Traditional Fabrication Research Articles

Compositionally gradient Al2O3–B4C/Al composites with interpenetrating structure and tailored properties via material extrusion-based additive manufacturing and pressure infiltration

ABSTRACT Traditional fabrication methods for metal–ceramic composites often struggle to achieve the level of control needed for material on-demand design and property optimisation, despite the potential for enhanced performance. This study presents a novel approach that overcomes these limitations by combining material extrusion-based additive manufacturing and pressure infiltration techniques, which enables the fabrication of compositionally graded Al2O3–B4C/Al layered composites with tailored properties. Precise control over the B4C/Al2O3 ratio allows for the fine-tuning of key mechanical properties, including bending strength, fracture toughness, and fracture work. The composites exhibit anisotropic behaviour, with performance influenced by the ceramic composition, loading direction, and layer spacing. A notable observation is the enhancement of damage tolerance through multi-crack propagation as the Al2O3 content in the ceramic layers increases. Additionally, wear tests demonstrate exceptional abrasion resistance, highlighting the synergistic effects of B4C hardness and Al2O3 toughness. This research establishes novel strategies for the design and fabrication of metal–ceramic composites with tailored properties, paving the way for their implementation in demanding applications where a combination of strength, toughness, and wear resistance is critical.

A Review of Modeling, Simulation, and Process Qualification of Additively Manufactured Metal Components via the Laser Powder Bed Fusion Method

Metal additive manufacturing (AM) has grown in recent years to supplement or even replace traditional fabrication methods. Specifically, the laser powder bed fusion (LPBF) process has been used to manufacture components in support of sustainment issues, where obsolete components are hard to procure. While LPBF can be used to solve these issues, much work is still required to fully understand the metal AM technology to determine its usefulness as a reliable manufacturing process. Due to the complex physical mechanisms involved in the multiscale problem of LPBF, repeatability is often difficult to achieve and consequently makes meeting qualification requirements challenging. The purpose of this work is to provide a review of the physics of metal AM at the melt pool and part scales, thermomechanical simulation methods, as well as the available commercial software used for finite element analysis and computational fluid dynamics modeling. In addition, metal AM process qualification frameworks are briefly discussed in the context of the computational basis established in this work.

Preparation and Application of Nature-inspired High-performance Mechanical Materials.

Natural materials are valued for their lightweight properties, high strength, impact resistance, and fracture toughness, often outperforming human-made materials. This paper reviews recent research on biomimetic composites, focusing on how composition, microstructure, and interfacial characteristics affect mechanical properties like strength, stiffness, and toughness. It explores biological structures such as mollusk shells, bones, and insect exoskeletons that inspire lightweight designs, including honeycomb structures for weight reduction and impact resistance. The paper also discusses the flexibility and durability of fibrous materials like arachnid proteins and evaluates traditional and modern fabrication techniques, including machine learning. The development of superior, multifunctional, and eco-friendly materials will benefit transportation, mechanical engineering, architecture, and biomedicine, promoting sustainable materials science. STATEMENT OF SIGNIFICANCE: Natural materials excel in strength, lightweight, impact resistance, and fracture toughness. This review focuses on biomimetic composites inspired by nature, examining how composition, microstructure, and interfacial characteristics affect mechanical properties like strength, stiffness, and toughness. It analyzes biological structures such as shells, bones, and exoskeletons, emphasizing honeycomb strength and lightness. The review also explores the flexibility and durability of fibrous materials like arachnid proteins and discusses fabrication techniques for biomaterials. It highlights impact-resistant materials that combine soft and hard components for enhanced strength and toughness, as well as lightweight, wear-resistant biomimetic materials that respond uniquely to cyclic stress. The article aims to advance sustainable materials science by exploring innovations in multifunctional and eco-friendly materials for various applications.

Bioinspired In Situ Synthesis of High-Strength Bulk CO2 Mineralized Ceramics at Room Temperature.

