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Quartz material irradiated by femtosecond laser has increasingly attracted widespread attention for the micro-fabrication of photonic devices. Mechanism exploration is beneficial for accelerating the digital progress of laser processing. However, the mechanism between femtosecond laser and quartz is complicated and needs further theoretical investigation. This paper established the theoretical model based on the ionization model with the Drude equation to study the space–time evolution of free electron density and its influence on the absorption coefficient, reflectivity, and ablation depth. In addition, we achieved a 10 × 10 micro-holes array with a pore size less than 10 μm, cone angle less than 2° in a 0.25 mm thick quartz on the condition of a laser pulse energy Ep = 3 μJ, scanning velocity v = 0.1 mm/s, and defocusing distance Δf = −0.3 mm via the bottom-up femtosecond laser processing. The work gives a new insight into further understanding the ablation mechanism of transparent materials etching by the femtosecond laser. It provides a practical technical scheme for preparing commercial quartz photonic devices. [ABSTRACT FROM AUTHOR]

Herein, the first photochemical microscale continuous oscillatory baffled reactor, that is, Photo‐μCOBR, was designed and evaluated. Computational fluid dynamics simulations were used to optimize the key structural parameter and operating conditions. Then, the mixing process was simulated and the μCOBR was shown to be more than 23 times faster than the straight channel both under oscillating conditions. Finally, a glass Photo‐μCOBR was fabricated by femtosecond laser internal engraving technology, and the photocatalytic gas–liquid oxidation of dihydroartemisinic acid was performed. A yield of 65.9% was achieved in a residence time of ~120 s and at a gas–liquid flow rate ratio of 1:3 (vs. 18.6% in the capillary photomicroreactor under identical conditions). The results in this work offer guidelines for the design and operation of microscale COBRs, and the as‐fabricated Photo‐μCOBR displays good potential for gas–liquid photochemical reactions. [ABSTRACT FROM AUTHOR]

Sodium hydroxide (NaOH) is increasingly drawing attention as a highly selective etchant for femtosecond laser-modified fused silica. Unprecedented etching contrasts between the irradiated and pristine areas have enabled the fabrication of hollow, high-aspect-ratio structures in the bulk of the material, overcoming the micrometer threshold as the minimum feature size. In this work, we systematically study the effect of NaOH solutions under different etching conditions (etchant concentration, temperature, and etching time) on the tracks created by tightly focused femtosecond laser pulses to assess the best practices for the fabrication of hollow nanostructures in bulk fused silica. [ABSTRACT FROM AUTHOR]

Perovskite photovoltaics have attracted significant attention in both academia and industry, benefiting from the superiorities of high efficiency, low cost, and simplified fabrication process. Importantly, long‐term stability is essential for practical industrialization; however, the stability challenge remains a significant impediment. Notably, stability is an essential prerequisite for practical applications. Unfortunately, as the device area increases, even to the module level, the efficiency gradually diminishes, and the stability deteriorates. This review summarizes the advances in perovskite photovoltaic technology stability from comprehensive perspectives, including the atomic‐scale, grain boundary, film morphology, interface, charge transport layer, electrode, laser etching, and module encapsulation. First, the review highlights the ongoing importance of stability in the industrialization of perovskite photovoltaics. Then, the review presents the stability challenge and explores the relationship between efficiency and stability in large‐area photovoltaic modules, shedding light on the stability issue. Later, the review explains the stability issue in terms of structure, chemistry, interfaces, device design, operation, and external environment, and proposes stability strategies ranging from the atomic‐scale to module encapsulation. Finally, the review emphasizes various improvement strategies, particularly multilevel synergistic optimization, offering fundamental guidance for the industrialization of perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We demonstrate a genuine method for three-dimensional pictorial reconstructions of two-dimensional, three-dimensional, and hybrid specimens based on confocal Raman data collected in a back-scattering geometry of a 532-nm setup. The protocol, or the titular PRISM (Phase-Resolved Imaging Spectroscopic Method), allows for sub-diffractive and material-resolved imaging of the object's constituent material phases. The spacial component comes through either the signal distal attenuation ratio (direct mode) or subtle light-matter interactions, including interference enhancement and light absorption (indirect mode). The phase component is brought about by scrutinizing only selected Raman-active modes. We illustrate the PRISM approach in common real-life examples, including photolithographically structured amorphous Al2O3, reactive-ion-etched homoepitaxial SiC, and Chemical Vapor Deposition graphene transferred from copper foil onto a Si substrate and AlGaN microcolumns. The method is implementable in widespread Raman apparatus and offers a leap in the quality of materials imaging. The lateral resolution of PRISM is stage-limited by step motors to 100 nm. At the same time, the vertical accuracy is estimated at a nanometer scale due to the sensitivity of one of the applied phenomena (interference enhancement) to the physical property of the material (layer thickness). [ABSTRACT FROM AUTHOR]

To evaluate and compare the shear bond strength of composite resin restorations in primary teeth, following cavity preparation with both traditional dental burs and laser irradiation. One hundred primary molars extracted from the children visiting our department were collected and randomly divided into five groups (A-E) with 20 teeth in each group. In groups A, B, C, D, and E the teeth samples were etched with phosphoric acid, Er; YAG laser followed by acid etching, Er, Cr: YSGG laser followed by acid etching, Er; YAG laser etching only and Er, Cr: YSGG laser etching only, respectively. Following, all the samples were restored with composite resin and subjected to 500 cycles of thermocycling. The shear bond strength of the resin composite was analyzed. The type of fractures was also noted. Data obtained were subjected to statistical analysis. The mean value of shear bond strength of Group A, B, C, D, and E was 17.562 ± 0.810, 15.928 ± 0.415, 14.964 ± 0.566, 11.833 ± 0.533 and 11.187 ± 0.517, respectively. Adhesive failure was most commonly seen in all the groups. The phosphoric acid etching remains a highly effective technique for pre-treating dentin in composite resin restorations. The shear strength of composite resin to the dentin of laser-prepared cavity in primary teeth can be improved by the addition of acid etching. [ABSTRACT FROM AUTHOR]

