Electromagnetic Interference Shielding Fabric Research Articles

Capillarity-assisted assembly of composite fibers to enable highly conductive fabrics for electromagnetic interference shielding

Poor adhesion between silver nanomaterials and substrates seriously restricts the development of electronic composite devices. In this work, flexible and conductive silver nanowires/fibroin/degummed silk (AgNWs/fibroin/dSF) composite fibers with high adhesion and conductivity via capillarity-assisted assembly for electromagnetic interference (EMI) shielding are designed and fabricated by a facile and scalable all-solution dip-coating method. The nanocomposite fiber possesses high conductivity with a resistance of 8.8 Ω/cm at a low AgNWs/fibroin loading of 19.3 wt%. The assistance of the capillary force in the fiber highly increases the mass of deposited AgNWs. Furthermore, the AgNWs show high adhesion on the fibers in the tape-peel test. The enhanced deposition factors and mechanisms are detailly investigated. Moreover, the composite fibers are further woven into a soft and flexible fabric. The composite fabric shows an absorption-dominated EMI shielding performance with an efficient shielding effectiveness of 38 dB. The capillarity-assisted assembly is an attractive procedure for constructing high-conductive and uniform coatings for a wide application.

Lightweight and flexible Ag-wrapped polyimide aerogel fabrics for electromagnetic interference shielding

Lightweight, flexible and highly effective electromagnetic interference (EMI) shielding fabrics are urgent demanded to protect the human body from harmful electromagnetic radiation. However, the design of fiber microstructures for achieving high-performance EMI shielding still remains significant challenges. Herein, novel EMI shielding fabrics have been designed based on polydopamine-assisted Ag deposition on polyimide (Ag@PI) aerogel fabrics. The Ag@PI aerogel fabric integrates highly conductive Ag and leverages the three-dimensional porous structure of aerogel to facilitate multiple reflections and interface polarization of electromagnetic waves. The Ag@PI aerogel fabrics exhibit ultra-high electromagnetic interference shielding performance of 89.4 dB owing to their unique porous structure, while the Ag@PI fabric without porous structure is only 65.1 dB. The normalized specific shielding effectiveness (SSE) of the Ag@PI aerogel fabrics is up to 812.7 dB cm3 g−1, significantly exceeding that of other EMI shielding textiles reported so far.

Superhydrophobic self-extinguishing cotton fabrics for electromagnetic interference shielding and human motion detection

• Multifunctional cotton fabric has been prepared via a layer-by-layer method. • Cotton-10BL-Si shows superhydrophobic and self-extinguishing behaviors. • Cotton-10BL-Si has great potential in EMI shielding and motion sensors. • Cotton-10BL-Si shows satisfying washability and durability. Multifunctional intelligent fire-safe cotton fabric promises next-generation fire-fighting uniform and sensor applications. However, cotton fabrics' hygroscopicity and intrinsic flammability significantly impede their potential applications in industries. Herein, we report a superhydrophobic fireproof cotton fabric (PEI-APP-PEI-MXene) generated via sequential layer-by-layer deposition of polyethyleneimine (PEI), ammonium polyphosphate (APP), and titanium carbide (MXene), followed by hydrophobic treatment with silicone elastomer. Compared to untreated cotton, the treated cotton fabric with 10 polymolecular layers exhibits ∼43% and ∼42% reductions in the peak heat release rate and total heat release, respectively, a desired UL-94 V-0 rating, and a high limiting oxygen index (LOI) value of 39.5 vol.%. In addition to that, the treated fabrics displayed improved electromagnetic interference (EMI) shielding and motion-sensing abilities. The presented work provides a facile and effective surface modification approach to generate multifunctional cotton fabrics with promising practical applications.