Traditional high-temperature fabrication methods for ceramics suffer from significant energy consumption and limit the development of advanced ceramics incorporating temperature-sensitive materials. While bioinspired mineralization provides an effective strategy to realize the room-temperature preparation of ceramics, scaling up production remains a challenge. Herein, we demonstrate a room-temperature procedure for the fabrication of large-scale ceramics by using the carbonation reaction of sodium alginate (SA)-doped γ-dicalcium silicate (γ-C2S) compacts. This bioinspired in situ mineralization process regulates molecular interactions and microscopic crystal alignment, resulting in the formation of CO2 mineralized ceramics with specifically oriented mesocrystals and exceptional mechanical properties rivaling those of biological materials. Through this strategy, we demonstrate that the advanced ceramic composites with compressive strength approaching 300 MPa can be fabricated at a large scale, with the additional benefits of fixing about 200 kg of CO2 per ton of CO2 mineralized ceramics. Our innovative approach shows great potential for the efficient and cost-effective fabrication of large-scale and high-performance bioceramics, aligning with the goals of sustainable development involving reducing the energy consumption and achieving carbon neutrality.

Solar-Thermal Performance of Sparked Stainless Steel-based Solar Absorber under Solar Concentration

Solar absorbers are indispensable components in concentrated solar-thermal (CST) energy systems. Material selection is crucial in optimizing the performance of these systems. Traditional fabrication methods for solar absorbers often rely on chemical processes, which can be both costly and environmentally detrimental. This study presents the first investigation of the solar-thermal performance of a stainless steel absorber fabricated through a non-chemical sparking process in a tip-substrate configuration. Stainless steel, recognized for its cost-effectiveness and high-temperature thermal stability, emerges as a promising candidate for solar absorber applications. The sparked stainless steel exhibited enhanced solar absorptivity of 84.0% and thermal emissivity of 47.3%, representing increases of approximately 33% and 13.7%, respectively, compared to bare stainless steel. Raman spectroscopy and atomic force microscopy confirmed the formation of a random nanotexture of magnetite on the sparked surface, contributing to the improved optical properties. The solar-thermal performance of the sparked stainless steel is maximized at 84.0% when the absorber temperature aligns with the ambient temperature or under conditions of extreme optical concentration. To maintain a solar-thermal performance exceeding 70% at elevated absorber temperatures of 150 °C, 250 °C, 350 °C, and 450 °C, optical concentrations of 5, 13, 28, and 52, respectively, are required.

On the surface roughness of 316L stainless steel fabricated using L-PBF additive manufacturing

Additive manufacturing (AM) offers numerous advantages over traditional fabrication methods such as manufacturing complex parts. However, a significant limitation lies in the restricted surface quality, hindering its widespread use. While parts produced through conventional manufacturing techniques such as milling and grinding typically have an average roughness (Ra) value of less than 1–2 μm, those manufactured using laser powder bed fusion (LPBF) AM usually fall within the range of 10 to 30 μm. Surface roughness plays a critical role in various applications, as certain uses necessitate superior surface quality to prevent premature failure due to surface-induced cracking. Subpar surface quality not only compromises the strength, wear resistance, and corrosion resistance of parts but also impacts the precision of the fabricated components. Therefore, it is imperative to optimize the fabrication process and enhance the surface quality of metal parts. Moreover, the surface quality of each layer dictates the bonding strength between adjacent layers and process stability, as a high-quality preceding surface is essential for ensuring the integrity of subsequent layers. Consequently, surface roughness significantly influences process stability and the properties of metal parts produced through LPBF. This work aims at evaluating surface roughness of as printed 316L stainless steel parts made using LPBF AM process and their effects on tensile properties of the produced samples. Microscopic analyses are done to evaluate the roughness (including Ra, Rq, and Sa parameters) at different locations to evaluate the effects of different printing parameters on their size distributions. In addition, the macro-mechanical behaviour of the as printed samples is compared with the ones with polished surface.

