Self-Healing Liquid Metal Magnetic Hydrogels for Smart Feedback Sensors and High-Performance Electromagnetic Shielding

Lightweight, breathable and self-cleaning polypyrrole-modified multifunctional cotton fabric for flexible electromagnetic interference shielding

The thriving of wearable electronics and the emerging new requirements for electromagnetic interference (EMI) shielding have driven the innovation of EMI shielding materials towards lightweight, wearability and multifunctionality. Herein, the hierarchical polypyrrole nanotubes (PNTs)/PDMS structures are rationally constructed on the textile for obtaining multifunctional and flexible EMI shielding textiles by in-situ polymerization and surface coating. The modified cotton fabric possesses a conductivity of about 2715.8 S/m and an SET of 28.2 dB in the X band when the thickness is only 0.5 mm. After ultrasonic treatment, cyclic bending and washing, the conductivity and EMI shielding performance remain stable and exhibit long-term durability. Importantly, the textile's inherent lightweight, breathable and soft properties have been completely retained after modification. This work shows application potentiality in the field of EMI pollution protection and affords a novel path for the construction of multifunctionally wearable and durable EMI shielding materials.

Magnetically Responsive Gallium-Based Liquid Metal: Preparation, Property and Application

Magnetically responsive soft smart materials have garnered significant academic attention due to their flexibility, remote controllability, and reconfigurability. However, traditional soft materials used in the construction of these magnetically responsive systems typically exhibit low density and poor thermal and electrical conductivities. These limitations result in suboptimal performance in applications such as medical radiography, high-performance electronic devices, and thermal management. To address these challenges, magnetically responsive gallium-based liquid metals have emerged as promising alternatives. In this review, we summarize the methodologies for achieving magnetically responsive liquid metals, including the integration of magnetic agents into the liquid metal matrix and the utilization of induced Lorentz forces. We then provide a comprehensive discussion of the key physicochemical properties of these materials and the factors influencing them. Additionally, we explore the advanced and potential applications of magnetically responsive liquid metals. Finally, we discuss the current challenges in this field and present an outlook on future developments and research directions.

Proton Hydrogel-Based Supercapacitors with Rapid Low-Temperature Self-Healing Properties

Hydrogel-based supercapacitors are an up-and-coming candidate for safe and portable energy storage. However, it is challenging for hydrogel electrolytes to achieve high conductivity and rapid self-healing at subzero temperatures because the movements of polymer chains and the reconstruction capability of broken dynamic bonds are limited. Herein, a highly conductive proton polyacrylamide-phytic acid (PAAm-PA) hydrogel electrolyte with rapid and autonomous self-healing ability and excellent adhesion over a wide temperature range is developed. PA, as a proton donor center, endows the hydrogels with high conductivity (102.0 mS cm-1) based on the Grotthuss mechanism. PA can also prevent the crystallization of water and form multiple reversible hydrogen bonds in the polymer network, which solves the dysfunction of self-healing hydrogels in a cryogenic environment. Accordingly, the hydrogel electrolytes demonstrate fast low-temperature self-healing ability with a self-healing efficiency of 79.4% within 3 h at -20 °C. In addition, the hydrogel electrolytes present outstanding adhesiveness on electrodes due to the generation of hydrogen bonds between PA and activated carbon electrodes. As a result, the integrated hydrogel-based supercapacitors with tight bonding electrode/electrolyte interface deliver a 139.5 mF cm-2 specific capacitance at 25 °C. Moreover, the supercapacitors display superb self-healing ability, achieving 92.1% of capacitance recovery after three cutting-healing cycles at -20 °C. Furthermore, the supercapacitors demonstrate only 6.4% capacitance degradation after 5000 charging-discharging cycles at -20 °C. This work provides a roadmap for designing all-in-one flexible energy storage devices with excellent self-healing ability over a wide temperature range.