This paper presents an industrial wireless control and monitoring system for laser cutters and engravers based on computer numerical control (CNC), which aims to improve the overall performance, efficiency, and safety of the CNC machine and its peripherals as an ecosystem by allowing users to operate and maintain it remotely using Wi-Fi. The developed system is implemented through a dynamic hardware module and a multi-OS user application, thereby establishing real-time and simplified communication between the operator and the Laser Cutter/Engraver-CNC ecosystem for remote control and monitoring functions. Further, the system allows for configuring machine settings, and the start or stop of cutting or engraving processes. A Laser Cutter/Engraver-CNC ecosystem prototype was built and used in a test-validated environment to confirm the effectiveness of this system design. [ABSTRACT FROM AUTHOR]

Inconel® 718, known for its excellent mechanical properties in extreme conditions, presents machining challenges due to its low machinability. The chip formation process, influenced by its high ductility and low thermal conductivity, leads to material adhesion and high cutting forces. Ceramic tools have been proposed to mitigate these inconveniences. Textured cutting tools have emerged as a promising solution, aiming to optimise tool-chip contact and, with it, the tribological conditions and the cutting forces. This study investigates the influence of textured grooves on ceramic tools when turning Inconel® 718. Two groove inclinations, 0° and − 25° relative to the cutting edge, were tested. Texturing was performed using a laser station. Experimental results showed improved tool wear characteristics with textured tools, indicating favourable chip extraction and reduced material adhesion. Cutting forces were notably lower with textured tools compared to the reference tool, attributed to reduced notch wear and altered chip flow. Chip morphology analysis revealed differences in chip shape and thermal stability between the reference and textured tools. In conclusion, textured tools, particularly those with − 25° inclined grooves, demonstrated enhanced performance in machining Inconel® 718. [ABSTRACT FROM AUTHOR]

This article presents a low-cost apparatus designed for teaching geometric optics experiments to first-year university students. The apparatus is made of medium-density fiberboard and uses glass optical elements to verify the laws of reflection and refraction. It allows for the direct observation of lateral displacement caused by a rectangular plate and the determination of the refractive index of the plate's material. Additionally, it enables investigation of refraction through a Littrow prism by determining its minimum deviation angle. The apparatus is economic, safe, and easy to use, making it suitable for educational purposes. The authors acknowledge the contributions of the Optics Research Group at Damietta University and Mohamed A. Atwa to the implementation of the apparatus. [Extracted from the article]

Fused silica with surface structures has potential applications in microfluidic, aerospace and other fields. To fabricate structures with high dimensional accuracy and surface quality is of paramount importance. However, it is indeed a challenge to strike a balance between accuracy and efficiency at the same time. Here, a temporally shaped femtosecond laser Bessel-beam-assisted etching method with dual-control of incubation effect is proposed to achieve this balance. Instead of layer-by-layer ablation continuously with Gaussian pulses, silica is modified discretely by double pulse Bessel beam with one single layer. During the modification process, incubation effect is dual-controlled in single shot process and spatial scanning process to generate even modified region efficiently. Then, the modified region is etched to form designed structures such as microholes, grooves, etc. The proposed method exhibits high efficiency for fabrication of surface structures in fused silica. [ABSTRACT FROM AUTHOR]

This study designed laser engraving and resin pre-coating (RPC) treatments on an aluminum alloy (AA) surface to construct through-the-thickness "epoxy pins" for improving the bonding strength with carbon fiber reinforced polymer (CFRP). A laser engraving treatment was used to create a pitted structure on the AA surface; higher wettability was acquired and greater vertical spaces were formed to impregnate epoxy resin, resulting in stronger mechanical interlocking. The RPC technique was further used to guide high-viscosity epoxy resin into pits to form the epoxy coatings and to minimize defects between the resin and the substrate. The bonding strength of the specimen treated with both laser engraving with a unit dimension of 0.3 mm and RPC increased up to 227.1% in comparison with that of the base. The failure modes of the hybrid composites changed from the debonding failure of the AA surface to the delamination-dominated failure of the laminated CFRP composites. It was confirmed that laser engraving is a feasible and effective method when combined with RPC for treating AAs to improve the bonding strength of AA-CFRP composites, which provides a reference for preparing high-performance hybrid composites with metals. [ABSTRACT FROM AUTHOR]

The results of the study of radiation produced by the electrical explosion of Al foil with a thickness of 4 μm with an artificial periodic structure of periodic holes with 50–400 μm steps created by laser engraving are presented. The experiments were carried out on a KING pulse high-current generator (220 kA, 40 kV, 300 ns). Images of exploded foils were recorded using pinhole cameras with a 20 μm aperture on a four-frame microchannel plate camera with 5 ns temporal resolution. In experiments on the electrical explosion of thin foils, it was shown that the application of an artificial periodic structure to the foil leads to a much more uniform radiation in the UV spectrum range along the entire length and width of the foil. Uniform radiation was observed from 20 to 70 ns. It is shown that such radiation can be used for the imaging of test objects or plasma objects like exploded wires. [ABSTRACT FROM AUTHOR]