Transparent glass force plate with CrN strain gauges featuring a notch structure

Abstract Microforce plate is a powerful tool as force sensors in the field of microelectromechanical systems (MEMS). These force plates can be used to quantitatively measure the minute insects' ground reaction forces and microdroplets' collision forces. During such measurements, there is often a demand specification for observing the interface between the object and the plate from the backside. However, transparent materials were not compatible with traditional MEMS force plate fabrication processes. Here, we propose a fabrication process for a transparent glass force plate by forming a 3D notch structure on a glass substrate using chromium nitride (CrN) as a strain gauge. The force plate was designed as a 10 × 10 × 0.1 mm plate supported by beams on all four sides. The plate shape and groove formation were easily realized by applying a laser machining process to glass cutting. The force applied to the plate was measured using CrN strain gauges placed on a support beam. The fabricated force plate achieved a force resolution of less than 1 mN in the range of 100 mN. Additionally, the positional error across the entire plate was approximately ±10%. The proposed glass force plate is expected to be utilized in small-force measurements such as droplet collision observations, which require transparent plates for optical observation.

From concept to wearable: 3D printed jewellery using FDM technology

ABSTRACT This study explores the transformative potential of 3D-printing, specifically Fused Deposition Modeling in the fashion industry with a focus on jewellery production. The research highlights the advantages of 3D printing over traditional fabrication methods, emphasising its design flexibility and ability to create intricate, customised pieces. This study involved designing various jewellery pieces using commercial design software such as Rhinoceros and Adobe software, followed by 3D printing with a commercially available inexpensive FDM printer. The research identified key challenges in the 3D printing process, including material limitations, print speed, and quality issues. Further, an online survey conducted among 152 respondents revealed a significant interest in 3D-printed jewellery, with customisation and design uniqueness being the primary factors influencing purchase decisions. The findings of this work underscore the need for further exploration of 3D printing applications in fashion, particularly in education and historical jewellery recreation, to maximise its potential and address industry-specific challenges.

Enhancing thermo-mechanical properties of additively manufactured PLA using eggshell microparticle fillers

Polylactic acid (PLA) is a widely studied polymer for potential biomedical applications and is one of the most commonly used polymers for additive manufacturing or 3D printing. Additive manufacturing (AM) technology is a fast-rising method of fabrication of polymer parts compared to other traditional fabrication techniques. In recent years, natural plant-based and animal-based fibers have shown immense potential to be used as fillers or reinforcements for polymer composites. In this study, chicken eggshell particles (ESP) have been used as inorganic calcium carbonate fillers to enhance PLA's mechanical properties. Four different concentrations (0 wt%, 1 wt%, 3 wt%, and 5 wt%) of PLA/ESP composite filaments have been extruded using a single screw extruder. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses were used to determine the chemical composition of eggshell powder, showing peaks matching with that of calcium carbonate (CaCO3). Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis show the effect of the filler on the PLA composite's thermal stability, indicating that pristine PLA has the highest melting temperature of 152 °C while the 5 wt% has the lowest melting temperature of 147 °C. The addition of eggshell particles slightly enhanced the compressive strength and dynamical mechanical properties of the PLA/ESP composites. The eggshell powders enhanced the dynamic mechanical property of PLA, with the 3 wt% concentration having the highest storage modulus at room temperature, with 5.2 % and 3.6 % increase for the filament and 3D printed samples respectively. Finally, the eggshell particles did not have much effect on the tensile and flexural strength of the composite, however, it enhanced the compressive strength of PLA with the 5 wt% sample having an average strength of 66.50 MPa and modulus of 2.27 GPa, respectively.

3D-Printed Lithium-Ion Battery Electrodes: A Brief Review of Three Key Fabrication Techniques.

