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Repulsive magnetic field–assisted laser-induced plasma micromachining for high-quality microfabrication
摘要： Surface micro-/nanostructures are widely used in the fabrication of various functional microsystems. Laser-induced plasma micromachining can greatly improve surface quality in terms of recast layers and thermal defects compared with laser direct writing. Magnetic field has the ability to constrain plasma diffusion and can ensure the stability of laser-induced plasma processing. This paper compares the effects of laser direct–writing processing and laser-induced plasma processing of single-crystal silicon at the micro-/nanoscale, and emphatically analyzes the material removal mechanism of repulsive magnetic field–assisted laser-induced plasma micromachining. It is shown that the volume of the laser-induced plasma was constrained under the influence of Lorentz force, a high-quality smooth microgroove without thermal defects was obtained, and its line width was reduced by 30%.
关键词： Laser-induced plasma micromachining,Magnetic confinement,Thermal defects,Micro-/nanofabrication
更新于2025-11-21 11:24:58
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Micropatterning MoS2/Polyamide Electrospun Nanofibrous Membranes Using Femtosecond Laser Pulses
摘要： The capability of modifying and patterning the surface of polymer and composite materials is of high significance for various biomedical and electronics applications. For example, the use of femtosecond (fs) laser ablation for micropatterning electrospun nanofiber scaffolds can be successfully employed to fabricate complex polymeric biomedical devices, including scaffolds. Here we investigated fs-laser ablation as a flexible and convenient method for micropatterning polyamide (PA6) electrospun nanofibers that were modified with molybdenum disulfide (MoS2). We studied the influence of the laser pulse energy and scanning speed on the topography of electrospun composite nanofibers, as well as the irradiated areas via scanning electron microscopy and spectroscopic techniques. The results showed that using the optimal fs-laser parameters, micropores were formed on the electrospun nanofibrous membranes with size scale control, while the nature of the nanofibers was preserved. MoS2-modified PA6 nanofibrous membranes showed good photoluminescence properties, even after fs-laser microstructuring. The results presented here demonstrated potential application in optoelectronic devices. In addition, the application of this technique has a great deal of potential in the biomedical field, such as in tissue engineering.
关键词： femtosecond laser,micromachining,composite nanofibers,electrospinning,MoS2
更新于2025-11-21 11:08:12
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Microstructure and Characteristic of Biomedical Titanium Alloy Based on Picosecond Laser Micromachining
摘要： Laser micromachining has become a hotspot in recent years due to its high precision, non-contact and adjustable parameter. In this paper, TC4 titanium alloy implant samples were conducted to obtain specific surface textures through picosecond laser. The laser parameters which directly influenced the microstructure and characteristic of surface textures were optimized within the context of laser power, scanning speed and scanning number via response surface methodology. The microstructure was evaluated using scanning electron microscope (SEM) while the feature size of the surface textures was measured through surface 3D profiler. In addition, endothelial cell culture was conducted to investigate the biofunctionalization of samples with specific surface textures. It demonstrated that well-structured textures played an important role in promoting cell adhesion and proliferation for titanium alloy implants.
关键词： Picosecond laser micromachining,Microstructure,Biofunctionalization,Titanium alloy
更新于2025-09-23 15:22:29
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Live E. coli bacteria label-free sensing using a microcavity in-line Mach-Zehnder interferometer
摘要： The paper presents the first study to date on selective label-free biosensing with a microcavity in-line Mach-Zehnder interferometer induced in an optical fiber. The sensing structures were fabricated in a single-mode fiber by femtosecond laser micromachining. In contrast to other studies of this sensing scheme, where only the sensitivity to refractive index changes in the cavity was investigated, this research used chemical surface treatment of the sensor to ensure detection specificity. Immobilized MS2 bacteriophages were applied as recognition elements specifically targeting live E. coli C3000 bacteria. It is shown that the sensor allows for real-time monitoring of biological phenomena taking place on the surface of the microcavity. The developed biosensor exhibits ultrahigh refractive index sensitivity of 15,000 nm/RIU and is capable of detecting live E. coli bacteria concentrations as low as 100 colony forming units (CFU)/mL in liquid volume as low as picoliters.