1CoFe/C Nanosheets on Hollow Carbon Fibers as Composite Fabrics for Electromagnetic Interference Shielding

¹CoFe/C Nanosheets on Hollow Carbon Fibers as Composite Fabrics for Electromagnetic Interference Shielding

Flexible, conductive and multifunctional cotton fabric with surface wrinkled MXene/CNTs microstructure for electromagnetic interference shielding

Although ultrathin and flexible conductive textiles are promising for smart wearable electronic devices, the seamless integration of electromagnetic interference (EMI) shielding textiles, strain sensors and Joule heater is still a huge challenge. Herein, a conductive cotton fabric with cross-linked wrinkled microstructure is fabricated via a facile spray-coating approach, formed by carbon nanotubes (CNTs) as skeletons and Ti3C2Tx MXene nanosheets as stacking layers. Benefiting from the unique wrinkled microstructure, the resultant fabric exhibits high EMI shielding effectiveness (EMI SE) of 46.05 dB in the X-band at a thickness of only 138 µm. Furthermore, the specific EMI SE (SSE/t) of the resultant fabric is up to 6.71 × 103 dB cm2 g−1, significantly exceeding most of the currently reported polymeric EMI shielding materials. Due to the high electrical conductivity, the resultant fabric also displays excellent Joule heating performance (46.6 ℃ for PMC3C at the driven voltage of 2 V) and sensitive strain responses. More importantly, the resultant fabric demonstrates outstanding stability and anti-fouling property, offering a huge potential for long-term applications in harsh environments. This work provides a facile strategy to develop multifunctional EMI shielding fabric for human motion detection and personal thermal management.

Integrated hierarchical macrostructures of flexible basalt fiber composites with tunable electromagnetic interference (EMI) shielding and rapid electrothermal response

Adjustable and durable EMI shielding fabrics with excellent mechanical performance are urgently required owing to the rapid growing of electronics in industrial, military and aerospace fields. Herein, a highly flexible and durable conductive basalt fabric (BF) composite was firstly fabricated by integrating Ti 3 C 2 T x nanosheets and conformal natural rubber-Ti 3 C 2 T x layer via a facile spray-drying method. The effects of the natural rubber outlayer with or without Ti 3 C 2 T x nanosheets on the composite are examined to determine the optimal composition and structure. The Ti 3 C 2 T x nanosheets form a continuous and compact nacre lamellar coating on the surface of the external BF fibers, resulting in the main EMI shielding function. Especially, the conductive natural rubber-Ti 3 C 2 T x (TNR) outlayer could not only protect the inner Ti 3 C 2 T x coating, but also form conductive connections between conductive BF fibers. The resultant EMI shielding basalt fabrics possess hierarchical macrostructures, which could even obtain an ideal EMI SE value of 41.53 dB. Besides, the TNR outlayer could also fasten the fabric structure and protect the conductive network, which led to negligible decreases after repeatedly bending to 10.0 mm radius for 200 cycles (99.0% retention), sonication for 30 min (98.8% retention) and peeling for 200 cycles (94.4% retention). Moreover, such fabrics also showed outstanding electro-thermal property. Even if applied a low voltage of 4 V, the temperature would immediately reach up to over 70 °C, which also possess excellent cycling stability. Consequently, this work reveals an effective and facial technology for preparing a much more competitive EMI shielding fabric. • EMI shielding basalt fiber composites were developed with hierarchical structure. • Multilayer coating was prepared by the spray-drying technique. • The resultant textile possesses adjustable EMI shielding performance and rapid electrothermal response. • The resultant textile exhibits superior durability under continous external forces.

Preparation of Flexible Carbon Fiber Fabrics with Adjustable Surface Wettability for High-Efficiency Electromagnetic Interference Shielding.

In the 5G era, for portable electronics to operate at high performance and low power levels, the incorporation of superior electromagnetic interference (EMI) shielding materials within the packages is of critical importance. A desirable wearable EMI shielding material is one that is lightweight, structurally flexible, air-permeable, and able to self-clean. To this end, a bioinspired electroless silver plating strategy and a one-step electrodeposition method are utilized to prepare an EMI shielding fabric (CEF-NF/PDA/Ag/50-30) that possesses these desirable properties. Porous CEF-NF mats with a spatially distributed silver coating create efficient pathways for electron movement and enable a remarkable conductivity of 370 S mm-1. When tested within a frequency range of 8.2-12.4 GHz, this highly conductive fabric not only achieves an EMI shielding effectiveness (EMI SE of 101.27 dB at 5028 dB cm2 g-1) comparable to a very thin and light metal but also retains the unique properties of fabrics-being light, structurally flexible, and breathable. In addition, it exhibits a high contact angle (CA) of 156.4° with reversible surface wettability. After having been subjected to 1000 cycles of bending, the performance of the fabric only decreases minimally. This strategy potentially provides a novel way to design and manufacture an easily integrated EMI shielding fabric for flexible wearable devices.