In recent years, 3D printing has emerged as a promising technology in energy storage, particularly for the fabrication of Li-ion battery electrodes. This innovative manufacturing method offers significant material composition and electrode structure flexibility, enabling more complex and efficient designs. While traditional Li-ion battery fabrication methods are well-established, 3D printing opens up new possibilities for enhancing battery performance by allowing for tailored geometries, efficient material usage, and integrating multifunctional components. This article examines three key 3D printing methods for fabricating Li-ion battery electrodes: (1) material extrusion (ME), which encompasses two subcategories-fused deposition modeling (FDM), also referred to as fused filament fabrication (FFF), and direct ink writing (DIW); (2) material jetting (MJ), including inkjet printing (IJP) and aerosol jet printing (AJP) methods; and (3) vat photopolymerization (VAT-P), which includes the stereolithographic apparatus (SLA) subcategory. These methods have been applied in fabricating substrates, thin-film electrodes, and electrolytes for half-cell and full-cell Li-ion batteries. This discussion focuses on their strengths, limitations, and potential advancements for energy storage applications.

Facile Preparation of Polymerizable Deep Eutectic Solvents Under Mild Conditions for Multisensory Ionic Skins

AbstractPolymerizable deep eutectic solvents (PDESs) have emerged as promising building blocks for next‐generation eutectic gels, offering new opportunities for the development of advanced electronic devices. Traditional PDES fabrication typically involves heating and extended processing time. In this study, a facile method where a solid‐solid mixture of lithium bis(trifluoromethane) sulfonimide (LiTFSI) and acrylamide (AAm) rapidly forms a PDES at room temperature, significantly simplifying the ionogel preparation is presented. By combining this PDES with another system, comprising 3‐[dimethyl‐[2‐(2‐methylprop‐2‐enoyloxy)ethyl]azaniumyl]propane‐1‐sulfonate (SBMA) and ethylene glycol (EG), an eutectic gel is successfully fabricated with exceptional mechanical and conductive properties. This gel exhibits a fracture stress of 0.8 MPa, fracture energy of 3.7 kJ m−2, adhesion strength of 60 kPa, transmittance over 90%, high conductivity (0.113 S m−1), and an outstanding temperature tolerance ranged from ‐50 to 50 °C. Notably, the absence of chemical crosslinkers and the presence of reversible interactions such as hydrogen bonding and ion‐dipole electrostatic forces impart excellent self‐healing capabilities. These combined features position the gel a promising candidate for multisensory ionic skins, capable of detecting pressure, temperature, humidity, and sweat. This work pioneers the rapid, mild‐condition synthesis of PDESs, paving the way for new techniques in ionic skin development.

The Impact of Current Fabrication Methods on the Fit Accuracy of Removable Partial Dentures: A Systematic Review and Meta-Analysis

Background: The fit accuracy of removable partial dentures (RPDs) is essential for the functionality, patient comfort, and durability of RPDs. Traditional fabrication methods, like lost-wax casting, are reliable, but labor intensive, potentially affecting the fit accuracy of RPDs. Advances in digital fabrication techniques offer new avenues to improve RPD precision. This systematic review and meta-analysis will assess the impact of digital fabrication methods on the fit accuracy of RPDs compared to conventional techniques. Objective: To evaluate whether digital fabrication methods, specifically CAD/CAM and additive manufacturing, offer superior fit accuracy for RPD frameworks over conventional methods. Methods: The study protocol was registered with PROSPERO (registration number CRD42024586891). A comprehensive literature search was conducted across PubMed, the Cochrane Library, Scopus, and Ovid MEDLINE databases, covering publications published up to July 2024. The inclusion criteria comprised in vitro studies comparing the fit accuracy of digital versus conventional RPD fabrication techniques, with quantitative outcomes, such as the mean gap size or seating accuracy. The data were extracted and synthesized using a random-effects meta-analysis model. Results: Eleven studies met the inclusion criteria, with seven studies included in the meta-analysis. The mean gap size for digitally fabricated RPDs was 140 µm, compared to 164 µm for conventional methods, with a weighted mean difference (WMD) of 26.29 µm, favoring digital techniques. The subgroup analysis indicated variability in the fit across different digital techniques, with milling showing the best results, although the differences were not statistically significant. Limitations: The analysis included only in vitro studies, limiting the clinical generalizability of the findings. Additionally, heterogeneity in the study design and measurement methods persisted, which could have impacted the overall conclusions. Conclusions: Digital fabrication methods demonstrated a trend toward improved fit accuracy in comparison to conventional techniques, although the differences were modest. Future research should focus on standardizing digital workflows and conducting clinical trials to confirm these findings.

