Multiresponsive MXene (Ti3C2Tx)-Decorated Textiles for Wearable Thermal Management and Human Motion Monitoring

Unperceivable Designs of Wearable Electronics

Wearable smart electronics are taking an increasing part of the consumer electronics market, with applications in advanced healthcare systems, entertainment, and Internet of Things. The advanced development of flexible, stretchable, and breathable electronic materials has paved the way to comfortable and long-term wearables. However, these devices can affect the wearer's appearance and draw attention during use, which may impact the wearer's confidence and social interactions, making them difficult to wear on a daily basis. Apart from comfort, one key condition for user acceptance is that these new technologies seamlessly integrate into our daily lives, remaining unperceivable to others. In this review, strategies to minimize the visual impact of wearable devices and make them more suitable for daily use are discussed. These new devices focus on being unperceivable when worn and comfortable enough that users almost forget their presence, reducing psychological discomfort while maintaining accuracy in signal collection. Materials selection is crucial for developing long-term and unperceivable wearable devices. Recent developments in these unperceivable electronic devices are also covered, including sensors, transistors, and displays, and mechanisms to achieve unperceivability are discussed. Finally, the potential applications are summarized and the remaining challenges and prospects are discussed.

Balancing catalyst-intermediate interactions: Unlocking high-performance MXene-supported catalysts for two-electron water oxidation reaction from single atoms to nanoparticles

Two-electron water oxidation reaction (2e-WOR) provides an eco-friendly and cost-efficient approach to H2O2 synthesis. ZnO-based catalysts exhibit outstanding H2O2 activity and selectivity. Exploring the relationship between the structure of different zinc-based catalysts and their 2e-WOR performance is crucial for the rational design and development of high-performance catalysts. In this work, MXene (Ti3C2Tx) nanosheets were employed as supports to prepare zinc single atoms, ZnO nanoclusters and nanoparticles on MXene. Structural characterization, electrocatalytic evaluation, and density functional theory (DFT) calculations revealed distinct differences in catalyst performance. Zn-SA/MXene and ZnO-NC/MXene exhibit strong interactions with OH radicals, resulting in adsorption energies that greatly exceed the optimal range of -2.4∼-1.6 eV. This excessive interaction hinders efficient hydrogen peroxide production. In contrast, ZnO-NP/MXene achieves a balanced interaction with OH, with adsorption energy approaching the optimal range, leading to superior 2e-WOR activity. These findings highlight the critical role of tuning the interaction strength between active sites and OH radicals to achieve optimal catalytic performance. This work offers valuable theoretical insights and experimental validation for designing high-performance 2e-WOR catalysts, demonstrating that neither excessively strong nor weak interactions are conducive to maximizing efficiency.

High-Performance Flexible Strain Sensors: The Role of In-Situ Cross-Linking and Interface Engineering in Liquid Metal-Carbon Nanotube-PDMS Composites

The increasing demand for high-performance strain sensors has driven the development of innovative composite systems. This study focused on enhancing the performance of composites by integrating liquid metal, carbon nanotubes, and polydimethylsiloxane (PDMS) in an innovative approach that involved advanced interface engineering, filler synergy, and in situ cross-linking of PDMS in solution. Surface modification of liquid metal with allyl disulfide and hydrogen-containing polydimethylsiloxane significantly improved its stability and dispersion within the polymer matrix. Through in situ cross-linking in solution and subsequent segment rearrangement after solvent evaporation, a continuous filler network was formed within the composite. The composites exhibited enhanced thermal stability, achieving a thermal conductivity of up to 2.13 W/(m·K) while simultaneously attaining a high electrical conductivity of 416 S/cm. The composite demonstrated excellent thermal management capabilities, alongside remarkable mechanical properties, including over 400% elongation at break and a low modulus of 0.587 MPa, even at high filler content. These attributes make the composite highly suitable for flexible strain sensor applications. Notably, the composite demonstrated outstanding strain sensing capabilities, effectively monitoring both human motion and handwriting. This work highlighted the critical roles of interface modification, filler interactions, and in situ cross-linking in achieving significant improvements in thermal, electrical, and sensing performance, thereby advancing the potential applications of flexible electronic materials.

Cellulose-based functional textiles through surface nano-engineering with MXene and MXene-based composites

The emergence of smart textiles with the ability to regulate body temperature, monitor human motion, exhibit antibacterial properties, sound fire alarms, and offer fire resistance has sparked considerable interest in recently. MXene displays remarkable attributes like high metallic conductivity, electromagnetic shielding capability, and photothermal/electrothermal properties. Furthermore, due to the highly polar surface groups, MXene nanosheets show exceptional hydrophilic properties and are able to establish strong connections with the polar surfaces of natural fabrics. This review focuses on the most recent developments in altering the surface of cellulosic textiles with MXene and MXene-based composites. The combination of MXene with other modifier agents, such as phosphorous compounds, graphene, carbon nanotube, conductive polymers, antibacterial macromolecules, superhydrophobic polymers, and metal or metal oxide nanoparticles, imparts diverse functionalities to textiles, such as self-cleaning and fire resistance. Moreover, the synergistic effects between these modifier agents with MXenes can improve MXene-related properties like antibacterial, photothermal, electrothermal, and motion- and fire-sensing characteristics.

Architectural design and affecting factors of MXene-based textronics for real-world application

Today, textile-based wearable electronic devices (textronics) have been developed by taking advantage of nanotechnology and textile substrates. Textile substrates offer flexibility, air permeability, breathability, and wearability, whereas, using nanomaterials offers numerous functional properties, like electrical conductivity, hydrophobicity, touch sensitivity, self-healing properties, joule heating properties, and many more. For these reasons, textronics have been extensively used in many applications. Recently, new emerging two-dimensional (2D) transition metal carbide and nitride, known as MXene, nanomaterials have been highly considered for developing textronics because the surface functional groups and hydrophilicity of MXene nanoflakes allow the facile fabrication of MXene-based textronics. In addition, MXene nanosheets possess excellent electroconductivity and mechanical properties as well as large surface area, which also give numerous opportunities to develop novel functional MXene/textile-based wearable electronic devices. Therefore, this review summarizes the recent advancements in the architectural design of MXene-based textronics, like fiber, yarn, and fabric. Regarding the fabrication of MXene/textile composites, numerous factors affect the functional properties (e.g. fabric structure, MXene size, etc.). All the crucial affecting parameters, which should be chosen carefully during the fabrication process, are critically discussed here. Next, the recent applications of MXene-based textronics in supercapacitors, thermotherapy, and sensors are elaborately delineated. Finally, the existing challenges and future scopes associated with the development of MXene-based textronics are presented.

