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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 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]

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]

This work presents the optimization of the fabrication procedure for laser-induced graphene (LIG) electrodes intended for biopotentials acquisition. The results presented in this study demonstrate a significant improvement with respect to the performance obtained for other LIG-based electrodes previously reported in the literature. In particular, we propose the use of a galvanometric laser instead of a CNC laser to improve the engraving resolution and the LIG synthesis process, thus enhancing the surface area of the interface skin–electrode. For that, we have studied the resistance of the resulting LIG patterns as a function of the laser parameters (engraving power and scan speed) seeking their optimization. After tunning the laser fabrication process, we have fabricated and characterized electrocardiogram (ECG) electrodes with different surface areas using a commercial silver-based electrode as a reference. Thus, circular electrodes with a diameter of 15 mm, 10 mm and 6.5 mm were used to acquire the ECG on different volunteers using a commercial equipment. The signals acquired were processed afterwards with cutting edge processing techniques to perform a statistical analysis in terms of sensitivity, specificity, positive prediction and accuracy for the detection of QRS complexes. The results demonstrate that the proposed electrodes improve the signal acquisition with respect to the previously reported LIG-based electrodes in terms of noise and do present comparable or even better results than commercial electrodes (even with a smaller surface area) with the additional advantage of not requiring the use of an electrolyte gel. [ABSTRACT FROM AUTHOR]

By imitating the special microstructure of four typical biological surfaces, four types of texture on YT15 alloy steel surface are studied by laser etching, including V-shaped groove, U-shaped groove, rhombic pit and circular pit. The results show that textured surface can not only reduce friction and wear, but also improve hydrodynamic lubrication. Wear occurs due to abrasive and adhesive wear. The unidirectional convergence of groove structure is conducive to fluid flow and has good hydrodynamic lubrication characteristics, especially V-groove. The groove texture is suitable for high speed and medium to high load conditions. The pit texture provides stable hydrodynamic lubrication and optimal friction reduction and wear resistance, especially rhombic pits. Pit texture is suitable for high load conditions. Therefore, the change of texture shape and arrangement is of great significance to improve the tribological properties of workpiece surface under different working conditions, and has a certain research value. [ABSTRACT FROM AUTHOR]

The successful development of a dual-mode sensing chip for deoxynivalenol (DON) detection using photoelectrochemical (PEC) and electrochromic visualization techniques is reported. By laser etching technology, different functional areas, including the photoanode, the cathode, and the electrochromic area, are fabricated on indium tin oxide (ITO) glass. Then, these three areas are further respectively modified with PEC active materials, platinum nanoparticles, and Prussian blue. Under light illumination, photocurrents generate between the photoanode and the cathode due to the separation of photo-induced electrons and holes in the TiO2/3DNGH material. Meanwhile, the photo-induced electrons are transferred to Prussian blue on the visualization area, which will be reduced to colorless Prussian white. The binding of DON molecules and aptamers can promote electron transfer and reduce the recombination of electrons and holes, allowing for simultaneous quantitative detection of DON using either the photocurrent or color change. The sensor chip has a broad detection range of DON concentrations of 1 fg⋅mL−1 to 100 pg⋅mL−1 in the PEC mode with the limit of detection of 0.37 fg⋅mL−1, and 1 to 250 ng⋅mL−1 in the visualization mode with the limit of detection of 0.51 ng⋅mL−1. This portable dual-mode sensor chip can be used in both laboratory and field settings without the need for specialized instruments, making it a powerful tool for ensuring food safety. At the same time, the analysis of the standard addition method of the actual sample by using the sensor chip shows that, in the PEC mode, the recoveries of the dual-mode aptasensor chip were 91.3 to 99.0% with RSD values of 1.73~2.55%, and in visualization mode, the recoveries of the dual-mode aptasensor chip were 99.2 to 102.0% with RSD values of 1.00~6.21%, which indicate good accuracy and reproducibility. [ABSTRACT FROM AUTHOR]

In the machining of large size parts, one of the most important problems is the long processing time. Hence, it is very important to find new methods to save the processing time of the large part machining. This research presents the idea of a cooperative laser engraving system in which a work area is divided into multiple sections and the sections are distributed to multiple different laser heads. The different laser heads work on their given sections simultaneously and all finished works are integrated to complete a target geometry in a reduced amount of time compared to the traditional method of engraving by a single laser head. This research aims to study the feasibility of the new idea and adoptability of the idea for the industrial use. By adopting two laser heads and some basic algorithms developed in this research, the new cooperative engraving method was able to finish the engraving in about 73% of the time of the engraving by a single laser head and about 60% by further improving the machining algorithm. In terms of the energy consumption, all of the different algorithms using 2 laser heads consumed similar amount of energy of about 5 kWh whereas the engraving by a single laser head consumed about 3 kWh. The main findings of this research are that the new idea of area sectioning strategy could be very efficient and effective method for large part machining and the idea can be further developed for the realistic applications. Some issues arising from the cooperative machining system and future research topics are also discussed. [ABSTRACT FROM AUTHOR]

Counterfeit products pose significant economic, security, and health risks. One approach to mitigate these risks involves establishing product provenance by tracing them back to their manufacturing origins. However, current identification methods, such as barcodes and RFIDs, have limitations that make them vulnerable to counterfeiting. Similarly, nonvolatile memories, physically unclonable functions, and emerging techniques like Diamond Unclonable Security Tag and DNA fingerprinting also have their own limitations and challenges. For a traceability solution to gain widespread adoption, it must meet certain criteria, including being inexpensive, unique, immutable, easily readable, standardized, and unclonable. In this paper, we propose a solution that utilizes ultrashort pulsed lasers to create unique, unclonable, and immutable physical tags. These tags can then be read nondestructively using far-field Terahertz (THz) spectroscopy. The primary objective of this paper is to investigate the feasibility of our proposed approach. We aim to assess the ability to distinguish laser marks with varying depths, evaluate the sensitivity of THz reading to laser engraving parameters, examine the capacity to capture high-information-density marks, and explore the ability to capture subsurface tags. By addressing these aspects, our method holds the potential to serve as a universal solution for a wide range of traceability applications. [ABSTRACT FROM AUTHOR]