Fabricating Solventless Electrodes in Lithium-Ion Batteries through Additive Manufacturing

The development of advanced electrode materials is crucial for improving lithium-ion batteries (LIBs), which are increasingly in demand for portable electronics, electric vehicles, and grid storage applications. Traditional electrode fabrication methods often rely on the use of solvents (such as the commonly used NMP), which increases energy consumption, can pose environmental challenges, and limit the performance of the electrodes. The use of additive manufacturing (AM) techniques such as direct ink writing (DIW), fused filament fabrication (FFF), and inkjet printing (IJP) has gained significant interest due to their potential to fabricate complex, customizable structures without the need for solvents. Yet that potential has not been reached and currently these 3D printing approaches still rely on solvents. A solventless approach can lead to greener manufacturing processes, a decrease in production cost, and the enhancement of electrode performance through precise control over material architecture.Previous studies have explored the potential of additive manufacturing in fabricating electrodes for LIBs, demonstrating the capability to produce three-dimensional structures that maximize the surface area and facilitate efficient ion transport. These materials have shown comparable or superior performance to traditionally fabricated electrodes, with enhanced cycling stability and improved rate capability. These improvements are attributed to the optimized microstructure and better material utilization, which are achievable through precise control over the additive manufacturing process. Other studies have proven the feasibility of solventless fabrication of electrodes by yielding similar results with the additional benefit of saving costs by cutting down on energy consumption. However, little to no work exists combining the complete elimination of solvents and the AM process. In this work, we will employ advanced additive manufacturing techniques to fabricate solventless electrodes for lithium-ion batteries. By optimizing the composition and structure of the electrode materials, we aim to enhance the electrochemical properties such as capacity, cycling stability, and rate capability. Electrochemical and particle characterization has revealed that solventless electrodes fabricated through optimized additive manufacturing exhibit different microstructures than those of the conventional slurry casted electrodes. Parameters such as printing fidelity, layer thickness, and active material composition can be varied to study their effects on the mechanical, thermodynamic, and electrochemical properties of the electrodes. Using these insights, the next generation of rechargeable batteries can be built with the ability to control design not only making them more efficient, but more applicable.This work aims to investigate a possible method of additive manufacturing that can be used in conjunction with the fabrication of a solventless electrode for lithium-ion batteries. The findings will contribute to the development of greener, more efficient energy storage devices with tailored performance characteristics for a wide range of applications.

(Invited) Binder-Free Sulfur-Carbon Composite Electrodes for High Energy Density Lithium-Sulfur Batteries

In the scientific mission for sustainable and efficient energy storage solutions, the importance of developing high performance energy storage systems along with environmentally friendly manufacturing technologies has become important. Among various energy storage systems, Lithium-Sulfur (Li/S) batteries are particularly noteworthy for their high theoretical specific energy (2,600 Wh/kg) and cost-effectiveness, traits largely attributable to abundance and favorable properties of sulfur. This positions Li/S batteries as a compelling alternative to the prevalent lithium-ion batteries, setting a new horizon in the pursuit of advanced energy storage solutions. A critical aspect of Li/S battery manufacturing is the fabrication process of sulfur electrodes, traditionally reliant on the slurry casting method with polymer binders like N-Methyl-2-pyrrolidone (NMP), which poses environmental and economic challenges due to the energy-intensive slurry drying and subsequent NMP vapor recovery processes. Although alternatives such as aqueous binders have been explored, they offer limited benefits in reducing the overall environmental impact. Moreover, the use of binders generally increases the resistance of electrodes due to their insulating nature, affecting the electrochemical performance of battery electrodes. Our research marks a significant departure from conventional practices by introducing a novel binder-free and solvent-free approach to fabricate sulfur-carbon composite electrodes. This pioneering method represents a paradigm shift towards green energy technology, addressing both the environmental and economic concerns associated with traditional electrode fabrication. This advancement contributes significantly to reducing the environmental footprint of battery technologies, aligning with the global imperative for cleaner energy solutions. Our comprehensive study focuses on the structural, compositional, and electrochemical characteristics of the binder-free sulfur-carbon electrodes produced through this method. Utilizing advanced spectroscopic and imaging techniques, we examine the mechanisms that underlie the enhanced performance of these electrodes. The investigation reveals critical insights into the morphological and crystalline attributes that promote electrochemical activity, as well as the synergistic interactions between sulfur and carbon in the absence of traditional polymer binder.