Cross-stacking aligned non-woven fabrics with automatic self-healing properties for electromagnetic interference shielding

Efficient, flexible and self-healing electromagnetic interference (EMI) shielding materials are highly desirable and valuable for electromagnetic shielding industry. Furthermore, in order to achieve a commercial-grade EMI shielding effectiveness, a large amount of filler is required. Here, a kind of self-healing EMI shielding fabric was fabricated by preparing aligned carbon nanotube-poly (2-hydroxyethyl methacrylate) (CNT-PHEMA) non-woven fabric through magnetic-field-assisted electrospinning and cross-stacking aligned fabric layers. The unique aligned CNT stacking and porous structure enable that the materials can effectively absorbing EMI even at very low CNT loading amount (0.17 wt%). The host-guest interaction between β-cyclodextrin (β-CD) and adamantane (Ad) moieties not only made the fabric can adhere together automatically but also self-heal the scratch under 100% humidity environment. After the healing, the EMI shielding property can be restored 90.86 ± 3.90%.

Bio-inspired Fabrication of Cu-Ni Coatings onto Mercerized Flax Fabric by Electroless Plating

This research mainly prepared a bio-friendly electromagnetic interference (EMI) shielding fabric, and discussed the influence of the grammage (i.e. 120 g/m2, 160 g/m2 and 210 g/m2, etc) of fabric substrate on the preparation of metal-based EMI shielding conductive fabric by electroless plating. A series of steps involved mercerization, dopamine (DoPA) modification, Ni0 seeding and electroless copper-nickel (Cu-Ni) plating were carried out to fabricate ideal EMI shielding fabric. The prepared Cu-Ni fabric endowed relatively high EMI shielding effectiveness (SE) (34.80-42.00 dB) ranging from 30 to 4500 MHz, which made it a huge potential in the field of wearable EMI shielding. Moreover, another discovery was that a relative higher grammage may lead to a lower total metal loading. Furthermore, Fourier transformation infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements were conducted to verify the introduction of functional groups in mercerization, modification and activation procedures. The crystalline phases and morphologies of resulting Cu-Ni coatings were characterized by X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) measurements. The atomic ratio (at.%) of Cu and Ni in the sample was determined by Energy Dispersive X-ray Spectroscopy (EDX) measurements. Overall, the Cu-Ni alloy fabric prepared in this research met the requirements of health, coating lining and EMI shielding.

Axial Alignment of Carbon Nanotubes on Fibers To Enable Highly Conductive Fabrics for Electromagnetic Interference Shielding.

Conductive coatings show great promise for next-generation electromagnetic interference (EMI) shielding challenges on textile; however, their stringent requirements for electrical conductivity are difficult to meet by conventional approaches of increasing the loading and homogeneity of conductive nanofillers. Here, the axial alignment of carbon nanotubes (CNTs) on fibers that were obtained by spontaneous capillary-driven self-assembly is shown on commercial cotton fabrics, and its great potential for EMI shielding is demonstrated. The aligned CNTs structurally optimize the conductive network on fabrics and yield an 81-fold increase in electrical conductivity per unit of CNT, compared with the disordered CNT microstructure. The high-efficiency electrical conductivity allows a several-micron-thick coating on insulating fabrics to endow an EMI shielding effectiveness of 21.5 dB in the X band and 20.8 dB in the Ku band, which meets the standard shielding requirement in commercial applications. It is among the minimum reported thicknesses for conductive nanocomposite coatings to date. Moreover, the coated fabrics with aligned CNTs possess a desirable stability upon bending, scratching, stripping, and even washing, which is attributed to the dense CNT packing in the aligned microarchitecture. This work presents the anisotropic structure on large areas by self-assembly, offering new opportunities for next-generation portable and wearable electronic devices.