Microporous Cobalt Ferrite with Bio-Carbon Loosely Decorated to Construct Multi-Functional Composite for Dye Adsorption, Anti-Bacteria and Electromagnetic Protection

Currently, facing electromagnetic protection requirement under complex aqueous environments, the bacterial reproduction and organic dye corrosion may affect the composition and micro-structures of absorbers to weaken their electromagnetic properties. To address such problems, herein, a series of CoFe2O4@BCNPs (cobalt ferrite @ bio-carbon nanoparticles) composites are synthesized via co-hydrothermal and calcining process. The coupling of magnetic cobalt ferrite and dielectric bio-carbon derived from Apium can endow the composite multiple absorption mechanisms and matched impedance for effective microwave absorption, attaining a bandwidth of 8.12 GHz at 2.36 mm and an intensity of -49.85 dB at 3.0 mm. Due to the ROS (reactive oxygen species) stimulation ability and heavy metal ions of cobalt ferrite, the composite realizes an excellent antibacterial efficiency of 99% against Gram negative bacteria of Escherichia coli. Moreover, the loose porous layer of surface stacked bio-carbon can promote the adsorption of methylene blue for subsequent eliminating, a high removal rate of 90.37% for organic dye can be also achieved. This paper offers a new insight for rational design of composite's component and micro-structure to construct multi-functional microwave absorber for satisfying the electromagnetic protection demand in complicated environments.

Plasma Engineering toward Improving the Microwave-Absorbing/Shielding Feature of a Biomass-Derived Material

During the past decade, ever-increasing electromagnetic pollution has excited a global concern. A sustainable resource, facile experimental scenario, fascinating reflection loss (RL), and broad efficient bandwidth are the substantial factors that intrigue researchers. This research led to the achievement of a brilliant microwave-absorbing material by treating pampas as biomass. The carbon-based microfibers attained by biowaste were treated by plasma under diverse environments to amplify their microwave-absorbing features. Moreover, a pyrolysis scenario was performed to compare the results. The reductive processes were performed by H2 plasma and carbonization. However, the CO2 plasma was performed to regulate the heteroatoms and defects. Interestingly, polystyrene (PS) was applied as a microwave-absorbing matrix. The aromatic rings existing in the absorbing medium establish electrostatic interactions, elevating interfacial polarization, and physical characteristics of PS augment the practical applications of the final product. The manipulated biomasses were characterized by Raman, X-ray diffraction, energy-dispersive spectroscopy, field emission scanning electron microscopy, and diffuse reflection spectroscopy analyses. Eventually, the microwave-absorbing features were estimated by a vector network analyzer. The plasma-treated pampas under H2/Ar blended with PS gained a maximum RL of -90.65 dB at 8.79 GHz and an efficient bandwidth (RL ≤ -10 dB) of 4.24 GHz with a thickness of 3.20 mm; meanwhile, plasma treatment under CO2 led to a maximum RL of 97.99 dB at 14.92 GHz and an efficient bandwidth of 7.74 GHz with a 2.05 mm thickness. Particularly, the biomass plasmolyzed under Ar covered the entire X and Ku bands with a thickness of 2.10 mm. Notably, total shielding efficiencies of the treated bioinspired materials were up to ≈99%, desirable for practical applications.

Multifunctional Conductive Hydrogel Composites with Nickel Nanowires and Liquid Metal Conductive Highways

The dramatic growth of smart wearable electronics has generated a demand for conductive hydrogels due to their tunability, stimulus responsiveness, and multimodal sensing capabilities. However, the substantial trade-off between mechanical and electrical properties hinders their multifunctionality. Here, we report a double-network hydrogel composite that features a conductive "highway" constructed using magnetic-field-aligned nickel nanowires and liquid metal. The liquid metal fills the gaps between the aligned nickel nanowires. Such interconnected structures can form efficient conductive paths at low filler content, resulting in high conductivity (1.11 × 104 S/m) and mechanical compliance (Young's modulus, 89 kPa; toughness, 721 kJ/m3). When used as a wearable sensor, the hydrogel displays a high sensitivity and fast response for wireless motion detection and human-machine interaction. Furthermore, by exploiting its outstanding conductivity and electrical heating capacity, the hydrogel integrates electromagnetic shielding and thermal management functionalities. Owing to these all-around properties, our design offers a broader platform for expanding hydrogel applications.

