalable coating technology for flame retardancy and electromagnetic interference (EMI) shielding applications. The ACMPP are constructed by incorporating the ammonium polyphosphate/chitosan/multi-walled carbon nanotubes (ACM) composites with core-multi-shell structure into PEDOT:PSS (PP). The low-cost ACM composites demonstrate the promising potential to substitute complex manufacturing processes with an easy electrostatic self-assembly. The as-obtained ACMPP/CC composites display favorable air permeability (69.65 mm·s-1), efficient water vapor transmittance (273.17 kg·m-2·d-1), and high-efficiency flame retardancy (36.8 % of limiting oxygen index), coupled with excellent EMI shielding capacity (59.36 dB in the X band) and shielding stability. The simplicity and scalability of the approach in this work offers a highly cost-performance paradigm to construct next generation flexible textiles for flame retardancy and electromagnetic interference shielding applications.

Lightweight, Robust, and Multifunctional Polyimide-Based Carbon Foams for Electromagnetic Interference Shielding and Thermal Insulation

Lightweight, Robust, and Multifunctional Polyimide-Based Carbon Foams for Electromagnetic Interference Shielding and Thermal Insulation

Multifunctional wood-bamboo hybrid materials for effective electromagnetic interference shielding

With the emergence of industries such as custom home furnishing and prefabricated construction, the demand for functional engineered wood products is increasing. However, traditional engineered wood products have low strength and limited functionality. To address concerns about electromagnetic radiation and other safety hazards in household environments, we developed a multifunctional material with a wood-bamboo multilayer structure, where a bamboo layer with excellent electromagnetic shielding and mechanical properties is bonded to the wood surface. Uniform integration of copper nanoparticles endows the bamboo layer with excellent electromagnetic interference (EMI, 40 dB), shielding effectiveness (SE) and good hydrophobic properties. The wood-bamboo hybrid materials demonstrate excellent flexural strength (70.1 MPa) and flame-retardant performance (self-extinguishing within 10 seconds after ignition). The potential applications of wood-bamboo hybrid materials can extend to various fields such as construction engineering, building decoration and electronic products.

Trunk-Inspired SWCNT-Based Wrinkled Films for Highly-Stretchable Electromagnetic Interference Shielding and Wearable Thermotherapy

HighlightsElephant trunk-inspired anisotropic wrinkling structures were formed on a sandwich-like conductive film through a controlled shrinking method.The wrinkled conductive network could withstand up to 200% tensile strain and exhibits a strain-enhanced electromagnetic interference shielding effectiveness when stretching parallel to the electric field polarization direction.

Conductive water-based graphene suspension for electromagnetic interference shielding via spray coating on SiP module

Conductive inks have been widely used to develop electronic devices, such as sensors, RFID antennas, and transistors. Electronic utilization is a coating that forms conductive films for electromagnetic interference shielding (EMI Shielding). This process also can be employed to cover electronic modules called System in Package (SiP). A technology known as conformal shielding utilizes spray coating with metallic inks to form a conductive layer over the SiP. Traditionally, copper or silver inks have been the primary materials employed due to their high electrical conductivity. Conversely, these metallic inks are associated with significant costs, environmental impacts, and complex production methods. In this context, water-based graphene dispersion could be an alternative to EMI Shielding for electronic chips. Graphene is attractive due to its excellent electrical and thermal properties, reduced cost, and being an environmentally friendly material. In this study, a water-based graphene suspension was developed and applied via spray coating to form films for electromagnetic shielding. The graphene dispersion in water utilized Carboxymethyl cellulose (CMC). Characterizations of the graphene suspension, including morphology, particle size distribution, and chemical analysis, were conducted. The resistivity of the resulting films and their shielding effectiveness (SE) were measured. Electronic chip modules were painted to assess coverage. The study demonstrated the successful formulation of a stable water-graphene suspension exhibiting favorable electrical resistivity (2.8 × 10−2 Ω.cm) after drying at 300 °C for 1 h. The resulting film achieved a shielding effectiveness of −9 dB at 1.0 GHz. Graphene film completely covered the electronic chips, indicating an alternative conformal shielding.

Ultrafine Aramid Nanofiber-Assisted Large-Area Dense Stacking of MXene Films for Electromagnetic Interference Shielding and Multisource Thermal Conversion.