Flexible MXene/Nanocellulose Composite Aerogel Film with Cellular Structure for Electromagnetic Interference Shielding and Photothermal Conversion

With the rapid development of wearable devices and integrated systems, protection against electromagnetic waves is an issue. For solving the problems of poor flexibility and a tendency to corrode traditional electromagnetic interference (EMI) shielding materials, two-dimensional (2D) nanomaterial MXene was employed to manufacture next-generation EMI shielding materials. Vacuum-assisted filtration combined with the liquid nitrogen prefreezing strategy was adopted to prepare flexible MXene/cellulose nanofibers (CNFs) composite aerogel film with unique cellular structure. Here, CNFs were employed as the reinforcement, and such a cellular structure design can effectively improve the shielding effectiveness (SE). In particular, the composite shows an outstanding EMI SE of 54 dB. Furthermore, the MXene/CNFs composite aerogel film exhibited prominent and steady photothermal conversion ability, which could obtain the maximum equilibrium temperature of 89.4 °C under an 808 nm NIR laser. Thus, our flexible composite aerogel film with appealing cellular construction holds great promise for wearable EMI shielding materials and heating applications in a cold and complex practical environment.

Waterproof, Light Responsive, and Highly Sensitive Fabric Strain Sensor for Flexible Electronics

Corrosion resistant, durable, and lightweight flexible strain sensor with multiple functionalities is an urgent demand for modern flexible wearable devices. However, currently developed wearable devices are still limited by poor environmental adaptability and functional singleness. In this work, a conductive fabric with multifunctionality in addition to sensing was successfully prepared by assembling zero dimensional silver nanoparticles (AgNPs) and one-dimensional carbon nanotubes (CNTs) layer by layer on the surface of the elastic polypropylene nonwoven fabric (named PACS fabric). Polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS) added as binder materials favored strong interaction between conductive fillers and the fabric. Benefiting from the synergistic interaction among the conductive fillers with different dimensions and the fabric, the strain sensor based on the conductive fabric showed high sensitivity (GF up to 8064), wide detection range (0-200%), and excellent stability and durability (more than 10000 stretch-release cycles). Besides, the prepared conductive fabric showed superhydrophobicity (water contact angle = 154°) with excellent durability. This ensured the performance stability of the fabric sensor in harsh environments. At the same time, the fabric also showed excellent photothermal conversion performance (90 °C at a power density of 0.2 W/cm2 within 20 s). The PACS fabric strain sensor proved excellent performance and environmental adaptability, revealing great potential to be applied in human motion monitoring, self-cleaning, biomedicine, and other fields.

A review on accelerated development of skin-like MXene electrodes: from experimental to machine learning

Foreshadowing future needs has catapulted the progress of skin-like electronic devices for human-machine interactions. These devices possess human skin-like properties such as stretchability, self-healability, transparency, biocompatibility, and wearability. This review highlights the recent progress in a promising material, MXenes, to realize soft, deformable, skin-like electrodes. Various structural designs, fabrication strategies, and rational guidelines adopted to realize MXene-based skin-like electrodes are outlined. We explicitly discussed machine learning-based material informatics to understand and predict the properties of MXenes. Finally, an outlook on the existing challenges and the future roadmap to realize soft skin-like MXene electrodes to facilitate technological advances in the next-generation human-machine interactions has been described.

3D Janus structure MXene/cellulose nanofibers/luffa aerogels with superb mechanical strength and high-efficiency desalination for solar-driven interfacial evaporation

Interfacial solar steam generation (ISSG) is considered to be an attractive technique to address the water shortage. However, developing a sustainable thermal management, salt rejection, and excellent mechanical strength ISSG device for long-term stability desalination is still a challenge. Herein, a biomass ISSG device with superb mechanical properties was prepared by introducing a luffa sponge as the skeleton and constructing the MXene/cellulose nanofibers (CNFs) aerogels via freeze-drying. The Janus MXene-decorated CNFs/luffa (JMCL) aerogels integrated the multifunction of fast water transport, good thermal management, and efficient photothermal conversion in a single module, to achieve high-efficiency desalination. 3D Janus structure endowed the JMCL aerogel with opposite wettability, which is feasible to construct the localized photothermal generation and self-floating. The mechanical strength of JMCL aerogels is 437 times that of MXene/CNFs aerogels. The JMCL aerogels delivered a water evaporation rate of 1.40 kg m^-2h^-1 and an efficiency of 91.20% under 1 sun illumination. The excellent salt resistance during 24 h working and long-term solar vapor generation of up to 28 days were achieved. The multifunctional JMCL aerogels with 3D Janus structure offer new insights for developing good durability and eco-friendly biopolymer-based steam generators.

Nanocellulose-Assisted Construction of Multifunctional MXene-Based Aerogels with Engineering Biomimetic Texture for Pressure Sensor and Compressible Electrode

Multifunctional architecture with intriguing structural design is highly desired for realizing the promising performances in wearable sensors and flexible energy storage devices. Cellulose nanofiber (CNF) is employed for assisting in building conductive, hyperelastic, and ultralight Ti3C2Tx MXene hybrid aerogels with oriented tracheid-like texture. The biomimetic hybrid aerogels are constructed by a facile bidirectional freezing strategy with CNF, carbon nanotube (CNT), and MXene based on synergistic electrostatic interaction and hydrogen bonding. Entangled CNF and CNT "mortars" bonded with MXene "bricks" of the tracheid structure produce good interfacial binding, and superior mechanical strength (up to 80% compressibility and extraordinary fatigue resistance of 1000 cycles at 50% strain). Benefiting from the biomimetic texture, CNF/CNT/MXene aerogel shows ultralow density of 7.48 mg cm-3 and excellent electrical conductivity (~ 2400 S m-1). Used as pressure sensors, such aerogels exhibit appealing sensitivity performance with the linear sensitivity up to 817.3 kPa-1, which affords their application in monitoring body surface information and detecting human motion. Furthermore, the aerogels can also act as electrode materials of compressive solid-state supercapacitors that reveal satisfactory electrochemical performance (849.2 mF cm-2 at 0.8 mA cm-2) and superior long cycle compression performance (88% after 10,000 cycles at a compressive strain of 30%).