LM-Gel Plasticine Based on Binary Cooperative with Kneadable Shaping and Conductivity

Liquid metal (LM)-based polymers have received growing interest for wearable health monitoring, electronic skins, and soft robotics. However, fabricating multifunctional LM-based polymers, in particular, featuring a convenient shaping ability while offering excellent deformability and conductivity remains a challenge. To overcome this obstacle, here, we propose a strategy to prepare LM-Gel "plasticine" (LGP) with great deformability, which is composed of a PVA (poly(vinyl alcohol)) soft network and an LM conductive phase. LGP can be easily constructed into different shapes such as plasticine and can be applied to different conditions (such as building a 3D circuit, circuit repair, and switch). Meanwhile, LGP has great conductivity (2.3 × 104 S/m) after surface annealing. Besides, LGP has a good electric heating performance, which shows the potential for application in wearable heating devices. Thus, this approach not only provides a way to prepare LM-polymer plasticine but also provides a novel perspective toward extending the applied range of LM-polymer composites.

Hollow Metal-Organic Framework/MXene/Nanocellulose Composite Films for Giga/Terahertz Electromagnetic Shielding and Photothermal Conversion

With the continuous advancement of communication technology, the escalating demand for electromagnetic shielding interference (EMI) materials with multifunctional and wideband EMI performance has become urgent. Controlling the electrical and magnetic components and designing the EMI material structure have attracted extensive interest, but remain a huge challenge. Herein, we reported the alternating electromagnetic structure composite films composed of hollow metal-organic frameworks/layered MXene/nanocellulose (HMN) by alternating vacuum-assisted filtration process. The HMN composite films exhibit excellent EMI shielding effectiveness performance in the GHz frequency (66.8 dB at Ka-band) and THz frequency (114.6 dB at 0.1-4.0 THz). Besides, the HMN composite films also exhibit a high reflection loss of 39.7 dB at 0.7 THz with an effective absorption bandwidth up to 2.1 THz. Moreover, HMN composite films show remarkable photothermal conversion performance, which can reach 104.6 °C under 2.0 Sun and 235.4 °C under 0.8 W cm-2, respectively. The unique micro- and macro-structural design structures will absorb more incident electromagnetic waves via interfacial polarization/multiple scattering and produce more heat energy via the local surface plasmon resonance effect. These features make the HMN composite film a promising candidate for advanced EMI devices for future 6G communication and the protection of electronic equipment in cold environments.

Compositional and Hollow Engineering of Silicon Carbide/Carbon Microspheres as High-Performance Microwave Absorbing Materials with Good Environmental Tolerance

Microwave absorbing materials (MAMs) characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications. Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions, while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals. Herein, we have successfully implemented compositional and structural engineering to fabricate hollow SiC/C microspheres with controllable composition. The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites. The formation of hollow structure not only favors lightweight feature, but also generates considerable contribution to microwave attenuation capacity. With the synergistic effect of composition and structure, the optimized SiC/C composite exhibits excellent performance, whose the strongest reflection loss intensity and broadest effective absorption reach - 60.8 dB and 5.1 GHz, respectively, and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies. In addition, the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.

Stretchable, Transparent, and Ultra-Broadband Terahertz Shielding Thin Films Based on Wrinkled MXene Architectures

With the increasing demand for terahertz (THz) technology in security inspection, medical imaging, and flexible electronics, there is a significant need for stretchable and transparent THz electromagnetic interference (EMI) shielding materials. Existing EMI shielding materials, like opaque metals and carbon-based films, face challenges in achieving both high transparency and high shielding efficiency (SE). Here, a wrinkled structure strategy was proposed to construct ultra-thin, stretchable, and transparent terahertz shielding MXene films, which possesses both isotropous wrinkles (height about 50 nm) and periodic wrinkles (height about 500 nm). Compared to flat film, the wrinkled MXene film (8 nm) demonstrates a remarkable 36.5% increase in SE within the THz band. The wrinkled MXene film exhibits an EMI SE of 21.1 dB at the thickness of 100 nm, and an average EMI SE/t of 700 dB μm-1 over the 0.1-10 THz. Theoretical calculations suggest that the wrinkled structure enhances the film's conductivity and surface plasmon resonances, resulting in an improved THz wave absorption. Additionally, the wrinkled structure enhances the MXene films' stretchability and stability. After bending and stretching (at 30% strain) cycles, the average THz transmittance of the wrinkled film is only 0.5% and 2.4%, respectively. The outstanding performances of the wrinkled MXene film make it a promising THz electromagnetic shielding materials for future smart windows and wearable electronics.