Polymers are often used as adhesives to improve the mechanical properties of flexible electromagnetic interference (EMI) shielding layered films, but the introduction of these insulating adhesives inevitably reduces the EMI performance. Herein, ultrafine aramid nanofibers (UANF) with a diameter of only 2.44 nm were used as the binder to effectively infiltrate and minimize the insulating gaps in MXene films, for balancing the EMI shielding and mechanical properties. Combining the evaporation-induced scalable assembly assisted by blade coating, flexible large-scale MXene/UANF films with highly aligned and compact MXene stacking are successfully fabricated. Compared with the conventional ANF with a larger diameter of 7.05 nm, the UANF-reinforced MXene film exhibits a "brick-mortar" structure with higher orientation and compacter stacking MXene nanosheets, thus showing the higher mechanical properties, electrical conductivity, and EMI shielding performance. By optimizing MXene content, the MXene/UANF film can achieve the optimal tensile strength of 156.9 MPa, a toughness of 2.9 MJ m-3, satisfactory EMI shielding effectiveness (EMI SE) of 40.7 dB, and specific EMI SE (SSE/t) of 22782.4 dB cm2/g). Moreover, the composite film exhibits multisource thermal conversion functions including Joule heating and photothermal conversion. Therefore, the multifunctional MXene/UANF EMI shielding film with flexibility, foldability, and robust mechanical properties shows the practical potential in complex application environments.

Multifunctional Wearable Electronic Based on Fabric Modified by PPy/NiCoAl-LDH for Energy Storage, Electromagnetic Interference Shielding, and Photothermal Conversion.

With the rapid advancement of electronic technology, traditional textiles are challenged to keep up with the demands of wearable electronics. It is anticipated that multifunctional textile-based electronics incorporating energy storage, electromagnetic interference (EMI) shielding, and photothermal conversion are expected to alleviate this problem. Herein, a multifunctional cotton fabric with hierarchical array structure (PPy/NiCoAl-LDH/Cotton) is fabricated by the introduction of NiCoAl-layered double hydroxide (NiCoAl-LDH) nanosheet arrays on cotton fibers, followed by polymerization and growth of continuous dense polypyrrole (PPy) conductive layers. The multifunctional cotton fabric shows a high specific areal capacitance of 754.72 mF cm-2 at 5mA cm-2 and maintains a long cycling life (80.95% retention after 1000 cycles). The symmetrical supercapacitor assembled with this fabric achieves an energy density of 20.83µWh cm-2 and a power density of 0.23 mWcm-2. Moreover, the excellent electromagnetic interference shielding (38.83dB), photothermal conversion (70.2 °C at 1000mWcm-2), flexibility and durability are also possess by the multifunctional cotton fabric. Such a multifunctional cotton fabric has great potential for using in new energy, smart electronics, and thermal management applications.

Electromagnetic Interference Shielding and Joule Heating Properties of Flexible, Lightweight, and Hydrophobic MXene/Nickel-Coated Polyester Fabrics Manufactured by Dip-Dry Coating and Electroless Plating.

High-performance electromagnetic interference (EMI) shielding materials with high flexibility, low density, and hydrophobic surface are crucial for modern integrated electronics and telecommunication systems in advanced industries like aerospace, military, artificial intelligence, and wearable electronics. In this study, we present flexible and hydrophobic MXene/Ni-coated polyester (PET) fabrics featuring a double-layered structure, fabricated via a facile and scalable dip-dry coating process followed by electroless nickel plating. Increasing the dip-dry coating iterations up to 10 cycles boosts the MXene loading content (∼31 wt %) and electrical conductivity (∼86 S/cm) of MXene-coated PET fabrics, while maintaining constant porosity (∼95%). The addition of a Ni layer enhances hydrophobicity, achieving a high water contact angle of ∼114° compared to only MXene-coated PET fabrics (∼49°). Furthermore, the 30 μm thick MXene/Ni-coated PET fabric demonstrates superior electrical conductivity (∼113.8 S/cm) and EMI shielding effectiveness (∼35.7 dB at 8-12 GHz) compared to only MXene- or Ni-coated PET fabrics. The EMI shielding performance of the MXene/Ni-coated PET fabric remains more stable in an air environment than only MXene-coated fabrics due to the outer Ni layer with excellent hydrophobicity and oxidation stability. Additionally, the MXene/Ni-coated PET fabric exhibits impressive Joule heating performance, swiftly converting electrical energy into heat and reaching high steady-state temperatures (32-92 °C) at low applied voltages (0.5-1.5 V).

Absorption-dominant electromagnetic interference shielding material using MXene-coated polyvinylidene fluoride foam

