Flexible capacitive sensors (FCSs) are widely used in wearable electronics and human-machine interaction, yet their force-electrical responses are often described only by numerical simulation or empirical calibration. In this work, an analytically simplified force-electrical transfer function is developed for FCSs with differential dielectric architectures based on a CNT/PDMS conductive silicone rubber dielectric. The model combines a Yeoh hyperelastic constitutive description, a stress-dependent permittivity relationship, and sequential mechanical--electrostatic finite element analysis to establish a continuous pressure-capacitance response within 0-100 kPa. The simplified transfer function agrees closely with FEA results (R-2 > 0.999), while the experimentally measured capacitance responses show good agreement with the model (R-2 > 0.95, NRMSE < 8%). The model further predicts a near-optimal differential ratio around 25%, and the fabricated 26% structure exhibits the strongest response among the tested configurations, demonstrating the utility of the proposed model for model-guided sensor design. In addition, the fabricated FCS shows a fast response time of 0.1 s and stable performance over more than 6000 cycles. Demonstrations on the finger, hip, and plantar regions further confirm its applicability for practical human-contact pressure sensing.

The development of electrochemical sensors (ECSs) with enhanced sensitivity has emerged as a focal point in contemporary sensor technology research due to the important biochemical roles of hydrogen peroxide (H2O2) in the industrial and biological fields. In this paper, a high-performance ECS based on laser-irradiated carbon nanotube (LICNT) electrode as the working electrode (ECS-LICNT) for sensitive detection of H2O2 is designed and fabricated to achieve long-term monitoring of trace concentrations of H2O2. The thickness and surface microcluster structure of LICNT electrodes were optimized by precise control of laser energy density and CNT suspension dose. The ECS-LICNT, designed with a dual mechanism combining surface laser-induced oxidation to increase active point density and ordered microcluster structure to enhance effective active area, possesses a high sensitivity of 475 mu A & centerdot;mM(-1)& centerdot;cm(-2) in a wide range (10-9000 mu M), surpassing most reported pure carbon-based sensors. In addition, the sensor exhibits excellent stability (current decay <5% within 7200 s) and reproducibility (RSD = 2.3%, n = 7), maintaining 95.8% of its initial response even after 28 days of storage. The ECS demonstrates sufficient sensitivity to accurately determine H2O2 concentration in the presence of interfering substances such as ascorbic acid (AA), glucose (Glu), and uric acid (UA). It can be foreseen that this sensor provides a novel strategy for designing efficient ECSs and has broad application prospects in the fields of biomedicine and food safety detection.

The monitoring of biophysical signal parameters, including respiration, heartbeat, and fetal movement (FM), is essential for disease prevention and diagnosis. In this article, to achieve long-term monitoring of biophysical signals, a high-sensitivity flexible capacitive sensor (FCS) based on carbon nanotube (CNT)-filled dielectric composite (DC) with multilayer pore architecture is designed and fabricated, where the exquisite structure of DC is constructed based upon the characteristics of low surface vapor pressure of 1,2-propanediol (1,2-PG) and 3-D printing technology (3-D-p), while the electrode material has consisted of conductive silicone rubber (CSR) filled with silver-coated glass fiber (AGF). The fabricated sensor exhibits a low detection limit (12 Pa), a high sensitivity in a wide range (2.3 kPa( -1) to pressure load less than 1.5 kPa, and 0.73 kPa( -1) to the pressure between 1.5 and 12.5 kPa), fast response time (0.3 s), and excellent stability ( >10(4) cycles). Numerical simulation and mechanism analysis indicate that the varying dielectric constant of CNT-filled DC with pressure is the key to high sensitivity for the sensor, and the pore architecture enlarges the load response range. The FCS is sensitive enough to capture simultaneously multiple signals of subtle movements, including breathing, heartbeat, and skin touching in the abdomen, which could be distinguished with the help of post-digital analysis. It is foreseeable that the sensor has a broad perspective application in the field of biophysical signal monitoring in-home or medical electronic healthcare.

