Two-dimensional (2D) materials open up exciting possibilities for the study of ion transport behavior for green energy. Here, a simple and effective strategy to fabricate high-conductivity nanofluidic channels based on exfoliated montmorillonite (MTM) nanosheets is proposed. The resource-rich and low-cost layered MTM was first exfoliated into monolayer nanosheets using Exolit OP 550. Subsequently, the MTM nanosheets with Exolit OP 550 were assembled into 2D nanofluidic devices by the layer-by-layer self-assembly method. The results show that Exolit OP 550 exfoliates different types of layered MTM into monolayer nanosheets with uniform contrast and integrity. The reconstructed Na-MTM nanofluidic device has the highest ionic conductance. The ionic conductivity of the Na-MTM 2D nanofluidic device was effectively improved after Li+ modification with a higher charge density. After further optimizing the content of Exolit OP 550, the ion conductivity of the MTM nanofluidic device reached 4.66 × 10-4 S cm-1, which is 55.3% higher than the highest known value among the same nanofluidic devices. Interestingly, this nanofluidic device exhibited a very high sensitivity in detecting water evaporation, which can reach 10-12 S s-1 in resolution. This economically viable strategy may advance the study of low-dimensional ion transport properties in new energy coatings and the design of evaporation detectors.

ABSTRACT Robust hydrogel‐elastomer integration is crucial for soft electronics and robotics but hindered by interfacial fragility. Here, we present a spatially confined in situ photopolymerization strategy to grow hydrogel coatings directly from polydimethylsiloxane (PDMS). By confining the active radicals within the solvent‐swollen elastomeric boundary, this strategy achieves a bottom‐up growth. Crucially, both experimental characterizations and molecular dynamics (MD) simulations reveal a hydrogen‐bond‐mediated discrete nucleation process during the coating formation. This localized pre‐organization serves as physical evidence of the bottom‐up growth, which constructs a dual‐anchoring interface featuring simultaneous covalent grafting and topological entanglement. The dual‐anchoring (DA) hydrogel coatings achieve high interfacial toughness, long‐term stability, and applicability to other elastomers. We further extend this protocol for fabricating patterned conductive hydrogel coatings with high‐resolution reproduction of micron‐scale features. Furthermore, it enables rapid in situ fabrication of thin‐film actuators with enhanced actuation performance. This strategy presents a convenient protocol for integrating advanced hydrogel functionalities into soft matter systems.

Developing efficient hydrogen evolution catalysts is crucial for hydrogen production via water splitting; however, achieving high catalytic performance in single-atom catalysts remains challenging. In this study, we report a single-atom catalyst (SA-Ru-MoS2) featuring a combined defect design, prepared under mild conditions. In this catalyst, single-atom Ru substitution and sulfur vacancies jointly modify molybdenum disulfide (MoS2). The results show that this design exposes more active sites of the catalyst, thereby significantly improving the HER performance of MoS2. The overpotential at a current density of 10 mA & sdot;cm- 2 was 24 mV, and the Tafel slope was 31 mV & sdot;dec- 1. Notably, no significant degradation in current density was observed over 72 h at constant current densities of 10, 50 and 100 mA & sdot;cm- 2. This finding highlights its exceptional stability, making it promising for potential industrial applications. This study provides efficient hydrogen evolution reaction (HER) catalysts. In addition, it offers new insights into catalyst design by employing single-atom defect combination strategies.

The myocardial organ-on-a-chip platform represents a transformative approach for replicating cardiac physiological functions in vitro, with significant potential for drug screening and disease modeling applications. Dynamic mechanical stimulation enhances both structural and functional maturation of cardiac tissues, leading to improved contractile performance, while real-time contractility monitoring provides essential data for investigating cardiac disease mechanisms and evaluating pharmacological interventions. However, integrating mechanically stimulated mature myocardial tissue cultures with real-time detection of weak contractile activity remains challenging. Here, an integrated platform that combines programmable mechanical stimulation with real-time contractile force monitoring was developed. The system employs aligned fiber scaffolds to guide three-dimensional (3D) cardiac tissue formation. Meanwhile, a wireless tunable magnetic actuation unit applying physiological relevant mechanical stimulation was employed demonstrating remarkable efficacy in enhancing sarcomeric structure (42.9% increase in sarcomere length, from 1.42 to 2.10 µm) and contractile function (47.5% increase in force amplitude, from 19.47 to 28.72 µN). An embedded flexible sensor based on liquid metal for real-time monitoring of contraction force was introduced, achieved a minimum detectable force of 1.52 µN. The system addresses current limitations in cardiac tissue engineering where stimulation and sensing platforms are typically separate, integrating both dynamic maturation enhancement and continuous contractile performance monitoring.