Ceramic materials, while strong, often lack flexibility and energy absorption. Inspired by tough natural structures like nacre, toughening strategies have shown significant potential in ceramic materials. This study investigates the static and cyclic flexural properties (i.e., energy absorption, stiffness, and strength) of the bioinspired ceramic-polymer composites, particularly concerning the influence of macro and micro patterns. Using a subtractive manufacturing platform enabled by ultra-short pulsed picosecond lasers, we engrave a range of macro and micro patterns onto alumina tiles, mimicking natural armor designs. The composites are then fabricated by stacking laser-engraved tiles with an interlayer of Surlyn®, a commercial monomer. The results demonstrate that the static/cyclic performance and toughening mechanisms are closely linked to the lasered bioinspired surface patterns and stacking sequence. Specific macro architectures and stacking sequences led to significantly increased energy absorption (up to 85%) through mechanisms like crack deflection and plastic deformation of the soft phase. Micro patterns, on the other hand, improved the ceramic's strength (up to 140%) by influencing how the materials interact at the interface. This research not only advances our understanding of bioinspired armor but also paves the way for a new generation of ceramic composites with superior properties, targeting applications in defense (aerospace and vehicle armor) and personal protective equipment (PPE).

Joule heating electrodes (JHEs) are required for thermal actuation systems. A highly stretchable, patternable, and low‐voltage operating JHE based on hybrid layers of silver nanowires and carbon nanotubes are reported. The conductive layers are applied on a locally pre‐strained bistable electroactive polymer (BSEP) membrane to form a wrinkled conductive surface with a low resistance of 300 Ω/sq, and subsequently patterned to a serpentine trace by laser engraving. The resistance of the resulting JHE electrode remains nearly unchanged up to 80−90% area strain. By applying a voltage of 7 − 9 V to the electrode, the temperature of the BSEP membrane increased to ~60 °C, well above the polymer's phase transition temperature of 46 °C, thereby lowering its modulus by a factor of 103. An electronic Braille device based on the JHEs on a BSEP membrane is assembled with a diaphragm chamber. The electrode is patterned into 3 × 2 individually addressable pixels. Through Joule heating of the pixels and local expansion of the BSEP membrane using a pneumatic pressure, the pixels deformed out of the plane by over 0.5 mm to display Braille letters. The Braille content can be refreshed for 20 000 cycles at the same operating voltage. [ABSTRACT FROM AUTHOR]

Polymer-derived ceramics (PDCs) are increasingly recognized as promising materials for high-temperature thin/thick film sensors (HTTFSs). However, a large linewidth and poor dimensional accuracy have severely restricted the practical application of PDCs HTTFSs. Our study employed a picosecond laser to precisely pattern the polymer-derived ceramic (PDC) thick film while applying no obvious damage to the interface between ceramic and substrate. Through parameters optimization, the laser-affected area was minimized to 6 μm wide, and a minimum feature size of about 30 μm was achieved. Furthermore, 7 rounds of high-temperature tests of the patterned film revealed good temperature-resistance repeatability within a temperature range of up to 800 °C. To demonstrate practical application potential, we successfully fabricated a heat flux sensor, and it exhibited a sensitivity of 1.32 mV/(kW/m2), a response time of 600 ms, and excellent repeatability over a range of 0–75.4 kW/m2. In summary, this paper proposes a novel approach toward miniaturizing the linewidth of the polymer-derived ceramics thick film sensor, showing significant potential for precise measurements in extreme environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Urine analysis stands as a critical diagnostic tool, offering insights into health and disease. However, current techniques demand sophisticated equipment or significant sample processing for urine examination, reducing their suitability for regular point‐of‐care assessments. This study introduces a novel multi‐component sensing platform to address these constraints. The proposed sensor array can detect sodium (Na+), potassium (K+), ammonium (NH4+), calcium (Ca++), chloride (Cl−), and pH levels, thus, enabling real‐time urine analysis. This sensing platform utilizes an extended gate (EG)‐field effect transistor (FET) design employing EG electrodes made of LASER engraved graphene on flexible Kapton substrates. These experimental findings from individual sensors demonstrate consistent linear responses to ion levels, discrimination of specific ions among interferences, and operational stability over time. Additionally, the six‐channel sensor array exhibits notable sensitivity and selectivity in a urine environment, effectively discerning various ions and pH, illustrating its efficacy for urine analysis and validating its potential for reliable point‐of‐care diagnostics. [ABSTRACT FROM AUTHOR]

Stretchable pressure sensor arrays are ideal for biomimetic electronic skin (e‐skin). However, conventional pressure sensors exhibit noticeable strain interference when stretched. This article introduces an advanced fabrication method based on dual‐band laser selective etching to create stretchable pressure sensor arrays free from strain interference. An intact sensitive film is sandwiched between the top and bottom electrodes and then etched into separate sensing cells. Silicone gel with an extremely low Young's modulus (0.157 kPa) is employed as the strain buffer layer, filling the space within sensing cells to absorb device strain during stretching. The pressure sensor arrays demonstrate exceptional interference‐free performance, with the resistance of sensing cells remaining unchanged under strains exceeding 20%. Pressure sensor arrays of 32 × 32 units are manufactured, showcasing a resistive response time of ≈40 ms during compression and 20 ms during release, along with a sensitivity of 0.7702 kPa−1 within the range of 1–70 kPa. Finally, the sensor arrays are integrated into a robotic hand as biomimetic e‐skin, coupled with deep learning algorithms, successfully identifying static and dynamic pressure distributions and achieving an average precision rate of over 99% in recognizing 2D shapes and objects. [ABSTRACT FROM AUTHOR]

