Graphene is widely used to reinforce metal matrix composites due to its excellent physical and mechanical properties. However, its poor interfacial wettability and dispersion problems in copper-based brazing filler metals still limit its application effect.This study explored the influence of graphene on the sintering behavior and structural properties of copper nanoparticles under different doping conditions through molecular dynamics simulation combined with experimental methods. The results show that an appropriate amount of well-dispersed graphene helps promote the densification process and improve the structural stability, while graphene in the agglomerated state may have an adverse effect on the mechanical properties. This work provides theoretical support and experimental basis for optimizing the application of graphene in copper-based brazing metals.

This study investigates the size-dependent mechanical behavior and deformation mechanisms of sintered copper (Cu) nanoparticles (NPs) through micro-pillar (2–6 μm diameter) compression tests, scanning electron microscopy (SEM), transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD) analysis and molecular dynamics (MD) simulations. In-situ micro-pillar compression tests reveal a 25.9% reduction in yield strength (812 ± 64 MPa to 643 ± 47 MPa) with increasing pillar size, attributed to dislocation starvation in smaller pillars and porosity-driven strain localization in larger ones. TKD quantifies dynamic grain refinement (24.9% reduction in grain size) and geometrically necessary dislocation (GND) density escalation (74.8%), driven by stress gradients and grain boundary-mediated plasticity. Nanoindentation-derived elastic modulus (48.3 ± 11.1 GPa) exceeds micropillar values (29.5–33.9 GPa), reflecting substrate constraints in bulk testing. Microstructural analysis identifies a transition from shear banding in high-porosity pillars to uniform plasticity in denser systems, mediated by texture evolution (Brass/S components) and Schmid factor redistribution (62% increase in high-slip-activity grains). MD simulations of pressure-sintered Cu NPs elucidate atomic-scale mechanisms: dislocation nucleation at sintering necks, pore collapse-induced strain localization, and grain boundary sliding. These findings establish a multiscale framework linking porosity, grain refinement, and dislocation dynamics to mechanical performance, emphasizing microstructural optimization for enhanced reliability in microelectronic applications. The integration of MD simulations bridges atomic-scale mechanisms to microscale deformation, providing actionable insights for tailoring sintered Cu NPs via reduced porosity and controlled grain boundary architectures.

This study introduces a novel strategy for fabricating flexible nitrogen dioxide (NO₂) gas sensors based on Indium Oxide (In₂O₃) nanoparticles (NPs) employing selective reduction laser sintering (SRLS) technology. The SRSL technology utilizes ultraviolet (UV) laser selective reduction sintering to precisely and rapidly create oxygen vacancy (OV) defects in In₂O₃ NPs. These oxygen vacancies (OVs) enhance the active adsorption sites and contribute additional free electrons, significantly improving sensor performance at room temperature. The sensors demonstrate excellent response (S = 460.9 at 10 ppm), rapid response/recovery times (τ_resp/τ_reco = 27/570 s), and superior selectivity (response ratio > 400), in addition to robust resistance to light and humidity (under ppm-level NO₂ gas). The sensors also exhibit a low detection limit (200 ppb), a high signal-to-noise ratio (94.8 dB), and good long-term stability (25 days). Moreover, under photo-assisted conditions, the recovery speed of the sensors is further improved. This technology not only provides an innovative strategy for the development of high-performance flexible NO₂ gas sensors but also broadens the application potential of laser direct writing (LDW) technology in advanced materials and sensor fabrications.

With the rapid advancement of power semiconductor packaging technologies, Smart P2 Packagingaging has emerged as a pivotal innovation for enhancing system performance and miniaturization. This study systematically investigates the thermal conduction characteristics and stress distributions of copper-filled vias (CFVs) in Smart P2Pack frontal interconnects through coupled thermal-mechanical finite element analysis. Results indicate that increasing CFV diameter enhances vertical heat conduction but causes localized heat accumulation and stress concentration due to the low thermal conductivity of encapsulation materials, elevating interfacial failure risks. Conversely, expanding CFV pitch promotes dispersed heat flow and reduces chip temperature but concurrently lowers local structural stiffness and exacerbates stress concentration. Optimal CFV design thus requires balancing thermal diffusion performance and mechanical constraints to ensure structural reliability and thermal stability.

