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The rapid development of flexible electronics and soft robotics has an urgent demand for materials with wide-range switchable stiffness. Here, we report a polymer network that can isochorically and reversibly switch between soft ionogel and rigid plastic accompanied by a gigantic stiffness change from about 600 Pa to 85 MPa. This transition is realized by introducing polymer vitrification to regulate the liquid–liquid phase separation, namely the Berghmans’ point in the phase diagram of binary gel systems. Regulating the Lewis acid-base interactions between polymer and ionic liquids, the stiffness-changing ratio of polymer network can be tuned from 10 to more than 10 5 . These wide-range stiffness-changing ionogels show excellent shape adaptability and reconfigurability, which can enhance the interfacial adhesion between ionogel and electrode by an order of magnitude and reduce interfacial impedance by 75%. The development of flexible electronics and soft robotics demands materials with wide-range switchable stiffness. Here, the authors report a polymer network that can isochorically and reversibly switch between a soft ionogel and a rigid plastic accompanied by a large stiffness change.

Object detection, as a fundamental task in computer vision, has been developed enormously, but is still challenging work, especially for Unmanned Aerial Vehicle (UAV) perspective due to small scale of the target. In this study, the authors develop a special detection method for small objects in UAV perspective. Based on YOLOv3, the Resblock in darknet is first optimized by concatenating two ResNet units that have the same width and height. Then, the entire darknet structure is improved by increasing convolution operation at an early layer to enrich spatial information. Both these two optimizations can enlarge the receptive filed. Furthermore, UAV-viewed dataset is collected to UAV perspective or small object detection. An optimized training method is also proposed based on collected UAV-viewed dataset. The experimental results on public dataset and our collected UAV-viewed dataset show distinct performance improvement on small object detection with keeping the same level performance on normal dataset, which means our proposed method adapts to different kinds of conditions.

Flexible pressure sensors usually require functional materials with both mechanical compliance and appropriate electrical performance. Most sensors based on materials with limited compressibility can hardly balance between high sensitivity and broad pressure range. Here, we prepare a heterophasic ionogel with shape and stiffness memory for adaptive pressure sensors. By combining the microstructure alignment for stiffness changing and shape memory micro-inclusions for stiffness fixing, the heterophasic ionogels reveal tunable compressibility. This controllable pressure-deformation property of the ionogels results in the pressure sensors’ programmable pressure-resistance behavior with tunable pressure ranges, varied detection limits, and good resolution at high pressure. Broad pressure ranges to 220 and 380 kPa, and tunable detection limit from 120 to 330 and 950 Pa are realized by the stiffness memory ionogel sensors. Adaptive detection is also brought out to monitor tiny pressure changes at low stiffness and distinguish different human motions at high stiffness. Using shape and stiffness memory materials in pressure sensors is a general design to achieve programmable performance for more complex application scenarios. Flexible pressure sensors require functional materials accounting for mechanical compliance and electrical performance simultaneously but sensor materials often suffer from limited compressibility which decreases sensitivity over a large pressure range. Here, the authors demonstrate a heterophase ionogel with shape and stiffness memory for adaptive pressure sensing

Highlights Two-dimensional (2D) materials are highlighted for their exceptional mechanical, electrical, optical, and chemical properties, making them ideal for fabricating high-performance wearable biodevices. The review categorizes cutting-edge wearable biodevices by their interactions with physical, electrophysiological, and biochemical signals, showcasing how 2D materials enhance these devices' functionality, mainly including self-powering and human-machine interaction. 2D materials enable multifunctional, high-performance biodevices, integrating self-powered systems, treatment platforms, and human-machine interactions, though challenges remain in practical applications. The proliferation of wearable biodevices has boosted the development of soft, innovative, and multifunctional materials for human health monitoring. The integration of wearable sensors with intelligent systems is an overwhelming tendency, providing powerful tools for remote health monitoring and personal health management. Among many candidates, two-dimensional (2D) materials stand out due to several exotic mechanical, electrical, optical, and chemical properties that can be efficiently integrated into atomic-thin films. While previous reviews on 2D materials for biodevices primarily focus on conventional configurations and materials like graphene, the rapid development of new 2D materials with exotic properties has opened up novel applications, particularly in smart interaction and integrated functionalities. This review aims to consolidate recent progress, highlight the unique advantages of 2D materials, and guide future research by discussing existing challenges and opportunities in applying 2D materials for smart wearable biodevices. We begin with an in-depth analysis of the advantages, sensing mechanisms, and potential applications of 2D materials in wearable biodevice fabrication. Following this, we systematically discuss state-of-the-art biodevices based on 2D materials for monitoring various physiological signals within the human body. Special attention is given to showcasing the integration of multi-functionality in 2D smart devices, mainly including self-power supply, integrated diagnosis/treatment, and human–machine interaction. Finally, the review concludes with a concise summary of existing challenges and prospective solutions concerning the utilization of 2D materials for advanced biodevices.