Suppression of secondary electron emission (SEE) from metal surfaces is crucial for enhancing the performance of particle accelerators, spacecraft, and vacuum electronic devices. Earlier research has demonstrated that either etching the metal surface to create undulating structures or coating it with materials having low secondary electron yield (SEY) can markedly decrease SEE. However, the effectiveness of growing vertical graphene (VG) on laser-etched metal surfaces in suppressing SEE remains uncertain. This study examined the collective impact of these methods by applying nanoscale arrays of VG coating using plasma-enhanced chemical vapor deposition on Ni substrates, along with the formation of micrometer-sized microcavity array through laser etching. Comparative tests conducted revealed that the SEY of the samples subjected to VG coating on a microcavity array was lower compared to samples with either only a microcavity array or VG coating alone. Additionally, the crystallinity of VG grown on substrates of varying shapes exhibited variations. This study presents a new method for investigating the suppression of SEE on metal surfaces, contributing to the existing body of knowledge in this field. [ABSTRACT FROM AUTHOR]

This study aims to establish and optimize a process for the fabrication of 3D microstructures of the biocompatible polymer Parylene C using hot embossing techniques. The different process parameters such as embossing temperature, embossing force, demolding temperature and speed, and the usage of a release agent were optimized, utilizing adhesive micropillars as a use case. To enhance compatibility with conventional semiconductor fabrication techniques, hot embossing of Parylene C was adapted from conventional stainless steel substrates to silicon chip platforms. Furthermore, this adaptation included an investigation of the effects of the hot embossing process on metal layers embedded in the Parylene C, ensuring compatibility with the ultra-thin Parylene printed circuit board (PCB) demonstrated previously. To evaluate the produced microstructures, a combination of characterization methods was employed, including light microscopy (LM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). These methods provided comprehensive insights into the morphological, chemical, and structural properties of the embossed Parylene C. Considering the improved results compared to existing patterning techniques for Parylene C like plasma etching or laser ablation, the developed hot embossing approach yields a superior structural integrity, characterized by increased feature resolution and enhanced sidewall smoothness. These advancements render the method particularly suitable for diverse applications, including but not limited to, sensor optical components, adhesive interfaces for medical wearables, and microfluidic systems. [ABSTRACT FROM AUTHOR]

Nanosecond pulsed laser etching for fabricating anti-reflective gratings and inducing synchronous laser annealing was performed on Ag/AZO films. The optimum grating pitch was determined by performance analyses of laser-etched unidirectional gratings, based on which laser-etched bidirectional gratings were fabricated to further determine the optimum grating tilt angle. The results revealed that with the increase of grating pitch, the grating ridge total-side-area was gradually decreased to cause a gradually weakened anti-reflective effect, but the superimposed heat-affected zones between adjacent grooves became smaller or even disappeared, which brought about different synchronous laser annealing effects. The unidirectional grating-textured film with a medium grating pitch of 200 μm showed the best overall performance under the combined influence from anti-reflective gratings and synchronous laser annealing. For the bidirectional gratings, although increasing the grating tilt angle did not change the grating ridge total-side-area, it would enable the laser energy to be more uniformly distributed on the whole film surface, producing a better synchronous laser annealing effect. The bidirectional grating-textured film with a grating tilt angle of 90° had the best overall performance with the highest FOM value of 2.18 × 10−2 Ω−1 that was ∼3.2 times that of the as-prepared film. The results are instructive for preparing high-performance TCO-based films. [ABSTRACT FROM AUTHOR]

Surface textured materials can exhibit enhanced properties due to their unique morphology, large surface area, and modified surface properties. The laser etching process has garnered significant attention for its capability to create textures on sample surfaces, resulting in a substantial improvement of surface properties. In this study, we investigate the application of femtosecond laser etching on solid electrolytes. To achieve this, an axicon lens is employed to transform the conventional Gaussian beam into a Bessel beam, with an extended focal depth that facilitates the laser etching process. A telescope laser system with a Bessel beam having a focal length of 2 mm is constructed based on finite element analysis. Glassy LAGP [Li1.5Al0.5Ge1.5(PO4)3] with a thickness of 2 mm is successfully etched simultaneously on both surfaces using this approach. Utilization of femtosecond laser pulses effectively prevents sample melting during the process. As predicted by finite element analysis, wider ditches are observed on the surface compared to those on the backside due to higher laser intensity at the surface region. By modifying the parameters of the telescope laser system, size and depth control can be achieved for these ditches. [ABSTRACT FROM AUTHOR]

Investigating the optimal laser processing parameters for industrial purposes can be time-consuming. Moreover, an exact analytic model for this purpose has not yet been developed due to the complex mechanisms of laser processing. The main goal of this study was the development of a backpropagation neural network (BPNN) with a grey wolf optimization (GWO) algorithm for the quick and accurate prediction of multi-input laser etching parameters (energy, scanning velocity, and number of exposures) and multioutput surface characteristics (depth and width), as well as to assist engineers by reducing the time and energy require for the optimization process. The Keras application programming interface (API) Python library was used to develop a GWO-BPNN model for predictions of laser etching parameters. The experimental data were obtained by adopting a 30 W laser source. The GWO-BPNN model was trained and validated on experimental data including the laser processing parameters and the etching characterization results. The R2 score, mean absolute error (MAE), and mean squared error (MSE) were examined to evaluate the prediction precision of the model. The results showed that the GWO-BPNN model exhibited excellent accuracy in predicting all properties, with an R2 value higher than 0.90. [ABSTRACT FROM AUTHOR]