Superhydrophobic/Flame Retardant/EMI Shielding Fabrics: Manufacturing Techniques and Property Evaluations

Electromagnetic pollution interferes with electronic equipment in proximity and jeopardizes human health, which urges the development of electromagnetic interference (EMI) shielding materials. It is urgent to develop electromagnetic interference (EMI) shielding materials. However, the preparation of materials with superhydrophobicity, flame retardancy and EMI shielding properties is still challenging. In this study, we invented a core-spun yarn feeding device, which uses polysulfonamide (PSA) roving as a coating material and stainless steel wire as the core material to prepare a conductive core-spun yarn, which solves the problem of the wire having an easily exposed fabric surface. The finally prepared conductive fabric was subjected to Waterproof 2P hydrophobic treatment to form a superhydrophobic flame-retardant EMI shielding fabric. The results show that the hydrophobic treatment creates a thin film over the woven fabrics, and the contact angle of the fabric surface can reach 155°. The hydrophobic treatment will not damage the shielding effect and slightly increase the dB value. The average dB value of PSA-SS-1’ and PSA-SS-2’ are increased by 0.82 dB and 1.92 dB, respectively. When composed of conductive wrapped yarns for both the warp and weft yarns, the electromagnetic interference shielding effectiveness (EMI SE) of conductive fabrics is beyond 30 dB at 0–3000 MHz and the burnt depth is shorter than 40 mm. As for real applications, superhydrophobic/flame retardant/EMI SE fabrics can be used in a moist and complex environment with retaining conductivity and shielding effectiveness.

Rapid computation model for accurate evaluation of electromagnetic interference shielding effectiveness of fabric with hole based on equivalent coefficient

Though electromagnetic interference (EMI) shielding fabric with rectangular hole has wide application in various fields, there is not a mature approach to calculate its shielding effectiveness (SE) at present. This paper constructs a rapid computation model of the SE of the EMI shielding fabric with hole based on equivalent coefficient. Firstly, the rectangular hole characteristic is analyzed and a structure model of the rectangular hole under the consideration of the hole edge characteristic is described. The equivalent relationship between the fabric hole and the standard hole is presented according to the equivalent theory. The rapid computation model of the SE of the EMI shielding fabric with hole is built including the equivalent coefficient and transmission coefficient according to the EMI shielding theory and the method to determine the equivalent coefficient is also given. Finally, the computation model is verified by experiments. The results show that the accuracy and the computational efficiency of the proposed model are good, and the model can be applied to the fabrics with wide weaves and various rectangular hole sizes.

Comparison of polyelectrolyte and sodium dodecyl benzene sulfonate as dispersants for multiwalled carbon nanotubes on cotton fabrics for electromagnetic interference shielding

ABSTRACTCotton fabrics with multiwalled carbon nanotubes (MWCNTs) dispersed by Nafion, a polyelectrolyte, and sodium dodecyl benzene sulfonate (SDBS), a surfactant, were prepared for electromagnetic interference (EMI) shielding. The fabrics were characterized by scanning electron microscopy and vector network analysis. The fabrics with the Nafion–MWCNT coating possessed a better shielding efficiency (SE) than those with the SDBS–MWCNT coating because of a more uniform dispersion of MWCNTs, which improved the electrical conductivity and EMI shielding properties. The maximum SE value of the fabric reached 11.48 dB, and the specific SE was 39.6 dB cm3/g. The reflectivity and absorptivity were calculated separately to determine the main mechanism of EMI shielding. The absorptivity was 68.6% at 12 GHz for the Nafion–MWCNT‐coated fabric; this showed that the dominant mechanism of EMI shielding for the treated fabrics was absorption. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40588.

Virtual metal model for fast computation of shielding effectiveness of blended electromagnetic interference shielding fabric

Blended electromagnetic interference (EMI) shielding fabric has an important application in the EMI shielding fields, but its shielding effectiveness (SE) computation remained unsolved. This study proposes a fast computation method which builds a virtual metal model according to fabric structure parameters to calculate the SE of the EMI shielding fabric. The above analysis involves the calculation of metal fiber content per unit volume of the EMI shielding fabric according to the structure of the fabric, followed by construction of a virtual metal model and computation of its thickness. Then a relation between the SE of the EMI shielding fabric and the SE of the virtual metal model is explored. A conversion coefficient of the SE computation of plain, twill and satin weave fabric is determined by experiments. A fast computation of the SE based on the virtual metal model is built. After a number of experiments, results show that the relative error is low and the computation is fast and is satisfied for the normal blended EMI shielding fabrics.