A new electrochemical device fabricated by the combination of 3D printing manufacturing and laser-generated graphene sensors is presented. Cell and electrodes were 3D printed by the fused deposition modeling (FDM) technique employing acrylonitrile butadiene styrene filament (insulating material that composes the cell) and conductive filament (lab-made filament based on graphite dispersed into polylactic acid matrix) to obtain reference and auxiliary electrodes. Infrared-laser engraved graphene, also reported as laser-induced graphene (LIG), was produced by laser conversion of a polyimide substrate, which was assembled in the 3D-printed electrochemical cell that enables the analysis of low volumes (50–2000 μL). XPS analysis revealed the formation of nitrogen-doped graphene multilayers that resulted in excellent electrochemical sensing properties toward the detection of atropine (ATR), a substance that was found in beverages to facilitate sexual assault and other criminal acts. Linear range between 5 and 35 μmol L−1, detection limit of 1 μmol L−1, and adequate precision (RSD = 4.7%, n = 10) were achieved using differential-pulse voltammetry. The method was successfully applied to beverage samples with recovery values ranging from 80 to 105%. Interference studies in the presence of species commonly found in beverages confirmed satisfactory selectivity for ATR sensing. The devices proposed are useful portable analytical tools for on-site applications in the forensic scenario. [ABSTRACT FROM AUTHOR]

Pool boiling heat transfer has numerous applications. This experiment investigates the effect of laser etching of polished copper and copper foam surfaces on pool boiling heat transfer of deionized water in this context. The laser-machined samples had the same width, depth, and different vertical microchannels. The results showed that when compared to the polish surface, the CHF and HTC both improved. At the same time, the laser etching copper foam surface had a much higher strengthening effect than the laser etching polish surface, and it performed better under low heat flux conditions. The CHF can be reinforced 3.71 times, while the HTC can be reinforced 5.28 times. The physical model of the same structure was also calculated with ANSYS, and the results were comparable to the experimental results. When compared to smooth or single structure surfaces, the composite structure demonstrated superior heat transfer performance of pool boiling. [ABSTRACT FROM AUTHOR]

A significant bottleneck exists for mass-production of ion-selective electrodes despite recent developments in manufacturing technologies. Here, we present a fully-automated system for large-scale production of ISEs. Three materials, including polyvinyl chloride, polyethylene terephthalate and polyimide, were used as substrates for fabricating ion-selective electrodes (ISEs) using stencil printing, screen-printing and laser engraving, respectively. We compared sensitivities of the ISEs to determine the best material for the fabrication process of the ISEs. The electrode surfaces were modified with various carbon nanomaterials including multi-walled carbon nanotubes, graphene, carbon black, and their mixed suspensions as the intermediate layer to enhance sensitivities of the electrodes. An automated 3D-printed robot was used for the drop-cast procedure during ISE fabrication to eliminate manual steps. The sensor array was optimized, and the detection limits were 10–5 M, 10–5 M and 10–4 M for detection of K+, Na+ and Ca2+ ions, respectively. The sensor array integrated with a portable wireless potentiometer was used to detect K+, Na+ and Ca2+ in real urine and simulated sweat samples and results obtained were in agreement with ICP-OES with good recoveries. The developed sensing platform offers low-cost detection of electrolytes for point-of-care applications. [ABSTRACT FROM AUTHOR]

Conventional glassy carbon electrodes (GCE) cannot meet the requirements of future electrodes for wider use due to low conductivity, high cost, non-portability, and lack of flexibility. Therefore, cost-effective and wearable electrode enabling rapid and versatile molecule detection is becoming important, especially with the ever-increasing demand for health monitoring and point-of-care diagnosis. Graphene is considered as an ideal electrode due to its excellent physicochemical properties. Here, we prepare graphene film with ultra-high conductivity and customize the 3-electrode system via a facile and highly controllable laser engraving approach. Benefiting from the ultra-high conductivity (5.65 × 105 Sm−1), the 3-electrode system can be used as multifunctional electrode for direct detection of dopamine (DA) and enzyme-based detection of glucose without further metal deposition. The dynamic ranges from 1–200 µM to 0.5–8.0 mM were observed for DA and glucose, respectively, with a limit of detection (LOD) of 0.6 µM and 0.41 mM. Overall, the excellent target detection capability caused by the ultra-high conductivity and ease modification of graphene films, together with their superb mechanical properties and ease of mass-produced, provides clear potential not only for replacing GCE for various electrochemical studies but also for the development of portable and highperformance electrochemical wearable medical devices. [ABSTRACT FROM AUTHOR]

The surface of the commercial CoCr28Mo alloy was textured using a 20W pulsed fiber laser according to different beam scan strategies. Surface roughness and drop contact angle measurements made on the textured surface were used to evaluate the effects of process parameters. The surface topography was highly affected by both scan direction and beam overlaps named pulse-to-pulse overlap and scan overlap. As the beam overlap ratio increased, the amount of heat transferred to the unit area also increased, which caused more metal to evaporate in the interaction zone and form a more considerable amount of molten and re-solidified metal layer, resulting in a chaotic texture formation on the surface. The mean surface roughness values of textured surfaces for eighteen test samples ranged from 1 to 7 μm. These surface roughness values were in the micro-scale roughness value range. According to the results of the drop contact angles, the surface topography significantly changed the wettability. The test results were also analyzed by the Taguchi method considering signal-to-noise ratios and evaluated by analysis of variance. Considering the highest S/N values for each parameter, the optimum parameters combination for the laser engraving process was 45°/-45° for scan direction, 70 % for power, 1000 mm/s for scan speed, 50 kHz for frequency, 0.01 mm for hatch distance, and 75 ns for pulse duration. [ABSTRACT FROM AUTHOR]