A novel five-surface phosphor-in-glass (FS-PiG) structure for high illumination and excellent color uniformity in large-view scale LEDs for sensor light source application is demonstrated. YAG phosphor (Y3Al5O12:Ce3+) was uniformly mixed with ceramic and sintered at 680 °C to form a phosphor wafer. Sophisticated laser engraving was employed on the phosphor wafer to form saddle-shaped large-view scale FS-PiG LEDs. The performance of the FS-PiG LEDs exhibited an illumination of 401 lm, average color temperature (CCT) of 5488 K ± 110 K, and color coordinates (CIE) of (0.3179 ± 0.003, 0.3352 ± 0.003). In contrast to convention single-surface phosphor-in-glass (SS-PiG) LEDs, the performance exhibited an illumination of 380 lm, average CCT of 5830 K ± 758 K, and CIE of (0.3083 ± 0.07, 0.3172 ± 0.07). These indicated that the performance of the FS-PiG LEDs was higher than the SS-PiG LEDs for illumination, CCT, and CIE by 1.7, 7, and 23 times, respectively. Furthermore, the FS-PiG LEDs demonstrate a lower lumen loss of 2% and a reduced chromaticity shift of 5.4 × 10−3 under accelerated aging at 350 °C for 1008 h, owing to the high ceramic melting temperature of up to 510 °C. In this study, the proposed FS-PiG large-view scale LEDs with excellent optical performance and high reliability may be promising candidates to replace the conventional phosphor-in-organic silicone material used in high-power LEDs for the next generation of sensor light sources, display, and headlight applications. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the microleakage of light-cured and self-cured adhesives on enamel surfaces selectively etched with Er, Cr: YSGG laser or 35% phosphoric acid. A total of 60 class V cavities were prepared 1 mm above the cemento-enamel junction (CEJ). The specimens were randomly divided into six groups. Group 1: Clearfil SE Bond with no conditioning, Group 2: Tokuyama Universal Bond with no conditioning, Group 3: Clearfil SE Bond conditioned with 35% phosphoric acid, Group 4: Tokuyama Universal Bond conditioned with 35% phosphoric acid, Group 5: Clearfil SE Bond conditioned with Er, Cr: YSGG laser and Group 6: Tokuyama Universal Bond conditioned with Er, Cr: YSGG laser. Microleakage was evaluated qualitatively (visually) and quantitatively (ImageJ). The data were analyzed using IBM SPSS V23 and submitted to Kruskal–Wallis and Wilcoxon tests. The significance level was set at p < 0.05. In all evaluation methods, the microleakage scores exhibit significant differences (p*<0.001). Group 1 and Group 3 exhibited similar and lower microleakage values than the Group 5. In the occlusal margin, the microleakage values were similar in Group 2, Group 4, and Group 6, whereas in the gingival margin Group 4 showed significantly lower leakage compared to Group 2. Regardless of the etching protocols and adhesive systems used, less microleakage was observed on the occlusal surface than on the gingival surface. Phosphoric acid etching provides better results than laser etching for enamel surface treatment on both occlusal and gingival surfaces. [ABSTRACT FROM AUTHOR]

In this research, a novel electrochemical biosensor is proposed based on inducing graphene formation on polyimide substrate via laser engraving. Graphene polyaniline (G-PANI) conductive ink was synthesized by planetary mixing and applied to the working zone of the developed sensor to effectively enhance the electrical signals. The laser-induced graphene (LIG) sensor was used to detect alpha-fetoprotein (AFP) and 17β-Estradiol (E2) in the phosphate buffer saline (PBS) buffer and human serum. The electrochemical performance of the biosensor in determining these biomarkers was investigated by differential pulse voltammetry (DPV) and chronoamperometry (CA). In a buffer environment, alpha-fetoprotein (AFP) and 17β-Estradiol detection range were 4–400 ng/mL and 20–400 pg/mL respectively. The experimental results showed a limit of detection (LOD) of 1.15 ng/mL and 0.96 pg/mL for AFP and estrogen, respectively, with an excellent linear range (R2 = 0.98 and 0.99). In addition, the designed sensor was able to detect these two types of biomarkers in human serum successfully. The proposed sensor exhibited excellent reproducibility, repeatability, and good stability (relative standard deviation, RSD = 0.96%, 1.12%, 2.92%, respectively). The electrochemical biosensor proposed herein is easy to prepare and can be successfully used for low-cost, rapid detection of AFP and E2. This approach provides a promising platform for clinical detection and is advantageous to healthcare applications. [ABSTRACT FROM AUTHOR]

This study focused on effective methods of laser engraving treatment (LET), plasma spraying, and resin pre-coating (RPC) to manufacture the reinforced adhesive joints of titanium alloy and carbon fiber-reinforced polymer (TA-CFRP) composites. The combined treatments contributed to the creation of a better adhesive bonding condition and offer a vertical gap between circular protrusions to form epoxy pins and carbon nanotube (CNT)-reinforced epoxy pins. The bonding strength of the TA-CFRP composite was reinforced by 130.6% via treatments with a twice-engraving unit of 0.8 mm, plasma spraying, and RPC. The original debonding failure on the TA surface was changed into the cohesive failure of the epoxy adhesive and delamination-dominated failure of the CFRP panel. Overall, laser engraving has been confirmed as an effective and controllable treatment method to reinforce the bonding strength of the TA-CFRP joint combined with plasma spraying and RPC. It may be considered as an alternative in industry for manufacturing high-performance metal–CFRP composites. [ABSTRACT FROM AUTHOR]