Quasi-Hyperbolic Framework Graphite Foam-Based Composites with High Thermal Conductivity and Electromagnetic Shielding Properties Fabricated by an Electrochemical Expansion Method

Nowadays, the rapid development of electronic devices requires composites with high thermal conductivity and good electromagnetic shielding properties. The key challenge lies in the construction of high-performance conductive networks. Herein, an electrochemical expansion graphite foam (EEG) with a quasi-hyperbolic framework was prepared by an electrochemical expansion method, and then the epoxy resin (EP) was filled to fabricate the composites. The graphite plate was first electrochemically intercalated and then foamed, in which plasticization was caused by weak oxidation in intercalation and the quasi-hyperbolic framework was induced by foaming during expansion. These processes were characterized by Fourier transform infrared (FTIR), micro-Raman, X-ray photoelectron spectroscopy (XPS), and so on. Based on the highly efficient quasi-hyperbolic framework and high-quality graphite structure, the thermal conductivity of the composite reached 43.523 W/(m·K), and total electromagnetic interference (EMI) shielding (SET) reached 105 dB. The heat transfer behavior was simulated by finite element analysis (FEA) in detail. This method of preparing high thermal conductivity and electromagnetic shielding materials has a good application prospect.

Dendrimer-assisted defect and morphology regulation for improving optical, hyperthermia, and microwave-absorbing features

Electromagnetic pollution and cancer are phenomena that essentially endanger the future of humanity. Herein, multiple approaches are being proposed to solve the aforementioned issues. Recent studies have demonstrated that by regulating the morphology, defect, and phase of materials, their microwave absorbing, optical, and hyperthermia properties are tunable. Calcium ferrite with proper dielectric, magnetic, and biocompatible characteristics was chosen as a substantial candidate to promote its microwave-absorbing properties by regulating its structure. Spinel CaFe2O4 was synthesized through sol-gel and solvothermal routes and its phase, defect, and morphology were manipulated using innovative procedures. Glucose was applied as conventional defecting and templating agent; interestingly, a dendrimer was designed to bear and form nanoparticles. More importantly, a novel reductive process was designed to fabricate one-put Ca/Fe3O4 using a solvothermal method. Particularly, polypropylene (PP) was employed as a practical polymeric matrix to fabricate the eventual product. Structures were molded at a low filling ratio to evaluate their optical and microwave-absorbing performance. As expected, defects, morphology, and phase play a pivotal role in tuning the optical and microwave-absorbing properties of calcium ferrite derivates. Interestingly, the dendrimer-assisted (D-A) formation of CaFe2O4 demonstrated a fascinating reflection loss (RL) of 70.11 dB and an efficient bandwidth (RL ≤ -20 dB) of 7.03 GHz with ultralow thickness (0.65 mm) and filling ratio (10 wt%), attaining proper shielding efficiency (SE) and hyperthermia desirable for its practical application as a material for shielding buildings and cancer therapy. The presented perspective develops new inspirations for architecting microwave absorbing/shielding materials with advanced applications in therapeutic issues.

A temperature and pressure dual-responsive, stretchable, healable, adhesive, and biocompatible carboxymethyl cellulose-based conductive hydrogels for flexible wearable strain sensor

The study aimed to develop a novel temperature and pressure dual-responsive conductive hydrogel with self-healing, self-adhesive, biocompatible, and stretchable properties, for the development of multifunctional anti-counterfeiting and wearable flexible electronic materials. A conductive hydrogel based on carboxymethyl cellulose (CMC) was synthesized by simple "one pot" free radical polymerization of CMC, acrylamide (AAm) and acrylic acid (AAc). The hydrogel displayed temperature responsiveness and possessed an upper critical solution temperature (UCST) value. In addition, hydrogels also had surprising pressure responsiveness. The synthesized hydrogels were characterized by FTIR, TGA, DSC, and XRD analysis. Importantly, the obtained hydrogels exhibited exceptional mechanical properties (stress: 730 kPa, strain: 880%), fatigue resistance, stretchability, self-healing capability, self-adhesive properties, and conductivity. In addition, valuable insights were obtained into the synthesis and application of flexible anti-counterfeiting and camouflage materials by the temperature and pressure dual-responsive hydrogels. Moreover, the prepared hydrogel, with an electrically sensitive perception of external strain (GF = 2.61, response time: 80 ms), can be utilized for monitoring human movement, emotional changes, physiological signals, language, and more, rendering it suitable for novel flexible anti-counterfeiting materials and versatile wearable iontronics. Overall, this study provided novel insights into the simple and efficient synthesis and sustainable manufacturing of environmentally friendly multifunctional anti-counterfeiting materials and flexible electronic skin sensors.