The application of pressure-driven ceramic-based membrane for the treatment of saline wastewater and desalination–A review

Ceramic-based membranes, known for their stability, mechanical strength, and anti-fouling properties, have garnered significant attention for their application in treating saline wastewater and ion rejection. As a green technology, the preparation process of ceramic membranes does not need to use a large number of organic solvents, showing the characteristics of environmental friendliness. This review comprehensively examines recent advancements and optimization strategies in the preparation of ceramic membranes. The discussion encompasses both traditional fabrication methods and innovative techniques such as co-sintering, the introduction of sacrificial layers, and 3D printing. Additionally, the review delves into surface engineering design strategies, including functionalized modifications and the construction of new separation layers on ceramic supports. These advanced designs, such as polyamide/ceramic and graphene oxide/ceramic composite membranes, leverage the strengths of multiple materials, resulting in enhanced separation performance, mechanical strength, and resistance to chemical and thermal stress. The review also highlights the recent ceramic-based membranes applications in saline water treatment. Finally, the challenges and future prospects of ceramic-based membranes are discussed in detail.

Replication of Leaf Surface Structures on Flat Phosphor-Converted LEDs for Enhanced Angular Color Uniformity.

We explored the use of biomimetic structures, including those that mimic leaf structures, to enhance the angular color uniformity of flat phosphor-converted light-emitting diodes (pcLEDs). The distinct microstructures found on natural leaf surfaces, such as micro-scale bumps, ridges, and hierarchical patterns, have inspired the design of artificial microstructures that can improve light extraction, scattering, and overall optical performance in LED applications. The effects of these leaf surface microstructures on the phosphor layer of flat pcLEDs were evaluated. An imprinting technique was employed to directly replicate the surface morphology structures from fresh plant leaves. The results indicated that this method provided excellent scattering capability and reduced the disparity in light output between blue and yellow light emissions from flat pcLEDs at various angles. Subsequently, uniform correlated color temperature in the flat pcLEDs was achieved, reducing the yellow ring effect. Furthermore, the availability of diverse wrinkle and surface patterns from a wide range of natural prototypes could reduce design costs compared with traditional mold fabrication, making the method suitable for application in mass production.

A digital duplicating obturator with 3D printing technology

Obturators are vital for restoring function and appearance in patients with maxillofacial defects, though traditional fabrication involves multiple clinical visits and extended production time. This technique report details a digital approach using computer-aided design/manufacturing (CAD/CAM) and 3D printing to duplicate an obturator for a 74-year-old patient with maxillary bone necrosis. By using a chairside intraoral scanner, we obtained a digital model of the existing obturator, avoiding traditional impression-taking and reducing procedural discomfort. A 3D-printed obturator was fabricated, adjusted with a tissue conditioner, and refined to ensure optimal fit. Laboratory processes included using specialized materials and retention techniques. The digital workflow minimized patient visits and improved comfort, underscoring CAD/CAM and 3D printing's potential to enhance clinical efficiency and quality of life for patients requiring complex prosthetic rehabilitation. This approach highlights the practical benefits of integrating digital and analog methods in maxillofacial prosthetics. (Int J Maxillofac Prosthetics 2024;7:16-19)