The use of SiO2 ceramic materials is increasingly prevalent in both industrial and artisanal craftsmanship. These materials exhibit excellent mechanical properties, making them challenging to process, especially after firing. The paper explores the application of CO2 lasers for engraving ceramic materials, addressing challenges in traditional processing methods and offering insights into optimizing laser parameters for enhanced engraving performance. Through simulations using COMSOL Multiphysics software and experimental validations, the thermal interaction between CO2 lasers and SiO2 ceramic substrates is thoroughly investigated. Parameters such as power, scanning speed, pulse width, and repetition frequency are examined to understand their influence on engraving depth, resolution, and surface quality. The research compares continuous wave (CW) and pulsed modes, highlighting their advantages and limitations. The most suitable set of technological parameters is selected for experimentations on unfired and fired ceramic samples. The results demonstrate the effectiveness of CO2 lasers in engraving ceramics and their potential for various industrial applications. This research provides comprehensive insights into applying CO2 laser technology to ceramic materials. [ABSTRACT FROM AUTHOR]

In this paper, a nanosecond laser was used to etch the surface of graphene nanoplatelets reinforced ZK60 (GNPs/ZK60) matrix composites, and the effects of different scanning speeds, pulse repetition frequency and laser power on the etched morphology of the machined surface were investigated. The experimental results show that the etched groove width and heat affected zone width of GNPs/ZK60 composites are significantly increased compared with ZK60 material due to the influence of graphene, and the growth rate of the difference in heat affected zone width between GNPs/ZK60 composites and ZK60 materials is most significantly affected by the pulse repetition frequency. In addition, the dross height increases with the increase of laser power, while the scaly dross structure becomes increasingly clear. [ABSTRACT FROM AUTHOR]

At present, perforation of high aspect ratio through glass vias (TGVs) is one of the primary factors limiting the development of glass interposers. Herein, it is based on a large number of experiments, combined with mechanistic analysis, to realize the perforation of ultrahigh/high aspect ratio fused silica TGVs using selective laser‐induced etching. First, the effect of the number of pulses as well as other laser parameters on the etching selectivity is systematically investigated. It is found that the formation of nanochannels in fused silica is crucial in determining the high selectivity. Subsequently, a model based on diffusion theory is proposed to mathematically explain the reasons for the high selectivity generation. Finally, the perforations of TGVs with diameters of 5.4–26.4 μm, aspect ratios of 11.7–61.3, and vertical sidewalls are achieved, at a laser treatment speed of ≈10 000 TGVs per minute. This research can serve as an essential reference for the manufacturing of TGVs with high aspect ratios and glass interposers with high interconnection density. [ABSTRACT FROM AUTHOR]

The most crucial initial step in the metallization process of electroplating is the local contact openings in dielectric layers. In this article, an ultraviolet picosecond laser (UV‐ps), is used to open the front and back dielectric layer of the precursor of n‐TOPCon solar cells. By changing the laser parameters and spot overlap rate, the surface morphology of laser etching under different conditions is obtained and characterized by optical microscope and scanning electron microscope. The results indicate that there are three separate laser shock zones in the dielectric layer under the action of Gaussian light spot, and the corresponding ablation mechanisms are proposed. The longitudinal distribution of B element is characterized by secondary ion mass spectrometry to explore the effect of laser on its pn junction. In addition, the electrical characterization of lifetime photoluminescence is measured and calibrated using WCT120, and this indicates that the majority of the amorphous silicon is recrystallized when applying a fast firing oven process, and this hence improve the minority carrier lifetime and implied open‐circuit voltage. The laser damage to the emitter at the laser‐ablated regions is investigated using the emitter saturation current density, J0laser extracted by WCT120. [ABSTRACT FROM AUTHOR]

To address the challenge of lubricating oil creep loss in aerospace equipment, a biomimetic structure combining a wetting gradient with a geometric diversion pattern inspired by the peristome region of the Nepenthes pitcher plant is designed. A two-phase flow-field simulation is performed to investigate directional droplet transport on this biomimetic structure. Hydrothermal deposition and laser etching methods are then used to prepare surfaces incorporating this structure on a titanium substrate, and directional droplet transport is observed using high-speed photography. It is found that regions on this surface with a biomimetic structure region are superhydrophilic with a contact angle of 0°, while regions without any such structure are superhydrophobic with a contact angle of 159°. With increasing curvature of the biomimetic structural units, the self-actuation effect of the biomimetic structure on droplets decreases. The effects of the other structural parameters in the case of zero curvature is studied, and it is found that the droplet transport rate increases with increasing lateral spacing and longitudinal spacing between biomimetic structural units and decreases with increasing angle of inclination of these units and increasing droplet viscosity. The designed biomimetic structure is thus able to realize efficient directional transport of water and lubricating oil, with the transport rate being determined by the biomimetic structural parameters and the droplet viscosity. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (English Edition) is the property of Journal of Donghua University Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Water-lubricated material is the fundamental ingredient of a water-lubricated bearing (WLB), of which the friction and wear properties directly affect the working performance and service life of a WLB. We designed a micron-scale stripe texture and fabricated a negative microtexture mold by femtosecond laser etching. The microtextures were fabricated onto the surface of Thordon and polyurethane water-lubricated materials by a precision thermoforming machine. Tribological tests showed that the microstripe texture on water-lubricated materials had lower friction and wear properties than that on pristine surface materials. The results demonstrated that the presence of the microstripe texture effectively improved the friction and anti-wear properties of the water-lubricated materials. This study provides a new idea for the design and preparation of water-lubricated materials with good water-lubricating and anti-wear properties. [ABSTRACT FROM AUTHOR]