Smart Triboelectric Nanogenerators Based on Stimulus-Response Materials: From Intelligent Applications to Self-Powered Systems

Smart responsive materials can react to external stimuli via a reversible mechanism and can be directly combined with a triboelectric nanogenerator (TENG) to deliver various intelligent applications, such as sensors, actuators, robots, artificial muscles, and controlled drug delivery. Not only that, mechanical energy in the reversible response of innovative materials can be scavenged and transformed into decipherable electrical signals. Because of the high dependence of amplitude and frequency on environmental stimuli, self-powered intelligent systems may be thus built and present an immediate response to stress, electrical current, temperature, magnetic field, or even chemical compounds. This review summarizes the recent research progress of smart TENGs based on stimulus-response materials. After briefly introducing the working principle of TENG, we discuss the implementation of smart materials in TENGs with a classification of several sub-groups: shape-memory alloy, piezoelectric materials, magneto-rheological, and electro-rheological materials. While we focus on their design strategy and function collaboration, applications in robots, clinical treatment, and sensors are described in detail to show the versatility and promising future of smart TNEGs. In the end, challenges and outlooks in this field are highlighted, with an aim to promote the integration of varied advanced intelligent technologies into compact, diverse functional packages in a self-powered mode.

Emerging MXene-Based Flexible Tactile Sensors for Health Monitoring and Haptic Perception

Due to their potential applications in physiological monitoring, diagnosis, human prosthetics, haptic perception, and human-machine interaction, flexible tactile sensors have attracted wide research interest in recent years. Thanks to the advances in material engineering, high performance flexible tactile sensors have been obtained. Among the representative pressure sensing materials, 2D layered nanomaterials have many properties that are superior to those of bulk nanomaterials and are more suitable for high performance flexible sensors. As a class of 2D inorganic compounds in materials science, MXene has excellent electrical, mechanical, and biological compatibility. MXene-based composites have proven to be promising candidates for flexible tactile sensors due to their excellent stretchability and metallic conductivity. Therefore, great efforts have been devoted to the development of MXene-based composites for flexible sensor applications. In this paper, the controllable preparation and characterization of MXene are introduced. Then, the recent progresses on fabrication strategies, operating mechanisms, and device performance of MXene composite-based flexible tactile sensors, including flexible piezoresistive sensors, capacitive sensors, piezoelectric sensors, triboelectric sensors are reviewed. After that, the applications of MXene material-based flexible electronics in human motion monitoring, healthcare, prosthetics, and artificial intelligence are discussed. Finally, the challenges and perspectives for MXene-based tactile sensors are summarized.

Ag NW-Embedded Coaxial Nanofiber-Coated Yarns with High Stretchability and Sensitivity for Wearable Multi-Sensing Textiles

The emerging intelligent piezoresistive yarn/textile-based sensors are of paramount importance for skin-interface electronics, owing to their unparalleled features including softness, breathability, and easy integration with functional devices. However, employing a facile way to fabricate 1D sensing yarns with mechanical robustness, multi-functional integration, and comfortability is still demanded for satisfying the practical applications. Herein, a facile one-step synchronous conjugated electrospinning and electrospraying technique is innovatively employed to continuously construct an Ag NW-embedded polyurethane (PU) nanofiber sensing yarn (AENSY) with hierarchical architecture. This 1D AENSY with weavability and stretchability can be woven into AENSY textile-based sensors integrated with functions of strain and pressure sensing. In this embedded multi-scale architecture, Ag NWs are evenly embedded and locked in the oriented and twisted PU nanofiber (PUNF) scaffold, forming the hierarchical mechanical sensing layer on the surface of the AENSY with favorable stability. Meanwhile, the presence of the elastic PUNFs enhances porosity, elasticity, and considerable deformation space, which in turn endow the AENSY textile-based sensor with a gauge factor (GF) up to 1010, a pressure sensitivity up to 16.7 N^-1, high stretchability up to 160%, and high stability under long-term cycles. In addition, the AENSY textile-based sensor exhibits light weight and the unique advantage of skin-friendliness with the human body, which can be directly and conformally attached to the curved human skin to monitor the various human movements. Furthermore, the weavable AENSYs can be integrated into smart textiles with sensing arrays, which are capable for spatial pressure and strain mapping. Thus, the continuous one-step developing process and the stable embedded-twisted fiber structure provide a promising strategy to develop innovative smart yarns and textiles for personalized healthcare and human-machine interfaces.

Toward Continuous Breath Monitoring on a Mobile Phone Using a Frugal Conducting Cloth-Based Smart Mask

A frugal humidity sensor that can detect changes in the humidity of exhaled breath of individuals has been fabricated. The sensor comprises a humidity-sensitive conducting polymer that is in situ formed on a cloth that acts as a substrate. Interdigitated silver electrodes were screen-printed on the modified cloth, and conducting threads connected the electrodes to the measurement circuit. The sensor's response to changing humidity was measured as a voltage drop across the sensor using a microcontroller. The sensor was capable of discerning between fast, normal, and slow breathing based on the response time. A response time of ∼1.3 s was observed for fast breathing. An Android-based mobile application was designed to collect sensor data via Bluetooth for analysis. A time series classification algorithm was implemented to analyze patterns in breathing. The sensor was later stitched onto a face mask, transforming it into a smart mask that can monitor changes in the breathing pattern at work, play, and sleep.

A Review of Electro Conductive Textiles Utilizing the Dip-Coating Technique: Their Functionality, Durability and Sustainability

The presented review summarizes recent studies in the field of electro conductive textiles as an essential part of lightweight and flexible textile-based electronics (so called e-textiles), with the main focus on a relatively simple and low-cost dip-coating technique that can easily be integrated into an existing textile finishing plant. Herein, numerous electro conductive compounds are discussed, including intrinsically conductive polymers, carbon-based materials, metal, and metal-based nanomaterials, as well as their combinations, with their advantages and drawbacks in contributing to the sectors of healthcare, military, security, fitness, entertainment, environmental, and fashion, for applications such as energy harvesting, energy storage, real-time health and human motion monitoring, personal thermal management, Electromagnetic Interference (EMI) shielding, wireless communication, light emitting, tracking, etc. The greatest challenge is related to the wash and wear durability of the conductive compounds and their unreduced performance during the textiles' lifetimes, which includes the action of water, high temperature, detergents, mechanical forces, repeated bending, rubbing, sweat, etc. Besides electrical conductivity, the applied compounds also influence the physical-mechanical, optical, morphological, and comfort properties of textiles, depending on the type and concentration of the compound, the number of applied layers, the process parameters, as well as additional protective coatings. Finally, the sustainability and end-of-life of e-textiles are critically discussed in terms of the circular economy and eco-design, since these aspects are mainly neglected, although e-textile' waste could become a huge problem in the future when their mass production starts.

