Search

Most stretchable film strain sensors generally present nonlinear electrical responses to applied strain, leading to an inaccurate acquisition of sophisticated signals, difficult signal processing, and zero‐calibration, which hampers practical applications severely. Here, a Janus hetero‐structured microarray film sensor is developed by in‐situ growth of silver nanoparticles on the surface of micro‐patterned elastomer films fabricated via low‐temperature imprinting followed by scraping‐induced particle trapping. Heterogeneous property designs in both modulus and electrical conductivity via introducing polymer microarrays enable modulating the electron transport manner in the conductive layer of elastic Janus films upon stretching, allowing to tune signal linearity effectively. Therefore, such a hetero‐structured film sensor shows good signal linearity (fluctuation of gauge factor [GF] below ±0.02) and relatively high sensitivity (GF > 10) within 55% strain, a detection limit of 0.2% strain, and a response/recovery time of 16.3/46.9 ms, respectively. Correspondingly, it enables monitoring human respiration and body motion with higher resolution compared with the nonlinear one, meanwhile, it is capable of detecting tiny pressure to discriminate braille alphabets via touch identification. Overall, it unveils a simple strategy to fabricate film strain sensors for high‐resolution healthcare and body motion monitoring, as well as electronic skins toward tactile sensing and touch identification. [ABSTRACT FROM AUTHOR]

Macrophages are highly heterogeneous and exhibit a diversity of functions and phenotypes. They can be divided into pro‐inflammatory macrophages (M1) and anti‐inflammatory macrophages (M2). Diabetic wounds are characterized by a prolonged inflammatory phase and difficulty in healing due to the accumulation of pro‐inflammatory (M1) macrophages in the wound. Therefore, hydrogel dressings with macrophage heterogeneity regulation function hold great promise in promoting diabetic wound healing in clinical applications. However, the precise conversion of pro‐inflammatory M1 to anti‐inflammatory M2 macrophages by simple and biosafe approaches is still a great challenge. Here, an all‐natural hydrogel with the ability to regulate macrophage heterogeneity is developed to promote angiogenesis and diabetic wound healing. The protocatechuic aldehyde hybridized collagen‐based all‐natural hydrogel exhibits good bioadhesive and antibacterial properties as well as reactive oxygen species scavenging ability. More importantly, the hydrogel is able to convert M1 macrophages into M2 macrophages without the need for any additional ingredients or external intervention. This simple and safe immunomodulatory approach shows great application potential for shortening the inflammatory phase of diabetic wound repair and accelerating wound healing. [ABSTRACT FROM AUTHOR]

Acute kidney injury (AKI), as a common oxidative stress‐related renal disease, causes high mortality in clinics annually, and many other clinical diseases, including the pandemic COVID‐19, have a high potential to cause AKI, yet only rehydration, renal dialysis, and other supportive therapies are available for AKI in the clinics. Nanotechnology‐mediated antioxidant therapy represents a promising therapeutic strategy for AKI treatment. However, current enzyme‐mimicking nanoantioxidants show poor biocompatibility and biodegradability, as well as non‐specific ROS level regulation, further potentially causing deleterious adverse effects. Herein, the authors report a novel non‐enzymatic antioxidant strategy based on ultrathin Ti3C2‐PVP nanosheets (TPNS) with excellent biocompatibility and great chemical reactivity toward multiple ROS for AKI treatment. These TPNS nanosheets exhibit enzyme/ROS‐triggered biodegradability and broad‐spectrum ROS scavenging ability through the readily occurring redox reaction between Ti3C2 and various ROS, as verified by theoretical calculations. Furthermore, both in vivo and in vitro experiments demonstrate that TPNS can serve as efficient antioxidant platforms to scavenge the overexpressed ROS and subsequently suppress oxidative stress‐induced inflammatory response through inhibition of NF‐κB signal pathway for AKI treatment. This study highlights a new type of therapeutic agent, that is, the redox‐mediated non‐enzymatic antioxidant MXene nanoplatforms in treatment of AKI and other ROS‐associated diseases. [ABSTRACT FROM AUTHOR]