The burgeoning potential of wearable electronic sensors in revolutionizing healthcare and human-computer interaction has catalyzed a surge of research interest in recent years. To achieve close conformity between sensors and complex curved surfaces while ensuring sensitivity, the development of high-performance flexible electrodes has become a critical challenge. Based on the limitations of existing electrode materials, we innovatively developed a laser-irradiated carbon nanotube-based flexible electrode (LICNT). By monitoring the resistance response of LICNT electrodes under cyclic loading-unloading conditions, we quantitatively evaluate their interfacial bonding strength to optimize electrode fabrication processes. This electrode exhibits excellent comprehensive performance, not only resolving the issue of insufficient sensor sensitivity caused by conductive silicone rubber as an electrode but also overcoming the poor stretchability of metal materials like copper foil. Through systematic comparisons of conductivity, mechanical stability, and the impact on the performance of flexible capacitive pressure sensors (FCS) among conductive silicone rubber (CSR-AgF), copper foil tape (Tape-Cu), conductive fabric tape (Tape-Fabric), and the novel carbon nanotube electrode (CNT), experimental results demonstrate that this new flexible electrode performs exceptionally well in terms of electrical and mechanical properties, showing broad application potential in wearable electronic sensors. This study provides an important reference for the selection of electrode materials for future wearable electronic sensors.

Flexible sensors have been widely applied in electronic skin, soft robotics, and wearable intelligent devices. Among these, flexible capacitive sensors (FCSs) exhibit significant potential owing to their high sensitivity, excellent mechanical flexibility, and stability. To address the challenge of electrode flexibility in capacitive sensors, this study developed a flexible conductive film (FCF) embedded in PDMS via a spray-coating technique. Carbon nanotubes (CNTs) and graphene (GR) were uniformly dispersed in acetone through ultrasonic treatment and then spray-coated to form a homogeneous conductive layer. Subsequently, a PDMS encapsulation layer was sprayed atop the conductive layer, forming a composite structure with both electrode and encapsulation layers having a thickness below 50 mu m. SEM analysis confirmed excellent interfacial adhesion between the conductive and PDMS layers. The FCF exhibited a resistance variation (Delta R/R-0) below 2 under 50% strain and maintained this low variation under multimodal strain loads of 20%, 30%, and 50% for 500 cycles. Additionally, the FCSs based on this FCF demonstrated stable capacitive responses at both 0% and 20% strain. The outstanding resistance stability and ultrathin structure make the FCF particularly suitable for use as electrodes in FCSs.

Fabric sensors weaving together with clothing exhibit a promising prospect in health monitoring and motion recognition due to their simple structure and enhanced wearing comfort. In this study, fabric sensors based on wire of conductive silicone rubber (wCSR) are developed, which exhibit both resistive and capacitive responses to applied tensile strains. The wCSR (delta k = 180 %, sigma b = 6.1 MPa) in a controlled diameter is prepared by a onestep formation process using a self-developed wet spinning device. A fiber resistive sensor (FRS) based on the wCSR exhibits a gauge factor (GF) of 2.7 to tensile strain (0-160 %) and excellent cyclic stability (104 cycles). Meanwhile, another further developed woven fabric capacitive sensor (wFCS) with a unique textile structure, demonstrates a capacitive response to tensile strain with high sensitivity (GF = 1.5), low hysteresis (rH = 2.1 %), and good cyclic stability (104 cycles, rP = 11.0 %).The wFCS sewn directly into clothing captures accurately dynamic signals of respiration and various joint movements in a comfortable and non-intrusive manner with their amplitudes of capacitance changes (Delta C/C0) are 0.07, 0.2, and 0.4 for respiration, wrist joint movements, and elbow joint movements, respectively. Furthermore, a sensor system composed of wFCSs woven in a knitted glove is designed to detect the postures of different fingers on one palm, indicating its capability to capture realtime multi-finger movements.