Microwave-assisted ZnO-decorated carbon urchin resembling 'shish-kebab' morphology with self-healing and enhanced electromagnetic shielding properties

Herein, inspired by Acacia auriculiformis fruit, the shish-kebab-like growth of ZnO on carbon urchin (ZnO@CU) was designed using microwave radiation, thus leading to a hierarchal 3D structure that can promote multiple internal reflections through polarization centers. This hierarchal structure was then dispersed in a designer polyetherimide (PEI) matrix containing dynamic covalent bonds that can undergo metathesis, triggered by temperature, to harness self-healing properties in the composite. Such key attributes are required for their potential use in EMI shielding applications where frequent repairs are indispensable. Morphological investigation revealed that the ZnO flower was periodically nucleated like 'shish-kebab' structures on CU surfaces. CU was designed from short carbon fibers using a facile modified method. The EMI shielding performance of the resulting composites was investigated in the X-band, illustrating a shielding effectiveness of -40.6 dB for 2 wt% of ZnO@CU loading, and the composite can be preserved after the self-healing procedure. The ZnO 'kebabs' on 'CU shish' facilitated multiple scattering and numerous polarization centers to improve the EMI shielding performances at extremely low filler contents. In addition, the mechanical and thermal properties of the composite showed improved structural integrity and superior resistance to extreme temperatures, respectively. Overall, the proposed ZnO@CU/PEI composite has great potential to fulfill the increasing demands for lightweight EMI shielding materials in many fields.

Polyvinyl alcohol/chitosan based nanocomposite organohydrogel flexible wearable strain sensors for sports monitoring and underwater communication rescue

Hydrogel-based flexible wearable sensors have garnered significant attention in recent years. However, the use of hydrogel, a biomaterial known for its high toughness, environmental friendliness, and frost resistance, poses a considerable challenge. In this study, we propose a stepwise construction and multiple non-covalent interaction matching strategy to successfully prepare dynamically physically crosslinked multifunctional conductive hydrogels. These hydrogels self-assembled to form a rigid crosslinked network through intermolecular hydrogen bonding and metal ion coordination chelation. Furthermore, the freeze-thawing process promoted the formation of poly(vinyl alcohol) microcrystalline domains within the amorphous hydrogel network system, resulting in exceptional mechanical properties, including a tensile strength (2.09 ± 0.01 MPa) and elongation at break of 562 ± 12 %. It can lift 10,000 times its own weight. Additionally, these hydrogels exhibit excellent resistance to swelling and maintain good toughness even at temperatures as low as -60 °C. As a wearable strain sensor with remarkable sensing ability (GF = 1.46), it can be effectively utilized in water and underwater environments. Moreover, it demonstrates excellent antimicrobial properties against Escherichia coli (Gram-negative bacteria). Leveraging its impressive sensing ability, we combine signal recognition with a deep learning model by incorporating Morse code for encryption and decryption, enabling information transmission.

Sn Whiskers from Ti2 SnC Max Phase: Bridging Dual-Functionality in Electromagnetic Attenuation

In the ever-evolving landscape of complex electromagnetic (EM) environments, the demand for EM-attenuating materials with multiple functionalities has grown. 1D metals, known for their high conductivity and ability to form networks that facilitate electron migration, stand out as promising candidates for EM attenuation. Presently, they find primary use in electromagnetic interference (EMI) shielding, but achieving a dual-purpose application for EMI shielding and microwave absorption (MA) remains a challenge. In this context, Sn whiskers derived from the Ti2 SnC MAX phase exhibit exceptional EMI shielding and MA properties. A minimum reflection loss of -44.82 dB is achievable at lower loading ratios, while higher loading ratios yield efficient EMI shielding effectiveness of 42.78 dB. These qualities result from a delicate balance between impedance matching and EM energy attenuation via adjustable conductive networks; and the enhanced interfacial polarization effect at the cylindrical heterogeneous interface between Sn and SnO2 , visually characterized through off-axis electron holography, also contributes to the impressive performance. Considering the compositional diversity of MAX phases and the scalable fabrication approach with environmental friendliness, this study provides a valuable pathway to multifunctional EM attenuating materials based on 1D metals.