Organic solvents have been commonly used in the printing process for a long time in gravure printing applications. Using organic solvents in solvent-based ink is responsible for fire hazards, volatile organic compounds emission, and increasing extra printing costs. The current study aimed to replace solvent-based ink with water-based ink to reduce volatile organic compound emissions and carbon footprints in gravure printing without affecting overall printing quality in order to fill a research gap because none of the studies were reported as best of all authors' knowledge. The polyethylene terephthalate film was printed by laser engraved cylinder having reduced engraving cell depth compared to electronically engraved printing cylinders which result in less consumption of printing ink, hence reducing the raw materials consumption. The cost of printing one kg of polyethylene terephthalate film with water-based ink was reduced by 1.85US$, and volatile organic compounds emissions were reduced from 3373 ppm to 2478 ppm compared to solvent-based ink. The use of water-based ink also reduced the carbon footprint by 3.04 kg. The current study shows that strict implementation of water-based ink has a high potential for saving the cost and reducing the emission of volatile organic compounds, which are very dangerous to the ambient environment, humans, and society. This study's outcome will help prepare the benchmark for green manufacturing systems in gravure printing applications to improve the environment and humanity. [ABSTRACT FROM AUTHOR]

In this study, micro/nanostructures are fabricated on the surface of 3Cr13 stainless steel via laser etching, and a superhydrophobic coating with silver nanoparticles (AgNPs) is prepared by utilizing the reduction-adsorption properties of polydopamine (PDA). We investigate the effect of soaking time from the "one-step method" on the reduction of nano-Ag, surface wettability, and antibacterial properties. Scanning electron microscopy is performed to analyze the distribution of nano-Ag on the surface, whereas X-ray energy dispersive spectroscopy and X-ray photoelectron spectroscopy are used to analyze the crystal structures and chemical compositions of different surfaces. Samples deposited with PDA on their surface are soaked in a 1H,1H,2H,2H-perfluorodecyltriethoxysilane water-alcohol solution containing AgNO3 for 3 h. Subsequently, a "one-step method" is used to prepare low-adhesion superhydrophobic surfaces containing AgNPs. As immersion progresses, more AgNPs are deposited onto the surface. Compared with the polished surface, the samples prepared via the "one-step method" show significant antibacterial properties against both gram-negative Escherichia coli and gram-positive Staphylococcus aureus. The antibacterial properties of the surface improve as immersion progresses. [ABSTRACT FROM AUTHOR]

Stretchable electronics is playing an integral role in fields such as wearable electronics and soft robots. Among soft conductive materials, liquid metal is drawing intense attention as an electrode material due to its liquid nature at room temperature. However, the merits of liquid metal conductor are limited by the presence of substrates or enclosed microchannels from physical disturbances by the underlying substrate when applying it to 3D surface and modifying complex circuit. To overcome this limitation, we develop freestanding patterned liquid metal thin-film conductor (FS-GaIn). FS-GaIn was achieved by introducing metal nanowires to liquid metal and subsequent sequential selective laser processing and etching of directly patterned traces. FS-GaIn can be applied directly to nonflat surface without substrates. When incorporated into electrical circuits, FS-GaIn shows high electrical conductivity, stretchability, and stability. The concept of freestanding liquid metal can open a functionality to the conventional liquid metal electronics. [ABSTRACT FROM AUTHOR]

This paper presents the results of experiments on the laser plasma-chemical etching of diamond and sapphire in relation to the technological process of separating wafers into crystals with electronic devices formed on their surface with the topological design nanonorms. [ABSTRACT FROM AUTHOR]

The self-cleaning property of superhydrophobic surfaces is very useful for outdoor devices where dust accumulation is problematic. One of the novel methods to make a surface superhydrophobic is to engineer the surface with T-shaped or overhang structures, however, up-to-date preparation methods of such structures such as chemical etching or direct laser writing are usually costly, complicated and unscalable. Herein, we report a facile and scalable spraying method utilizing nano-silica to engineer overhang structure-based superhydrophobic coatings on UV curable polyurethane acrylate (PUA) micro-posts. By optimizing the spraying conditions, the overhang structures can be tunable so that an optimized T-shaped micro-post structure can be prepared in one step to achieve the desired superhydrophobicity and the transparency of the as-prepared film. The micropatterned PUA films were coated with nano-silica 1, 2, 3, and 4 times, with the 3-time coating yielding the best superhydrophobicity and transparency. This film shows a static contact angle (CA) of 150.7° ± 3.5° and a roll-off angle (RA) of 9° ± 1.8°. The as-fabricated film maintains its consistent superhydrophobicity after 60 days of outdoor exposure to sunlight. Moreover, its excellent mechanical properties are also proved by the water impacting and sandpaper abrasion tests. The fabrication technique is uncomplicated and scalable thereby showing the great potential of the film in applications of solar cells and other outdoor electronic devices protection. [ABSTRACT FROM AUTHOR]