The degradation of rubber performance in service environments is closely associated with the blooming behavior of additives in the rubber. This study investigates surface precipitates and changes in tensile properties of nitrile butadiene rubber (NBR) after storage at 85 degrees C in air. The morphology, elemental composition, phase composition, and functional groups of the precipitates were analyzed by scanning electron microscopy, energy dispersion spectroscopy, X-ray diffraction, and fourier transform infrared spectroscopy. Based on the morphology of internal rubber particles and precipitates and variations in the Zn/C mass ratio (ERZn), the reaction between zinc oxide and stearic acid in rubber under long-term thermal environment was determined. Four stages of blooming for the mixture of zinc oxide and zinc stearate were inferred, and the impact of the blooming on the degradation of tensile properties of NBR was established. A dramatic decrease in the elongation at break (delta k) of NBR was correlated with the blooming of zinc stearate and its correspondingly weakened plasticizing effect.Highlights The core-shell structured mixture of ZnO and Zn(St)2 bloomed onto the surface of nitrile butadiene rubber. The ratio of mass percentages of Zn to C evaluated the blooming process of additives. The migration and blooming process of precipitates were divided into four stages. The decrease in elongation of the rubber was attributed to the blooming of Zn(St)2. The core-shell structured mixture of zinc oxide and zinc stearate bloomed onto the surface of nitrile butadiene rubber after thermal aging 85 degrees C for 130 days. The blooming process of mixtures was driven by the thermal stress generated in the reaction between zinc oxide and stearic acid. The decrease in elongation of the rubber was attributed to the blooming of Zn(St)2. image

Waste enameled copper wire is an important secondary source of copper and often recovered by removing their organic paint layer through pyrolysis. This research focused on studying co-pyrolysis behaviors of poly(ethylene terephthalate) (PET) paint of waste enameled wires, mixed with a small amount of polyvinyl chloride (PVC) which is part of electric wires or cables. The results indicated that mixing PVC with a mass fraction of 10% into enameled PET wire paint (EPET) would significantly affect pyrolysis products, especially the chlorinated compounds, as well as increase energy consumption of the pyrolysis process. TG-FTIR and Py-GC/MS analyses showed that the chlorinated organics were mainly generated in the second stage of pyrolysis. Chloroesters such as terephthalic acid, di(2-chloroethyl) ester were dominant over other chloroorganic compounds, and their formations were attributed to the addition reaction of aromatic vinyl esters with HCl which formed from PVC pyrolysis. It is also worth mentioning that the chemically active acid chlorides including propanoyl chloride and benzoyl chloride were detected in the products, and they were proposed to be formed from the HCl acidolysis of esters that produced from pyrolytic EPET. Besides pyrolysis products, energy consumption of pyrolysis process also was closely correlated to the interactions between pyrolytic PVC and EPET. The average co-pyrolysis activation energy was calculated by Kissinger-Akahira-Sunose (KAS) method and was about 15 kJ/mol higher than that of EPET. These should be consequences of reactions between HCl and EPET. Since PVC is the minority component in the pyrolysis mixture that HCl eliminated from the few PVC was mostly consumed by EPET to form chloroorganic compounds, which negatively influences EPET degradation.

"材料性能"是高等院校材料、化学、机械、环境科学等专业重要的专业基础课之一,教学过程融入思政元素,使其发挥鸡尾酒效应,可在帮助学生学习掌握专业知识的同时,引导学生树立正确的世界观、人生观和价值观,实现教学目标和育人目标的同向同行.通过分析上课过程中教师的自身政治素养、教学能力、授课方法、课程评价方法等因素对思政元素在"材料性能"课程中鸡尾酒效应的影响,对如何利用思政元素的鸡尾酒效应实现教学内容和育人元素的紧密结合提出了相应的建议.

With the rapid development of the 3rd semiconductors, the metal nanoparticles are investigated to be applied in the die-attached interconnect materials. However, the organic solvent used in the nanoparticle paste needs to be addressed. In this work, we adopted the liquid phase reduction method to synthesize Cu–Ag core–shell micro/nano-mixed particles (Cu@Ag MNPs), which achieved better anti-oxidation properties than Cu MNPs. Due to the suitable boiling point and viscosity, the electrical properties and hardness of the sintered films prepared by polyethylene glycol 400 (PEG-400) are better than those of ethylene glycol and α-terpineol. The electrical properties reach 43.82 µΩ cm and the hardness reach 61.3 HV at 300 °C. The shear strength of the joint sintered by Cu@Ag MNPs paste with PEG-400 can reach 20.14 MPa at 300 °C. Besides, the sintered Cu@Ag MNPs film exhibits a denser structure than Ag MNPs and Cu MNPs film. Therefore, Cu@Ag MNPs have great development prospects in the 3rd semiconductors.