Large amounts of binder system waste are produced upon the recovery of energetic components in scrapped hydroxyl-terminated polybutadiene (HTPB) propellant. This study investigated the biodegradability of the binder system waste using a microbial enrichment solution as the biodegradation medium. We measured the binder system weight loss and performed Fourier-transform infrared (FT-IR), thermogravimetric (TG), and scanning electron microscopy (SEM) analyses of the binder system after 60 days of biodegradation. The results show the binder system film weight decreased by approximately 43% and stabilized after 50 days. The FT-IR analysis shows a reduction in C=O and C-O bond signals, whereas N-H, C-N, and C=C bond signals remain nearly unchanged. The TG analysis shows that the difference between the DOA weight in the initial film and that of the thermal decomposition was almost equal to the weight loss of the binder system film after biodegradation. The SEM analysis shows irregular pits on the film. The binder system has a certain biodegradability, which is mainly caused by its plasticizer component, i.e., DOA. HTPB-based polyurethane, the other major component, is difficult to degrade by microorganisms. As such, the binder system was pretreated with sodium methoxide-methanol solution as a depolymerization reagent, and the pretreated product yielded higher biodegradability.

The emergence of Organ-on-a-Chip (OoC) has significantly advanced biomedical research mainly on aspects of disease modeling and drug research. The need for real-time and continuous monitoring of the OoCs has been driving the development of integrated sensors on-chip. To meet these needs across different scales, from microscopic to macroscopic, primary sensing strategies for in situ sensor integration typically include electrical, optical, and mechanical approaches. This review focuses on the detection methodologies driven by these requirements and analyzes the core sensing elements involved. It further explores current innovative pathways for achieving in situ sensing integration and discusses the future prospects brought about by the development of models in OoC and sensing technologies.

Digital light processing (DLP) has emerged as one of the most promising methods for constructing intricate 3D hydrogel structures. However, the material availability of hydrogels is quite limited for resin vat-based printing. To overcome this issue, we propose a surface tension confined digital light processing (STC-DLP) technique that utilizes liquid surface tension and surface-treated substrates to confine the hydrogel solution during printing, to minimize the solution consumption. The "top-down" DLP printing enables layer-by-layer curing of hydrogel solutions into controlled 3D structures. A soft and a rigid hydrogel solution was selected as demonstration. By adding hydrogel solution with desired volume, highly accurate microtissue models, flexible sensors, and microfluidic chips with complex 3D structures were fabricated with high solution availability. This approach achieves efficient utilization of hydrogel solutions, and is expected to be especially applicable for printing of scarce or expensive materials.

Enclosed liquid-solid triboelectric nanogenerators (LS-TENGs) have gained widespread attention due to the advantages of self-storage of liquid and less susceptibility to contamination, but are limited by the low output power density. Here, a tubular bulk effect electricity nanogenerator (TBE-ENG) is reported by inserting an internal electrode with an appropriate depth between the fluorinated ethylene propylene (FEP) film and the glass cross-section in the tube. The TBE-ENG can achieve an output current of 5.0 mA and a peak power density of 2169 W m-3 after adding a 1 M sodium chloride solution, which are much higher than those of the enclosed LS-TENGs in previous studies. The mechanism of TBE-ENG is elucidated via an equivalent capacitor model, and the effects of the electrode spatial position, dielectric layer thickness, and liquid properties on the output performance are well revealed in combination with experiments. Moreover, the applicability of TBE-ENG and its application for driving electronic devices are demonstrated. This work lays the groundwork for the design of higher-performance enclosed LS-TENGs, and greatly expands the application of the bulk effect.

