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Precise laser trimming of alloy strip resistor: A comparative study with femtosecond laser and nanosecond laser
摘要： Laser trimming has become one of the powerful tools for precise manufacturing of alloy resistors that are widely used in electrical vehicles, electrical controlling, and in appliances. In this work, the influence of femtosecond laser trimming is compared with nanosecond laser trimming. The authors found that lasers focused on different heights relative to the sample surface induced significant changes in surface morphologies. The resistance change was systematically investigated as a function of cutting lengths and cutting depths of different laser powers for both lasers. The experiments display that femtosecond laser trimming has a higher precision of the resistance adjustment than nanosecond laser trimming. The periodic ripple structure by the femtosecond laser was investigated at the focus position above, onto, or beneath the surface. The period of a low frequency ripple structure (LFRS) on the ablated groove bottom is about 600–700 nm when the laser focuses just right on the surface but changes to 490–560 nm when focusing above or beneath the surface. The period of a high frequency ripple structure is about 100–380 nm at the vertical direction of LFRS. The period of low frequency ripple on the outside of the groove is smaller than that on the groove bottom for all three focusing cases. The period of the LFRS is not sensitive to the laser power. The range of the resistor value change in the s-polarized light direction of the femtosecond laser is more than that in the p-polarized light direction.
关键词： Fe-Cr-Al alloy resistor,micromachining,femtosecond laser trimming,nanosecond laser trimming
更新于2025-09-23 15:19:57
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Laser Micromachining of Lithium Niobate-Based Resonant Sensors towards Medical Devices Applications
摘要： This paper presents a micromachining process for lithium niobate (LiNbO3) material for the rapid prototyping of a resonant sensor design for medical devices applications. Laser micromachining was used to fabricate samples of lithium niobate material. A qualitative visual check of the surface was performed using scanning electron microscopy. The surface roughness was quantitatively investigated using an optical surface profiler. A surface roughness of 0.526 μm was achieved by laser micromachining. The performance of the laser-micromachined sensor has been examined in different working environments and different modes of operation. The sensor exhibits a Quality-factor (Q-factor) of 646 in a vacuum; and a Q-factor of 222 in air. The good match between the modelling and experimental results shows that the laser-micromachined sensor has a high potential to be used as a resonance biosensor.
关键词： medical devices,laser micromachining,sensors,lithium niobate,biosensors
更新于2025-09-23 15:19:57
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A 38 dBi Gain, Low-Loss, Flat Array Antenna for 320 GHz to 400 GHz Enabled by Silicon-On-Insulator Micromachining
摘要： Two high-gain ?at array antenna designs operating in the 320 – 400 GHz frequency range are reported in this paper. The two antennas show measured gains of 32.8 dBi and 38 dBi and consist of a 16 × 16 (256) element array and a 32 × 32 (1024) element array, respectively, which are fed by a corporate H-tree beamforming network. The measured operation bandwidth for both antennas is 80 GHz (22 % fractional bandwidth), and the total measured ef?ciency is above ?2.5 dB and above ?3.5 dB for the two designs in the whole bandwidth. The low measured loss and large bandwidth are enabled by optimizing the designs to the process requirements of the SOI micromachining technology used in this work. The total height of the antennas is 1.1 mm (1.2 λ at the center frequency), with sizes of 15 mm × 18 mm and 27 mm × 30 mm for both arrays. The antennas are designed to be directly mounted onto a standard WM-570 waveguide ?ange. The design, fabrication, and measurements of eight prototypes are discussed in this paper and the performance of the antennas compared to the simulated data, as well as manufacturability and fabrication repeatability are reported in detail.
关键词： terahertz radiation,corporate beamforming network,array antennas,silicon micromachining,silicon on insulator,waveguide arrays,submillimeter-wave antennas
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Optical Coupling of 3D Silicon Micromirrors
摘要： Free space optical coupling is considered the important feature which affects on the performance of the optical systems. Where coupling elements such as lenses and mirrors are aided in overcome the divergence of the Gaussian beams and to achieve phase matching. Here we concentrate on the studying of the free space coupling of 3D (spherical) mirror based on the propagation of a Gaussian beam. The design and fabrication of 3D mirror in the Optical microelectromechanical systems (MEMS) are studied. The coupling efficiency is a very important factor in the design of any MEMS circuit. High coupling efficiency is obtained by assembling optical parts which increase the integration effort. In this work, we report a high coupling efficiency, monolithically integrated 3D silicon micromirror that is capable of influencing on the Gaussian beams which propagate in the plane of the silicon substrate. A micromachining method is presented for fabricating the 3D micromirror.