In harsh offshore environments, large-area sintered nano-copper (Cu) interconnections, which serve as die attachment material or thermal interface material (TIM), are prone to degradation from hydrogen sulfide (H2S) corrosion. This study introduced a film-forming technique based on atmospheric pressure plasma jet (APPJ) to improve the corrosion resistance of large-area sintered nanoCu joint. The corrosion protection mechanism against H2S-containing atmospheric corrosion was investigated using both experimental methods and density functional theory (DFT) simulations. The key findings were as follows: (1) The deposition film, primarily composed of a Si-O3 network, effectively protected sintered Cu plate from corrosion by H2S gas, and maintaining the mechanical performance of sintered Cu joint after 384 h of H2S testing. (2) The dissociation products of the APPJ-treated precursor hexamethyldisiloxane (HMDSO), −OSiCH3 and −OSi(CH3)3, formed stable chemical bonds on the sintered nanoCu surface, resulting in the formation of −OSiCH3(O-CH3)2 fragments. (3) The −OSiCH3(O-CH3)2 fragments were unreactive toward to corrosion agents such as H2S, O2, and H2O, and also serving as a barrier to block their access to the sintered nanoCu surface. This study provided a comprehensive understanding of the corrosion protection mechanism of sintered nanoCu using APPJ-deposited films, offering valuable insights for improving the reliability of power electronics.

This study explores the potential of pressureless nano-copper sintering for power chip interconnections. As electronics evolve towards miniaturization and higher power density, traditional interconnection materials such as nano-silver, despite their excellent thermal and electrical properties, face challenges like high cost and susceptibility to electromigration. Nano-copper, with comparable electrical conductivity and superior thermal performance at a lower cost, emerges as a promising alternative. The study examines the impact of sintering atmosphere and temperature on shear strength. Results show that nitrogen-protected environments significantly enhance bonding by preventing oxidation, while samples sintered in air exhibit minimal strength due to surface oxidation. Additionally, sintering at 230°C provides stronger bonds compared to 200°C, indicating improved diffusion and bonding at higher temperatures. SEM analysis of samples sintered at 300°C demonstrates optimal bonding, with minimal voids, making 300 ° C an ideal sintering temperature for reliable power chip packaging using nano-copper.

The significance of wafer bonding is fundamental to the progression of electronic systems. Common fabrication techniques for Cu pillars play a crucial role in establishing resilient and efficient interconnects within semiconductor devices. It is imperative to explore the potential of nano-copper as an alternative material to overcome limitations associated with conventional copper. The use of nano copper paste in manufacturing has the potential to simplify the process, potentially reducing the number of steps compared to conventional methods. This study delves into the intricacies of wafer-level packaging (WLP), with a particular focus on hybrid bonding processes utilizing nanocopper sintering. Through the application of Finite Element Method (FEM) simulations, we investigate the stress distribution and thermal dynamics inherent in the sintering and hybrid bonding of both bulk copper and nanocopper materials. Our findings illuminate the superior mechanical and thermal properties of nanocopper, which contribute to reduced stress concentrations and enhanced mechanical integrity in semiconductor packaging. The research highlights the pivotal role of nanocopper sintering in advancing WLP technologies, offering insights into optimizing sintering and bonding parameters for improved device reliability and performance.

Flexible strain sensors based on nanomaterials have sparked a lot of interest in the field of wearable smart electronics. Laser induced graphene (LIG) based sensors in particular stand out due to their straightforward fabrication procedure, three-dimensional porous structures, and exceptional electromechanical capabilities. Recent studies have focused on LIG composites, however, it is still difficult to achieve great sensitivity and excellent linearity in a wide linear working range. Herein, a strain sensor with high sensitivity and good linearity is prepared in this work, which was realized by carbonizing the polyimide film coated with HfSe₂ to obtain three-dimensional porous graphene nanosheets decorated with HfSe₂ (HfSe₂/LIG). After being transferred to the flexible substrate of Ecoflex, it exhibits high stretchability, hydrophobicity and robustness, and obtains excellent electromechanical properties. The HfSe₂/LIG strain sensor demonstrated high sensitivity (gauge factor, GF ≈ 46), a low detection limit (0.02%), good linearity (R² = 0.99) in a large working range (up to 30%), and a quick response time (0.20 s). Additionally, it exhibits good stability and consistent behavior across a large number of strain/release test cycles (>3000 cycles). With these benefits, the sensor can be used to monitor various limb movements (including finger, wrist and neck movements) and minute artery activity, and can generate reliable signals. Therefore, the HfSe₂/LIG-based sensor has enormous potential for use in wearable intelligent electronics and movement monitoring.