关键词： label-free biosensing,E. coli C3000 bacteria,refractive index sensitivity,MS2 bacteriophages,femtosecond laser micromachining,microcavity in-line Mach-Zehnder interferometer,optical fiber
更新于2025-09-23 15:21:21
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[Laser Institute of America ICALEO?? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16a??20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Enhanced drilling of transparent materials with ultrashort pulses
摘要： Ablative processes for transparent materials processing still remains a hot topic, as current techniques still have their limitations in ablation rates and quality, particularly for features on the order of a millimeter or less. In this publication, we present results of recent work on laser micromachining of sapphire with ultrashort pulsed lasers in the sub-picosecond regime. We accomplish this by using bottom-up processing with laser ablation, which has demonstrated the ability to generate zero-taper features with relatively high aspect ratios (>1:1) in many transparent materials. In previous work with <1ps (1030nm) sources, we have demonstrated the ability to drill ≤250μm diameter holes in 430μm thick c-plane sapphire. Here, we extend the scope of this work to examine additional methods and laser parameters presented here. In particular we examine the benefits of frequency conversion to 515nm wavelength, allowing smaller spots and higher fluence levels is compared to trials at the fundamental wavelength. We find no compelling differences in minimum achievable taper or drilling time for processes with 1030nm vs. 515nm performed with similar fluences, but the smaller spot size and increased fluence afforded with 515nm light allows for faster bottom-up drilling. Additionally, we test the effects of water-assisted processing by placing the sapphire wafer in contact with a water bath for better extraction of particulate matter during processing. Processes with a water bath are found to allow holes with 2° taper to be drilled in ≤5 seconds, which is a decrease in cycle time of ≥50% for holes with ≤2° taper in air.
关键词： laser micromachining,bottom-up processing,sapphire,ultrashort pulses,water-assisted processing
更新于2025-09-23 15:21:01
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Deep and high precision cutting of alumina ceramics by picosecond laser
摘要： Ceramics possess high thermal and chemical resistance, low density, and high compressive strength; however, the machining complications imposed by their inherent brittleness limit their range of applications. Laser cutting technology can offer an automated manufacturing technique for machining these brittle materials. In this paper, a laser cutting method, so-called wobbling, was developed for performing deep, high precision, and defect-free laser cutting of industrial grade alumina ceramics. This work explored picosecond laser process parameters such as focal position, linear speed, and wobble amplitude in order to control cut depth and optimize cut quality in terms of kerf width, kerf taper, surface cleanness, while avoiding crack formation. The morphology and cut quality were evaluated using 3D laser scanning microscopy and scanning electron microscopy (SEM). Picosecond laser cutting process parameters were optimized, achieving a maximum material removal rate of ~10 mm3/min. It was shown that the laser cutting process developed via these experiments represents an effective and efficient manufacturing tool that can be incorporated in engineered net shaping systems.
关键词： Laser cutting,Material removal rate,Ablation,Ultrafast laser micromachining,Alumina ceramics
更新于2025-09-23 15:21:01
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Micromachined Filters at 450 GHz With 1% Fractional Bandwidth and Unloaded Q over 700
摘要： This paper presents two silicon-micromachined narrowband 4th order waveguide filter concepts with center frequency of 450 GHz, which are the first narrowband submillimeter-wave filters implemented in any technology with a fractional bandwidth as low as 1%. Both filters designs are highly compact and have axial port arrangements, so that they can be mounted directly between two standard waveguide flanges without needing any split-block interposers. The first filter concept contains two TM110 dual-mode cavities of circular shape with coupling slots and perturbations arranged in two vertically stacked layers, while the second filter concept is composed of four TE101 series resonators arranged in a folded, two-level topology without cross-couplings. Prototype devices are fabricated in a low-surface roughness deep-silicon etching on silicon-on-insulator wafers. The measured passband insertion loss of two prototype devices of the dual-mode circular-cavity filters is 2.3 dB, and 2.6 dB for three prototypes of the folded filter design. The corresponding extracted unloaded quality factors of the resonators are 786±7 and 703±13 respectively, which are the best so far reported for submillimeter-wave filters in any technology. The presented filters are extremely compact in terms of size; their footprints have areas of only 0.53 and 0.55 mm2, respectively, and the thickness between the waveguide flanges is 0.9 mm.