Highlights: The split-ring topography is studied systematically from wettability, evaporation assembly to optoelectronic devices. An efficient dual-function laser etching scheme has been developed to fabricate the split-ring lyophilic pattern and the lateral electrode array simultaneously. A non-contact human-machine interface based on CsPbBr3 perovskite photodetector arrays has been successfully applied to wearable devices, automobile displays, robot remote control. Photodetectors with long detection distances and fast response are important media in constructing a non-contact human–machine interface for the Masterly Internet of Things (MIT). All-inorganic perovskites have excellent optoelectronic performance with high moisture and oxygen resistance, making them one of the promising candidates for high-performance photodetectors, but a simple, low-cost and reliable fabrication technology is urgently needed. Here, a dual-function laser etching method is developed to complete both the lyophilic split-ring structure and electrode patterning. This novel split-ring structure can capture the perovskite precursor droplet efficiently and achieve the uniform and compact deposition of CsPbBr3 films. Furthermore, our devices based on laterally conducting split-ring structured photodetectors possess outstanding performance, including the maximum responsivity of 1.44 × 105 mA W−1, a response time of 150 μs in 1.5 kHz and one-unit area < 4 × 10–2 mm2. Based on these split-ring photodetector arrays, we realized three-dimensional gesture detection with up to 100 mm distance detection and up to 600 mm s−1 speed detection, for low-cost, integrative, and non-contact human–machine interfaces. Finally, we applied this MIT to wearable and flexible digital gesture recognition watch panel, safe and comfortable central controller integrated on the car screen, and remote control of the robot, demonstrating the broad potential applications. [ABSTRACT FROM AUTHOR]

The method of two-stage formation of hollow channels in glass by direct laser writing and subsequent selective etching is profitably used in the manufacture of microfluidics devices. In the present work, the influence of the concentration of the etching solution, the velocity of the laser beam, and the energy of laser pulses on the etching rate, selectivity, and roughness of hollow channels in quartz glass were investigated. For hollow channels, an etching rate 300 μm/h can be achieved together with very high selectivity (680) by using a 1M NaOH solution. [ABSTRACT FROM AUTHOR]

The first results of studying the electric explosion of thin aluminum foils of different thickness with an artificial relief created by laser engraving are described. The experiments were conducted on a BIN high-current pulsed generator (270 kA, 300 kV, 100 ns). Images of exploded foils placed in a returned current circuit (amplitude 80 kA) were obtained by X-ray projection radiography in the radiation of a hybrid X-pinch which was the main load of the generator. The influence of artificial relief on the resulting picture of the explosion is studied in foils both with a pronounced own structure and without it. It is shown that an artificial structure in the form of grooves perpendicular to the foil's own structure and parallel to the current can substantially slow down the development of instabilities in the exploded foil. [ABSTRACT FROM AUTHOR]

The super-hydrophobic microstructures were fabricated on the surface of AZ91 magnesium alloy by laser–chemical composite etching and stearic acid modification. The results show that the special concave and convex structures and grooves arranged in micro-scale were formed on the surface of specimens after laser etching. The sharpened grid grooves and rice-husk-like structures were constructed on the surface after CuCl2 solution etching. After laser–chemical composite etching and stearic acid modification, the surface presents good super-hydrophobicity and low adhesion with the water contact angle of 158.4°. Moreover, water droplets can easily roll off the surface of super-hydrophobic samples and carry contaminants along the rolling path. The corrosion resistance test shows that the magnesium alloy with super-hydrophobic structure has higher self-corrosion potential, lower self-corrosion current density and significantly higher impedance, indicating that it has good corrosion resistance. [ABSTRACT FROM AUTHOR]

The aim of this paper is to determine the effect of aluminium surface preparation on the load-bearing capacity of laser-joined aluminium–polypropylene (Al-PP) specimens. The surface of the aluminium is prepared by chemical cleaning and laser engraving. The effect of pulse frequency, engraving speed and repetition number during laser engraving is investigated on the geometric parameters of the structure (straight groove) created on the surface of AA6082 aluminium alloy. Quasi-static shear testing of Al-PP joints is performed to determine how the amount and distance of the grooves affect the load-bearing capacity of the joints. The highest ultimate shear force (1250 ± 35 N) was achieved when many (21) grooves were formed with a laser engraving frequency of 20 kHz, a slow engraving speed (5 mm s−1) and many engraving repetitions (10) in the aluminium specimen. This corresponds to a shear strength of 3.1 MPa, which is 72.5% of the shear strength of the PP material used. Microscopic evaluation of joint cross-sections confirmed that the molten PP completely filled the grooves on the aluminium surface. [ABSTRACT FROM AUTHOR]

In this work we present a facile method for the fabrication of several capacitive transduction electrodes for sensing applications. To prepare the electrodes, line widths up to 300 μ m were produced on polymethyl methacrylate (PMMA) substrate using a common workshop laser engraving machine. The geometries prepared with the laser ablation process were characterised by optical microscopy for consistency and accuracy. Later, the geometries were coated with functional polymer porous cellulose decorated sensing layer for humidity sensing. The resulting sensors were tested at various relative humidity (RH) levels. In general, good sensing response was produced by the sensors with sensitivities ranging from 0.13 to 2.37 pF/%RH. In ambient conditions the response time of 10 s was noticed for all the fabricated sensors. Moreover, experimental results show that the sensitivity of the fabricated sensors depends highly on the geometry and by changing the electrode geometry sensitivity increases up to 5 times can be achieved with the same sensing layer. The simplicity of the fabrication process and higher sensitivity resulting from the electrode designs is expected to enable the application of the proposed electrodes not only in air quality sensors but also in many other areas such as touch or tactile sensors. [ABSTRACT FROM AUTHOR]

A photoelectrochemical (PEC) biosensor based on a multiple signal amplification strategy was established for highly sensitive detection of microRNA (miRNA). TiO2 was prepared on the surface of titanium sheet by laser etching to improve its stability and photoelectrical properties, and CuInS2-sensitized TiO2 was used to form a superior photoelectrical layer, which realized the initial signal amplification. The electron donor dopamine (DA) was modified to H2 as a signal regulator, which effectively increased the photocurrent signal. To further amplify the signal, an enzyme-free hybridization reaction was implemented. When target let-7a and fuel-DNA (F-DNA) were present, the base of H1 specifically recognized let-7a and forced dopamine@AuNPs-H2 away from the electrode surface. Subsequently, the end base of H1 specifically recognized F-DNA, and let-7a was replaced and recycled to participate in the next cycle. Enzyme-free circulation, as a multifunctional amplification method, ensured the recycling of target molecules. This PEC sensor for let-7a detection showed an excellent linear response from 0.5 to 1000 pM with a detection limit of 0.12 pM. The intra-batch RSD was 3.8% and the recovery was 87.74–108.1%. The sensor was further used for clinical biomolecular monitoring of miRNA, showing excellent quantitative detection capability. [ABSTRACT FROM AUTHOR]