Constructing low‐tortuosity structure is a facile and effective strategy to significantly improve the electrochemical performances of thick electrodes of batteries. In this study, the low‐tortuosity structured electrodes with an array grooved structure are fabricated using a method of laser etching post‐processing, promoting excellent electrochemical performance of sodium‐ion batteries (SIBs). The effects of laser post‐processing parameters including the etching shape, interval, and scan number on the structures and electrochemical performances of the prepared electrodes are investigated. Results show that the array grooved structures of the laser‐treated electrodes not only reduce the tortuosity to enhance the ion transfer efficiency, but also provide extra space to accommodate more electrolyte, which helps strengthen the electrochemical reaction kinetics of the electrodes. The proposed electrode with a parallelogram etching shape, an interval of 0.1 mm, and a scan number of 10 can produce a high rate capacity of 120.7 mAh g−1 at 500 mA g−1 and an outstanding cycle performance with a high capacity maintenance rate of 97.8% after 200 cycles. This study validates a new method to create low‐tortuosity electrodes for SIBs by optimizing the process parameter, which can be potentially extended to the fabrication of other advanced energy storage devices. [ABSTRACT FROM AUTHOR]

In the last decade, increased availability of 3d printers and laser cutters has led to development of specialized market for producing models as souvenirs and personalized gifts. One type of such models are city scale-models. The topic of this research deals with the examination of various laser engraving and laser cutting techniques, as well as the application of 3d printing in the production of specialized city scale-models. The aim of the research is to find the most efficient way of realising this project while fulfilling the following criteria: production time, quality of the final result (need for additional processing) and total production costs. Results of this research are successfully fabricated city scale-models and a tabular overview containing data on the basis of which the best approach can be determined, in relation to given predispositions. [ABSTRACT FROM AUTHOR]

Purpose: To compare the shear bond strength between polyetheretherketone (PEEK) and heat activated polymethylmethacrylate (PMMA) resin after laser treatment. Materials and Methods: A total of 128 PEEK discs were fabricated (10 mm diameter and 2 mm thickness) and allocated into two groups. Group 1 was subjected to surface treatment followed by thermal cycling for 5000 cycles and group 2 was subjected to surface treatment followed by thermal cycling for 10,000 cycles. Each group was further subdivided into four subgroups (n = 16) which were: no surface treatment; primer treatment; acid etching; and laser surface treatment. PEEK was then bonded with PMMA resin using the conventional flasking technique. The shear bond strength was evaluated using a universal testing machine with a crosshead speed of 1 mm/min. Statistical analysis was done using one‐way ANOVA for comparing within groups, followed by Tukey HSD test. Student's T‐test was done to evaluate between the two groups. Results: In group 1, the highest shear bond strength was exhibited by the laser group (19.08 ± 0.16 MPa) followed by the acid etch group (14.84 ± 0.23 MPa), and the primer group (6.43 ± 0.20 MPa), while the least shear bond strength was observed in the no surface treatment group (4.98 ± 0.34 MPa) which was found to be significant (p < 0.05). In group 2, the highest shear bond strength was observed in the laser group (18.21 ± 0.23 MPa) followed by the acid etch group (13.77 ± 0.48 MPa), and the primer group (6.04 ± 0.11 MPa), while the least shear bond strength was observed in no surface treatment group (4.35 ± 0.21 MPa) which was found to be significant (p < 0.05). Conclusion: The shear bond strength between PEEK and PMMA resin was highest for specimens that were surface treated with laser and followed by specimens treated with acid etching, primer application, and without surface treatment, respectively. Increasing thermal cycling from 5000 cycles to 10,000 cycles also reduced the bond strength. [ABSTRACT FROM AUTHOR]

Semi-embedded periodic Ag grids were combined with FTO/glass substrates based on laser direct writing to prepare transparent electrodes (TEs). The laser etching parameters (scanning velocity and energy density), grid shape, and unit-grid circumcircle radius were systematically optimized. The optimal scanning velocity and energy density for obtaining ideal laser-etched grooves were determined to be 10 mm/s and 1.6 J/cm2, respectively. The hexagonal Ag grid/FTO TE using the 1.00-mm unit-grid circumcircle radius prepared from the optimal laser etching parameters showed significantly decreased sheet resistance and slightly lowered light transmittance as compared to the FTO/glass substrate. This TE was employed for fabricating a transparent heater (TH), which could reach a steady-state temperature of 137.7 °C within 60 s at a voltage of 4.0 V and maintain good heating and cycling stability in 10 continuous switch heating/cooling cycles under different voltages (0.8–4.0 V). The application prospect of the TH was demonstrated by a de-icing experiment. Introducing semi-embedded periodic Ag grids with a suitable grid shape and unit-grid circumcircle radius can contribute to a great improvement in electrical conductivity of the substrate and, thus, its comprehensive performance, providing a great inspiration for optimized preparation of high-performance TEs. [ABSTRACT FROM AUTHOR]

Hydrophobic surfaces have attracted great attention due to their ability to repel water, and metallic surfaces are particularly significant as they have several benefits, for example they self-clean and do not corrode in marine environments, but also have several applications in the aircraft, building and automobile industries. Tungsten is an ideal material for metallic surfaces due to its remarkable mechanical properties. However, conventional micromachining methods of micro- or nanostructures, including mechanical fabrication and laser and wet etching are incapable of balancing functionality, consistency and cost. Inspired by the etching process of silicon, deep etching of bulk tungsten has been developed to achieve versatile microstructures with the advantages of high efficiency, large scale and low cost. In this article, fabrication methods of tungsten-based hydrophobic surfaces using an ICP deep etching process were proposed. Micro- or hierarchical structure arrays with controllable sidewall profiles were fabricated by optimizing etching parameters, which then exhibited hydrophobicity with contact angles of up to 131.8°. [ABSTRACT FROM AUTHOR]

