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The electro-mechanical response of conductive carbon-nanotube(CNT)-polymer composites is vital when they are used as smart-sensing materials. Clarifying the variation trend of resistance with strain is the key to design and regulate the piezoresistive property of such material. Here, we present some finite element simulations to predict the electro-mechanical response using a geometrical model comprising two hollow cylindrical CNTs and a cuboid matrix. The electrical contact between CNTs is represented by some elements which account for quantum tunnelling effects and capture the sensitivity of conductivity to separation. Different from classical simulations using solid model or one-dimensional beam model, in which the tunnelling resistance between two CNTs changes monotonously with strain, the results in this work show that the trend is non-monotonic in some cases, i.e. it increases at first and then decreases with the uniaxial compressive strain when the elastic modulus of the matrix is high. In addition, factors affecting the different variation trends are discussed in details, which include geometric model, elastic modulus and Poisson’s ratio of the matrix, and orientation angle. [ABSTRACT FROM AUTHOR]

Up to now, it is a major challenge to protect leading edge of the blades from solid particle erosion. Herein, we propose a structure optimization strategy to fabricate non‐woven (NW) enhanced thermoplastic polyurethane nanocomposite films (thermoplastic polyurethane [TPU]‐NW@G/Cx) with "sandwich‐like" structure by hot pressing technology. TPU NW/graphene nanoplates/carbon nanotube (NW@G/Cx) interlayer film were first fabricated by spraying method. Then the interlayer film was laminated between TPU films to fabricate nanocomposite films. Such prepared TPU‐NW@G/Cx film shows excellent solid particle erosion resistance and high‐tensile strength. For example, the "steel‐and‐mortar" structure of NW fabric in TPU film results in high‐tensile strength of 45 MPa and storage modulus of 21.2 MPa for TPU‐NW@G/C1.0, increasing by 25% and 171% compared with original TPU film (35 MPa, 8 MPa), respectively. In addition, compared with pure TPU film, the "sandwich‐like" structure endows TPU‐NW@G/C1.2 with excellent solid particle erosion resistance and the thermal conductivity (0.251 W/m·K). These superior properties extends application of the TPU‐NW@G/Cx film on wind turbine blades. [ABSTRACT FROM AUTHOR]

Superhydrophobic conductive rubber band with synergistic dual conductive layer was designed and prepared for high-performance strain sensor, showing great potential for full-range monitoring of human motion and physiological signal, especially in the water environment. [Display omitted] Wearable electronic devices have received increasing interests because of their excellent flexibility, stretchability, and human friendliness. As the core components, flexible strain sensors integrated with wide working range, high sensitivity, and environment stability, especially in moisture or corrosive environments, remain a huge challenge. Herein, synergistic carbon nanotubes (CNTs)/reduced graphene oxide (rGO) dual conductive layer decorated elastic rubber band (RB) was successfully developed and treated with hydrophobic fumed silica (Hf-SiO 2) for preparing superhydrophobic strain sensor. As expected, stable entangled CNTs layer and ultrasensitive microcracked rGO layer endow the sensor with extremely low detection limit (0.1%), high sensitivity (gauge factor is 685.3 at 482% strain), wide workable strain range (0–482%), fast response/recovery (200 ms/200 ms) and favorable reliability and reproducibility over 1000 cycles. Besides, the constructed Hf-SiO 2 coating also makes the sensor exhibit excellent superhydrophobicity, self-cleaning property, and corrosion-resistance. As a proof of concept, our prepared high-performance strain sensor can realize the full-range monitoring of human motions and physiological signals even in the water environment, including pulse, vocalization, joint bending, running, and gesture recognition. Interestingly, it can also be knitted into a tactile electronic textile for spatial pressure distribution measurement. Thus, this study provides a universal technique for the preparation of high-performance strain sensors with great potential applications in the field of next-generation intelligent wearable electronics. [ABSTRACT FROM AUTHOR]

