Search

Flexible transparent electromagnetic interference (EMI) shielding films in visual windows are crucial for the innovation of optoelectronic devices, but the challenge of balancing light transmittance and EMI shielding effectiveness (SE) still exists. Herein, this work described a flexible transparent MXene@SWNTs/PC film with a hierarchical conductive layer that was fabricated via an alternating rotation spraying method. The multi-scale hierarchical structure configured with 1D SWNTs and 2D MXene endow the obtained film with good comprehensive properties, i. e, low sheet resistance of 32.8 Ω/sq at 56.1% light transmittance, thus causing a satisfactory EMI SE of 20.8 dB. Moreover, the transparent shielding films exhibit remarkable flexibility, which can maintain steady EMI SE after 1000 continuous bending cycles. More importantly, the low sheet resistance and high light absorption capacity of hybrid conductive layer facilitate the transparent shielding film with low-voltage-driven electric heating effect and outstanding photothermal conversion ability, respectively, ensuring the normal operation under extreme cold condition. The combination of good light transmittance, satisfactory EMI shielding performance, and multi-source thermal response enables MXene@SWNTs/PC film to have great potential as a transparent shielding film in emerging optoelectronic devices. A multifunctional MXene@SWNTs/PC film with hierarchical structure prepared via an alternating rotation spraying process, integrating capabilities of light transmittance, EMI shielding, and multi-source thermal response together. [Display omitted] [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]

Constructing surface hierarchical layer is regarded as an effective surface modification of carbon fibers (CFs) to enhance their composites mechanical properties. However, this method usually deteriorates the intrinsic properties of CF and the hierarchical layer is not fully compatible with thermal processing of the polymer. Here, a novel hierarchical layer consisting of polydopamine, polyethyleneimine and multi-walled carbon nanotubes without damages to CF was successfully decorated on CF surface (CNT@PP-CF) for simultaneously enhancing the mechanical and the electromagnetic interference (EMI) shielding properties of CF reinforced polyamide 66 (PA66) composite. The CNT@PP hierarchical layer with dynamic imine bonds enhanced the interfacial wettability and bonding between CF and PA66 during thermal processing. Compared with that of untreated-CF, the interfacial shear strength and tensile strength of CNT@PP-CF/PA66 composite were increased by 52.3% and 19.2%, respectively. Meanwhile, the EMI shielding performance was enhanced by 89.6%. This improvement would be ascribed to the dynamic imine polar groups and heterogeneous interfaces in the hierarchical layers which enhanced the conductive and dielectric losses of composites. Our research provided a novel approach based on dynamic covalent bond exchanges to achieve the functional and structural integration of CF reinforced thermoplastic resin composites. [Display omitted] • A new hierarchical layer modified method based on dynamic imine bond was proposed. • Dynamic imine bonds exchanges improved the interfacial properties of composite. • Mechanical properties and EMI shielding performance were enhanced simultaneously. • This method is suitable for CF/thermoplastic composites during thermal processing. [ABSTRACT FROM AUTHOR]

In this study, an internal electrode triboelectric nanogenerator (IE-TENG) design is proposed to enhance the stability, durability, and long-term performance of TENGs. By embedding a mesh-structured metal electrode in the friction layer, the IE-TENG becomes more flexible, lightweight, and robust than the traditional external electrode TENG (EE-TENG). When using copper mesh internal electrodes with higher grid density, the greater output can be achieved by comparing a series of polydimethylsiloxane(PDMS)-based IE-TENG. An equivalent output was obtained when using 60 copper mesh compared to EE-TENG, and the trend maintains for tribonegative low-density polyethylene (LDPE) and tribopositive polyamide (PA) polymers, which verifies the usability of the approach and the effective induction area of the internal electrode. The internal electrode design significantly enhanced the tolerance of the device to harsh environments and guaranteed excellent output stability. In addition, the IE-TENGs possess superior resistance to external interference and had about one time shorter saturation time for surface charges. As a demonstration, the IE-TENG can be used for collecting motion-sensing signals and detecting various sports activities. This study provides a novel strategy for the designing and customizing of highly integrated TENGs with enhanced durability for practical long-term applications. An embedded metal electrode design is proposed for developing highly integrated durable TENGs. The internal electrode TENGs (IE-TENGs) not only possess equvalent output performance to the traditional external electrode TENGs, but also demonstrate superior long-term stability, charge saturation velocity, flexibility, and tolerence to harsh environments. [Display omitted] • A design of embedded electrode for improving the integration of TENG is proposed. • The IE-TENG demonstrated more stable long-term signals, and high tolerance to the harsh environment. • The embedded electrode strategy enhanced the tolerance of the TENGs to interference from the external environment. • The IE-TENGs possess about one time shorter saturation time for surface charges. [ABSTRACT FROM AUTHOR]