Abtract: In recent years, the development boom of the triboelectric nanogenerator (TENG) has attracted the attention of many researchers. Compared with the research on the surface structure and chemical modification of the friction layer, the improvement of the spatial structure of the friction layer has a profound impact on triboelectricity. This study uses laser etching technology to design the friction layer of TENG as a micro-pillar array, which increases its friction area. This structure is also conducive to the rapid contact and separation of the friction layer. Through the test, the open-circuit voltage Voc and short-circuit current the amplitudes of Isc are as high as 49 V and 1.008 μA, respectively; and the output power of this TENG device is 56.82 μw, the output signal of 5000 s is repeatedly tested and has good stability and consistency. In terms of practical application: The device charges 1.1, 3.3, 4.7 and 10 μF capacitors for 100 s and can store voltage values of 3.92, 2.06, 1.82 and 1.35 V. At the same time, TENG can collect the mechanical energy of human movement, showing great potential in wearable electronic devices and other fields. [ABSTRACT FROM AUTHOR]

Quantitative mass spectrometric analysis of small-volume samples (e.g., < 1 μL) has been a challenge mainly due to the difficulties with sample handling and its injection into the system for analysis. Herein we report a microfluidic analytical platform coupling a droplet generator with conventional electrospray ionization–mass spectrometry (ESI–MS) that enables multiple analyses of a μL-sized sample with sensitivity and repeatability. In an analysis by droplet generator–assisted ESI–MS (DG-ESI–MS), a sample of μL volume is pulled into a sampling capillary and its equal nL-sized portions are generated by a droplet generator and analyzed by ESI–MS at time intervals of choice. The droplet generator is made of PMMA sheets by laser engraving conveniently and at a low cost. In a study to achieve effective ESI–MS detection of water-in-oil droplets, it's found that the problem of MS signal suppression by oil can be solved by using an appropriate organic carrier with ESI-enhancing additives. The proposed DG-ESI–MS method has linear calibration curves for both adenine and phenylalanine with LODs at the sub-μM level. Application of the present analytical platform for monitoring substrate concentration changes in an enzymatic reaction solution of 3 μL is demonstrated. [ABSTRACT FROM AUTHOR]

Recent increasing interest in light guide plates (LGPs) based on the advanced manufacturing towards optoelectronics applications has emerged as a potential technology. The aim of this study was to estimate the optical characteristics on practical verification of laser-engraved glass light guide plate with concave microstructures. The case study can use the industrial ability of picosecond laser (pico-laser) technique, a type of ultrafast laser pulses, to directly engrave a glass sheet (Corning Iris® Glass) with functional concave microstructures for fabricating an LGP. Eight small pieces of samples with array of microstructures engraved on different processing conditions were made for measuring optical characteristics before and after the samples were etched by hydrofluoric acid. Here, the engraved 6-inch LGP structures can make light exit from the LGP uniformly. Additionally, the two optimized LGPs were put in a 7.8-inch backlight module where the measured results showed the uniformity of spatial luminance was 0.9. The study demonstrated the one-step process utilizing pico-laser technique, yielding for the design of microstructures of thinner large-sized liquid crystal display (LCD) products in the manufacturing of LGPs for lighted-up in a backlight unit (BLU). [ABSTRACT FROM AUTHOR]

For the last few years, due to the importance of superhydrophobic metal surface and its practical applications, it has attracted wide attention. Laser-induced superhydrophobic metal surface correspondence is one of the more intriguing processes being researched. However, it is still a challenge to shorten the time of wettability transition (from superhydrophilic to superhydrophobic). In this paper, the superhydrophobic surface with controllable adhesion was obtained by nanosecond laser etching and heat treatment of the aluminum plates. The impact of heat treatment temperature and time on the surface wettability of a laser-ablated aluminum plate was studied. It was found that heat treatment can promote the surface conversion from superhydrophilic to superhydrophobic and shorten the conversion time. It can also be observed that when the temperature increases from 100°C to 200°C, the time required for corresponding wettability transformation will be less, and the optimal process parameters are a heating temperature of 150°C and heating time is 1.5h. This study provides a simple and efficient way for preparation of superhydrophobic surfaces on metal, which should help with the commercialization of superhydrophobic surfaces. [ABSTRACT FROM AUTHOR]

Laser processing results in modified mechanical properties and microstructural evolution due to high temperatures and fast cooling rates. Different laser surface treatment techniques are under investigation for their potential to alter local microstructure and properties while maintaining properties of the bulk material. Fatigue life of laser-engraved powder metallurgy steel is shown to be significantly reduced compared to as-sintered material, suggesting a degree of microstructural modification with engraving. The misorientation, dislocation density, and phase of samples engraved with a 2D matrix pattern using one laser pass and five laser passes are characterized using optical microscopy and SEM-EBSD, and a CFD simulation of the laser process quantifies the temperature profile of each laser engraving. Deep-engraved samples are seen to result in a possible martensitic transformation at the surface of the engraved region because of increased time at elevated temperature and extreme cooling rates. These findings reinforce the importance of understanding microstructural evolution during precision tailoring via laser surface modification. [ABSTRACT FROM AUTHOR]