Highly stretchable anti-freeze hydrogel based on aloe polysaccharides with high ionic conductivity for multifunctional wearable sensors

Conductive hydrogels have limitations such as non-degradability, loss of electrical conductivity at sub-zero temperatures, and single functionality, which limit their applicability as materials for wearable sensors. To overcome these limitations, this study proposes a bio-based hydrogel using aloe polysaccharides as the matrix and degradable polyvinyl alcohol as a reinforcing material. The hydrogel was crosslinked with borax in a glycerol-water binary solvent system, producing good toughness and compressive strength. Furthermore, the hydrogel was developed as a sensor that could detect both small and large deformations with a low detection limit of 1 % and high stretchability of up to 300 %. Moreover, the sensor exhibited excellent frost resistance at temperatures above -50 °C, and the gauge factor of the hydrogel was 2.86 at 20 °C and 2.12 at -20 °C. The Aloe-polysaccharide-based conductive hydrogels also functioned effectively as a wearable sensor; it detected a wide range of humidities (0-98 % relative humidity) and exhibited fast response and recovery times (1.1 and 0.9 s) while detecting normal human breathing. The polysaccharide hydrogel was also temperature sensitive (1.737 % °C-1) and allowed for information sensing during handwriting.

A multifunctional hydrogel dressing with high tensile and adhesive strength for infected skin wound healing in joint regions

Most hydrogel dressings are designed for skin wounds in flat areas, and few are focused on the joint skin regions which undergo frequent movement. The mismatch of mechanical properties and poor fit between a hydrogel dressing and a wound in joint skin results in hydrogel shedding, bacterial infection and delayed healing. Therefore, it is of great significance to design and prepare a multifunctional hydrogel with high tensile and tissue-adhesive strength as well as other therapeutic effects for the treatment of joint skin wounds. In this work, a multifunctional hydrogel was reasonably prepared by simply mixing polyvinyl alcohol (PVA), borax, tannic acid (TA) and iron(III) chloride in certain proportions, which was further used to treat the skin wounds at the joint of the hind limb. Acting as the physical crosslinkers, borax and TA dynamically bond with PVA and provide the resulting hydrogel with strong tensile, fast shape-adaptive and self-healing properties. The photothermal bacteriostatic activity of the hydrogel is attributed to the formation of a metallic polyphenol network (MPN) between ferric ions and TA. In addition, the hydrogel exhibits high levels of adhesion, hemostatic performance, antioxidant abilities, and biocompatibility, and shows great potential to promote joint skin wound healing.

Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano-Aerogel via Abundant Nano-Sized Cavities and Attenuation Interfaces

Pre-polymerized vinyl trimethoxy silane (PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization, sol-gel transition and supercritical CO2 drying. The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size (30-40 nm), high specific surface area (559 m2 g-1), high void fraction (91.7%) and enhanced mechanical property: (1) the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect (beneficial for infrared (IR) stealth); (2) the heterogeneous interface was beneficial for IR reflection (beneficial for IR stealth) and MWCNT polarization loss (beneficial for electromagnetic wave (EMW) attenuation); (3) the high void fraction was beneficial for enhancing thermal insulation (beneficial for IR stealth) and EMW impedance match (beneficial for EMW attenuation). Guided by the above theoretical design strategy, PVTMS@MWCNT nano-aerogel shows superior EMW absorption property (cover all Ku-band) and thermal IR stealth property (ΔT reached 60.7 °C). Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity, an extremely high electromagnetic interference shielding material (66.5 dB, 2.06 mm thickness) with superior absorption performance of an average absorption-to-reflection (A/R) coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz (A/R ratio more than 10) was experimentally obtained in this work.