The resistance response behavior of graphene composites is vital for the application of flexible sensing materials. In this study, a new simplified finite element analysis (SFEA) method is proposed to predict the electricity and the strain response probability of graphene composites with local agglomerates and normal distribution of filler size. In the SFEA, the conducting channels in the classical tunneling effect are searched algorithmically in fillers rather than in the composite and converted into equivalent circuits to calculate approximately the electrical properties of the composites, which saves computing resources distinctively. The resistance response model was established with a translation algorithm, which is applicable to evaluate the resistance response to large strain load. The effects of the filler length, agglomeration and different size distribution of filler on the electrical properties of the composites are studied as well. The results revealed that the dispersion of agglomerates contributes to the enhancement of the electrical properties of composite materials. However, this enhancement may be weakened with the large size distribution of fillers. Furthermore, the size distribution of fillers exhibits a negative impact on the electrical properties of composite materials. The predicted electrical properties of the static model agree with the experimental data basically. These results are important for the evaluation and design of graphene composites as sensing materials in flexible sensors.

Pyrolysis is a promising technology in recycling copper from enamelled wires. Nevertheless, due to the unclear pyrolysis characteristics, the sorting of enamelled wires is deficient in the pyrolysis process. This work systematically investigated the pyrolysis characteristics of polyester enamelled wire (EPET), polyester imine enamelled wire (EPEI) and polyurethane enamelled wire (EPU). The decomposition behaviours showed that the mass loss for EPEI and EPET was around 1.9%, while it was about 1.5% for EPU. The pyrolysis temperature intervals and peaks for both EPEI and EPET appeared in the range of 320 -500 degrees C and around 420 degrees C, while it was in a larger range of 228 -657 degrees C for EPU, and the peak was about 280 degrees C. The average activation energies (E) calculated with Flynn-Wall-Ozawa (FWO) model demonstrated that EPEI and EPET were respectively 275.8 kJ/mol and 296.9 kJ/mol, while it was 194.2 kJ/mol for EPU. TG-FTIR results proved that the-CH,-C--O,-CH2, and-OH were the main functional groups in the pyrolysis process for the three enamelled wires. Moreover, Py-GC/MS results indicated that the main pyrolysis product was benzoic acid for EPET and EPEI, while it was not observed for EPU. The pyrolysis mechanism displayed that the kinds of pyrolysis products were directly related to the connected aromatic functional group. The complicated pyrolysis products for EPU were mainly caused by the generation of isocyanate. Accordingly, EPU could be separately pyrolyzed, while EPET and EPEI were suitable for co-pyrolyzed. In consideration of improving pyrolysis efficiency and reducing energy consumption, the classification treatment by this method could be extended.

The emission of chlorinated pollutants is one of the main problems when recovering copper (Cu) via pyrolysis from waste enameled wires. This is mainly attributed to other wastes which possess high poly(vinyl chloride) content, such as electrical wires and cables, which are often recycled together with enameled copper wires. In this research, to control the chlorinated pollutants, copper(II) oxide (CuO) was chosen and demonstrated to be an efficient dechlorinating agent, and CuO did not introduce any impurities that influence the quality of the recovered Cu. The pyrolysis and co-pyrolysis of polyester enameled wires, PVC, and CuO were investigated, and special attention was paid to chlorinated compounds in released pyrolytic products. In particular, the co-pyrolysis of this ternary mixture was studied for the first time, and some new pyrolysis behaviors were discovered. For example, the results of Py-GC/MS analyses showed that the addition of CuO removed about 75% of the chloro-organic products, the main types of which were chloroaromatic compounds rather than the more toxic chloroesters. Moreover, pyrolysis gases were collected and characterized via ion chromatography, and the results showed that the chlorine content in the pyrolysis gases decreased by about 71%. TG analysis indicated that CuO only minimally affected the pyrolysis of polyester paint. However, through the chlorine fixation effect, CuO influenced the dechlorination and dehydrochlorination of PVC, as well as secondary reactions between HCl and pyrolysis products of polyester paint, therefore changing the products and behaviors of co-pyrolysis. Mechanism of reducing chlorine-containing pollutants and reaction mechanism of forming typical pyrolysis products closely correlated to the effects of CuO were also proposed, providing theoretical guidance for the recycling of waste enameled wires.