关键词： micromachining technology,microfabrication,waveguide filters,all-pole filters,dual-mode filters
更新于2025-09-23 15:21:01
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Digitization for Highly Accurate 3D Laser Processing of Customera??specific Tools
摘要： Cutting tool manufacturing by laser technology has developed quickly during the past fifteen years. Compared to conventional machining methods such as grinding or eroding, laser processing does not require any additional elements such as coolant, grinding wheels, erosion wire, discs, etc. If ultrashort laser pulses are used together with optimized laser parameters, heat input into the material can be negligible. Additionally, there are no processing forces or tool wear present during laser manufacturing. For these many reasons, autonomous production of metallic or diamond tools is feasible and highly interesting.
关键词： Autonomous Production,Ultrahard Materials,Laser Micromachining,Ultrashort Laser Pulses,Tool Manufacturing
更新于2025-09-23 15:19:57
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Process development and characterization towards microstructural realization using laser micromachining for MEMS
摘要： This paper presents the process development and characterization towards microstructural realization using laser micromachining for MEMS. Laser micromachining technique is environmental friendly, fast patterning and able to avoid multi steps in conventional lithography based microfabrication techniques. This research focuses on understanding the dimensional properties of materials of the laser beam on the silicon wafers where microstructures were fabricated. Four main parameters like rectangular variable aperture (RVA-XY) size, number of pulse, stage/table feed rate and laser energy play important role in laser ablation process. The pattern of the microchannel or line with 1 cm length was drawn by AutoCAD software or any CAD software. The pattern in the CAD software is then transferred onto the silicon wafer by using laser micromachining. Finally, high power microscope (HPM) and Stylus Profiler will be used as measurement tools for observing and analysing the width and depth of the microchannel structures fabricated by laser micromachining. When using bigger size of RVA, it will lead to bigger microchannel width. There are a little effects or almost comparable in term of microchannel depth if varying all parameters’ value. Surface roughness test also needs to be considered before choosing the best setting for the laser ablation.
关键词： Microstructure,Micromachining,Laser,Parameter
更新于2025-09-23 15:19:57
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Investigation of a Bragg Grating-Based Fabrya??Perot Structure Inscribed Using Femtosecond Laser Micromachining in an Adiabatic Fiber Taper
摘要： This paper presents the fabrication of a fiber Bragg grating (FBG)-based Fabry–Perot (FP) structure (7 mm total length) in an adiabatic fiber taper, investigates its strain and temperature characteristics, and compares the sensing characteristics with a standard polyimide coated FBG sensor. Firstly, a simulation of the said structure is presented, followed by the fabrication of an adiabatic fiber taper having the outer diameter reduced to 70 μm (core diameter to 4.7 μm). Next, the sensing structure, composed of two identical uniform FBG spaced apart by a small gap, is directly inscribed point-by-point using infrared femtosecond laser (fs-laser) micromachining. Lastly, the strain and temperature behavior for a range up to 3400 με and 225 ?C, respectively, are investigated for the fabricated sensor and the FBG, and compared. The fabricated sensor attains a higher strain sensitivity (2.32 pm/με) than the FBG (0.73 pm/με), while both the sensors experience similar sensitivity to temperature (8.85 pm/?C). The potential applications of such sensors include continuous health monitoring where precise strain detection is required.
关键词： Fabry–Perot,microfiber sensor structure,direct writing,sensor for structural health monitoring,point-by-point fabrication,femtosecond laser micromachining,harsh environment fiber sensor
更新于2025-09-23 15:19:57