The three-dimensional printing of thermoset materials is of use in the development of flexible electronics and soft robotics. However, the process typically involves the deposition and removal of supporting materials that require extensive cycles of pre- and post-processing. Here we describe a three-dimensional printing method for constructing functional and arbitrary free-standing thermoset structures without using supporting materials. The approach integrates in situ laser-induced solidification with direct ink writing. During printing, the integrated laser is focused on a micro-sized polymer jet, leading to thermoset crosslinking in less than 0.25 s through a strong photothermal effect. The process offers a resolution as fine as 50 μm, with mechanical properties tunable by up to tenfold and electrical properties by up to 20-fold. We used this approach to print stretchable electronics with stiffness gradients for strain inhibition, flexible sensors with high sensitivity and three-dimensional soft magnetic robots for actuation functions. A three-dimensional printing method that integrates in situ laser-induced solidification with direct ink writing can be used to create stretchable electronics with stiffness gradients, flexible pressure sensors with high sensitivity and soft magnetic robots for actuation functions.

Pulse diagnosis, particularly the three positions and nine indicators (TPNIs) method, serves as a vital clinical assessment tool in traditional Chinese medicine (TCM). Recent years have witnessed significant research efforts toward standardizing pulse diagnosis through radial artery waveform analysis, as these waveforms encode substantial physiological information. However, conventional pulse acquisition instruments predominantly use rigid mechanical finger designs that compromise sensor-skin adhesion and incorporate overly complex control systems that impede device miniaturization. In this study, we present a novel digital flexible microfluidics-based system for automated TPNI pulse extraction. The proposed platform represents a lowcost, portable diagnostic device capable of assessing pulse characteristics at three distinct anatomical positions (Cun, Guan, and Chi) and three clinically relevant pressure levels (Fu, Zhong, and Chen), all within a compact form factor measuring <64 x 46 x 12 mm(3). Remarkably, the system achieves position selection or pressure control using just two independent digital pneumatic actuators. Experimental results demonstrate that the microfluidic platform successfully emulates the TCM pulse diagnosis process, acquiring position- and pressure-dependent pulse waveforms. The implementation incorporates a location decoder for interfinger pressure switching and a dedicated pressure regulator for precise-level adjustment. This work advances the development of cost-effective, flexible portable devices that adhere to TCM diagnostic principles while improving standardization.

Microelectrode arrays (MEAs) have ushered in a new era of in vitro drug screening and cardiotoxicity evaluation. However, the morphological constraints of two-dimensional (2D) planar culture and the mechanical rigidity of conventional electrodes hinder the formation of myocardial tissues that closely resemble native physiological conditions and limit the accuracy of drug efficacy analysis based on electrophysiological signals. Here, we present a flexible MEA platform enabled by a composite additive manufacturing approach, with key steps including melt electrowriting of microfibers, electrostatic spraying of insulation layer, and electrospinning of nanofiber scaffolds. This design integrates suspended, flexible microfiber electrodes with tightly adhered nanofiber scaffolds, creating a 3D ordered culture environment for myocardial tissue culture while ensuring adaptable electrophysiological signal recording. The aligned nanofiber scaffolds promote oriented myocardial growth and enhance sarcomere length by 29 % compared to random fibers, resulting in a propagation speed of 15.835 cm/s. The flexible and stretchable microfiber electrodes, approximately 20 μm in diameter, conform dynamically to tissue deformation during beating. Furthermore, the platform's functional performance is validated using isoproterenol and verapamil, confirming its potential for on-chip drug screening applications. These results highlight the promise of the suspended, flexible, and aligned MEAs for on-chip drug screening.

Confronting the impending exhaustion of traditional energy, it is urgent to devise and deploy sustainable clean energy alternatives. Osmotic energy contained in the salinity gradient of the sea-river interface is an innovative, abundant, clean, and renewable osmotic energy that has garnered considerable attention in recent years. Inspired by the impressively intelligent ion channels in nature, the developed angstrom-scale 2D channels with simple fabrication process, outstanding design flexibility, and substantial charge density exhibit excellent energy conversion performance, opening up a new era for osmotic energy harvesting. However, this attractive research field remains fraught with numerous challenges, particularly due to the complexities associated with the regulation at angstrom scale. In this review, the latest advancements in the design of angstrom-scale 2D channels are primarily outlined for harvesting osmotic energy. Drawing upon the analytical framework of osmotic power generation mechanisms and the insights gleaned from the biomimetic intelligent devices, the design strategies are highlighted for high-performance angstrom channels in terms of structure, functionalization, and application, with a particular emphasis on ion selectivity and ion transport resistance. Finally, current challenges and future prospects are discussed to anticipate the emergence of more anomalous properties and disruptive technologies that can promote large-scale power generation.