在不同沉积路径下采用冷金属过渡电弧增材制造技术制备了H13钢成形件,基于热-弹塑性有限元法对成形件的热历程进行了分析,并通过试验研究了成形件的显微组织和硬度.结果表明:同向和双向路径沉积得到5层单道和单层5道成形件的热历程基本一致,双向沉积5层单道成形件第3层中间点的峰值温度远高于双向沉积单层5道成形件第3道中间点,5层单道成形件的热累积效应更明显;5层单道成形件的板条状马氏体组织比单层5道成形件的粗大;同向沉积5层单道成形件在同一高度上的硬度略高于双向沉积成形件,同向沉积和双向沉积单层5道成形件在水平方向的硬度分布基本相同,5层单道成形件的平均硬度略低于单层5道成形件.

Flexible strain sensors have been improved in sensing performance with the assistance of materials design, novel manufacturing, and microstructure fabrication. In this study, graphene was efficiently dispersed in ethanol and then re-dispersed into silicon rubber (SR) matrix, functioning as a flexible strain resistance sensor (FSRS) with functional macrostructure and modified microstructure to further improve the sensitivity. A stable dispersion of graphene was obtained in an ultrasound-aided ball milling process, where absolute ethanol was selected as the solvent and sodium dodecyl sulfonate as the surfactant. Graphene-filled conductive SR was embedded in the polydimethylsiloxane matrix as a conductive sensing layer, and the high sensing performance (GF = 25 ± 2) was achieved using a spiral printed. Micropores with an optimized interspacing of 10 mm were further introduced into the spiral CSM, and the results presented a significant improved sensitivity (GF = 51 ± 4) of the fabricated FSRS under a working strain (20%–30%) and cyclic test (>10 4 cycles). The FRSR was sensitive enough to monitor various movements of single and multi-joints of human body and identify the rhythm of music sound, which exhibited its potential application as a wearable flexible sensor.

In the process, micro/nano mixed Cu-Ag particles were produced by a two-step method, which included the preparation of Cu nanoparticles and Ag doping in micro and nano Cu particles. SEM was provided to observe the morphology of particles and sintered conductive films. The EDS was adopted to identify the element distribution of these particles. The phase was analyzed by X-ray diffraction. In addition, to evaluate the oxidation stability of micro/nano mixed Cu-Ag particles, they were compared with Cu nanoparticles. The thermogravimetric analysis showed that the oxidation stability of micro/nano mixed Cu-Ag particles was stronger than that of Cu nanoparticles. Finally, the conductive ink was prepared by a mixture of synthetic particles and organic solvent and sintered on an alumina ceramic substrate. To obtain the sintering morphology and electrical properties, we compared the micro/nano mixed Cu-Ag particles with Cu nanoparticles after sintering. This study shows that the micro/nano mixed Cu-Ag particles can be applied in the printing electronics field.

The characteristics of graphene, including good mechanical properties, low density, high thermal conductivity, and high electron mobility, have led to the usage of graphene-filled composites in various fields. So far, the conductive mechanism of graphene-filled composites is controversial. In this paper, a numerical analysis model was developed based on RVE (representative volume element) theory, where the macroscopic model was equivalently replaced by a microscopic model. The graphene filler was modeled as a two-dimensional rectangle that was positioned and angled arbitrarily without intersecting with each other for the sake of numerical calculation. On the finite element model, Ohm's law and the tunneling effect were combined, and a subroutine was constructed for real-time estimation of the distance between graphene fillers in a cell, with Ohm's law being substituted by the tunneling effect for distances less than 3 nm. The electrical conductivity of graphene-filled composites was further numerically analyzed based on the influence of different boundary conditions. The numerical analysis results were in good agreement with the experiments. This work demonstrates that the tunneling effect dominates the conduction mechanism of conductive particle-filled composites at the percolation threshold and above and can be helpful to explain the response mechanism of flexible particle-filled composite sensors.