In this paper, linear micro textures that parallel to the sawtooth edge were fabricated on the surface of the high-speed steel W6Mo5Cr4V2 circular saw blade by laser engraving. Furthermore, cutting performance of micro textured circular saw blade (TCS) and traditional circular saw blade (CS), including sawing arc length, sawing force, sawing temperature, machined surface roughness, and wear mechanism, were investigated in sawing 304 stainless steel pipes under the cutting fluid condition. Results showed that the largest sawing arc length and sawing force were occurred on the circular saw blade sawing outward from the inner wall. In addition, TCS exhibited better cutting performance mainly due to the following two aspects, on the one hand, the effective sawtooth-chip contact length was reduced due to the micro textures fabricated on the sawtooth surface; on the other hand, cutting fluid can be better penetrated into the micro textures and formed stable lubrication film in sawtooth-chip contact interface. [ABSTRACT FROM AUTHOR]

Micro-pyramid functional surfaces are currently widely used in various advanced scientific, technological, industrial, and engineering fields with their excellent performances of compactness, light weight and higher heat transfer performance. Many recent studies have introduced micro cutting as a method to achieve high-quality micro pyramid surfaces. This paper concerns a micro-pyramid with a height and slope of 60 μm and 30°. Firstly, numerical simulation of the optical effect related to micro-pyramid surfaces was carried out to reveal the mechanism of functional surface imaging and its typical and potential applications. The simulated optical effect shows that the micro-pyramid can form four virtual images on the same side of an object. Next, a novel and simple fabrication method for micro-pyramidal structures was developed by using cross cutting with a 120° V-tip diamond tool by ultra-precision raster milling (UPRM), which can obtain good surface quality, high form accuracy and efficient productivity in contrast to grinding, laser machining and etching. Finally, precision injection molding was employed to replicate a micro-pyramid on the PMMA for optical testing. Although the quality of molded micro pyramid pattern decreased, optical testing showed that clear images were obtained, and the experimental results were consistent with the simulation results. [ABSTRACT FROM AUTHOR]

Laser engraving is an essential tool of automatic drawings and 3D printers. When the laser engraving tasks become large and complicated, engraving process will be time-consuming. To improve the time and energy efficiency, the trajectory optimization of laser engraving is studied. The trajectory of laser engraving robot is modelled as a large-scale traveling salesman problem (TSP), by converting grayscale images into halftone images. To solve the large-scale TSP, two-layered ant colony system (ACS) is newly proposed to combine k-means, top-layer ACS, and bottom-layer ACS. Finally, we use the presented algorithm to optimize the path of four engraving instances which include tens of thousands of discrete points. Experimental results show that this method can reduce laser engraving time by about 50% compared with traditional engraving methods. [ABSTRACT FROM AUTHOR]

The rapid development of wearable and portable electronics has resulted in an urgent desire for lightweight, flexible microsystems integrated with energy storage devices and other in-plane devices. An approach is proposed herein to develop an in-plane flexible microsystem on graphite paper containing an all-solid-state microsupercapacitor and a photoconductor-type photodetector based on perovskite film, where a simple, low-cost, and scalable strategy involving laser etching, electrochemical exfoliation, and electrochemical deposition can be used to fabricate the all-solid-state microsupercapacitor. The as-fabricated microsupercapacitor device exhibits high capacitance and reliable stability under testing through 100,000 cycles of dynamic bending. In the integrated microsystem, the microsupercapacitor is used to drive the photoconductive detector. It turns out that the designed integrated system exhibits a stable photocurrent response comparable to a detector driven by an external power source. This work paves the way for the fabrication of integrated microsystems where sensor systems are driven by integrated energy storage devices, applicable to future wearable and portable electronics. [ABSTRACT FROM AUTHOR]

Preparation and property optimization of silver (Ag)-embedded fluorine-doped tin oxide (FTO) films were achieved based on laser etching, sputtering Ag layers, furnace annealing, sputtering aluminum-doped zinc oxide (AZO) layers and laser annealing. Specifically, a nanosecond pulsed laser (λ = 532 nm) was used to etch grooves on FTO films before sputtering 5-nm-thick Ag layers, with an aim for enabling the Ag nanoparticles from the furnace-annealed Ag layers to be intensively embedded in the grooves under the thermal-induced dewetting effect. The optimal laser fluence for laser etching and temperature for furnace annealing were found to be 0.4 J/cm2 and 300 °C, respectively. The as-obtained Ag-embedded FTO film exhibited significantly improved optical and electrical properties, being attributed mainly to the decreased coverage area of the Ag nanoparticles on the FTO film surface and the furnace annealing effect. The subsequently sputtered 10-nm-thick AZO layer suppressed the internal light reflection from the Ag nanoparticles, and laser annealing further facilitated grain growth in the film. Therefore, the resulting film had the best comprehensive property with the highest figure of merit of 20.94 × 10–3 Ω–1, which was much higher than that of the original FTO film (7.65 × 10–3 Ω–1). This work may provide a new combined processing method for high-performance transparent conductive films. [ABSTRACT FROM AUTHOR]

A microcapillary grooved paper-based analytical device capable of dual-mode sensing (colorimetric and electrochemical detection) was demonstrated for analysis of viscous samples (e.g., human saliva). Herein, a hollow capillary channel was constructed via laser engraved micropatterning functions as a micropump to facilitate viscous fluidic transport, which would otherwise impede analysis on paper devices. Using salivary thiocyanate as a model analyte, the proposed device was found to exhibit a promising sensing ability on paper devices without the need for sample pretreatment or bulky instrumentation, as normally required in conventional methods used for saliva analysis. An extensive linear dynamic range covering detection of salivary thiocyanate for both high and trace level regimes (5 orders of magnitude working range) was collectively achieved using the dual-sensing modes. Under optimal conditions, the limit of detection was 6 μmol L−1 with a RSD of less than 5%. An excellent stability for the μpumpPAD was also observed for over 30 days. Real sample analysis using the proposed device was found to be in line with the standard chromatographic method. Benefitting from simple fabrication and operation, portability, disposability, low sample volume (20 μL), and low cost (< 1 USD), the μpumpPAD is an exceptional alternative tool for the detection of various biomarkers in saliva specimens. [ABSTRACT FROM AUTHOR]

