Iontronic pressure sensors hold great promise for electronic skins and related fields, yet conventional single-microstructure designs struggle to balance sensitivity and linear range, whereas ionic leakage induces signal drift. Herein, we present a highly effective anti-leakage iontronic sensor featuring a surface gradient microcone array. The design leverages the progressive deformation of multilevel microstructures and immobilizes ionic liquids within a thermoplastic polyurethane matrix via hydrogen bonding and electrostatic interactions. By optimizing additives and microstructural parameters, we achieved synergistic control over electromechanical properties and response behavior. The sensor exhibits a high sensitivity of 209 kPa-1 over a wide linear range of 10-200 kPa (R2 = 0.997), an ultralow detection limit of 2 Pa, a high-pressure resolution of 12 Pa under an 8 kPa preload, and a low signal drift rate of 4.6% over 3000 cycles. Applications demonstrated include encrypted Morse code transmission, physiological signal monitoring, joint motion recognition, and detection of 5 to 30 μm microvibrations. This work provides a mechanochemical synergistic strategy for designing high-performance flexible pressure sensors.

Limited by the nature of water, the narrow available range on temperature greatly hinders the application of hydrogels. Developing gel lubricants with high adaptability remains a major challenge. Benefiting from the intrinsic low freezing point and adaptability to harsh conditions, a eutectogel based on deep eutectic solvents is reported here. Systematic tribological tests confirmed that the eutectogel exhibited an exceptionally low friction coefficient (0.036), significantly enhanced load-bearing capacity and thermal stability, along with outstanding stability under varying friction conditions. The excellent lubrication performance arises from a synergistic effect of multiple mechanisms: shear-thinning of the network, formation of an adsorption film, and enhanced hydrogen bonding. A polyvinylpyrrolidone pretreatment is the key to suppressing the aggregation of MXene nanosheets through intermolecular interactions, enabling uniform nanomaterial dispersion within the gel matrix and thereby fully leveraging its lubrication performance. This strategy has been confirmed to be universally applicable across multiple eutectogel systems. The optimized eutectogel lubricant demonstrates a 94 % reduction in coefficient of friction and a 93 % decrease in wear volume, showcasing promising application prospects in the field of adaptive lubrication. This work provides a new insight for the development of high-performance, environmentally adaptive intelligent lubricating materials.

In the context of atmospheric re-entry technological breakthrough, addressing the oxidation issue of MoS2, as an important space solid lubricant, is an urgent challenge. As the edge-to-surface ratio notably increases with reduced lateral dimension of MoS2 nanosheet, more edge exposure brings vast coordinately unsaturated sites for adsorption and subsequent oxidation. In this work, based on a non-solvent induced polyvinylidene fluoride (PVDF) coacervation strategy, we prepare a core-shell structured MoS2@PVDF composite to investigate the impact of PVDF encapsulation on native oxidation and tribo-oxidation. Thermogravimetric analyses and Raman monitoring of MoO3 signal through in-situ laser heating indicate that the PVDF shell can act as a barrier to significantly slow down the oxidation rate of MoS2. The comparison between aged MoS2@PVDF and aged MoS2 shows that three times more oxygen content is detected in aged MoS2. The edge protection by PVDF encapsulation in humid air is highlighted by the lowest friction coefficient of MoS2@PVDF when it is used in itself and as filler in epoxy resin. The worn surface analyses bridge the oxidation and tribological performance as adsorbed water and oxygen molecules are activated to react with MoS2 to form MoO3 which induces severe abrasive wear and lubrication failure. By contrast, PVDF encapsulation can effectively preserve the lubricating capability of MoS2, providing a practical strategy toward environmentally robust solid lubricant with high adaptability and reliability.