In recent years, metal crack-based stretchable flexible strain sensors have attracted significant attention in wearable device applications due to their extremely high sensitivity. However, the tradeoff between sensitivity and detection range has been an intractable dilemma, severely limiting their practical applications. Herein, we propose a laser transmission pyrolysis (LTP) technology for fabricating high-performance flexible strain sensors based on (Au) metal cracks with the microchannel array on the polydimethylsiloxane (PDMS) surface. The fabricated flexible strain sensors exhibit high sensitivity [gauge factor (GF) of 2448], wide detection range (59% for tensile strain), precise strain resolution (0.1%), fast response and recovery times (69 and 141 ms), and robust durability (over 3000 cycles). In addition, experiment and simulation results reveal that introducing a microchannel array enables the stress redistribution strategy on the sensor surface, which significantly improves the sensing sensitivity compared to conventional flat surface sensors. Based on the excellent performance, the sensors are applied to detect subtle physiological signals, such as pulse and swallowing, as well as to monitor large-scale motion signals, such as knee flexion and finger bending, demonstrating their potential applications in health monitoring, human-machine interactions, and electronic skin.

The development of high-performance gas sensing materials is one of the development trends of new gas sensor technology. In this work, in order to predict the gas-sensitive characteristics of HfSe₂ and its potential as a gas-sensitive material, the interactions of nonmetallic element (O, S, Te) doped HfSe₂ monolayer and small molecules (NH₃ and O₃) have been studied by first-principles based on density functional theory. The results show that the adsorption of NH₃ and O₃ on pristine HfSe₂ monolayer is weak, and the adsorption strength can be significantly improved by doping O. And O-HfSe₂ is chemical adsorption to O₃ with large adsorption energy and transfer charge, and the band gap of O[sbnd]HfSe₂ disappears after adsorbing O₃, indicating that the adsorption of O₃ has a significant effect on the electrical properties of the substrate. These mean that O₃ is difficult to recover from the substrate surface, thus preventing O-HfSe₂ from developing into a sensitive material for O₃ detection. After doping S, the charge transfers and adsorption strength to NH₃ are the largest, but it is still small. So, the strain effect on the S-HfSe₂/NH₃ adsorption system is also studied. The results indicate that the adsorption strength of S-HfSe₂ to NH₃ can be enhanced by stretching S-HfSe₂ along x-axis. After absorbing NH₃, the conductivity of x-axis strained S-HfSe₂ changes, which suggest its sensitivity. And the predicted recovery times of S-HfSe₂ surfaces with ε_x=4%, 6% and 8% are 0.027 s, 1.153 s and 102.467 s, respectively, which suggests that the S-HfSe₂ monolayer has the potential to be developed as a sensitive material for NH₃ detection. These adsorption mechanism studies can also serve as a theoretical foundation for the experimental design of gas-sensing materials.

For the relevant properties of pristine and doped (Si, P, Se, Te, As) monolayer WS₂ before and after the adsorption of CO, CO₂, N₂, NO, NO₂ and O₂, density functional theory (DFT) calculations are made. Calculation results reveal that the monolayer WS₂ doped with P and As atoms can be substrate materials for NO and NO₂ gas sensors. However, after the subsequent CDD and ELF calculations, it is found that P-doped monolayer WS₂ adsorbs NO and NO₂ in a chemical way, while As-doped monolayer WS₂ adsorbs NO and NO₂ in a physical way. Also, the charge transfer between As-doped monolayer WS₂ and NO is relatively small and not easily detected. Besides, As-doped monolayer WS₂ system exhibits greater differences in optical properties (the imaginary part of reflectivity and dielectric function) before and after the adsorption of NO₂ gas than before and after adsorption of NO gas. These differences in optical properties assist sensor devices in making gas adsorption-related judgments. Through the analysis of the recovery time, DOS and PDOS, As-doped monolayer WS₂ is also verified to be a promising NO₂ sensing material, whose recovery time is calculated to be as short as 0.169 ms at 300 K.