Strong, flexible, and highly conductive cellulose nanofibril/PEDOT:PSS/MXene nanocomposite films for efficient electromagnetic interference shielding

Flexible and light weight electromagnetic interference (EMI) shielding materials with high electromagnetic shielding efficiency (SE) and excellent mechanical strength are highly demanded for wearable and portable electronics. In this work, for the first time, a freestanding and flexible cellulose nanofibril (CNF)/PEDOT:PSS/MXene (Ti₃C₂T_x) nanocomposite film with a ternary heterostructure was manufactured using a vacuum-assisted filtration process. The results show that compared with pure MXene films, the tensile strength of the optimized nanocomposite film increases from 8.88 MPa to 59.99 MPa, and the corresponding fracture strain increases from 0.87% to 4.60%. Intriguingly, the optimized nanocomposite film exhibited an impressive conductivity of 1903.2 S cm^-1, which is among the highest values reported for MXene and cellulose-based nanocomposites. Owing to the superior conductivity and unique heterostructure, the nanocomposite film exhibits a high EMI SE value of 76.99 dB at a thickness of only 58.0 μm. Taking into account the robust mechanical properties and remarkable EMI shielding performance, the CNF/PEDOT:PSS/MXene nanocomposite film could be a prospective EMI shielding material for a variety of high-end applications.

Cellulose nanofiber/molybdenum disulfide aerogels for ultrahigh photothermal effect

The photothermal materials have a broad range of applications in crude oil spills treatment, desalination, and photothermal therapy. However, the rational construction of aerogels with exceptional photothermal performance is highly desired yet still challenging. Herein, a class of stable aerogels comprised of molybdenum disulfide (MoS₂) nanoflowers and cellulose nanofibers (CNFs) was fabricated, affording extraordinary light-to-heat energy conversion capability. Benefiting from the intercalated porous structure, the resultant cellulose nanofibers/molybdenum disulfide (CNF/MoS₂) aerogels deliver an ultrahigh temperature output up to 260.4 °C with near infrared (NIR) laser power densities of 0.8 W cm^-2. Remarkably, when NIR laser power density increased to 1.0 W cm^-2, the aerogels began to burn, achieving the superhigh surface temperature of ∼ 690 °C. The combustion process of CNF/MoS₂ composite aerogels was evaluated in detail. Therefore, this work provides experiment evidence and theoretical basis for the rational applications of photothermal materials at high temperature in future.

Two-dimensional MXenes: recent emerging applications

MXenes, are a rapidly growing family of two-dimensional materials exhibiting outstanding electronic, optical, mechanical, and thermal properties with versatile transition metal and surface chemistries. A wide range of transition metals and surface termination groups facilitate the properties of MXenes to be easily tuneable. Due to the physically strong and environmentally stable nature of MXenes, they have already had a strong presence in different fields, for instance energy storage, electrocatalysis, water purification, and chemical sensing. Some of the newly discovered applications of MXenes showed very promising results, however, they have not been covered in any review article. Therefore, in this review we comprehensively review the recent advancements of MXenes in various potential fields including energy conversion and storage, wearable flexible electronic devices, chemical detection, and biomedical engineering. We have also presented some of the most exciting prospects by combining MXenes with other materials and forming mixed dimensional high performance heterostructures based novel electronic devices.

Generation of cost-effective MXene@polydopamine-decorated chitosan nanofibrous wound dressing for promoting wound healing

Herein, we designed and fabricated a MXene@polydopamine (MXene@PDA)-decorated chitosan non-woven fabric (M-CNF) hemostatic dressing with super hydrophilic properties for wound repair and regeneration. The M-CNF exhibit excellently wettability characteristics which can rapidly absorb water from blood. Moreover, M-CNF with 15 mg/mL MXene@PDA (M-CNF-15) show better antibacterial performance, excellent blood-clotting performance, better blood cell and platelet adhesion ability than CNF, displaying both active and passive hemostatic mechanisms to accelerate blood clotting in mouse-liver injury model. In addition, the M-CNF-15 also shows better wound healed performance than Tegaderm™ film in a full-thickness skin defect model, and further demonstrating that the MXene@PDA can promote fibrinogen reformation the at the initial phases of the wound healing process. Therefore, this strategy for designing and manufacturing of multi-functional M-CNF wound dressing will have great potential for active local hemostasis and wound repair and regeneration.

Wearable Ionogel-Based Fibers for Strain Sensors with Ultrawide Linear Response and Temperature Sensors Insensitive to Strain

Fiber-shaped stretchable strain and temperature sensors are highly desirable for wearable electronics due to their excellent flexibility, comfort, air permeability, and easiness to be weaved into fabric. Herein, we prepare a smart ionogel-based fiber composed of thermoplastic polyurethane (TPU) and ionic liquid (IL) by the facile and scalable wet-spinning technique, which can serve as a wearable strain sensor with good linearity (a correlation coefficient of 0.997) in an ultrawide sensing range (up to 700%), ultralow-detection limit (0.05%), fast response (173 ms) and recovery (120 ms), and high reproducibility. Attributed to these outstanding strain sensing performances, the designed TPU/IL ionogel fiber-shaped sensor is able to monitor both subtle physiological activities and large human motions. More interestingly, because of the fast response and high resolution to strain, the fiber-shaped sensor can be sewn into the fabric to secretly encrypt and wirelessly translate message according to the principle of Morse code. More importantly, a wearable strain-insensitive temperature sensor can be obtained from the ionogel fiber if it is designed into an "S" shape, which can effectively eliminate the interference of strain on temperature sense. It is found that the inaccuracy of temperature sense is within 0.15 °C when the sensor is subjected to 30% tensile strain simultaneously. Moreover, this strain-insensitive temperature sensor shows a monotonic temperature response over a wide temperature range (-15 to 100 °C) with an ultrahigh detecting accuracy of 0.1 °C and good reliability, owing to the fast and stable thermal response of IL. This temperature sensor can realize the detection of thermal radiation, proximity, and respiration, exhibiting enormous potential in smart skin, personal healthcare, and wearable electronics. This work proposes a simple but effective strategy to realize the essential strain and temperature sensing capabilities of wearable electronics and smart fabrics without mutual interference.

