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Oxygen concentration dependence of microstructure formed on Ni by backward pulsed laser deposition
摘要： In the automotive industry, direct joining between resin and metal without additional material is expected due to a growing need for hybrid structures composed of resin and metal. Roughening the metal surface before joining can improve the adhesion with the resin, and forming a microstructure on the metal surface by backward pulsed laser deposition could be a useful method. In the present study, we investigated the dependence of microstructure on the oxygen concentration in the ambient gas during surface processing for controlling the morphology of the microstructure. In the experiments, the oxygen concentration in the ambient gas composed of nitrogen and oxygen was controlled under atmospheric pressure, and microstructure characteristics, such as the shape and hardness, were analyzed. As a result, it was demonstrated that the formation range of the microstructure was constant regardless of the oxygen concentration, whereas a rougher microstructure was formed at higher oxygen concentrations, and a dense, flat microstructure was formed at lower oxygen concentrations. These results implied that the oxidation between the nanoparticles in the laser-induced plume and the ambient gas affects the mobility of the nanoparticles on the metal surface, leading to a transmutation in the morphology of the microstructure. Finally, it was shown that it is important to reduce the surface mobility of nanoparticles, such as processing under high oxygen concentration, to form a microstructure that improves adhesion.
关键词： Resin-metal joining,Backward pulsed laser deposition,Oxygen concentration,Microstructure,Nanosecond pulsed laser
更新于2025-09-23 15:21:01
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Using a nanosecond laser to pattern copper nanowire-based flexible electrodes: From simulation to practical application
摘要： Copper nanowire (Cu NW) electrodes have shown promise for use in next-generation transparent conducting films due to their high electrical conductivity, low-cost solution-based synthesis processes, and high transmittance properties. Recently, the use of lasers for the modification of nanostructures has received considerable attention. Despite the advantages of laser machining such as producing any shape in an accurate, time-saving, non-contact process, the laser patterning of Cu NW electrodes has not been extensively studied, particularly the heat effect of the laser irradiation process on the flexible substrate. In this report, we present experimental and computational results of a selective and direct patterning process by using nanosecond pulsed laser irradiation. The experimental and simulation results were used to optimize the laser ablation parameters for the patterning process of the ultra-long Cu NW transparent electrodes so as to not damage the flexible substrates. Finally, a bifunctional flexible smart-window was fabricated to demonstrate a practical application of the laser-patterned Cu NW electrodes.
关键词： Copper nanowires,Laser patterning,Flexible substrate,Nanosecond pulsed laser,Flexible smart-window
更新于2025-09-23 15:21:01
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Near-infrared nanosecond-pulsed laser-activated high efficient intracellular delivery mediated by nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles
摘要： Here, efficient intracellular delivery of molecules with high cell viability is reported using nanosecond-pulsed laser-activated plasmonic photoporation mediated by high-aspect-ratio nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles (nm-AuPNPs) at near-infrared wavelength. Upon laser illumination, nm-AuPNPs exhibit greater plasmonic extinction than spherical AuPNPs, which increase their energy efficiency and reduce the necessary illumination of light, effectively controlling cell damage and improving delivery efficiency. Nm-AuPNPs exhibit surface plasmon absorption at near infrared region with peak at 945 nm. Pulsed laser illumination at this plasmon peak triggers explosive nanobubbles, which create transient membrane pores, allowing the delivery of dyes, quantum dots and plasmids into the cells. The results can be tuned by laser fluence, exposure time, molecular size and concentration of nm-AuPNPs. The best results are found for CL1-0 cells, which yielded a 94% intracellular PI dye uptake and ~100% cell viability at 35 mJ/cm2 laser fluence for 945 nm wavelength. Thus, the presented approach has proven to have an inevitable potential for biological cell research and therapeutic applications.