The aim was to evaluate the optical changes of bleached human dentin and the efficacy of Er,Cr:YSGG laser on micro-shear bond strength (μSBS) of two adhesive systems for immediate and delayed applications. Seventy-two human dentin specimens (1 mm) were obtained. Colour measurements of 30 specimens (control and bleaching groups) were made at baseline, after bleaching and a 7-day delay. Differences at colour (ΔE00), translucency (ΔTP00) and whiteness (ΔWID) were calculated by recorded data. Forty-two specimens were used to compare μSBS of a self-etch (Clearfil SE Bond [SE]) and an etch-and-rinse (Prime&Bond NT [PBNT]) adhesive to bleached dentin. Additional to a negative group, six groups were contemplated for each adhesive, considering the time of composite application (immediate, delayed) and whether additional surface treatment by laser (1 W, 2 W) or not. Colour and μSBS data were statistically analysed. For optical analysis, only ΔE00 and ΔWID calculated for the difference between baseline and bleaching were found significantly different for control and bleaching groups. Whiteness of bleached specimens was remarkably decreased after a 7-day delay. Despite immediate applications of SE showing lower μSBS than negative control, delayed applications showed no significant differences except that of the 2 W laser etching. For PBNT, laser etching increased μSBS for both of the immediate and delayed applications, and no significant difference was observed from negative control. Related with the preferred adhesive system, Er,Cr:YSGG laser etching can be an alternative for optimal bond strength of immediate restorations, but the clinicians should always keep in mind that perceived colour and whiteness will change by the passing time which can affect the shade match. [ABSTRACT FROM AUTHOR]

We describe microfluidic fabrication results achieved using a 10.6 μm CO2 engraving laser on cast PMMA, in both raster and vector mode, with a 1.5″ lens and a High Power Density Focussing Optics lens. Raster written channels show a flatter base and are more U-shaped, while vector written channels are V shaped. Cross-sectional images, and, where possible, stylus profilometry results are presented. The sides of V-grooves become increasing steep with laser power, but broader shallower channels may be produced in vector mode by laser defocus, as illustrated. Smoothing of raster engraved channels by heated IPA etch, and transparency enhancement by CHCl3 vapour treatment are briefly discussed. An asymmetric Y meter is discussed as one method of diluting acid into seawater for dissolved CO2 analysis. Alternatively, microfluidic snake channel restrictors of different lengths in 2 channels may achieve the same result. Samples are fabricated with bases bonded by CHCl3 vapour treatment, and the devices are flow tested with either dilute food dye or DI water. Microfluidics fabricated in this manner have applications in ocean sensing of dissolved CO2 and other analytes, as well as broader sensing measurements, including biomedical sensors. [ABSTRACT FROM AUTHOR]

In the current study, the Si nano column layer via pulsed photo chemical etching with different laser pulse duty cycle 30 and 60% using short laser wavelength (405 nm) and laser intensity (100 mW/cm2) was formed and studied. Two types of Si nano column-based plasmonic Au-NP hot spot layers were synthesized and examined successfully as an efficient SERS layer for the detection of the ultra-low concentration of amoxicillin. Si nano columns exposed a great effect on the performance of the Au-NP hot spot SERS sensor showing a strong dependence on the density of the hot spot gaps within the sensitive layer. Enhancement factor (EF) of the Raman signal improved considerably with increasing the density of the hot spot gaps due to the coupling efficiency among the plasmonic Au-NPs and the molecules of amoxicillin within the hot spot regions. EF increased by about four orders of magnitude with decreasing the laser duty cycles due to the increase of the integrated plasmonic Au-NPs into the Si nano column layer. [ABSTRACT FROM AUTHOR]

Ultrahigh-precision machining of glass is indispensable for optical component fabrication and therefore for applications. In this regard, plasma jet assisted chemical etching technologies enable new fabrication processes for enhanced optical functionalities due to their deterministic localized machining capabilities. This technique has been successfully applied to fused silica and silicon. However, applications require specific glass properties are related to complex material compositions of the glass. Hence, reactive plasma etching of these optical glasses is a challenging task. For instance, etching of metal oxide containing glass like N-BK7 by a fluorine-based reactive atmospheric plasma jet (RAPJ) exhibits currently limitations due to the formation of non-volatile reaction products that remain on the glass surface as a layer. Therefore, a procedure consisting of RAPJ etching and laser ablation is proposed for the machining of N-BK7. The capability of laser-based removal of residual layers is compared to water-based solving of the residual layer. After RAPJ etching of N-BK7 using a CF4–O2 gas mixture with an average microwave power of 16 W, the samples are cleaned either by a water-based solvent or by the ablation with a nanosecond-pulsed ultraviolet laser. The laser irradiation with fluences of 2.8 J/cm2 results in a localized removal of the residual layer. It is demonstrated that the roughness of the laser-cleaned N-BK7 surface is similarly low as solvent-based cleaned samples but the pulsed laser enhanced cleaning allows a dry processing at atmospheric pressure as well as a localized processing with a high lateral resolution. [ABSTRACT FROM AUTHOR]

Glass has many attractive properties including transparency, durability, low electrical conductivity, and corrosion resistance, but its brittleness still limits the range of its applications. Three-dimensional laser engraving has been explored to generate three-dimensional (3D) networks of weak interfaces within the bulk of glass. These interfaces deflect cracks and dissipate energy by friction, with mechanisms that are similar to fracture in mollusk shells or teeth. Confocal microscopy was used to characterize the morphology of laser-induced microcracks in borosilicate glass and ceramic glass, and the effective toughness of laser-engraved interfaces was measured. The effect of microcrack spacing on interface morphology, damage parameter, fracture surface, and fracture toughness was explored. Architectured borosilicate glass panels based on a simple grid pattern were then fabricated. These all-brittle panels do not require mechanical confinement and can absorb significantly more impact energy than monolithic glass provided that the interface toughness is tuned properly. [ABSTRACT FROM AUTHOR]