Cu-Ag core-shell (CS) nanoparticle (NP) is considered as a cost-effective alternative material to nano silver sintering material in die attachment application. To further reduce the cost, the thickness of the Ag shell can be adjusted. Whereas the shell thickness will also affect the thermal stability of the Cu-Ag CSNPs. In this study, molecular dynamics simulation was applied to study the thickness effect on the thermal behavior of Cu-Ag CSNPs. The melting points of CSNPs and Pure NPs can be determined by the evolutions of Potential Energy (PE), and the Lindemann index (LI) of the system. The results indicated that the melting points of CS NPs were lower than monometallic NP and the melting point of CS NP is influenced by the size of the Cu core and the number of lattice mismatches. Moreover, the distribution of atoms’ LI showed that the premelting point is independent of shell thickness. However, the fraction of atoms that occurred premelting is increased with the decrease of the shell thickness. Otherwise, we also simulated the sintering process of double CS NPs with equal size.

Nano copper sintering technology has great potential to be widely applied in the wide-bandgap semiconductor packaging. In order to investigate the coalescence kinetics of copper nano particles for this application, a molecular dynamic (MD) simulation was carried out at low temperature on a special model containing two substrate and multiple particles in between. Accordingly, thorough microstructure and dislocation investigation was conducted to identify the atomic-scale evolution in the system. The corresponding findings could provide evidence on the new particle-substrate sintering mechanism. Furthermore, atomic trajectories tracking method was applied to study the rotation behavior of different sized nano particles. New rotation behavior and mechanism were described. Additionally, the study on the size effect of copper particles on the sintering process and coalescence mechanism was conducted via comparing the microstructural and dislocation distribution of 3 nm, 4 nm and 5 nm models. Finally, by comparing the MSD results at low and high temperature for each model, the dominant coalescence dynamics changes were obtained.

In this paper, tin oxidation (SnO x )/tin-sulfide (SnS) heterostructures are synthesized by the post-oxidation of liquid-phase exfoliated SnS nanosheets in air. We comparatively analyzed the NO2 gas response of samples with different oxidation levels to study the gas sensing mechanisms. The results show that the samples oxidized at 325 °C are the most sensitive to NO2 gas molecules, followed by the samples oxidated at 350 °C, 400 °C and 450 °C. The repeatabilities of 350 °C samples are better than that of 325 °C, and there is almost no shift in the baseline. Thus this work systematically analyzed the gas sensing performance of SnO x/SnS-based sensor oxidized at 350 °C. It exhibits a high response of 171% towards 1 ppb NO2, a wide detecting range (from 1 ppb to 1 ppm), and an ultra-low theoretical detection limit of 5 ppt, and excellent repeatability at room temperature. The sensor also shows superior gas selectivity to NO2 in comparison to several other gas molecules, such as NO, H2, SO2, CO, NH3, and H2O. After X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscope, and electron paramagnetic resonance characterizations combining first principle analysis, it is found that the outstanding NO2 sensing behavior may be attributed to three factors: The Schottky contact between electrodes and SnO x/SnS; active charge transfer in the surface and the interface layer of SnO x/SnS heterostructures; and numerous oxygen vacancies generated during the post-oxidation process, which provides more adsorption sites and superior bandgap modulation. Such a heterostructure-based room-temperature sensor can be fabricated in miniaturized size with low cost, making it possible for large-scale applications.

The authors regret that one of the affiliations (affiliation f) was incorrectly omitted in the original manuscript. The corrected list of affiliations is as shown below. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

In this work, the adsorption of toxic gaseous NO₂ and other gas molecules (NO, CO, CO₂, N₂, O₂, SO₂) on pristine and X-doped (X = Si, P, S, Te, As) two-dimensional (2D) WSe₂ have been detailed studied by performing density functional theory (DFT) calculations. Calculation results of adsorption energies and adsorption distances demonstrate that As-doped 2D WSe₂ (As-WSe₂) exhibits high selectivity not only towards NO₂, but also towards NO and SO₂. However, the charge transfer between NO and the substrate is too small to detect, and chemical bond forms between SO₂ and the substrate; both phenomena make As-WSe₂ substrate more suitable as a substrate material of the NO₂ sensor. To eliminate the interference of SO₂ on the adsorption of NO₂, coexistence of NO₂ and SO₂ is simulated. Results reveal that although the interaction between SO₂ and the As-WSe₂ substrate is stronger than that between NO₂ and the substrate, SO₂ molecule hardly interacts with the substrate when co-adsorbed with NO₂. Besides, calculation results of DOS and PDOS further confirm the sensitivity of As-WSe₂ towards NO₂; and those of the recovery time also highlight the extremely fast recovery rate of As-WSe₂ after adsorbing NO₂. The present findings make As-WSe₂ monolayer a potential substrate material of NO₂ gas sensors used in the atmospheric environment.