关键词： micromachining,3D silicon micromirrors,optical coupling,MEMS,Gaussian beams
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Singapore, Singapore (2019.4.27-2019.4.30)] 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Characteristics of Disturbance in Frequency 9 -150 kHz of Photovoltaic System under Fluctuated Solar Irradiance
摘要： Gallium nitride (GaN) is a wide bandgap semiconductor material and is the most popular material after silicon in the semiconductor industry. The prime movers behind this trend are LEDs, microwave, and more recently, power electronics. New areas of research also include spintronics and nanoribbon transistors, which leverage some of the unique properties of GaN. GaN has electron mobility comparable with silicon, but with a bandgap that is three times larger, making it an excellent candidate for high-power applications and high-temperature operation. The ability to form thin-AlGaN/GaN heterostructures, which exhibit the 2-D electron gas phenomenon leads to high-electron mobility transistors, which exhibit high Johnson’s figure of merit. Another interesting direction for GaN research, which is largely unexplored, is GaN-based micromechanical devices or GaN microelectromechanical systems (MEMS). To fully unlock the potential of GaN and realize new advanced all-GaN integrated circuits, it is essential to cointegrate passive devices (such as resonators and filters), sensors (such as temperature and gas sensors), and other more than Moore functional devices with GaN active electronics. Therefore, there is a growing interest in the use of GaN as a mechanical material. This paper reviews the electromechanical, thermal, acoustic, and piezoelectric properties of GaN, and describes the working principle of some of the reported high-performance GaN-based microelectromechanical components. It also provides an outlook for possible research directions in GaN MEMS.
关键词： HEMT,piezoelectric materials,micromachining,microelectromechanical systems,III-V,wide bandgap,resonators
更新于2025-09-19 17:13:59
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Experimental study on two-phase boiling in wavy copper microchannels fabricated with ultrafast laser micromachining
摘要： In this study, the sinusoidal wavy (SW) copper microchannels with triangular cross section were fabricated with the ultrafast laser micromachining approach. The flow boiling of de-ionized water in SW microchannel were experimentally studied under mass fluxes of 43.43-217.15 kg/(m2s) and heat fluxes of 0-590 kW/m2. The flow patterns in the SW microchannels were visually observed and the boiling heat transfer characteristics were analyzed based on the obtained data. It shows the SW microchannel has a maximum enhancement of 127.7% in local heat transfer coefficient with an acceptable increase of pressure loss compared to the straight one in present work. In SW microchannel, a low degree of superheat can trigger the onset of nucleate boiling. A slow decreasing tendency of local heat transfer coefficient under a high effective heat flux or a high vapor quality was observed. The heat transfer mechanism of flow boiling in SW microchannel was analyzed based on the experimental visualization. Nucleate boiling and thin film evaporation are the dominant modes under different thermal boundary conditions. The flow boiling instability phenomenon in microchannels can be diminished using the wavy structures.
关键词： Boiling heat transfer,Sinusoidal wavy microchannel,Flow instability,Ultrafast laser micromachining
更新于2025-09-19 17:13:59
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Femtosecond Laser-Micromachining of Glass Micro-Chip for High Order Harmonic Generation in Gases
摘要： We report on the application of femtosecond laser micromachining to the fabrication of complex glass microdevices, for high-order harmonic generation in gas. The three-dimensional capabilities and extreme flexibility of femtosecond laser micromachining allow us to achieve accurate control of gas density inside the micrometer interaction channel. This device gives a considerable increase in harmonics’ generation efficiency if compared with traditional harmonic generation in gas jets. We propose different chip geometries that allow the control of the gas density and driving field intensity inside the interaction channel to achieve quasi phase-matching conditions in the harmonic generation process. We believe that these glass micro-devices will pave the way to future downscaling of high-order harmonic generation beamlines.