High-Performance and Rapid-Response Electrical Heaters Derived from Cellulose Nanofiber/Silver Nanowire Nanopapers for Portable Thermal Management

High-performance electrical heaters with outstanding flexibility, superior portability, and mechanical properties are highly desirable for portable thermal management. However, it is still a huge challenge to simultaneously achieve competent electrical heating performances and excellent mechanical properties. Herein, inspired by the Janus structure, versatile electrical heaters are developed via a sequential assembly followed by a hot-pressing strategy. The elaborately designed Janus structure is composed of a nanofibrillated cellulose (NFC) layer and a partially wrapped silver nanowire (AgNW) skeleton in the NFC substrate. Owing to the perfect introduction of nano-soldered points induced by thermal welding decoration, the resultant NFC/AgNW papers (NAPs) possess great flexibility, excellent mechanical strength (176.75 MPa), extremely low sheet resistance (0.60 Ω/sq), and superior electrical stabilities against mechanical deformations. Moreover, benefitting from these fascinating attributes, the NAP-based electrical heaters exhibit a remarkable heating temperature (∼220 °C), ultrafast electro-thermal response (<10 s), and groundbreaking long-term stability (∼105 °C for >186 h) and repeatability (>20,000 cycles) with low AgNW contents and driving voltages (0.5-5.0 V), which far surpass those of the previously reported and conventional indium tin oxide-based Joule heaters. Impressively, large-area production feasibilities of NAPs are demonstrated and assembled into multifunctional applications, including personal thermal management, healthcare thermotherapy, multifunctional cups, and smart homes, indicating their promising potential for wearable devices, artificial intelligence, and specific heating systems in the fields of aerospace, military, and intelligent life.

Thermal management and control of wearable devices

The emergence of wearable devices over the recent decades has motivated numerous studies aimed at developing flexible or stretchable materials and structures for their electronic or optoelectronic functionalities. Like in conventional devices, electronic and optoelectronic components in wearable devices must be kept within certain temperature ranges to ensure reliability, performance, and/or functionality. But this must be accomplished without requiring any bulky heat sinks or other heat transfer augmentation elements. At the same time, the proximity of wearable devices to the human skin poses additional requirements of thermal comfort and safety. A growing body of literature is now focusing on the thermal management or control of wearable devices and related development of new materials and structures. The present article aims to provide a broad overview of such materials and structures and offer suggestions for future research directions.

Wearable RGO/MXene Piezoresistive Pressure Sensors with Hierarchical Microspines for Detecting Human Motion

Flexible piezoresistive pressure sensors may exhibit excellent sensing performances to be applied in wearable electronics, medical diagnosis, and electronic skin. Herein, we report a multi-layer and phased-responsive reduced graphene oxide/MXene-based piezoresistive pressure sensor with hierarchical microspines constructed by sandpaper as the template. Thanks to the multi-level and multi-layer structure, the obtained sensor realized phased response and showed wide detection range (up to 70 kPa), fast response (response/recovery time of 40/80 ms), and excellent working stability (1000 fatigue cycles). Furthermore, the sensor was successfully applied for detecting various human motions including pulse beats, cheek bulging, nodding, finger bending, speech recognition, handwriting, and other pressure signals. Besides, a 6 × 6 sensing matrix integrated by the sensors was able to sensitively perceive the distribution of plane pressure. The findings in this work conceivably stand out as a new strategy to fabricate high-performance piezoresistive pressure sensors in the fields of intelligent healthcare and medical diagnosis, wearable electronic devices, electronic skin, and human-machine interaction.

MXene-Based Textile Sensors for Wearable Applications

Textile-based sensors in the form of a wearable computing device that can be attached to or worn on the human body not only can transmit information but also can be used as a smart sensing device to access the mobile internet. These sensors represent a potential platform for the next generation of human-computer interfaces. The continuous emergence of new conductive materials is one of the driving forces for the development of textile sensors. Recently, a two-dimensional (2D) MXene material with excellent performance has received extensive attention due to its high conductivity, processability, and mechanical stability. In this paper, the synthesis of MXene materials, the fabrication of conductive textiles, the structural design of textile sensors, and the application of MXene-based textile sensors in the wearable field are reviewed. Furthermore, from the perspective of MXene preparation, wearability, stability, and evaluation standards, the difficulties and challenges of MXene-based textile sensors in the field of wearable applications are summarized and prospected. This review attempts to strengthen the connection between wearable smart textiles and MXene materials and promote the rapid development of wearable MXene-based textile sensors.

MXene/Polylactic Acid Fabric-Based Resonant Cavity for Realizing Simultaneous High-Performance Electromagnetic Interference (EMI) Shielding and Efficient Energy Harvesting

Proliferation in telecommunications and integrated/intelligent devices entails an intense concern for electromagnetic interference (EMI) shielding and versatility. It remains an activated passion to launch infusive EMI shielding materials integrated with self-powered peculiarities. Herein, a double-layered MXene/polylactic acid (PLA) fabric resonance cavity (D-MPF-RC) comprised of two MXene/PLA fabrics (MPFs) with alternating MXene and PLA structures that are separated by a poly(tetrafluoroethylene) (PTFE) frame is developed. The D-MPF-RC achieved 48.5 and 74.8% improvement in SE_T and SE_A, and 24.6% reduction in SE_R by introducing the double-layered structure and increasing the resonance cavity (RC) distance without varying the material composition and cost. A high shielding efficiency (SE) of 92.3 dB was obtained at an RC distance of 6 mm owing to the synergetic effects of multiple reflections and destructive EM wave interference. The tribopolarity difference between PLA and MXene and the RC structure made the D-MPF-RC a readily available triboelectric nanogenerator (TENG) that could convert mechanical energy into electricity. The D-MPF-RC TENG demonstrated an open-circuit voltage of 88 V and achieved a peak power density of 35.4 mW m^-2 on a 6.6 MΩ external resistor, which made it possible to charge capacitors and serve as a self-powered tactile sensor. This report offers new insights into the design of high-performance EMI shielding shields with a resonance cavity and proposes a feasible pathway to integrate them with energy harvesting capabilities.

Moisture-resistant MXene-sodium alginate sponges with sustained superhydrophobicity for monitoring human activities

Wearable mechanical sensors are easily influenced by moisture resulting in inaccuracy for monitoring human health and body motions. Though the superhydrophobic barrier has been extensively explored as passive water repel strategy on the sensor surface, the dense superhydrophobic surface not only limits the sensor working under large deformations but also inevitable degradation in high humidity or saturation water vapor environments. This work reports a superhydrophobic MXene-sodium alginate sponge (SMSS) pressure sensor with a low voltage Joule heating effect to provide sustain moisture-insensitive property for both sensing performance and superhydrophobicity by heating-driven water molecules away. Because of the positive temperature coefficient under pressure applied, the Joule heating can provides a stable temperature to the moisture-insensitivity property during the whole dynamic pressure cycled. Therefore, the pressure sensor with a simple spray-coating superhydrophobic coating on the outer layer demonstrates key capabilities even in extreme use scenarios with high humidity or water vapor and also provides stable and reliable bio-signal monitoring.