Traditional substrates of metallic interdigital electrodes (IEs) are rigid and undeformable, flexible interdigital capacitors are therefore appealing as strain sensors. In this study, interdigital capacitors were parametrically designed by 3D printing and encapsulated by spraying process. The interdigital circuits of the structure were printed with conductive silicone rubber filled with silver-coated glass fiber and carbon fiber, and the circuits were encapsulated with polydimethylsiloxane. Herein, the interdigital-flexible structures were parametrically designed and firstly served as capacitive sensor, namely flexible interdigital capacitive sensors (FICSs). The spaces between IEs, are extremely sensitive to strain, therefore provide the capacitors with excellent electromechanical behaviors. The optimized FICS benefited for a wide working range of strain (0%∼45%), high sensitivity (gauge factor = 2.7) to a tiny strain of 0.3%, stable working duration at different stretching speeds (18 mm min −1 , 36 mm min −1 and 72 mm min −1 ), prolonged service life (>800 cycles), as well as excellent capability to detect human movement (bulging, grasping and bending). Response mechanism of the FICS was modeled based upon its microstructure evolution, including the distances between IEs and the fillers migration. The printed FICSs with optimized structure provide a comprehensive thought in the design of electronics, further would inspire the branch of 3D printed electronics.

The accelerated application research of winde bandgap (WBG) power electronic devices intensively stimulates the interconnect materials to catch the capability of serving at high temperatures aligned with low-temperature sintering characteristics. Especially, it is urgently needed the interconnect materials to make the goal of anti-oxidation, anti-migration, and low porosity after sintering. Herein, a novel micro/nano-hybrid structure particles are fabricated by a mild one-step method, which structure is Ag nanoparticles coated Cu microparticle (Cu MP@Ag NPs) with the average size of Ag NPs and Cu MPs being 150 nm and 1.28 μm. Not only do the Cu MP@Ag NPs accomplish anti-oxidation properties at 200 °C for 30 min, but also achieve low-temperature bonding on bare Cu in the air atmosphere, and apart from that, Ag-Cu alloy is formed between Cu MPs and Ag NPs with the increase of sintering temperature. In comparison with Ag NPs paste and Cu MPs paste, Cu MP@Ag NPs paste swallows up the lowest porosity and highest shear strength results at 300 °C sintering, which ascribe to the exquisite micro/nano-hybrid structure particles and the formation of Ag-Cu alloy. The existence of Ag NPs makes the Cu MP@Ag NPs paste possess low-temperature sintering properties and decreases the porosity of the sintering layer by improving the staking density. Besides, the formation of Ag-Cu alloy for one reason is attributed to the formed metallic bonds between Ag NPs and Cu MPs in the synthesis process, and for another reason, it is caused by the greatly increased coarsening driving force by the size difference of the micro/nano-hybrid particles. Furthermore, the fracture mode of the joint using Cu MP@Ag NPs changes to ductile fracture from brittle fracture with the increase of sintering temperatures. This work demonstrates the facilely synthesized stunning micro/nano-hybrid structure particles (Cu MP@Ag NPs) achieve excellent sintering results and possess the potential application in WBG power electronic devices.

Wire-arc additive manufacturing (WAAM) has been considered as one of the potential additive-manufacturing technologies to fabricate large components. However, its industrial application is still limited by the existence of stress and distortion. During the process of WAAM, the scanning pattern has an important influence on the temperature field, distortion and final quality of the part. Four kinds of deposition patterns, including sequence, symmetry, in–out and out–in, were designed to deposit H13 steel in this study. An in situ measurement system was set up to record the temperature history and the progress of accumulated distortion of the parts during deposition. An S value was proposed to evaluate the distortion of the substrate. It was shown that the distortion of the part deposited by sequence was significantly larger than those of other parts. The distortion deposited by the out–in pattern decreased by 68.6% compared with sequence. The inherent strain method and strain parameter were introduced to expose the mechanism of distortion reduction caused by pattern variation.