Deep eutectic solvent (DES), when used as the continuous phase of eutectogels, can significantly improve their electrical and mechanical properties due to its excellent conductivity, freeze resistance and chemical stability. The development of eutectogels effectively solves the key limitations of traditional hydrogels and organogels, such as low-temperature freezing, high-temperature volatilization, and organic solvent leakage. It also realizes the collaborative optimization of environmental friendliness and comprehensive performance, which makes it show broad application prospects in the field of flexible sensing. This review summarizes the design principles, material selection, sensing mechanisms, and flexible sensing applications of eutectogels. By examining the design of eutectogels, the selection of DES, and the synthesis of the gel network, it provides a theoretical basis for the development of eutectogel-based sensor devices. A detailed description of the sensing mechanism is provided to elucidate the signal generation and transition in eutectogels toward the purpose of the practical applications. Finally, the application prospects of eutectogels for high-performance sensors and detection devices are discussed. Additionally, we provide a theoretical support for their structural design, performance optimization, and practical application.

The development of hydrogel-based flexible sensors is hindered by their inherent swelling and performance degradation in physiological environments. Inspired by the structure-function integration of natural muscle, a biomimetic multifunctional smart hydrogel with a triple-crosslinking structure via polyvinyl alcohol (PVA) crystalline domains, dynamic borate ester bonds, and high-density hydrogen bonds among phytic acid, PVA, and hydroxypropyl cellulose is designed in this study. The network ensures robust structural integrity and long-term stability while maintaining flexibility, exhibiting a swelling ratio of only 2.5% in simulated body fluid (SBF) after 40 days. Embedded MXene nanosheets serve as nano-reinforcers, electronic conductive pathways, and photothermal converters, enabling near-infrared (NIR)-triggered reversible modulation of lubrication and electrical properties of the hydrogel. The obtained hydrogel demonstrates a stable ultra-low friction over extended friction periods (10 h) and exhibits a unique capability for synchronous monitoring of thermal, mechanical, and frictional stimuli through a single resistance signal. This design provides a promising platform for advanced applications in biomimetic articular cartilage, smart wearable interfaces, and adaptive soft robotics.

Solvent-free nanofluids (NFs) hold significant potential as lubricant additives, however, their dispersion in nonpolar oils is hindered by polar shell components. To address this issue, we designed and synthesized a core-shell structured MgAl-LDH-NFs comprising a flower-like MgAl-LDH core with inherent lubricating properties and a hydrophobic KH560-FL1000 shell. This design achieved improved dispersion stability in liquid paraffin. At an optimal concentration of 0.75 wt%, the MgAl-LDH-NFs significantly reduced the coefficient of friction by 48.5 % and wear volume by 88.8 %. This enhancement is attributed to the synergistic effect of the shell's adsorption capacity and the core's lubricity, which promoted the formation of a robust protective tribofilm. Solvent-free LDH-based nanofluids demonstrate considerable promise for demanding industrial applications for high-load machinery and precision manufacturing.

Liquid lubricants are crucial for advanced bearing equipment, as they help mitigate key tribological issues including friction and wear, thereby reducing the risk of failure and extending service life. Herein, a low-viscosity, high-affinity deep eutectic solvent (TB-C12OH DES) was synthesized by blending tetrabutylammonium chloride with 1-dodecanol using a simple heating-stirring method, and it was used as a high-performance lubricant for steel substrates. The as-synthesized TB-C12OH DES showed favorable physicochemical properties. Reciprocating friction tests demonstrated that TB-C12OH DES achieved low friction coefficients (0.081-0.090) and ultralow wear rates (3.02-4.75 × 10-9 mm3 N-1 m-1) under high-load conditions (2.16-3.12 GPa). These results are attributed to the formation of stable adsorption film and tribofilms consisting of carbonaceous compounds and iron oxides at the tribointerface through adsorption and tribochemical reactions. This straightforward preparation strategy not only meets specific lubricant requirements but also paves the way for the development of eco-friendly DES-based lubricants with high lubricating performance to address friction and wear challenges under complex operating conditions.