Energy-dissipation elastomers relying on their viscoelastic behavior of chain segments in the glass transition region can effectively suppress vibrations and noises in various fields, yet the operating frequency of those elastomers is difficult to control precisely and its range is narrow. Here, we report a synergistic strategy for constructing polymer-fluid-gels that provide controllable ultrahigh energy dissipation over a broad frequency range, which is difficult by traditional means. This is realized by precisely tailoring the relaxation of confined polymer fluids in the elastic networks. The symbiosis of this combination involves: elastic networks forming an elastic matrix that displays reversible deformation and polymer fluids reptating back and forth to dissipate mechanical energy. Using prototypical poly (n-butyl acrylate) elastomers, we demonstrate that the polymer-fluid-gels exhibit a controllable ultrahigh energy-dissipation property (loss factor larger than 0.5) with a broad frequency range (10 −2 ~ 10 8  Hz). Energy absorption of the polymer-fluid-gels is over 200 times higher than that of commercial damping materials under the same dynamic stress. Moreover, their modulus is quasi-stable in the operating frequency range. In most cases the frequency range of a damping material is adapted to a specific application. Huang et al. design a gel filled with a polymeric fluid that bypasses this problem and offers an unusually broad window over which vibrational energy is effectively dissipated.

Biological materials, such as bones, teeth and mollusc shells, are well known for their excellent strength, modulus and toughness 1 – 3 . Such properties are attributed to the elaborate layered microstructure of inorganic reinforcing nanofillers, especially two-dimensional nanosheets or nanoplatelets, within a ductile organic matrix 4 – 6 . Inspired by these biological structures, several assembly strategies—including layer-by-layer 4 , 7 , 8 , casting 9 , 10 , vacuum filtration 11 – 13 and use of magnetic fields 14 , 15 —have been used to develop layered nanocomposites. However, how to produce ultrastrong layered nanocomposites in a universal, viable and scalable manner remains an open issue. Here we present a strategy to produce nanocomposites with highly ordered layered structures using shear-flow-induced alignment of two-dimensional nanosheets at an immiscible hydrogel/oil interface. For example, nanocomposites based on nanosheets of graphene oxide and clay exhibit a tensile strength of up to 1,215 ± 80 megapascals and a Young’s modulus of 198.8 ± 6.5 gigapascals, which are 9.0 and 2.8 times higher, respectively, than those of natural nacre (mother of pearl). When nanosheets of clay are used, the toughness of the resulting nanocomposite can reach 36.7 ± 3.0 megajoules per cubic metre, which is 20.4 times higher than that of natural nacre; meanwhile, the tensile strength is 1,195 ± 60 megapascals. Quantitative analysis indicates that the well aligned nanosheets form a critical interphase, and this results in the observed mechanical properties. We consider that our strategy, which could be readily extended to align a variety of two-dimensional nanofillers, could be applied to a wide range of structural composites and lead to the development of high-performance composites. Layered nanocomposites fabricated using a continuous and scalable process achieve properties exceeding those of natural nacre, the result of stiffened matrix polymer chains confined between highly aligned nanosheets.

The temperature-mediated modulation of anisotropic electrostatics in response to changes of electrostatic permittivity in a hydrogel consisting of cofacially oriented electrolyte nanosheets imparts the hydrogel with actuation properties. Electrostatic repulsion, long used for attenuating surface friction 1 , 2 , is not typically employed for the design of bulk structural materials. We recently developed a hydrogel 3 with a layered structure consisting of cofacially oriented electrolyte nanosheets 4 . Because this unusual geometry imparts a large anisotropic electrostatic repulsion 5 to the hydrogel interior, the hydrogel resisted compression orthogonal to the sheets but readily deformed along parallel shear. Building on this concept, here we show a hydrogel actuator 6 , 7 , 8 , 9 , 10 , 11 that operates by modulating its anisotropic electrostatics 12 in response to changes of electrostatic permittivity associated with a lower critical solution temperature transition 13 , 14 . In the absence of substantial water uptake and release, the distance between the nanosheets rapidly expands and contracts on heating and cooling, respectively, so that the hydrogel lengthens and shortens significantly, even in air. An L-shaped hydrogel with an oblique nanosheet configuration can thus act as a unidirectionally proceeding actuator that operates without the need for external physical biases 15 , 16 , 17 , 18 .