Nitrogen-Doped Magnetic-Dielectric-Carbon Aerogel for High-Efficiency Electromagnetic Wave Absorption

Carbon-based aerogels derived from biomass chitosan are encountering a flourishing moment in electromagnetic protection on account of lightweight, controllable fabrication and versatility. Nevertheless, developing a facile construction method of component design with carbon-based aerogels for high-efficiency electromagnetic wave absorption (EWA) materials with a broad effective absorption bandwidth (EAB) and strong absorption yet hits some snags. Herein, the nitrogen-doped magnetic-dielectric-carbon aerogel was obtained via ice template method followed by carbonization treatment, homogeneous and abundant nickel (Ni) and manganese oxide (MnO) particles in situ grew on the carbon aerogels. Thanks to the optimization of impedance matching of dielectric/magnetic components to carbon aerogels, the nitrogen-doped magnetic-dielectric-carbon aerogel (Ni/MnO-CA) suggests a praiseworthy EWA performance, with an ultra-wide EAB of 7.36 GHz and a minimum reflection loss (RLmin) of - 64.09 dB, while achieving a specific reflection loss of - 253.32 dB mm-1. Furthermore, the aerogel reveals excellent radar stealth, infrared stealth, and thermal management capabilities. Hence, the high-performance, easy fabricated and multifunctional nickel/manganese oxide/carbon aerogels have broad application aspects for electromagnetic protection, electronic devices and aerospace.

Patterned Liquid-Metal-Enabled Universal Soft Electronics (PLUS-E) for Deformation Sensing on 3D Curved Surfaces

Liquid metals with metallic conductivity and infinitely deformable properties have tremendous potential in the field of conformal electronics. However, most processing methods of liquid metal electronics require sophisticated apparatus or custom masks, resulting in high processing costs and intricate preparation procedures. This study proposes a simple and rapid preparation method for patterned liquid-metal-enabled universal soft electronics (PLUS-E). The utilization of selective adhesion of the liquid metals on stretchable substrates and the adaptive toner mask enables rapid fabrication (<2 s/100 cm2), excellent stretchability (800% strain), and high forming accuracy (100 μm). Benefiting from the adaptive deformation of the substrate and toner mask, PLUS-E can be conformally applied to any shape of 3D surfaces. Besides, the stability of PLUS-E on 3D surfaces is improved by low-fluidity liquid metal composites. The finite element simulation is used to accurately forecast the deformation and resistance changes of the PLUS-E, and it provides guidance for device design and manufacturing. Finally, this method was utilized to develop various sensors for detecting human motion, catheter bending, and balloon expansion. All of them have obtained stable and reliable signal measurements, demonstrating the usefulness of PLUS-E in real-world applications.

A multi-layer core-shell structure CoFe2O4@Fe3C@NiO composite with high broadband electromagnetic wave-absorption performance

Enhancing the absorption strength of electromagnetic waves and broadening the absorption band are constant goals in designing and preparing absorbing materials. The use of composites has shown to be a very efficient method for acquiring broadband-absorbing materials, while the construction of a core-shell structure has demonstrated a significant enhancement in absorption capability. In this paper, the nanocomposite metal-organic framework (MOF) derivative CoFe2O3@C with a double core-shell structure and the nanocomposite MOF derivative CoFe2O4@Fe3C@NiO with a three-layered core-shell structure have been prepared using a chemical compound. The multi-layer structure provides more active sites for the multiple reflection and scattering of electromagnetic waves, effectively improving the attenuation capability. The effective absorption band (EAB) (reflection loss (RL) ≤ -5 dB) of both CoFe2O3@C and CoFe2O4@Fe3C@NiO are broadened compared to that of the ZIF-67 derivative. In particular, the minimum reflection loss (RLmin) of CoFe2O3@C was -52.7 dB at 13.3 GHz and 2.04 mm, and the EAB (RL ≤ -5 dB) is as wide as 9.35 GHz. Compared with the ZIF-67 derivative, the EAB exhibits a twofold rise, accompanied by a corresponding thickness increase of just 0.24 mm. At a matched thickness of 2.2 mm, the EAB of CoFe2O4@Fe3C@NiO can even reach 11.9 GHz.