Flexible wearable MXene Ti3C2-Based power patch running on sweat

Flexible supercapacitors (FSCs) have received a lot of interest as portable power sources for wearable electronics. The biocompatibility of electrodes and electrolytes in wearable FSCs is important to consider although research into these topics is still in its early stages. In this work, we developed a wearable FSC that uses MXene Ti₃C₂ nanosheets and polypyrrole-carboxymethylcellulose nanospheres composite (Ti₃C₂@PPy-CMC) as the active electrode material and sweat as the electrolyte. The electrochemical performances of Ti₃C₂@PPy-CMC FSC were analyzed using an artificial sweat solution and exhibited excellent specific capacitance, power density, cycling stability, and bending stability. To demonstrate a real application of Ti₃C₂@PPy-CMC FSC, a sweat-chargeable FSC patch has been developed that can be applied directly to human clothing and skin to power a portable electronic gadget when the wearer is exercising. A comprehensive electrochemical study of the FSC patch was also conducted in various sweat secretion body regions such as the finger, foot sole, and wrist. Ti₃C₂@PPy-CMC composite's outstanding electrochemical performance indicates its potential capabilities and biocompatibility in wearable energy storage devices.

Lignin-Based/Polypyrrole Carbon Nanofiber Electrode With Enhanced Electrochemical Properties by Electrospun Method

Tailoring the structure and properties of lignin is an important step toward electrochemical applications. In this study, lignin/polypyrrole (PPy) composite electrode films with microporous and mesoporous structures were designed effectively by electrostatic spinning, carbonization, and in situ polymerization methods. The lignin can not only reduce the cost of carbon fiber but also increase the specific surface area of composite films due to the removal of carbonyl and phenolic functional groups of lignin during carbonization. Besides, the compact three-dimensional (3D) conductive network structures were constructed with PPy particles densely coated on the lignin nanofibers, which was helpful to improve the conductivity and fast electron transfer during the charging and discharging processes. The synthesized lignin carbon fibers/PPy anode materials had good electrochemical performance in 1 M H2SO4 electrolyte. The results showed that, at a current density of 1 A g−1, the lignin carbon nanofibers/PPy (LCNFs/PPy) had a larger specific capacitance of 213.7 F g−1 than carbon nanofibers (CNFs), lignin carbon nanofibers (LCNFs), and lignin/PPy fiber (LPAN/PPy). In addition, the specific surface area of LCNFs/PPy reached 872.60 m2 g−1 and the average pore size decreased to 2.50 nm after being coated by PPy. Therefore, the independent non-binder and self-supporting conductive film is expected to be a promising electrode material for supercapacitors with high performance.

Novel Ti3C2Tx MXene wrapped wood sponges for fast cleanup of crude oil spills by outstanding Joule heating and photothermal effect

Remediation of crude oil spills is a great challenge owing to the poor mobility and high viscosity of crude oil. Herein, a porous polydimethylsiloxane@wood sponge/MXene (PDMS@WSM) with outstanding compressibility and hydrophobic/lipophilic ability was demonstrated as crude oil absorbent. The surface temperature of PDMS@WSM could quickly rise to 80 °C with a working voltage of 4 V and to 66 °C under simulated sunlight irradiation of 1.5 KW m^-2, respectively. Due to the excellent Joule heating and photothermal conversion effect, the PDMS@WSM displayed maximum adsorption capacity of 11.2×10⁵ g m^-3 within 6 min. The PDMS@WSM showed preferable reusability and cycle stability because of its brilliant compressibility. Moreover, the oil-collecting device based on PDMS@WSM could continuously collect crude oil spills, achieving an active collection of 25 mL crude oil within 150 s. Therefore, the porous PDMS@WSM absorbent exhibited great potential for crude oil spills remediation, energy regulation, and desalination of hypersaline water.

One-pot freezing-thawing preparation of cellulose nanofibrils reinforced polyvinyl alcohol based ionic hydrogel strain sensor for human motion monitoring

Ionic conductive hydrogels have been widely applied in sensors, energy storage and soft electronics recently. However, most of the polyvinyl alcohol (PVA) based ionic hydrogels are mainly fabricated by soaking the hydrogels in high concentration electrolyte solution which can induce the waste of electrolyte and solvent. Herein, we have designed cellulose nanofibrils (CNF) and ZnSO₄ reinforced PVA based hydrogels through a one-pot simple freezing-thawing method at low ZnSO₄ concentration without any soaking process. Furthermore, the hydrogel with 0.4% CNF exhibited stress up to 0.79 MPa (242% strain) and high ionic conductivity of 0.32 S m^-1 (0.07 M ZnSO₄). Moreover, hydrogel sensor displayed high linear gauge factor 1.70 (0-200% strain), excellent stability, durability and reliability. The integrated hydrogel sensor also showed excellent sensor performance for human motion monitoring. This work provides a new prospect for the design of cellulose reinforced conductive hydrogels via a facile method.

Recent Progress in Ti3C2Tx MXene-Based Flexible Pressure Sensors

The rapid development of consumer electronics, artificial intelligence, and clinical medicine generates an increasing demand for flexible pressure sensors, whose performance depends significantly on sensitive materials with high flexibility and proper conductivity. MXene, a type of 2D nanomaterial, has attracted extensive attention due to its good electrical conductivity, hydrophilicity, and flexibility. The synthesis methods for MXenes make it relatively easy to control their microstructure and surface termination groups. Hence, MXenes can obtain peculiar microstructures and facilely combine with other functional materials, making them promising prospects for use in flexible pressure sensors. In this Review, recent advances in MXenes are summarized, mainly focusing on the synthesis methods and their application in flexible pressure sensors. Finally, the challenges and potential solutions for future development are also discussed.