MXene (Ti3C2Tx), known for its exceptional electrical conductivity, unique two-dimensional structure, extensive surface functionality, and hydrophilicity, has emerged as a leading candidate for electromagnetic interference (EMI) shielding applications. Despite these excellent characteristics, EMI shielding materials based on MXene mostly utilize the reflection mechanism, which may cause secondary interferences. This study introduces an approach to utilize MXene as absorption-dominant EMI shielding materials. By engineering a porous layer of polyvinylidene fluoride (PVDF) atop MXene nanoflakes, we achieved a synergistic enhancement in EMI shielding effectiveness (SE) and absorptivity. The PVDF foam serves as an effective impedance matching layer, substantially enhancing the absorption of electromagnetic waves into the shielding material. Incorporating electrically conductive MXene nanoflakes to form a thin film creates a robust conductive network, fully leveraging its inherent performance. This network efficiently dissipates EM waves, thereby significantly enhancing the EMI SE. The shielding performance of this composite was thoroughly evaluated across both the X-band (8.2 GHz–12.4 GHz) and the Ka-band (26.5 GHz–40 GHz) frequencies. It demonstrated high EMI SE, attributed to mechanisms predominantly based on absorption. Specifically, it achieved an EMI SE of approximately 63.3 dB with high absorptivity (0.74) in the X-band and approximately 73.3 dB with high absorptivity (0.85) in the Ka-band. These findings underscore its potential as a route to develop absorption-dominant EMI shielding materials.

Structural Design of Multifunctional PET Non‐woven Fabric with Porous Dual‐Network for Infrared Stealth, Flame Retardant, and Electromagnetic Interference Shielding

With rapid advances in electronic and communication technology, electromagnetic interference and other problems are becoming increasingly prominent. Thus, electromagnetic interference shielding materials have recently garnered extensive attention. In this study, a multi‐walled carbon nanotube/polyurethane/non‐woven electromagnetic shielding material (CPNW) is developed using impregnation and nonsolvent‐induced‐phase separation techniques. Utilizing a three‐dimensional nonwoven network as the substrate, the “nonwoven fabric‐polyurethane‐carbon nanotube” composite is impregnated and cured via the non‐solvent‐induced‐phase separation method, resulting in a distinctive porous dual‐network structure that ensures robust interfacial bonding between carbon nanotubes, nonwoven fabric, and polyurethane. At a carbon nanotube content of 10% (based on the mass of nonwoven fabric), CPNW exhibited an electromagnetic interference shielding effectiveness of 28.8 dB, a thermal conductivity of 0.127 W m−1 K−1, and a burning time of 1 min and 15 s, demonstrating outstanding electromagnetic shielding, flame retardant, and infrared stealth capabilities. Overall, this study laid a theoretical groundwork for the development of multifunctional non‐woven electromagnetic shielding materials with widespread application potential in aerospace, military, artificial intelligence, and wearable electronics.

Dynamically Controllable Terahertz Electromagnetic Interference Shielding by Small Polaron Responses in Dirac Semimetal PdTe2 Thin Films

AbstractTerahertz (THz) electromagnetic interference (EMI) shielding materials is crucial for ensuring THz electromagnetic protection and information confidentiality technology. Here, it is demonstrated that high electrical conductivity and strong absorption of THz electromagnetic radiation by type‐II Dirac semimetal PdTe2 film make it a promising material for EMI shielding. Compared to MXene film, a commonly used metallic 2D material, the PdTe2 film demonstrates a remarkable 40.36% increase in average EMI shielding efficiency per unit thickness within a broadband THz frequency range. Furthermore, it is demonstrated that a photoinduced long life‐time THz transparency in Dirac semimetal PdTe2 films is attributed to the formation of small polarons due to the strong electron‐phonon coupling. A 15 nm‐thick PdTe2 film exhibits a photoinduced change of EMI SE of 1.1 dB, a value exceeding three times that measured on MXene film with a similar pump fluence. This work provides insights into the fundamental photocarrier properties in type‐II Dirac semimetals that are essential for designing advanced THz optoelectronic devices.

Multiscale Lamellar Regulation of Three-Dimensional Graphene-like Nanostructures for Electromagnetic Interference Shielding and Thermal Management

Multiscale Lamellar Regulation of Three-Dimensional Graphene-like Nanostructures for Electromagnetic Interference Shielding and Thermal Management

Oxhide gelatin-regulated aramid nanofiber/liquid metal films with sandwiched structure for electromagnetic interference shielding

Liquid metal (LM) based electromagnetic interference (EMI) shielding materials with high conductivity and continuous deformation capacity are important needs for meeting modern advanced electronic equipment. However, an independent free-standing film with LM is difficult to achieve due to its unique fluidity properties. Here, a simple alternating filtration film-forming method was utilized to orderly construct a sandwiched EMI shielding film with LM stabilized by bio-based oxhide gelatin (gel) as the intermediate conductive layer, and two films of aramid nanofibers/oxhide gel (ANF/gel) as the external insulating protective layers. This design not only prevents LM from being exposed to environmental conditions, but also reduces the risk of chemical corrosion in practical applications. Under optimal LM addition conditions, the sandwiched film (0.3-3 L) exhibited better EMI shielding performance of 50.4 dB in the X-band than the blended film (0.7 dB), as well as excellent mechanical properties (tensile strength of 65.8 MPa, strain 8.6 %). More importantly, the sandwiched film still maintained reliable EMI shielding performance after being experienced largely physical deformation. This study provides a new solution for preparing LM-based EMI shielding composites, and is expected to arouse pursuit of high EMI shielding effects of bio-based gel while also paying attention to their safety.