Real-time monitoring of mechanical lubrication is essential for predictive maintenance of industrial machinery, yet conventional sensors fail to discern the weak vibration signals that herald early-stage lubrication failure. Here we report an electric double-layer (EDL) capacitive sensor built on a topologically entangled ion gel dielectric. By combining a high monomer concentration with phytic acid (PA) regulation, we obtain an ion gel that exhibits low hysteresis (6.7 +/- 0.3%), and that forms rapidly through photopolymerization without chemical crosslinkers. Simulations reveal that PA converts intramolecular hydrogen bonds into stronger intermolecular "PA-amide" bonds, enhancing segmental mobility while preserving a high entanglement density, the molecular basis for the gel's low modulus and minimal energy dissipation. Digital light processing (DLP) 3D-printed micro-cone arrays further confer exceptional sensitivity (40,000 +/- 8000 kPa(-1)), a symmetrical response time of 89 +/- 8 ms and 92 +/- 10 ms, 1 mu m spatial resolution, and durability over 10,000 cycles. The device resolves microscale vibrations (0-60 mu m) at ultra-low frequencies (2-4 Hz), a regime inaccessible to conventional pressure sensors. Integrated with machine learning, it discriminates oil-lubricated from dry-friction states with an overall accuracy of 90.0% +/- 11%, marking considerable potential for in situ tribological diagnostics and intelligent condition monitoring of industrial machinery.

Covalent solvent-free nanofluids show excellent tribological properties, yet the effect of organic shell chain length on performance remains unclear. This work innovatively synthesized three MXene-based nanofluids (M1000 NFs, M2070 NFs, M3085 NFs) with tuned canopy chain lengths, revealing chain-dependent performance. Short-chain M1000 NFs achieved superior oxidative stability in water through dense surface grafting, maintaining performance over 180 days. As a water-based additive, M3085 NFs with extended chains reduced friction by 74% at 0.25 wt% via an optimized adsorption layer. Wear resistance depended mainly on MXene core concentration rather than chain length. These insights provide key design guidelines for high-performance aqueous MXene nanofluids, particularly addressing the coupled challenges of oxidative degradation and friction control.

Temporomandibular disorder (TMD), as a multifactorial oral disease, has long relied on diagnostic methods of clinical palpation and imaging. However, these approaches are highly subjective, costly, and invasive. Inspired by the principle of clinical palpation, this study proposed a noninvasive detection method based on reduced graphene oxide (rGO) composite aerogel piezoresistive sensing technology. A smart earbud sensor was designed and assembled to monitor the deformation of the anterior wall of the external auditory canal. The sensor exhibits an extremely low detection threshold of 14.5 Pa and a short response time of 64 ms, remains stable over 1000 compression cycles, and successfully captures subtle facial activities such as swallowing and mouth opening. In subsequent evaluations of temporomandibular joint (TMJ) motion, the sensor captured different signal patterns between volunteers with normal and abnormal mandibular motion patterns, and the sensing results showed consistency with clinical evaluation and cone-beam computed tomography-based osseous structural observations. To reduce the limitations associated with subjective judgment and further analyze the collected signals, a support vector machine model was introduced for preliminary classification analysis, achieving an accuracy of 91.7%. This work provides a new wearable perception strategy for objective and rapid screening of TMJ movement abnormalities, offering a potential complementary approach for future TMD-assisted assessment.

Supercapacitors have aroused widespread interest as advanced electrochemical energy storage devices owing to their excellent electrochemical performances in terms of power density, rate capability, and cycling stability. In these devices, the electrode material is the most important component that determines the performance. Therefore, extensive efforts on robust and efficient electrode materials have been carried out. Metal sulfides and phosphides are emerging as potential candidates for advanced supercapacitors due to their superior electrical conductivity and higher theoretical capacitance than their oxide counterparts. However, severe volume expansion and sluggish reaction kinetics largely hinder their cycling stability and rate capability. To further improve their electrochemical performance, strategies including nanostructuring, compositing, and designing architecture of electrodes, etc. have been investigated. In this chapter, the synthesis methods of metal sulfides/phosphides are presented. Subsequently, advanced electrode materials based on metal sulfides/phosphides with various structures, morphologies, compositions, and electrochemical performances are highlighted and discussed. Finally, the conclusions, challenges, and prospects of metal sulfides/phosphides as efficient electrochemical energy storage materials are proposed.