Benefitting from the wearability, ductility and portability, flexible and stretchable strain sensors display a more extensive field of applications than traditional sensors in terms of medical diagnosis, smart home, environmental monitoring and so on. However, the critical sensing performances, such as sensitivity, sensing range, stability and detection limit of flexible strain sensors still need to be improved. Microstructural optimization has been considered as an efficient strategy for tuning the performances. In this work, a carbon nanotubes (CNTs)/carbon black (CB)/thermoplastic polyurethane (TPU) fibrous film (CCTF) is prepared through electrospinning, spraying and ultrasonic anchoring technique. Synergetic conductive layers by combining CNTs/CB and CB are constructed on both sides of CCTF. In virtue of the optimization of microstructures and the synergetic conductive network, the obtained CCTF possesses an ultrawide response range (up to 500 % strain), high sensitivity (gauge factor, GF up to 1516), short response/recovery time (80/80 ms), low detection limit (0.05 % strain), favorable sensing stability and long-term durability. CCTF with excellent strain sensing performances is assembled as a strain sensor, which accounts for full range human biological signal acquisition, including joint movements, muscle tension, and facial micro-expressions. This paper provides a certain reference significance for the preparation and fabrication of next-generation flexible strain sensors with high performances. A flexible strain sensor based on carbon nanotubes (CNTs)/carbon black (CB)/thermoplastic polyurethane (TPU) film (CCTF) is fabricated through electrospinning, spraying and ultrasonic anchoring technologies. CCTF possesses excellent sensing performance due to the optimization of the microstructure, achieving a wide sensing range (up to 500 % strain), high sensitivity (GF up to 1516), low detection limit (0.05 % strain), and short response/recovery time (80/80 ms). [Display omitted] • A fibrous strain sensor with synergetic conductive networks of CNTs/CB and CB is fabricated. • The sensor possesses both a wide sensing range (500 % strain) and high sensitivity (GF up to 1516). • Low detection limit (0.05 % strain) and short response/recovery time have also been achieved. • The sensor is demonstrated to precise full range human biological signal acquisition. [ABSTRACT FROM AUTHOR]

Personalized rehabilitation training provides maximum help to stroke patients to alleviate the after-effects and restore the body to normal function. However, available monitoring devices have the disadvantages of being large, requiring professional guidance, and lacking intuitive signal display capabilities. Herein, a bio-inspired wearable high-performance strain sensor with a simple structure can simultaneous electrical signals and optical visualization in response to external stimuli. The sensor comprises a conductive layer with significant electromechanical behaviors of cellulose nanocrystals (CNC)/carbon nanotubes (CNTs)/MXene nanohybrid network, and a stretchable elastomer layer consisting of thermoplastic polyurethane and fluorescent agent. Benefiting from the designed microcracks and fluorescent material, the strain sensor exhibits ultra-high sensitivity (476800), ultra-low detection limit (0.005%), low response time (60 ms), wide working range (0–100%), and enables strain visualization for applications in visually rehabilitation training monitoring. Based on these sensing characteristics, the sensor shows great advantages in human motion and sound monitoring, with the integration of digital signals and visual images makes it show great potential in visually personalized rehabilitation training monitoring. [Display omitted] • Cellulose nanocrystals are introduced to modulate the sensitivity of the strain sensor. • CCMTPF has ultrahigh sensitivity of 476800 and ultralow detection limit of 0.005%. • CCMTPF achieves electric signals and visualization of optical images responses under strain. • CCMTPF has been demonstrated for visual rehabilitation training monitoring in real time. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible polymer PENGs were prepared with interface-engineered PVDF/CNTs nanofibers. • PVDF- g -MA stabilized electrospinning flow to yield defect-free composite nanofibers. • Interfacial anchoring of PVDF- g -MA promoted electroactive β -phase in PVDF matrix. • A small amount of PVDF- g -MA boosted piezoelectric outputs (10.6 V, 3.15 µW/cm2) • Our strategy enhanced PENG with preserved flexibility avoiding excessive filler use. Polymeric piezoelectric nanogenerators (PENGs) hold great promise for flexible energy harvesters and self-powered sensors. However, achieving high piezoelectricity in inherently piezoelectric polymers while maintaining their flexibility remains a challenge. Herein, we propose a simple yet effective approach to fabricate flexible and cost-effective PENGs based on interface-engineered composite nanofibers of poly(vinylidene fluoride) (PVDF)/carbon nanotubes (CNTs) using electrospinning. Our strategy involves the incorporation of a tailor-made interfacial coupling agent, maleic anhydride grafted PVDF (PVDF- g -MA), onto PVDF/CNTs interfaces. This mild interface-engineering strategy not only promotes interfacial interactions within composites but also stabilizes electrospinning flow jets, yielding defect-free nanofibers. More importantly, the interfacial anchoring of PVDF- g -MA molecules promotes the preferential crystallization of electroactive β -phase within PVDF matrix. By incorporating a small quantity of PVDF- g -MA (up to 1.0 wt%), our approach significantly enhances piezoelectric outputs while preserving flexibility. This eliminates the need for excessive nanofiller usage that can sacrifice the flexibility associated with conventional methods. Remarkably, the resulting composite nanofiber-based PENGs exhibit excellent piezoelectric performance, generating high output voltages (10.6 V) and remarkable power density (3.15 µW/cm2) under tiny force stimuli. Our findings open new avenues for efficient and scalable fabrication of polymeric piezoelectric nanogenerators for flexible and wearable energy harvesting and self-powered sensing applications. [ABSTRACT FROM AUTHOR]