Cf@BN/(CrZrHfNbTa)C–SiC high-entropy ceramic matrix composites with outstanding electromagnetic interference shielding and high-temperature resistance

Electromagnetic interference (EMI) shielding materials with excellent load-bearing and high-temperature resistance have attracted much attention for both civil and military applications. In this regard, mechanically robust (bending strength of 246 ± 15 MPa) Cf@BN/(CrZrHfNbTa)C–SiC high-entropy ceramic matrix composite with BN interphase was designed and fabricated in this work for highly EMI shielding performance and high-temperature resistance. As a result of the synergistic effect of multi-components, mean total EMI shielding efficiency (SET) of the composite with 3 mm thickness is up to 32.5 dB (higher than 99.9 % EMI shielding) in Ku-band. This indicates that thickness of the BN interphase has a remarkable effect on EMI shielding performance, indicating that the absorption coefficient (A) increases gradually with increasing BN thickness. The EMI shielding performance exhibit excellent high-temperature stability in an oxidation environment. Even after multiple high temperature oxidations in the temperature range of 400–800 °C, the composite remains outstanding EMI shielding performance. This study provides a structural and functional integrated EMI shielding material with a potential long service life at high temperatures.

Electromagnetic porous lignocellulosic matrix composites: A green electromagnetic shielding material with high absorption efficient electromagnetic interference

Electromagnetic interference (EMI) shielding materials play a vital role in human society, especially in light of the rapid development of electronic communication equipment. Therefore, it is urgent to develop green, high-efficiency EMI shielding materials. Wood, as a renewable raw material, possesses significant structural advantages in studying EMI materials due to its unique 3D pore structure. Herein, we report magnetoelectric lignocellulosic matrix composites derived from the delignified wood for efficient EMI shielding. The composite was fabricated by in-situ polymerization of PEDOT conductive coating and magnetic Fe3O4 in delignified wood. The conductive 3D pore structure of Fe3O4/PEDOT@wood could effectively cause dielectric loss and multiple internal reflections. Combined with the magnetic loss of Fe3O4, the material exhibited excellent EMI shielding effectiveness (SE), which could be attributed to the synergistic effect of dielectric and magnetic losses. The Fe3O4/PEDOT@wood showed excellent conductivity (103 S/m), good magnetism (26.7 emu/g), the EMI SE up to 59.8 dB, and high SEA/SET ratios of∼84.2 % to 95.7 % at 2 mm in X -band. Moreover, the material exhibited a high compressive strength and tensile strength of 100.8 MPa and 18.1 MPa, respectively. Therefore, this work provided a reference for the preparation of high-efficiency EMI shielding materials.

Chemical preparation methods of MXenes materials and exploration and application of their chemical mechanisms

As a new generation of 2D materials, MXenes have demonstrated various application prospects in fields such as energy storage, electromagnetic interference shielding, sensing devices, medicine, seawater desalination, and environmental restoration due to their rich functional groups, adjustable interlayer spacing structure, and high electrical conductivity. In recent years, this has led to widespread exploration and research from the outside world. This article mainly focuses on the latest developments in the production of MXenes by Chemical Vapor Deposition (CVD) method, and briefly discusses the pseudocapacitive effects and photovoltaic effects of MXenes materials within the energy storage domain, highlighting their outstanding performance in potassium-ion supercapacitors and perovskite solar cells in the photovoltaic field.

Ultralight reduced graphene oxide based foam with excellent electromagnetic interference shielding and superior mechanical properties

Reduced graphene oxide/carboxymethyl cellulose (RGO/CMC) foams with ultra-lightweight, excellent EMI shielding and mechanical robustness are fabricated based on a facile solution method and regulation of thermal reduction conditions. Results indicate that the two-step heating mode is good to obtain better EMI shielding properties. By introducing only 10 wt% of CMC, high electrical conductivity up to 34.7 S/m and EMI shieling effectiveness (SE) up to 34.6 dB are obtained. In addition, due to the connection effect of CMC, superior compressive strength and modulus as high as 8.3 KPa and 29.2 KPa are achieved, corresponding to an increase of 388.2% and 378.7%, respectively, compared to that of the RGO foam without CMC. Moreover, due to the ultralow density (∼4.1 mg/cm3) and high EMI SE of RGO/CMC, excellent specific shielding efficiency as high as 42195 dB.cm2/g is obtained, way much superior to that of other metal-, graphene-, and CNT-based carbon foams. This work will have great significance for facile fabricating efficient EMI shielding materials towards electronics and aerospace applications.