Compounding functional nanoparticles with highly conductive and porous carbon scaffolds is a basic pathway for engineering many important functional devices. However, enabling uniform spatial distribution of functional particles within a massively conjugated, monolithic and mesoporous structure remains challenging, as the high processing temperature for graphitization can arouse nanoparticle ripening, agglomerations and compositional changes. Herein, we report a unique “popcorn-making-mimic” strategy for preparing a highly conjugated and uniformly compounded graphene@NiFe 2 O 4 composite film through a laser-assisted instantaneous compounding method in ambient condition. It can successfully inhibit the unwanted structural disintegration and mass loss during the laser treatment by avoiding oxidation, bursting, and inhomogeneous heat accumulations, thus achieving a highly integrated composite structure with superior electrical conductivity and high saturated magnetization. Such a single-sided film exhibits an absolute shielding effectiveness of up to 20906 dB cm 2 g −1 with 75% absorption rate, superior mechanical flexibility and excellent temperature/humidity aging reliability. These performance indexes signify a substantial advance in EMI absorption capability, fabrication universality, small form-factor and device reliability toward commercial applications. Our method provides a paradigm for fabricating sophisticated composite materials for versatile applications. Cheng Yang and co-workers develop a “popcorn-making-mimic” strategy to fabricate a uniformly compounded graphene@NiFe2O4 composite film with strong electromagnetic interference shielding and absorption capability.

Ischemic stroke poses a substantial global health burden. Reliable biomarkers for risk stratification in critically ill stroke patients are lacking. This study investigates estimated pulse wave velocity (ePWV), a non-invasive measure of arterial stiffness, as a novel prognostic indicator for mortality in this population. This retrospective cohort study analyzed data from 3,408 adult ischemic stroke patients admitted to the ICU within the MIMIC-IV database. Patients were categorized by ePWV tertiles. The primary outcome was 28-day mortality (in-hospital and ICU). Multivariate Cox regression models were employed to assess the association between ePWV and mortality, adjusting for comprehensive clinical variables. Of the 3,408 patients, 481 (14.1%) died within 28 days of hospitalization. Non-survivors demonstrated significantly higher ePWV values (11.19 vs. 10.57, P < 0.001). Multivariate analysis revealed that ePWV was an independent predictor of both in-hospital (HR = 1.16, 95% CI: 1.05-1.28, P = 0.0033) and ICU 28-day mortality (HR = 1.31, 95% CI: 1.16-1.48, P < 0.0001). Subgroup analyses revealed significant interactions between ePWV and atrial fibrillation for in-hospital mortality (P = 0.0498) and mechanical ventilation for ICU mortality (P = 0.0294). For in-hospital mortality, the ePWV-associated risk was higher in patients with atrial fibrillation (HR 1.19, 95% CI: 1.07-1.31) compared to those without (HR 1.10, 95% CI: 0.98-1.23). For ICU mortality, the ePWV-associated risk was higher in patients without mechanical ventilation (HR 1.45, 95% CI: 1.24-1.70) compared to those with (HR 1.26, 95% CI: 1.11-1.44). ePWV is a promising biomarker for predicting mortality in critically ill ischemic stroke patients, particularly identifying high-risk subgroups with atrial fibrillation or those not receiving timely mechanical ventilation.

Functionalized hydrogels play an important part in chemistry, biology, and material science due to their unique microstructures. Characterization of these microstructures is the fundamental issue to improve the optical, mechanical, and biochemical performance of functionalized hydrogels. With the rapid development of fluorescence microscopy, a growing number of researchers have attempted to utilize this easily operated, noninvasive, and high-contrast technique to visualize the fine microstructure of hydrogels. Integration of a confocal system into fluorescence microscopy allows the sectioning and reconstruction of 3D hydrogel networks. The live recording function offers in situ and real-time images of dynamic behaviors within hydrogels. The development of super-resolution fluorescence microscopy has significantly promoted imaging quality from the submicron scale to the nanoscale. Based on these spectacular achievements, we reviewed the recent advances in fluorescence microscopic visualization of internal morphologies, mechanical properties, and dynamic structural changes. The scope of this review is to provide inspiration for researchers in chemistry, material science, and biology to study and fabricate functionalized hydrogels with the assistance of fluorescence microscopic visualization. This review highlights the recent advances in fluorescence microscopic visualization of synthetic hydrogels, bio-macromolecular hydrogels, organohydrogels, and supramolecular hydrogels. Topics related to the structural changes of hydrogels, hydrogel mechanics, and super-resolution imaging of hydrogels based on fluorescence microscopy are introduced. The design concepts, imaging mechanisms, and potential applications of the novel fluorescence visualization strategies are discussed in detail. Finally, our opinions on the major challenges of current research, possible solutions, and future directions are shared.