Big volume changes, the shuttle effect, and poor conductivity are well‐known, critical issues of sulfur electrodes that prevent practical application of lithium‐sulfur batteries. The design of active materials with a conductive shell provides an effective solution. Traditional strategies have long been limited for practical applications; however, by low productivity and time/energy consuming template‐based methods. Here, a facile template‐free self‐caging nanotechnology for the scalable fabrication of graphene@sulfur nanocages with atomic‐scale shells is reported. To do that, a new sulfur‐graphene nanochemistry based on a reductive sulfur solution and oxidative sulfonated‐graphene dispersion is developed for the first time. With only the help of mechanical mixing, sulfur particles are successfully synthesized in situ and encapsulated into reaction‐induced self‐assembled sulfonated‐graphene nanocages. These unique nanocages not only provide accommodation of the big volume changes in the active materials, but also exhibit robust polysulfide trapping capability due to the synergistic effects from physical blocking and strong chemical absorption. As a result, the resultant sulfur cathodes deliver superior electrochemical performance and have shown an extremely slow capacity decay of 0.019% per cycle at 0.5 C for over 2000 cycles. This study introduces a new self‐caging nanochemistry for scalable synthesis of functional nanocages with significant applications beyond lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

The development of wearable healthcare electronics has created higher demands on both the sensitivity and stretchability of flexible sensors. As it is generally difficult to obtain a trade-off between sensitivity and stretchability, the fabrication of strain sensors with both a wide operating range (≥100%) and high sensitivity (GF ≥ 100) remains a great challenge. Here, we propose for the first time a strategy based on the consolidation of two basic but seemingly paradoxical sensing mechanisms, i.e., slippage and crack propagation mechanisms, to greatly enhance the sensitivity of stretchable strain sensors. Based on stretchable polyurethane (PU) fibers, which can be easily woven into conventional fabrics to produce wearable devices, we present a multilayer sensing structured fiber sensor fabricated by layer-by-layer self-assembly of sliver nanowire (AgNW)/waterborne polyurethane (WPU) layers and MXene layers. The sensor simultaneously exhibits an ultrahigh sensitivity (GF = 1.6 × 107) and a wide operating range (up to 100%), as well as great reliability and stability (1000 cycles) and fast response (344 ms) and relaxation (344 ms). Moreover, smart fabrics were fabricated by integrating fiber strain sensors into different clothes and a prototype body posture monitoring, analysis, and correction system was presented for healthcare applications. Our work not only breaks down the technological wall between high sensitivity and high stretchability of strain sensors, but also shows the great potential applications of wearable, comfortable, and non-intrusive electronics for real-time health monitoring. [ABSTRACT FROM AUTHOR]

Efficient utilization of abundant solar energy for steam generation is an attractive, renewable, and environment-friendly technology for seawater desalination and wastewater purification, enabling solutions to address the global long-standing water scarcity issues. However, the low energy efficiency, high cost and complex systems with multiple components of state-of-the-art technologies hindered their practical applications. Herein, we report the first example of three-dimensional (3D) MXene architecture (3DMA)-based solar steam generators via a facile two-step dip coating process without any annealing or high temperature carbonization. The 3DMAs prepared by a cost-effective, scalable, simple fabrication method show effective broadband solar absorption (∼98%) and excellent solar thermal conversion ability based on 2D to 3D morphological transformation of MXenes, making good use of intrinsic theoretical photothermal performance of MXenes. The particularly hydrophilic nature of MXenes and the macroporous structure of melamine foam allow continuous water supply to 3DMAs owing to their strong capillary effect. As a result, the 3DMAs achieve water evaporation rates of 1.41 and 7.49 kg m−2 h−1 under solar illumination of 1 sun and 5 sun with a superb solar steam efficiency of up to 88.7% and 94.2%, respectively. This scalable 3DMA can be used to produce clean water from both seawater and wastewater with rejections close to 100% for organic dyes and metal ions. This work creates a platform to develop novel composite materials for solar-driven seawater desalination and wastewater purification via opening a new window for the utilization of MXenes as photothermal agents in practical applications. [ABSTRACT FROM AUTHOR]

1 vol% multiwalled carbon nanotubes (MWCNTs) is finely dispersed in poly(propylene) (PP)/boron nitride (BN) composites with the assistance of commercial ethylene‐α‐octene block copolymer (OBC) through a conventional melt‐compounding method, whereas serious agglomeration of MWCNTs occurs in the melt compounded PP/MWCNTs/BN composites. The good dispersion of MWCNTs facilitates the formation of a better conductive network to synergistically improve the thermal conductivity of PP/OBC/MWCNT/BN composites, up to 1.71 W m−1 K−1 at a BN content of 20 vol%. Meanwhile, the elastomeric OBC component leads to markedly enhanced impact toughness (>8.0 kJ m−2) and elongation at break (>23%) of the composites. This work sheds light on the fabrication of thermally conductive polymer composites with balanced mechanical performance through a conventional processing technique. [ABSTRACT FROM AUTHOR]