Highly sensitive and flexible capacitive sensors are in great demand for wearable electronics, which can be achieved by preparing micropatterns on their dielectric layer surface. However, most micropatterns are often molded with the silicon template acquired by complex processes which are very time-consuming and costly. Here, a dielectric layer with micropatterned arrays was prepared on the thermal plastic polyurethane (TPU) film with the help of a hot-air-gun, then assembled with an ITO/PET electrode to develop a capacitive sensor with a sandwich structure. The capacitive sensor based on TPU/ITO/PET composites exhibits sensitivity of over 0.026 kPa−1, shorter response/recovery time of 99 ms, wide working range (0–13 kPa) and remarkable stability over 5000 cyclic pressing or bending. Interestingly, such sensor can monitor various physiological signals of people (e.g., voice signal, finger bending and breath). More importantly, it can distinguish different sign languages according to capacitive changes in the case of different finger gestures. The method proposed in this study will paves a new avenue for the facile preparation of micropatterned surface to improve the performance of flexible capacitive sensors. The present work represents a facile and efficient method to achieve capacitive sensor that can not only exhibit excellent sensing performances, but also it can detect a series of physiological signals and realize sign language interpretation. [Display omitted] • A cost-effective method is proposed to fabricate micropatterned surface. • Micropatterned capacitive sensor has remarkable sensing performances. • Capacitive sensor can monitor various physiological signals in the body. • Capacitive sensor can realize sign language interpretation. [ABSTRACT FROM AUTHOR]

Stretchable strain sensors with integrated attributes of flexibility and robustness are urgently required owing to their promising applications in healthcare monitoring and environment detection. Herein, we achieved a highly stretchable thermoplastic polyurethane (TPU) mat (PUM) through electrospinning, then decorated with polyaniline (PANI) nanoparticles bridged by reduced graphene oxide (rGO) nanosheets by in-situ polymerization and ultrasonication. The rGO/PANI/TPU mat (GPTM) was then assembled as the strain sensor (GPTSS), showing a wide sensing range of 0.1%–300% strain, high gauge factor (GF) of 3000.2, favorable sensing stability, short response time (90 ms) and excellent long-term durability after 10000 stretching/releasing cycles, which endows the strain sensor with high discernibility for detecting intricate human motions. The GPTSS shows the capacity to precisely monitor ammonia gas (as low as 5 ppm), which can be used to detect harmful gases. The integrated capabilities of strain sensing and environmental monitoring promote the progress of high-performance electronics. [Display omitted] [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]

The rapid development of electronic devices has led to widespread demand and research on electronic packaging materials with electromagnetic shielding and thermal conductivity (TC) properties due to the inevitable issues of the electromagnetic radiation and thermal accumulation. However, there exists a huge challenge to simultaneously achieve high electromagnetic shielding and TC as well as the electrical insulation requirement as electromagnetic shielding predominantly relies on electrical conductivity of materials. Multilayer structure can endow composite materials with a variety of properties. Therefore, in this work, we fabricated sandwiched cellulose nanofiber/boron nitride nanosheet/Ti 3 C 2 T x MXene films by using a simple and effective alternating vacuum filtration method, and as a result, the special sandwich structure endows the film with excellent electromagnetic shielding, insulation and TC performance. The composite film has an extremely high electromagnetic shielding effectiveness up to 60.7 dB at 8.2 GHz as well as still maintains good electrical insulation properties due to the presence of the CNF/BNNS layer on the surface. Moreover, when the content of BNNS in the CNF/BNNS layer reaches 70 wt%, the sandwiched film has excellent in-plane TC of 19.97 W m−1 K−1. The sandwiched film with excellent electromagnetic shielding and high TC yet insulation performance has great application value in highly integrated electronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]