Cutlery and flatware designs are an everchanging phenomenon of the manufacturing industry. Worldwide hospitality businesses demand perpetual evolution in terms of aesthetics, designs, patterns, colours, and materials due to customers' demands, modernisation, and fierce competition. To thrive in this competitive market, modern fabrication techniques must be flexible, adoptive, fast, and cost effective. For decades, static designs and trademark patterns were achieved through moulds, limiting production to a single cutlery type per mould. However, with the advent of laser engraving and design systems, the whole business of cutlery production has been revolutionised. This study explores the possibility of creating diverse designs for stainless steel 304 flatware sets without changing the entire production process. The research analyses three key laser process parameters, power, scanning speed, and number of passes, and their impacts on the resulting geometry, depth of cut, surface roughness, and material removed. These parameters are comprehensively studied and analysed for steel and zirconia ceramic. The study details the effects of power, scanning speed, number of passages, and fluence on engraved geometry. Fluence (power*number of passages/scanning speed) positively influences outputs and presents a positive trend. Medium power settings and higher scanning speeds with the maximum number of passages produce high-quality, low-roughness optimised cavities with the ideal geometric accuracy for both materials. [ABSTRACT FROM AUTHOR]

Biometric fingerprint identification hinges on the reliability of its sensors; however, calibrating and standardizing these sensors poses significant challenges, particularly in regards to repeatability and data diversity. To tackle these issues, we propose methodologies for fabricating synthetic 3D fingerprint targets, or phantoms, that closely emulate real human fingerprints. These phantoms enable the precise evaluation and validation of fingerprint sensors under controlled and repeatable conditions. Our research employs laser engraving, 3D printing, and CNC machining techniques, utilizing different materials. We assess the phantoms' fidelity to synthetic fingerprint patterns, intra-class variability, and interoperability across different manufacturing methods. The findings demonstrate that a combination of laser engraving or CNC machining with silicone casting produces finger-like phantoms with high accuracy and consistency for rolled fingerprint recordings. For slap recordings, direct laser engraving of flat silicone targets excels, and in the contactless fingerprint sensor setting, 3D printing and silicone filling provide the most favorable attributes. Our work enables a comprehensive, method-independent comparison of various fabrication methodologies, offering a unique perspective on the strengths and weaknesses of each approach. This facilitates a broader understanding of fingerprint recognition system validation and performance assessment. [ABSTRACT FROM AUTHOR]

An experimental investigation of the laser engraved process is carried out on.2.5 mm.thick acrylic Polymethyl Methacrylate (PMMA).using Carbon Dioxide,(CO2) laser. PMMA is a typical polymer.suitable for manufacturing microfluidic chips (Y shape). Fabrication parameters have an influence on the mechanical properties of the manufactured components. The effects of laser power (20, 40, and 60 W) and scanning speed (250, 350, and 500 mm /s) were evaluated on the microstructure and mechanical characteristics of microfluidic chips. With an increase in laser power and a decrease in scanning speed, the stacking of melt pools became more organized, pores were less visible, and mechanical characteristics improved. At a power density of 60 W and a speed of 250 mm/s, the best mechanical parameters were obtained, including a yield strength of 20.72 MPa, an ultimate tensile strength of 30.81 MPa, and an elongation of 1.163 percent. For the same laser energy density, however, change in laser power has a greater influence on the pore defect than variation in scanning speed. [ABSTRACT FROM AUTHOR]

Copyright of Coatings & Protection / Tuceng yu Fanghu is the property of Coating & Protection Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A perfluoropolyether (PFPE)-based microfluidic device with cross-junction microchannels was fabricated with the purpose of producing uniform droplets. The microchannels were developed using CO2 laser engraving. PFPE was chosen as the main material because of its excellent solvent resistance. Polyethylene glycol diacrylate (PEGDA) was mixed with PFPE to improve the hydrophilic properties of the inner surface of the microchannels. The microchannels of the polydimethylsiloxane microfluidic device had a blackened and rough surface after laser engraving. By contrast, the inner surface of the microchannels of the PFPE-PEGDA microfluidic device exhibited a smooth surface. The lower power and faster speed of the laser engraving resulted in the development of microchannels with smaller dimensions, less than 30 μm in depth. The PFPE and PFPE-PEGDA microfluidic devices were used to produce uniform water and oil droplets, respectively. We believe that such a PFPE-based microfluidic device with CO2-laser-engraved microchannels can be used as a microfluidic platform for applications in various fields, such as biological and chemical analysis, extraction, and synthesis. [ABSTRACT FROM AUTHOR]

Limited attention has been paid to repellency and wettability‐confined transport of low‐surface‐tension liquids, such as oils, alcohols, and hydrocarbons. This is because repellency becomes very difficult for fluids with surface tension below 30 mN m−1. This situation is encountered in many engineering applications using organic liquids and thus, oleophobic surfaces are of high technological importance. In this work, a nanocomposite coating comprising of fluorinated silica micro‐ and nanoparticles (filler), a copolymer (binder), and traces of fluorinated polyhedral oligomeric silsesquioxane (additive, lowest surface‐energy crystalline material reported to date) is spray‐deposited on a surface pretextured by laser etching, a technique that requires no lithographic processing. The approach results in surfaces that can repel liquid hydrocarbons with surface tension as low as 21.14 mN m−1 and also hinder the spreading of heptane (19.74 mN m−1) at room temperature. The repellency of several organic liquids with surface tensions in the range of 19.7 – 27 mN m−1 is experimentally investigated and compared with water (baseline case). To study the effect of fluid properties, comparisons are performed between the distances traveled and the velocities of microliter droplets transported pumplessly on wedge‐shaped wettability‐patterned tracks that confine the liquids by the superoleophobic background surrounding the wettable tracks. [ABSTRACT FROM AUTHOR]