关键词： femtosecond laser micromachining,attosecond science,high order harmonic generation,de laval gas micro nozzle
更新于2025-09-19 17:13:59
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Low-Power, Multimodal Laser Micromachining of Materials for Applications in sub-5 ?μm Shadow Masks and sub-10 ?μm Interdigitated Electrodes (IDEs) Fabrication
摘要： Laser micromachining is a direct write microfabrication technology that has several advantages over traditional micro/nanofabrication techniques. In this paper, we present a comprehensive characterization of a QuikLaze 50ST2 multimodal laser micromachining tool by determining the ablation characteristics of six (6) different materials and demonstrating two applications. Both the thermodynamic theoretical and experimental ablation characteristics of stainless steel (SS) and aluminum are examined at 1064 nm, silicon and polydimethylsiloxane (PDMS) at 532 nm, and Kapton? and polyethylene terephthalate at 355 nm. We found that the experimental data aligned well with the theoretical analysis. Additionally, two applications of this multimodal laser micromachining technology are demonstrated: shadow masking down to approximately 1.5 μm feature sizes and interdigitated electrode (IDE) fabrication down to 7 μm electrode gap width.
关键词： interdigitated electrodes,ablation characteristics,multimodal laser micromachining,shadow mask
更新于2025-09-19 17:13:59
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[IEEE 2020 8th International Winter Conference on Brain-Computer Interface (BCI) - Gangwon, Korea (South) (2020.2.26-2020.2.28)] 2020 8th International Winter Conference on Brain-Computer Interface (BCI) - Implementation of multi-connected single-channel functional near-infrared spectroscopy system for hyperscanning study
摘要： A drug delivery system is used for targeting drugs to specific cells. Various drug carriers, that also reduce the side effects of unbound drugs, have been introduced and commercialized in the pharmaceutical field. Among them, synthetic biodegradable polymers have received much attention attributed to their low toxicity, controllable biodegradation rates, manufacturability, and low costs. This paper reviews the salient characteristics of biodegradable polymers as drug carriers and their microfabrication methods. The reviewed microfabrication methods include laser micromachining, rapid prototyping, replication, emulsification, microfluidic fabrication, and X-ray-lithography-based methods. For these microfabrication methods, critical dimensions, feature variety, solvent compatibility, production throughput, and tooling requirements are also summarized.
关键词： poly-capro-lactone (PCL),laser micromachining,emulsification,microfluidics,poly(lactic-co-glycolic acid) (PLGA),biodegradable polymers,Drug delivery systems (DDS),rapid prototyping,replication,x-ray-lithography,microfabrication,drug carriers
更新于2025-09-19 17:13:59
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Femtosecond lasers for high-precision orthopedic surgery
摘要： Laser micromachining with ultrashort pulses has shown great promise for clean, safe surgical treatment of bone tissue. However, comparisons of performance and development of “best practice” have been hampered by the difficulty of comparing results across a wide variety of experimental approaches and under surgically irrelevant conditions (e.g., dried, dead bone). Using a femtosecond (fs) pulsed laser system (τ = 140 fs, repetition rate = 1 kHz, λ = 800 nm), a comprehensive study of femtosecond laser microsurgery using the standard metrics of laser micromachining (ablation threshold, incubation effects, ablation rates, effect of focal point depth within the material and heat affected zone (HAZ)) was conducted on live, freshly harvested bovine and ovine cortical bone. Three important points of optimism for future implementation in the surgical theatre were identified: (1) the removal of material is relatively insensitive to the focal point depth within the material, removing the need for extreme depth precision for excellent performance; (2) femtosecond laser ablation of fresh bone demonstrates very little incubation effect, such that multiple passes of the laser over the same region of bone removes the same amount of material; and (3) the complete absence of collateral damage, heat- or shock-induced, on both the macro- and microscopic scales can be achieved readily, within a broad parameter range. Taken together, these results indicate a handheld or robotic deployed fiber laser platform for femtosecond laser microsurgery is a very viable prospect.
关键词： Laser ablation,Ultrafast laser micromachining,Femtosecond microsurgery,Laser micromachining,Orthopedic surgery
更新于2025-09-16 10:30:52