In this paper, a carbon nanotube (CNT)/polydimethylsiloxane (PDMS) conductive composite foam (CCF) was fabricated via a dual-solvent ice template (DSIT) process, whose structure features the conductive filler CNT "embedded" in the cell wall surface, and this CCF was applied to the field of flexible piezoresistive sensing. Benefiting from the sensitive conductive network constructed by the DSIT process, the CNT/PDMS CCF-based piezoresistive sensor can effectively detect compression strains down to 0.1% and exhibits excellent and stable response at compression strains up to 90%. In addition, the CCF shows fast response and recovery times (54 ms and 65 ms), as well as excellent durability and stability (2000 cycles). An electronic skin assembled from the CCF into 5 × 5 pixels was applied to detect the magnitude and spatial distribution of forces and strains. The CCF was also applied for roughness recognition, optical and thermal sensing responses, which shows its potential applications in personalized medical monitoring, electronic smart skin fabrication, external environment monitoring and other fields. [Display omitted] • The CNT/PDMS conductive composite foam (CCF) was prepared via the dual-solvent ice template (DSIT) process. • The CNT/PDMS CCF shows superior piezoresistive sensing capacity. • The CNT/PDMS CCF also possesses good optical and thermal response. • The CNT/PDMS CCF shows great potential for human motion detection and E-skin. [ABSTRACT FROM AUTHOR]

• Waterproof conductive fiber with microcracked synergistic conductive layer was designed. • High sensitivity and wide working range were achieved for the conductive fiber strain sensor. • Tunable sensing performance was achieved for the conductive fiber strain sensor. • The sensor can precisely distinguish various human movements and physiological signals. With the rapid development of wearable smart electronic devices, flexible strain sensors with high sensitivity in a wide working range are urgently demanded. Meanwhile, good self-cleaning and anti-corrosion properties are also essential for daily use. Herein, a waterproof conductive spandex fiber strain sensor with microcracked synergistic Ag nanoparticles (AgNPs)-carbon nanotubes CNTs conductive layer was designed and fabricated via the solvent swelling, non-solvent-induced phase separation (NIPS), and low surface energy treatment process. Benefiting from the stable synergistic conductive network and the ultrasensitive microcrack structure, the sensor exhibits excellent overall strain sensing performances, including high sensitivity (gauge factor is 48,310 within 335–400% strain), wide working range (0–400%), ultralow detection limit (0.1%), fast response/recovery time (80 ms/100 ms), and long-term fatigue resistance over 10,000 cycles, making it reliably and precisely distinguish both violent human movements and subtle physiological signals. More importantly, strain sensing range and sensitivity of the sensor can also be effectively tunned through changing the AgNPs loading in the synergistic conductive network, enabling it to be applicable for different application scenarios. What's more, the waterproof surface with good self-cleaning and anti-corrosion properties also endows the sensor with great potential for real-time body motion monitoring under humid and underwater environments without being interfered. This study provides a facile one-step method for the fabrication high-performance flexible strain sensor. [ABSTRACT FROM AUTHOR]