Materials with dense architectures are composed of stiff and strong building blocks that are arranged to interact through energy-dissipative interfaces. Examples of these materials include engineered constructions such as the Abeille vault and highly mineralized natural materials such as tooth enamel. Compared with synthetic materials, natural materials with dense architectures exhibit outstanding mechanical performance, serving as a continued source of inspiration and study. This review details the status of advances in the fabrication and mechanics of bioinspired materials with dense architectures. The fabrication methods include freeze-casting, mineralization, 3D printing, coating–assembling, and laser engraving. Micromechanics of the resulting materials are discussed in tension, flexion, fracture, puncture, and impact. The discussion shows that strength of these materials can be improved by decreasing the size of their building blocks to the nm–µm range. However, interface hardening mechanisms that are crucial to the spread of deformation and toughness have not yet been implemented at nm–μm scales although they have been successfully realized for materials with larger building blocks. Future directions to address this and other unmet challenges are discussed throughout the text. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the use of the Er,Cr:YSGG laser with the use of adhesive-removing pliers for removing remnant adhesive from the enamel surface. A total of 54 sound premolars were divided into two groups of 27. Each group was assigned one of two adhesive removal systems: the Er,Cr:YSGG laser, and adhesive-removing pliers. Shear bond strength was measured 24 h after bracket bonding, with the bracket bonding/debonding and residual adhesive removal procedures repeated twice after the first adhesive removal. Before the first bonding and after each adhesive removal procedure, the average surface roughness (Ra) of each tooth was measured. Additionally, 14 of the premolars were examined under a scanning electron microscope. There were no significant differences in the shear bond strength between the two removal systems or between the three debonding sequences. There were significant differences in the enamel surface roughness after each removal sequence between the adhesive removal systems, and a significant increase in the enamel surface roughness was noted in each group with successive removal sequences. The scanning electron microscope images revealed evaporation of the primer and adhesive on the enamel surface and laser etching of enamel in the laser removal group, and the remnants of primer and adhesive on the enamel surface after each removal sequence in the plier removal group. The Er,Cr:YSGG laser was useful for removing remnant adhesive from the enamel surface for bracket rebonding. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of Er:YAG etching on topography, microstructure, compressive strength, and shear bond strength (SBS) of All-Bond Universal adhesive to mineral trioxide aggregate-Angelus (AMTA) and Biodentine (BD). Methods and materials: Sixty cylindrical specimens of each cement (AMTA and BD) in five groups were prepared and stored for 72 h. The control groups were non-etched, and four other groups were acid-etched and laser-etched with a pulse energy of 60, 80, or 100 mJ, followed by compressive strength testing. Surface micromorphology and topography were evaluated. Similar groups were bonded using All-Bond Universal with self-etch and etch-and-rinse (acid-etch) approaches, and laser-etch 60, 80, and 100 mJ, and SBS was tested. Data were analyzed using two-way and one-way ANOVA and the Bonferroni post hoc tests (α = 0.05). Results: BD had a significantly higher compressive strength and SBS (except for laser-etch 100) compared to AMTA, regardless of the etching method (p < 0.001). Acid etching and laser etching 100 of both cements and laser etching 80 of BD alone produced a significantly lower compressive strength than that for the other groups. Contrary to BD, for AMTA, all the treatments significantly increased SBS compared to that of the self-etch group. Conclusions: Etching of AMTA was needed for stronger bonding; laser etching with 60 or 80 mJ without compromising compressive strength was recommended. Etching not only did not improve bonding ability of BD, but it also negatively affected the strength of BD. Clinical relevance: To achieve successful combined calcium silicate cement-resin material restoration, an adequate bond between the materials is mandatory. This might be provided with the ultramild adhesive through laser etching without compromising compressive strength, depending on cement composition and laser energy level used. [ABSTRACT FROM AUTHOR]

Highlights: The laser-engraved method was introduced to fabricate the electrode for the sensor. The sensor showed a wide linear working range, superior sensitivity, and fast response time and also exhibited excellent viability in a wet situation. Wireless integrated network sensors successfully monitored the health states. Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things (IoT) infrastructures. For flexible piezoresistive sensors, traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range, and it, however, remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region (> 100 kPa) and keep a reliable sensitivity. Herein, we devised a laser-engraved silver-coated fabric as “soft” sensor electrode material to markedly advance the flexible sensor’s linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa−1 yet a fast response time of only 4 ms as well as long-time durability, which was rarely reported before. The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone, further demonstrating its potential as a reliable electronic. Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor’s performance, we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future. [ABSTRACT FROM AUTHOR]

In this paper, a 3D simulation model for nanosecond pulsed laser engraving process is developed, using the finite element method (FEM) aiming at the prediction of the final geometry of the workpiece and optimizing the process. A general heat transfer model is adapted where the incidence laser beam causing the material ablation is modeled using a Gaussian surface heat source, taking into account the interaction between the laser beam, the workpiece material, and the generated metal-vapor plasma. To validate the simulation model, a large set of experiments was performed for the purpose of comparing the experimental with the simulation results. The experiments were conducted on stainless steel and a pressure vessel steel plate using the DMG MORI Lasertec 40 machine for various combinations of the three machining process parameters: average power, repetition rate, and scanning speed. The experimental results positively validated the simulation model. Τhe numerical results were examined and some conclusions were drawn about the effect of the machining parameters on the laser engraving process. [ABSTRACT FROM AUTHOR]

Investigation of a polished surface of germanium single crystals scanned with a focused beam of pulse-frequency modulated UV radiation of Nd:YAG laser showed evidence of laser-induced surface etching at subthreshold energy densities (E ∼ 0.5–1.15 J/cm2) in the absence of noticeable traces of crater formation. It is suggested that the ablation centers nucleate on dislocations escaping at the surface of germanium crystals. [ABSTRACT FROM AUTHOR]