Ultrafine Cellulose Nanofiber-Assisted Physical and Chemical Cross-Linking of MXene Sheets for Electromagnetic Interference Shielding

Transition metal carbides and nitrides (MXenes) have shown great potential for constructing thin, high-performance electromagnetic interference (EMI) shields. The challenges with these materials involve the weak interfacial interactions of MXenes, which results in inferior mechanical properties and structure of the MXene films and a conductivity/EMI shielding performance decay related to the poor MXene oxidation stability. Numerous efforts have been devoted to improving the mechanical properties or oxidation stability of the films, which always comes at the expense of EMI shielding performance. Here, ultrafine (≈1.4 nm) cellulose nanofibers are employed to achieve physical and chemical dual cross-linking of MXene (PC-MXene) nanosheets. The procedure involves drying of flexible and highly conductive PC-MXene films at ambient pressure and is energy-efficient and scalable. Compared to the MXene films, the PC-MXene films show significantly improved mechanical strength, hydrophobicity, oxidation stability, and are waterproof, without compromising the excellent EMI shielding effectiveness (SE). Moreover, the freestanding PC-MXene films reach a thickness of merely 0.9 µm and exhibit a high SE of 33.3 dB, which cannot be achieved by pure MXene films. This leads to ultrahigh thickness-specific SE and surface-specific SE values of 37 000 dB mm^-1 and 148 000 dB cm²  g^-1 respectively, significantly surpassing those of previously reported MXene-based films.

The Kinetics Studies on Hydrolysis of Hemicellulose

The kinetics studies is of great importance for the understanding of the mechanism of hemicellulose pyrolysis and expanding the applications of hemicellulose. In the past years, rapid progress has been paid on the kinetics studies of hemicellulose hydrolysis. In this article, we first introduced the hydrolysis of hemicelluloses via various strategies such as autohydrolysis, dilute acid hydrolysis, catalytic hydrolysis, and enzymatic hydrolysis. Then, the history of kinetic models during hemicellulose hydrolysis was summarized. Special attention was paid to the oligosaccharides as intermediates or substrates, acid as catalyst, and thermogravimetric as analyzer method during the hemicellulose hydrolysis. Furthermore, the problems and suggestions of kinetic models during hemicellulose hydrolysis was provided. It expected that this article will favor the understanding of the mechanism of hemicellulose pyrolysis.

Preparation and Application in Water Treatment of Magnetic Biochar

This paper reviews the preparation of magnetic biochar and its application in wastewater treatment, and briefly discusses the adsorption mechanism of biochar to remove pollutants and the modification methods of biochar. Due to the good physical and chemical properties of biochar, including its rough porous structure, it has been widely used to absorb pollutants from water. Magnetic biochar is commonly prepared by combining biochar with magnetic material. The biochar is endowed with the characteristics of the magnetic material, which could effectively solve the problems of difficult recovery and easy loss of adsorbent in water treatment. Magnetic biochar with high carbon content, large specific surface area, magnetic separation, and other excellent properties, has become a hot research topic in recent years. The preparation methods and application properties of magnetic biochar are reviewed. The future research directions of magnetic biochar are put forward to provide directions for further research and application of magnetic biochar materials.

Large-Scale, Cuttable, Full Tissue-Based Capacitive Pressure Sensor for the Detection of Human Physiological Signals and Pressure Distribution

The increasing demand for flexible and wearable electronics has promoted the rapid development of the pressure sensors capable of monitoring diverse human movements and physiological signals. However, more and more research requires the pressure sensor to possess high sensing performance and desires the fabrication to exhibit the characteristics of low cost, large-scale production, high reproduction, even disposability. Here, we propose a full tissue-based capacitive pressure sensor with a sandwiched structure consisting of two MXene-coated tissue electrodes and a blank tissue dielectric layer. The tight contact and adequate adsorption of the MXene sheets with the cellulose fibers endow the electrode with uniform conductivity and high stability over a large area. In addition, the flexible sensor could be conveniently cut into any shape and size to meet the diverse application requirements. Thereby, the pressure sensor exhibits a sensitivity of 0.051 kPa^-1 (<7 kPa), a wide detection range of 0.02-160 kPa, a fast response (∼100 ms), and good repeatability. The flexible device has been demonstrated to monitor a variety of human activities and physical stimuli. The assembled sensor array can accurately and reliably detect the pressure distribution.

All-Day Anti-Icing/Deicing Film Based on Combined Photo-Electro-Thermal Conversion

Solar energy-facilitated icephobic films have emerged as clean and renewable materials, which can potentially solve energy loss problems during anti-icing/deicing applications. However, there is a significant challenge for all-day and continuous anti-icing/deicing applications under practical conditions with insufficient sunlight or no sunlight. In this work, a chemical oxidation polymerization method was used to prepare in situ self-wrinkling porous poly(dimethylsiloxane) (PDMS)/polypyrrole (PPy) (POP-P) films based on a facile sugar template method. The porous-structured film enhanced light absorption by elongating the optical path for multiple reflections, maintaining an outstanding broad-band solar light absorption (295-2500 nm) and an exceptional photo-thermal effect. The light-to-heat performance showed a temperature enhancement from room temperature to 89.1 °C within 400 s under 1 sun illumination (q_i = 1.0 kW m^-2). In addition, this membrane also exhibited an electro-thermal effect at different voltages due to the Joule effect, and the saturation temperature could reach 75.4 °C at a voltage of 32 V. As an anti-icing/deicing material, this POP-P surface remained ice-free (-25 °C) throughout alternating of day and night, under conditions of a solar intensity of 0.8 kW m^-2 and a voltage of 25 V.

Developing a Multifunctional Silk Fabric with Dual-Driven Heating and Rapid Photothermal Antibacterial Abilities Using High-Yield MXene Dispersions

Two-dimensional material titanium carbide (Ti₃C₂T_x MXene) has been widely used for building diverse functional materials; however, the disadvantages of unsatisfactory yield and low concentration during the preparation process generally limit its large-scale promotion. In the present work, an MXene dispersion with enhanced yield (90%), high concentration (45 mg/mL), and excellent dispersibility was successfully prepared. Subsequently, the active MXene nanosheets were effectively in situ deposition onto the silk fiber by means of dip-coating, relying on van der Waals forces and hydrogen bonds. The obtained MXene-decorated silk fabric (MXene@silk) exhibits satisfactory electrical conductivity (170 mS/cm), excellent photothermal and electrothermal conversion properties, especially dual-drive energy conversion, rapid thermal responses, and long-term functional stability. Furthermore, UV protection factor of the fabric, and its antibacterial efficiency against Gram-negative Escherichia coli (E. coli) within 20 min of contact reach over 110 and 99%, respectively, demonstrating remarkable UV resistance and rapid photothermal antibacterial ability. Meanwhile, the fabric of MXene@silk still retains the original characteristics of breathability, softness, and skin-friendly properties compared to the untreated. The multifunctional fabric constructed through a facile and high-yield strategy shows a noticeable potential applying to smart textiles to meet people's multipurpose needs in the future.