• Synergistic MXene/CNTs based multifunctional TPU fabric (MCT-fabric) was prepared. • The MCT-fabric strain sensor shows both high sensitivity and broad sensing range. • The MCT-fabric shows superior EMI shielding effectiveness. • The MCT-fabric shows high efficient and long-term stable Joule heating capability. High-performance electronic textile with outstanding strain sensing, electromagnetic interference (EMI) shielding, and Joule heating performances are highly desirable for modern integrated smart wearable electronic devices. Herein, multifunctional electronic textile based on hybrid Ti 3 C 2 T x MXene and carbon nanotubes (CNTs) conductive nanomaterials coated thermoplastic polyurethane (TPU) non-woven fabric (MCT-fabric) is fabricated via a facile dip-coating approach. Based on the synergistic MXene/CNTs conductive coating and pre-stretching induced ultrasensitive microcrack structure, tunable conductive MCT-fabric strain sensor with high sensitivity (GF is as high as 9022), wide sensing range (∼210 %), rapid response/recovery time (140/160 ms), excellent long-term stability and reliability (∼1000 cycles) is successfully constructed. Besides, benefiting from the perfect synergistic conductive network and porous fibrous network structure, the MCT-fabric displays superior EMI shielding effectiveness (∼43 dB for the MCT-fabric with a thickness of 600 μm) and excellent thermal management performance including high Joule heating temperature at relatively low applied voltages, rapid Joule heating response, sufficient heating stability and reliability. This work indicates that the high-performance multifunctional electronic textile has attractive potential for strain sensing, EMI shielding and thermal management applications in artificial intelligence and emerging wearable electronics. [ABSTRACT FROM AUTHOR]

Compared to polymer fibers, it is still challenging for fabricating large-scale polymer products with superb mechanical properties. Herein, high density polyethylene (HDPE) films reinforced with carbon nanotubes (CNTs) were prepared via an ingenious high-speed melt stretching strategy. With employing a homemade two-drum extensional rheometer, the maximum 80 × stretch ratio of supercooled melt was realized within very short time of 220 ms. The achieved nanocomposite films present the highest tensile strength of 147 MPa in reported HDPE-based composites, while the Young's modulus keeps simultaneously a high level of 2300 MPa in spite of low filler fraction of 3 wt%. Furthermore, the nanocomposite films display an excellent erosion resistance, ensuring the durability in harsh using environments. Microstructural characterization indicates a strong synergy between high-speed melt stretching and CNTs in (1) forming the densely distributed shish-kebab superstructures, (2) making a nearly perfect orientation of shish-kebab crystal and (3) reinforcing the physical connectivity of shish-kebab network. The construction of such characteristic microstructures greatly improves the transfer of mechanical load and underlies a significant enhancement on the mechanical performance. Due to the ultrastrong nanocomposite films fabricated directly by melt processing, the current work is of guiding significance in engineering practice and lights a feasible path towards expanding applications of general plastics to some special occasions like collision protection and structural materials. [Display omitted] • PE/C nanocomposite films are fabricated by high-speed melt stretching. • Films show ultrahigh mechanical properties and excellent erosion resistance. • Dense shish-kebab superstructures with nearly perfect orientation are formed. • CNTs greatly reinforce physical connectivity of shish-kebab crystal network. [ABSTRACT FROM AUTHOR]