Achieving the ultralow coefficient of friction (COF) is the goal pursued by the industrial field. In this work, the macroscopic superlubricity with a COF of 0.003 on the DLC film was achieved at an approximate temperature of 45-100 degrees C when it slid against the steel ball with the lubrication of polyethylene glycol monolaurate (PEGM). The superlubricity state was achieved in a mixed lubrication regime, mainly containing boundary lubrication and thin film lubrication. The friction action under high temperature facilitated the chemisorption of PEGM molecules on the friction pair to form the tribochemical films, providing a low shear strength under boundary lubrication. Meanwhile, the PEGM molecules could form an ordered layer and a liquid layer on the tribochemical films due to the strong polarity of PEGM molecules, which attained the thin film lubrication to reduce friction. Moreover, the friction promoted the in situ generation of carbonaceous sheets in the contact region, providing low shear strength and reducing COF under boundary lubrication. This finding provides insight into the superlubricity mechanism of DLC film and expands its engineering application in superlubricity technology.

A major challenge in myocardial tissue engineering is replicating the heart’s highly complex three-dimensional (3D) anisotropic structure. Heart-on-a-chip (HOC) is an emerging technology for constructing myocardial tissue in vitro in recent years, but most existing HOC systems face difficulties in constructing 3D myocardial tissue aligned with multiple cell layers. Electrospun nanofibers are commonly used as scaffolds for cell growth in myocardial tissue engineering, which can structurally simulate the extracellular matrix to induce the aligned growth of myocardial cells. Here, we developed an HOC that integrates multi-layered aligned polycaprolactone (PCL) nanofiber scaffolds inside microfluidic chips, and constructed 3D thick and aligned tissue with a layered seeding approach. By culturing human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) on chip, the myocardial tissue on the two layered nanofibers reached a thickness of ~53 μm compared with ~19 μm for single-layered nanofibers. The obtained myocardial tissue presented well-aligned structures, with densely distributed α-actinin. By the third day post seeding, the hiPSC-CMs contract highly synchronously, with a contraction frequency of 18 times/min. The HOC with multi-layered biomimetic scaffolds provided a dynamic in vitro culture environment for hiPSC-CMs. Together with the layered cell-seeding process, the designed HOC promoted the formation of thick, well-aligned myocardial tissue.

Thrust roller bearings are widely used in heavy-duty mechanical components, but there is a major challenge that it needs for regular inspection of the lubricants to prevent bearing failure caused by leaks, wear, and contamination from impurities. Here, we have developed a prototype of a highly sensitive self-sensing smart thrust roller bearing (SS-TRB) based on triboelectric nanogenerator for the real-time monitoring of lubricating oil. The SS-TRB consists of four thrust cylindrical rollers, a cage, a seat ring, block-shaped stainless steel electrodes, copper film electrodes, polytetrafluoroethylene (PTFE) insulation film, and lubricating oil. The open-circuit voltage (Voc) of the SS-TRB are correlated to the applied load, rotational speed, and lubricating oil content. The SS-TRB can serve as a diagnostic tool for monitoring contaminants in lubricating oil because the Voc of the SS-TRB can directly reflect the presence of stainless steel powder, carbon powder, and alcohol in the lubricating oil. Additionally, the SS-TRB exhibits the remarkable sensitivity to the water content, as even a minimal intrusion of 0.01% can trigger a significant Voc change. This work has promising prospects in demanding applications, particularly in the heavy underwater equipment.