Embodied human-machine interaction (EHMI) is predicated on the utilization of human motion signals as a medium of communication, with the objective of achieving a more natural, immersive, intuitive, and efficient interactive experience. The utilization of flexible hydrogel sensors as the EHMI core perception device remains limited due to discomfort caused by heavy loads and mechanical constraints. The present study developed a novel low-constraint wearable hydrogel sensor patch (LCWHSP) based on the remote sensing mechanism of bionic spiders. The innovative integration of a Fenton-like reaction into light-curing 3D printing technology has facilitated the collaborative optimization of the printability and performance parameters of graphene-Fe3+ dynamically coordinated sodium alginate-polyacrylamide (GFSP) double crosslinked hydrogel sensitive materials. The cross-shaped structure design of the LCWHSP enables single-point multidimensional sensing on the skin interface, thereby effectively reducing the sensation of wearing a foreign object caused by high-density sensor arrays. High-precision recognition of hand movements was achieved by utilizing a signal acquisition system and a deep learning analysis model (with an accuracy rate of 98.60%). Further using in typical EHMI scenarios, such as controlling virtual interfaces and manipulating robotic arms, fully validated its practical application potential.

To address the need for friction-controllable interfaces in intelligent equipment and engineering, an anisotropic graphene oxide (GO) aerogel/epoxy resin composite (GA/EP) was developed in this study, which exhibits anisotropic trends in thermal conductivity, mechanical and tribological properties. The top side (T) of the GA/EP composite exhibits optimal tribological performance with a low coefficient of friction (COF) of 0.063 due to its higher thermal conductivity and elastic modulus than lateral side. The COF of lateral axis (LA) direction is 0.095, while that of lateral radial (LR) direction is 0.660. Molecular dynamics simulation results indicate that the low friction stress remains stable at 20-40 atmospheres (atm) in the LA direction that favors the formation of shear-friendly interfaces by reducing interactions between GA/EP and the counterpart, whereas LR's abrupt stress (50,000-100,000 atm) increase disrupts lubrication. This research meets the demand for differentiated dynamic COF, enhancing the potential of intelligent precision equipment in practical engineering applications.

Graphene aerogel (GA) has attracted wide attention for its potential applications in various fields. However, the graphene nanosheets in the GA framework often exhibit insufficient adhesion and interfacial contact due to weak interactions, resulting in fragile cell walls and poor structural stability. Here, inspired by the principle of "soft-hard" compounding, a class of GA with extraordinary structural stability and mechanical property was prepared based on the in-situ bonding interfacial engineering between different phases in Pickering emulsion. Through interfacial engineering, the fatal compounding drawback between fusing oily polymer soft chains and water-soluble hard graphene oxide (GO) nanosheets is resolved, which enables polydimethylsiloxane (PDMS) chains to in-situ adhere onto GO nanosheets, eventually resulting in compelling structural-stable PDMS/GO aerogel (PGOA) backbone. Later, PDMS/GA (PGA) can be easily obtained by simple reduction of PGOA. The obtained PGA achieves excellent structural stability, 97.5 % elasticity, 1.7 MPa compressive capacity, and unprecedented isotropic characteristics. The assembled flexible sensor based on PGA has a high sensitivity of 17.08 kPa(-1). Additionally, PGA has low thermal conductivity (0.0245-0.0301 W/(m center dot K)) and good flame retardancy (similar to 1000 degrees C). Because of these excellent properties, PGA has a wide range of potential applications in areas such as flexible sensing, thermal protection, and fire detection.

Solvent-free nanofluids (NFs) based on a variety of lubrication core materials have attracted extensive attention in tribology, but it is still an open field to explore the relationship between size of core and tribological properties of NFs. In this paper, the multi-layer, ultrathin and ultrafine layered double hydroxides solvent-free nanofluids (ML-LDH-NFs, UT-LDH-NFs and UF-LDH-NFs) are proposed for lubricant. Compared with UT-LDH-NFs, ML-LDH-NFs exhibit better friction reduction and wear resistance performance for the interlayer sliding in multi-layer layered double hydroxides, UF-LDH-NFs with smaller lateral size is easier to slip into the sliding interface to form tribofilm, and thus provide more effective friction-reducing and anti-wear. This research provides fundamental insights into size effects of core materials for solvent-free nanofluids lubricants.