At present, non-equilibrium thermodynamics is an important theory and method for studying the phenomenon of small scales. In this work, by studying the temperature changes of PN junctions under different voltage conditions and doping concentrations, the micro-scale semiconductor materials PN junctions in non-equilibrium thermodynamics and thermal phenomena are researched. It is found that under the effect of lower voltage, the temperature of the PN junction will first decrease and then increase, and as the voltage increases, this phenomenon will gradually disappear. This shows that under certain voltage conditions, the phenomenon of unbalanced junction temperature of the PN junction exists, which will provide a huge impetus for the development of the reliability of solar cells, light-emitting diodes, high-frequency devices, sensors and measurement methods.

Humidity sensors based on flexible sensitive nanomaterials are very attractive in noncontact healthcare monitoring. However, the existing humidity sensors have some shortcomings such as limited sensitivity, narrow relative humidity (RH) range, and a complex process. Herein, we show that a tin sulphide (SnS) nanoflakes-based sensor presents high humidity sensing behaviour both in rigid and flexible substrate. The sensing mechanism based on the Schottky nature of a SnS-metal contact endows the as-fabricated sensor with a high response of 2491000% towards a wide RH range from 3% RH to 99% RH. The response and recovery time of the sensor are 6 s and 4 s, respectively. Besides, the flexible SnS nanoflakes-based humidity sensor with a polyimide substrate can be well attached to the skin and exhibits stable humidity sensing performance in the natural flat state and under bending loading. Moreover, the first-principles analysis is performed to prove the high specificity of SnS to the moisture (H₂O) in the air. Benefiting from its promising advantages, we explore some application of the SnS nanoflakes-based sensors in detection of breathing patterns and non-contact finger tips sensing behaviour. The sensor can monitor the respiration pattern of a human being accurately, and recognize the movement of the fingertip speedily. This novel humidity sensor shows great promising application in physiological and physical monitoring, portable diagnosis system, and noncontact interface localization.

As the concentration of acetone (C₃H₆O) in exhaled gas of diabetics is significantly higher than that of healthy people. Here, the sensing performance of X doped MoSe₂ (X–MoSe₂, X = Ti, Ni and Cu) for acetone is studied theoretically. It is found that Ti–MoSe₂ shows absolute advantages in both adsorption energy and charge transfer. Additionally, the changes of bandgap for C₃H₆O/Ti–MoSe₂ in the adsorption process are the largest in all adsorption systems, indicating it will produce the largest electrical signal that can be detected. Besides, the co-adsorption system (consisting of C₃H₆O, H₂O, CO₂, N₂ and O₂) will be more stable after O₂ is removed and the adsorption site occupied by acetone restricts the contact of other disturbing gases with Ti–MoSe₂. Importantly, comparing with the reported acetone sensing materials ((110) face of SnO₂, (MgO)₁₂-graphene and oxygen-plasma-treated ZnO (ZnO–O)), Ti–MoSe₂ demonstrates its superiority in terms of the absolute value of charge transfer (0.37 e) and adsorption energy (2.42 eV). All these results show that Ti–MoSe₂ is expected to become the reliable sensing material for acetone and has enormous potential for the application in noninvasive and rapid detection of type-1 diabetes.

Exploring effective disinfection methods and understanding their mechanisms on the new coronavirus is becoming more active due to the outbreak of novel coronavirus pneumonia (COVID-19) caused by severe acute respiratory coronavirus 2 (SARS-CoV-2). By combining molecular dynamics and first-principles calculations, we investigate the interaction mechanism of chemical agents with 3CL hydrolase of SARS-CoV-2. The radial distribution functions indicate that the biocidal ingredients are sensitive to the unsaturated oxygen atoms of 3CL hydrolase and their interactions remarkably depend on the concentration of the biocidal ingredients. Besides, we find that the adsorption performance of the active ingredients for the unsaturated oxygen atoms is superior to other styles of atoms. These computational results not only decipher the inactivation mechanism of chemical agents against SARS-CoV-2 from the molecule-level perspective, but also provide a theoretical basis for the development and application of new chemical methods with a high disinfection efficiency.