In order to determine the curing reaction model and corresponding parameters of hydroxyl-terminated block copolyether (HTPE) and provide a theoretical reference for its practical application, the non-isothermal differential scanning calorimetry (DSC) method was used to analyze the curing processes of three curing systems with HTPE and N-100 (an aliphatic polyisocyanate curing agent), isophorone diisocyanate (IPDI), and a mixture of N-100 and IPDI as curing agents. The results show that the curing activation energy of N-100 and HTPE was about 69.37 kJ/mol, slightly lower than the curing activation energy of IPDI and HTPE (75.60 kJ/mol), and the curing activation energy of the mixed curing agent and HTPE was 69.79 kJ/mol. The curing process of HTPE conformed to the autocatalytic reaction model. The non-catalytic reaction order (n) of N-100 and HTPE was about 1.2, and the autocatalytic order (m) was about 0.3, both lower than those of IPDI and HTPE. The reaction kinetics parameters of the N-100 and IPDI mixed curing agent with HTPE were close to those of N-100 and HTPE. The verification results indicate a high degree of overlap between the experimental data and the calculated data.

Icing negatively impacts various industrial sectors and daily life, often leading to severe safety problems and substantial economic losses. In this work, a fluorinated resin coating with embedded graphene nanoflakes is prepared using a spin-coating curing process. The results shows that the ice adhesion strength is reduced by ≈97.0% compared to the mirrored aluminum plate, and the icing time is delayed by a factor of 46.3 under simulated solar radiation power of 96 mW cm-2 (1 sun) at an ambient temperature of -15 °C. The superior anti/de-icing properties of the coating are mainly attributed to the synergistic effect of the fluorinated resin with a low surface energy, the rough structure of the sandblasted aluminum plate, which reduces the contact area, and the embedded graphene nanoflakes with a superior photothermal effect. Furthermore, the hydrogen bonding competition effect between the exposed-edge oxygen-containing functional groups of the embedded graphene nanoflakes and water molecules further improves the anti-icing properties. This work proposes a facile preparation method to prepare coatings with excellent anti/de-icing properties, offering significant potential for large-scale engineering applications.

AbstractNanofluidic channels inspired by electric eels open a new era of efficient harvesting of clean blue osmotic energy from salinity gradients. Limited by less charge and weak ion selectivity of the raw material itself, energy conversion through nanofluidic channels is still facing considerable challenges. Here, a facile and efficient strategy to enhance osmotic energy harvesting based on drastically increasing surface charge density of MXenes subnanochannels via oxygen plasma is proposed. This plasma could break Ti–C bonds in the MXenes subnanochannels and effectively facilitate the formation of more Ti–O, C═O, O–OH, and rutile with a stronger negative charge and work function, which leads the surface potential of MXenes membrane to increase from 205 to 430 mV. This significant rise of surface charge endows the MXenes membrane with high cation selectivity, which could make the output power density of the MXenes membrane increase by 248.2%, reaching a high value of 5.92 W m−2 in the artificial sea‐river water system. Furthermore, with the assistance of low‐quality heat at 50°C, the osmotic power is enhanced to an ultrahigh value of 9.68 W m−2, which outperforms those of the state‐of‐the‐art two‐dimensional (2D) nanochannel membranes. This exciting breakthrough demonstrates the enormous potential of the facile plasma‐treated 2D membranes for osmotic energy harvesting.

Sustainable, clean, seawater-river interface osmotic energy shows great potential in replacing traditional fossil fuel sources. Two-dimensional (2D) nanofluidic channels, known for their high throughput, high integration density, and excellent scalability, render practical applications feasible for osmotic energy harvesting. However, 2D nanofluidic channels face challenges such as high internal resistance and high costs, which keep the ultimate goal of large-scale osmotic energy harvesting distant. Herein, a novel method to regulate ion transport resistance by constructing different hydrophilic asymmetric nanofluidic channels using bilayer membrane of vermiculite and MXene is proposed. Vermiculite nanosheets are prepared via polymer-assisted exfoliation method utilizing polyethyl-phosphate glycol ester. After simple stirring and maturation process, the exfoliation concentration can reach 20 phr within 8 h, which is 20 times higher than the previously reported maximum. The internal resistance of the bilayer membrane decreased from 24.1 k Omega to 15.0 k Omega as the direction of ions transport changes. Oxygen plasma assistance enabled the bilayer membrane to reach a maximum power density of 4.66 W m(-2). The high-efficiency preparation method of vermiculite nanosheets and the emphasis on membrane surface properties offer new insights into practical osmotic energy harvesting.