Research on the chemical structures and physicochemical properties of deep eutectic solvents (DESs) is crucial to develop high-performance DES-based lubricating materials for solving tribological problem, including friction and wear. Herein, a series of boric acid-based DESs (B-DESs) were synthesized using choline chloride (hydrogen bond acceptor, HBA) and sorbitol/boric acid (hydrogen bond donors, HBDs) through a simple heating-stirring method. The experimental investigations and quantum chemistry calculation demonstrated that B-DESs exhibited optimized chemical structures, favorable rheological properties, low melting points (below-61.6 degrees C), high thermostability (with decomposition temperatures exceeding 282 degrees C), and biocompatibility. As lubricants, they showed exceptional tribological performance, achieving macroscale superlubricity with a friction coefficient of similar to 0.0088 and excellent anti-wear properties on polyoxymethylene substrates even under high-load conditions. The exceptional lubrication performance was attributed to synergetic lubrication between the fluid nature of B-DESs and the self-lubrication property of the substrates, as well as the potential formation of lubricating films at the tribo-interface. This study introduces a novel and straightforward approach for synthesizing green and high-performance DES-based liquid superlubricity materials, and offering significant potential in bio-lubrication applications.

Polydimethylsiloxane (PDMS) is known for its exceptional mechanical stability, chemical resistance, and biocompatibility, making it highly suitable for flexible sensors. However, its inherently insulating properties limit its direct application as a sensing material, and its hydrophobic nature poses challenges for effective integration with conductive materials. To overcome these challenges, the present study proposes an innovative strategy that utilizes PDMS as the matrix material while MXene as a conductive filler, aiming to fabricate PDMS aerogels through a Pickering emulsion method. In this process, MXene nanosheets are first functionalized with sodium carboxymethyl cellulose (CMC), enhancing both emulsification and gelation to stabilize the Pickering emulsion composed of PDMS and MXene. Simultaneously, the modified MXene nanosheets act as precursors for constructing the aerogel framework. This method not only promotes the formation of a robust 3D PDMS network but also creates a stable, efficient conductive pathway using MXene nanosheets. The resulting aerogels exhibit remarkable flexibility, elasticity (>90 %), and compressive strength (9.3 MPa). Therefore, with a high sensitivity of 28.7 kPa(-1 )and exceptional electromechanical performance, the PCM sensor is well-suited for applications in human health detection and mechanical equipment monitoring. Furthermore, the PCM sensor can also be integrated with robotic arm for intelligent sensing tasks, showcasing significant potential for next-generation smart devices.

This paper presents a systematic review of vibration sensors and their application in industrial-monitoring systems, aiming to provide a comprehensive reference for both academic research and practical applications in this field. Through the classification of measured parameters and sensing principles, this work endeavors to establish a structured understanding of vibration sensor’s working mechanism and deliver an in-depth analysis of their recent research achievements. By integrating practical cases from typical domains, this manuscript comprehensively demonstrates the practical value and application potential of vibration sensors in equipment-monitoring systems, illustrating how these sensors are utilized to detect mechanical failures and enhance the performance and safety of industrial systems, such as wind turbine, tunnel boring machine, and aerospace engine. Looking forward, with the rapid advancement of the Internet of Things (IoT) and artificial intelligence (AI) technologies, vibration sensors are anticipated to evolve towards multifunctionalization, miniaturization and intelligentization, thereby forming a comprehensive monitoring network that improves overall efficiency and reliability of the mechanical systems.

This study presents a straightforward and rapid method for preparing graphene aerogel by integrating a sodium alginate (SA)-metal ion crosslinking system, a bubble template, and an osmotic dehydration process. Graphene oxide (GO) nanosheets were dispersed into the solution crosslinked by SA and metal ions, leading to rapid gelation of GO under ambient conditions. To minimize structural damage to the porous network caused by water molecules during the drying process, an osmotic dehydration technique was employed as an auxiliary drying method. This, combined with ambient-pressure drying, significantly improved both drying efficiency and structural integrity of the aerogel. The incorporation of the bubble template was crucial in stabilizing the pore structure by mitigating capillary forces. Following high-temperature thermal reduction, highly ordered and porous reduced GO aerogels were successfully obtained. Additionally, the potential application of these aerogels in the field of piezoresistive sensors was explored. This method provides a low-cost, efficient, and versatile approach of GA fabrication, offering promising prospects for a wide range of applications.