关键词： near-infrared wavelength,intracellular delivery,nanosecond-pulsed laser,gold-coated polystyrene nanoparticles,plasmonic photoporation
更新于2025-09-23 15:21:01
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Selective laser ablation and patterning on Ag thin films with width and depth control
摘要： Silver (Ag) films were deposited on glass substrates by radio frequency (RF) magnetron sputtering and then ablated by a 532 nm nanosecond pulsed laser. The effects of laser fluence and defocusing amount on the width and depth of laser-ablated grooves on 100- and 600-nm-thick Ag films were systematically investigated under single- and multi-scan ablation. The results suggested that the Ag films could be successfully removed from the substrate owing to laser-induced thermoelastic force or vaporization. It was confirmed that laser fluence and defocusing amount played very important roles in controlling the width and depth of the laser-ablated grooves. In the present work, grooves with widths ranging from 53 to 196 μm and depths ranging from 56 to 196 nm were obtained on 100-nm-thick Ag films by single-scan laser ablation, and laser ablation or removal with controllable depths was realized on 600-nm-thick Ag films by adopting single- or multi-scan (i.e., scanning numbers of 1–6). Furthermore, square spiral Ag patterns were successfully obtained by single- and multi-scan laser ablation and showed good electrical conductivity in a simple circuit. This work may have great potential applications in various fields that demand width and depth control of laser ablation/removal.
关键词： Width and depth control,Laser ablation,Ag thin films,RF magnetron sputtering,Nanosecond pulsed laser
更新于2025-09-23 15:19:57
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Silicon nanoparticle generation and deposition on glass from waste silicon powder by nanosecond pulsed laser irradiation
摘要： Silicon nanoparticles can be used for fabricating electrodes in high-performance lithium ion batteries and other high value-added products. Currently, silicon nanoparticles are fabricated by pulsed laser irradiation of single-crystal silicon wafers in water. In this study, we proposed silicon nanoparticle generation by using a nanosecond pulsed laser to irradiate waste silicon powder which is disposed from wire-saw slicing processes of silicon ingots. The laser-induced nanoparticles were backward-transferred and deposited on a glass substrate. It was found that the morphology and amount of the deposited nanoparticles was strongly dependent on the distance between the glass substrate and the waste silicon powder target. Raman spectroscopy showed that the silicon nanoparticles were crystalline, and the average size was ~10 nm. The obtained silicon nanoparticles had high purity, as the diamond abrasives included in the waste silicon powder were removed through oxidation and vaporization during laser irradiation.
关键词： Raman spectroscopy,Silicon crystal,Waste silicon powder,Nanoparticle,Nanosecond pulsed laser
更新于2025-09-23 15:19:57
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Cancer cella??specific protein delivery by optoporation with lasera??irradiated gold nanorods
摘要： The delivery of macromolecules into living cells is challenging since in most cases molecules are endocytosed and remain in the endo-lysosomal pathway where they are degraded before reaching their target. Here, a method is presented to selectively improve cell membrane permeability by nanosecond laser irradiation of gold nanorods (GNRs) with visible or near-infrared irradiation in order to deliver proteins across the plasma membrane, avoiding the endo lysosomal pathway. GNRs were labelled with the anti-EGFR (epidermal growth factor receptor) antibody Erbitux to target human ovarian carcinoma cells OVCAR-3. Irradiation with nanosecond laser pulses at wavelengths of 532 nm or 730 nm is used for transient permeabilization of the cell membranes. As a result of the irradiation, the uptake of an anti-Ki-67 antibody was observed in about 50 % of the cells. The results of fluorescence lifetime imaging show that the GNR detached from the membrane after irradiation.