Facile Fabrication of Densely Packed Ti3C2 MXene/Nanocellulose Composite Films for Enhancing Electromagnetic Interference Shielding and Electro-/Photothermal Performance

The development of modern electronics has raised great demand for multifunctional materials to protect electronic instruments against electromagnetic interference (EMI) radiation and ice accretion in cold weather. However, it is still a great challenge to prepare high-performance multifunctional films with excellent flexibilty, mechanical strength, and durability. Here, we propose a layer-by-layer assembly of cellulose nanofiber (CNF)/Ti₃C₂T_x nanocomposites (TM) on a bacterial cellulose (BC) substrate via repeated spray coating. CNFs are hybridized with Ti₃C₂T_x nanoflakes to improve the mechanical properties of the functional coating layer and its adhesion with the BC substrate. The densely packed hierarchical structure and strong interfacial interactions endows the TM/BC films with good flexibility, ultrahigh mechanical strength (>250 MPa), and desirable toughness (>20 MJ cm^-3). Furthermore, benefiting from the densely packed hierarchical structure, the resultant TM/BC films present outstanding EMI shielding effictiveness of 60 dB and efficient electro-/photothermal heating performance. Silicone encapsulation further imparts high hydrophobicity and exceptional durability against solutions and deformations to the multifunctional films. Impressively, the silicone-coated TM/BC film (Si-TM/BC) exhibits desirable low voltage-driven Joule heating and excellent photoresponsive heating performance, which demonstrates great feasibility for efficient thermal deicing under actual conditions. Therefore, we believe that the Si-TM/BC film with excellent mechanical properties and durability holds great promise for the practical applications of EMI shielding and ice accretion elimination.

Fascinating MXene nanomaterials: emerging opportunities in the biomedical field

In recent years, there has been rapid progress in MXene research due to its distinctive two-dimensional structure and outstanding properties. Especially in biomedical applications, MXenes have attracted widespread favor with numerous studies on biosafety, bioimaging, therapy, and biosensing, although their development is still in the experimental stage. A comprehensive understanding of the current status of MXenes in biomedicine will promote their use in clinical applications. Here, we review advances in MXene research. First, we introduce the methods of synthesis, surface modification and functionalization of MXenes. Then, we summarize the biosafety and biocompatibility, paving the way for specific biomedical applications. On this basis, MXene nanostructures are described with respect to their use in antibacterial, bioimaging, cancer therapy, tissue regeneration and biosensor applications. Finally, we discuss MXene as a promising candidate material for further applications in biomedicine.

Genetic Diversity, Chemical Components, and Property of Biomass Paris polyphylla var. yunnanensis

Paris polyphylla var. yunnanensis is a kind of biomass resource, which has important medicinal and economical values with a huge market. This review article aims to summarize the recent development of biomass P. polyphylla var. yunnanensis. The genetic diversity and chemical components of biomass P. polyphylla var. yunnanensis were reviewed based on the literature. Both the genetic diversity and genetic structure of biomass P. polyphylla var. yunnanensis were compared by using molecular marker technologies. All the extraction processes, harvest time, and drying methods on the chemical components were summarized in detail. The differences of arbuscular mycorrhizal fungi on the infection rate, diosgenin content, microorganisms, enzyme activities, rhizospheric environment, and endogenous hormones were discussed. This review article is beneficial for the applications of biomass P. polyphylla var. yunnanensis as a biomass resource in the biomedical field.

Multifunctional Lignin-Based Composite Materials for Emerging Applications

Lignin exhibited numerous advantages such as plentiful functional groups, good biocompatibility, low toxicity, and high carbon content, which can be transformed into composites and carbon materials. Lignin-based materials are usually environmentally friendly and low cost, and are widely used in energy storage, environment, electronic devices, and other fields. In this review article, the pretreatment separation methods like hydrothermal process are illustrated briefly, and the properties and categories of technical lignin are introduced. Then, the latest progress of lignin-based composites and lignin-derived carbon materials is summarized. Finally, the current challenges and future developments were suggested based on our knowledge. It is expected that this review paper favored the applications of composites and lignin-derived carbon materials in the future.

Recent Advances in Multidimensional (1D, 2D, and 3D) Composite Sensors Derived from MXene: Synthesis, Structure, Application, and Perspective

With the advent of the era of intelligent manufacturing, sensors, with various detection objects, have set off a wave of enthusiasm and reached new heights in medical treatment, intelligent industry, daily life, and so on. MXene, as an emerging family of 2D transition metal carbides/nitrides, possesses impressive electrical conductivity, outstanding structural controllability, and satisfying universality with other substrates. Consequently, MXene-based sensors with various functions show a booming growth based on great research potential of MXene. To promote the orderly and efficient development of MXene application in sensors, and further accelerate market-scale application of ideal sensors, in this review, a full range research effort on current MXene-based sensors is summarized. Starting with various synthesis methods of the raw material MXene, a comprehensive summary work along with 1D, 2D, or 3D MXene-based sensors on most recent works is put forward, including the preparation method, characteristic structure, and potential sensing application of each type of MXene-based composite sensors. Ultimately, insights of the opportunities and challenges on the strength of the current reported MXene-based sensor are given.

Superelastic, Fatigue-Resistant, and Flame-Retardant Spongy Conductor for Human Motion Detection against a Harsh High-Temperature Condition

The construction of wearable piezoresistive sensors with high elasticity, large gauge factor, and excellent durability in a harsh high-temperature environment is highly desired yet challenging. Here, a lightweight, superelastic, and fatigue-resistant spongy conductor was fabricated via a sponge-constrained network assembly, during which highly conductive graphene and flame-retardant montmorillonite were alternatively deposited on a three-dimensional melamine scaffold. The as-obtained spongy conductor exhibited a highly deformation-tolerant conductivity up to 80% strain and excellent fatigue resistance of 10,000 compressive cycles at 70% strain. As a result, the spongy conductor can readily work as a piezoresistive sensor and exhibited a high gauge factor value of ∼2.3 in a strain range of 60-80% and excellent durability under 60% strain for 10,000 cycles without sacrificing its piezoresistive performance. Additionally, the piezoresistive sensor showed great thermal stability up to 250 °C for more than 7 days and sufficient flame-retardant performance for at least 20 s. This lightweight, superelastic, and flame-retardant spongy conductor reveals tremendous potential in human motion detection against a harsh high-temperature environment.