Enhanced mechanical properties in transparent mullite glass-ceramics synthesized from EMT-type zeolites via spark plasma sintering

Transparent glass-ceramics offer a unique combination of optical clarity and the mechanical strength of ceramics, making them ideal for various advanced applications such as cell phone screens and telescope mirrors. However, traditional fabrication methods involve high temperatures and long processing times, which result in high energy consumption and limitations in material integration. In this study, we explore the fabrication of transparent mullite glass-ceramics from EMT-type zeolites using the spark plasma sintering (SPS) technique to address these challenges. By varying the concentrations of ammonium salts to replace Na+ in the zeolite, we modified the SiO2+Al2O3 content and successfully synthesized the mullite glass-ceramics at 950 °C. The resulting glass-ceramics exhibited high transmittance (>65 % in the visible region), improved mechanical properties with a Young's modulus up to 103 GPa, a Vickers hardness of 8.0 GPa, and an indentation fracture toughness of 1.8 MPa m1/2. X-ray diffraction and Raman spectroscopy confirmed the formation of mullite phases, with increased crystallinity and a strengthened glass structure, correlating with higher SiO2+Al2O3 content. The study demonstrates the potential of using high Al/Si ratio molecular sieves as precursors for high-performance glass-ceramics, offering significant advancements in both optical and mechanical properties.

Ultrasensitive and durable borophene-based humidity sensors for advanced human-centric applications

Borophene, a novel two-dimensional (2D) nanomaterials with high surface-to-volume ratio and abundant active sites, show great promise for humidity sensing applications, which are crucial for improving human comfort, public health, and device safety. However, traditional fabrication methods, such as drop-coating, face limitations including uncontrollable sensing layer thickness, poor water-damage resistance, and inherent variability between devices. In this work, we present a high-performance humidity sensor fabricated using borophene glass. The sensor demonstrates an impressive detection range (11–97 % RH), exceptional sensitivity (up to 1.83×105% at 97 % RH), low hysteresis (1.245 %), excellent repeatability, and relatively fast response (28.8 s)/recovery (2.6 s) times. Notably, the sensor exhibits thickness-dependent sensing performance, long-term stability, high selectivity, and water-damage resistance. First-principles calculations show that borophene exhibits an adsorption energy of 0.208 eV for H2O molecules, with the hole doping effect following adsorption driving the sensor’s response to varying relative humidity levels. The sensor’s sustained heightened sensitivity under high humidity conditions is attributed to the Grotthuss mechanism. Additionally, the sensor has been successfully integrated into various human-centric applications, including speech recognition, wireless monitoring of respiratory patterns, and non-contact switches. These advancements pave the way for the integration of borophene humidity sensors into smart devices and non-contact control systems, driving innovation in human–computer interaction and healthcare technologies.

No-impact trajectory design and fabrication of surface structured CBN grinding wheel by laser cladding remelting method

The structured grinding wheels have a specially designed macro or microstructure on the surface, with a relatively low average grinding force and temperature in the cutting zone and more space for chips and coolant. Most traditional grinding wheel fabrication methods, such as electroplating, sintering, and brazing, have the problems of poor abrasive grain holding strength, random abrasive distribution, or thermal deformation of the substrate. To address this, laser cladding remelting technology is introduced to fabricate the structured CBN grinding wheel. A no-impact trajectory was designed on the substrate of the grinding wheel, which can reduce the fluid friction in the channel and increase the fluid pressure at the outlet. The temperature and velocity fields of the grinding process were simulated to verify the feasibility of the designed structure theoretically. The optimal process parameters for the bonding among the metal bond, the abrasive grains, and the substrate were determined by orthogonal and full-scale factorial experiments. The chemical metallurgical reactions between CBN grain and metal bond, as well as between the metal bond and substrate, were formed, increasing the holding force of CBN grains. The method can realize the fabrication of high-strength and long-life structured grinding wheels with an orderly arrangement of abrasive grains. The micro-mechanism of fabrication was analyzed using element distribution measurement and XRD analysis.