关键词： gold nanorods,optical window,protein delivery,near infrared radiation,nanosecond pulsed laser
更新于2025-09-23 15:19:57
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Study of the physicochemical surface alterations and incubation phenomena induced on iron targets by nanosecond pulsed laser ablation in liquids: Effect on productivity and characteristics of the synthesized nanoscale zero-valent iron (nZVI) particles
摘要： This work presents a systematic study of the significant role of the surface physicochemical alterations produced during the laser ablation of massive iron disks submerged in different solvents on the generation of colloidal iron nanoparticles. For that purpose, the laser ablation thresholds and the incubation coefficients for various pulse numbers per site and pulse energies have been measured under distilled water (DW) and ethanol (EtOH). After that, a complete physicochemical characterization of these targets indicated higher threshold fluence values for the ablation experiments conducted in EtOH than those performed in DW. The threshold fluence values decreased also with the decrease of the pulse overlap for both solvents, being it much more pronounced in EtOH. In addition, the related incubation coefficient showed that the incubation effect is lower for experiments conducted in DW. The characteristics of the synthesized nZVI particles were also a function of the solvent nature and the pulse overlap: laser ablation in DW leaded to iron oxide nanoparticles, whereas core-shell iron nanoparticles were obtained in EtOH. Moreover, high pulse overlap values lead to chemical alterations, resulting in a decrease of the composition homogeneity and a strong increase of the nanoparticle polydispersity.
关键词： Incubation effect,Nanosecond pulsed laser ablation in liquids,Raman spectroscopy,Colloidal nanoscale zero-valent iron particles,Laser ablation threshold,Laser induced-chemical surface alteration
更新于2025-09-19 17:13:59
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Coloring stability analysis of nanosecond pulsed laser induced surface coloring on stainless steel
摘要： In this paper, a nanosecond pulsed laser was used to induce the surface coloring of stainless steel. The effect of process parameters, including defocusing distance, scanning speed, scanning interval, repetition frequency and release time on color marking and coloring stability were studied. For objective evaluation of color changes, a hand-held colorimeter and the CIEL*a*b* color difference formula were used. Finally, the process parameters range of six colors was given when the stability requirement is satisfied. The effect of the above process parameters on the stability of surface coloring was also studied.
关键词： Process parameters,Nanosecond pulsed laser,Stability analysis,Surface coloring
更新于2025-09-16 10:30:52
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Nano-to-micro diamond formation by nanosecond pulsed laser annealing
摘要： Here, we report the synthesis and characterization of nano-, micro-, twinned, and lonsdaleite diamonds, which are formed after melting and quenching of amorphous carbon or Q-carbon essentially at room temperature and atmospheric pressure. These conversions depend on the degree of undercooling, which is controlled by the laser parameters and thermal conductivities of the amorphous carbon and the substrate. The laser melting and undercooling provide liquid-phase packing of atoms similar to high-pressure, which facilitate the conversion of amorphous carbon into diamond or Q-carbon without using any catalyst. By changing the nucleation and growth rates, we have synthesized a wide range of sizes (4 nm to 3 μm) of diamond crystals. The formation of twinned and lonsdaleite diamonds is controlled by the quenching rate. Therefore, we have created a “factory of diamonds” at ambient conditions by nanosecond laser annealing, which will pave the pathway to design high-speed mechanical and electrical devices.
关键词： diamond formation,nanosecond pulsed laser annealing,Q-carbon,nano-to-micro diamonds,undercooling
更新于2025-09-16 10:30:52
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Influence of Pulse Duration on Effective Energy on Material Removal in Micro-processing of Mild Steel by Several Hundred Nanoseconds Pulsed Laser
摘要： A little longer pulse duration more than several hundred nanoseconds is the middle region between ablation and melting removal of material, and effective removal of material can be expected. However, influence of these phenomena on material removal characteristics has not been clarified sufficiently. Therefore, influence of pulse duration and laser intensity on plasma was investigated by measurements of transmittance of laser energy through the plasma. Finally, effective energy to material removal characteristics was discussed with calculated laser energy relating to removal volume of mild steel as a commonly used steel by using several hundred nanoseconds pulsed laser. Transmittance ratio of laser energy was high at long pulse duration in several hundred nanoseconds range under the same pulse energy condition, because there was low reduction rate of laser energy by laser induced plasma. A little long pulse duration could perform efficient processing of mild steel under the same pulse energy condition by using several hundred nanoseconds pulsed laser.
关键词： plasma,removal volume,effective energy,pulse duration,nanosecond pulsed laser
更新于2025-09-16 10:30:52