- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Femtosecond Laser Micromachining for Controlling Surface Wettability
摘要： The use of femtosecond laser to modify the surface of polymeric materials has received great attention in the last decade, due to the possibilities of tailoring the material’s properties yielding technological applications. Here, we report on the microfabrication of an azopolymer by using femtosecond laser pulses, aiming at the control of surface wettability. By properly patterning the polymeric surface structure we were able to increase the surface hydrophilicity, decreasing the water contact angle in about 20 degrees.
关键词： Laser ablation,hydrophilicity,femtosecond micromachining,azopolymer
更新于2025-09-16 10:30:52
-
Controlled Fabrication of Micro/Nano-Structures on Germanium Using Ultrashort Laser Pulses under Ambient Conditions
摘要： A technique for ordered fabrication of periodic freestanding micro/nano-structures on the crystalline germanium (Ge) <100> surfaces with 1064 nm wavelength ultrashort laser pulses under ambient conditions is presented. The laser radiation fluence used for obtaining the structures is close to the melting threshold (0.1 J/cm2) of Ge. The dimensions of structures range from hundreds of nanometres to a few microns. The orientation of the periodic surface structures depends on laser beam polarization direction. Arrays of structures are formed in rows parallel to the sample movement direction for samples machined with s-polarized laser pulses, but formed in the direction perpendicular to the movement for p-polarized pulses. The structures are fabricated under variable temperatures on sample surface owing to the changed interference between incident and reflected laser beams. A micro-Raman analysis of the processed surfaces shows a minor change in the spectral intensity as compared to the unprocessed surface and the material retains its crystallinity after laser irradiation.
关键词： Nano-structures,Femtosecond laser,Micromachining,Germanium
更新于2025-09-16 10:30:52
-
Conical microstructuring of titanium by reactive gas assisted laser texturing
摘要： Femtosecond laser micromachining is an important and flexible method to generate precisely targeted surfaces on various materials. On titanium, the laser structuring process strongly depends on the laser parameters. For example, an increasement of the pulse length and repetition rate favors melting processes instead of ablation and microstructuring. We report on an investigation of reactive halogens (iodine, bromine, chlorine) and halocarbons as additives to the laser structuring process of pure titanium and the common alloy Ti-6Al-4V with 0.75 ps laser pulses. The choice of the halogen allows control of whether solely the chemical composition or the surface microstructure should be altered. Bromine was found to be an efficient additive to generate homogeneous microstructures based on micropillars at convenient conditions (air, atmospheric pressure). The resulting surfaces have been characterised by thermal emission infrared photography, scanning electron microscopy, energy dispersive X-ray spectroscopy, reflective UV/Vis spectroscopy and contact angle measurements. The bromine/air processed titanium surfaces revealed superhydrophilicity, strongly increased thermal emissivity and a high absorptivity (“black metal”).
关键词： Superhydrophilicity,Reactive halogens,Absorptivity,Titanium,Femtosecond laser micromachining,Microstructuring,Thermal emissivity
更新于2025-09-16 10:30:52
-
[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Laser induced forward transfer of silver nanoparticles patterns
摘要： Laser-induced forward transfer (LIFT) with fs-pulses is used to produce silver nanoparticles patterns on glass substrates. LIFT is a versatile direct laser write technique in which a variety of materials can be transferred from a donor substrate to a receiver one. Here we present a study on the optimal parameters, such as scan speed and pulse energy, required to obtain a micrometric pattern on the transfer process. Spectroscopy analyses confirmed the composition and the formation of silver nanoparticles. Also, the electron localized microscopy deposition of silver nanoparticles, indicating such approach as a promising technique for the development of applications from electronics to photonics.
关键词： Femtosecond laser induced forward transfer,Micromachining,Silver nanoparticles
更新于2025-09-16 10:30:52
-
Micromachined Waveguide Interposer for the Characterization of Multi-port Sub-THz Devices
摘要： This paper reports for the first time on a micromachined interposer platform for characterizing highly miniaturized multi-port sub-THz waveguide components. The reduced size of such devices does often not allow to connect them to conventional waveguide flanges. We demonstrate the micromachined interposer concept by characterizing a miniaturized, three-port, 220–330-GHz turnstile orthomode transducer. The interposer contains low-loss micromachined waveguides for routing the ports of the device under test to standard waveguide flanges and integrated micromachined matched loads for terminating the unused ports. In addition to the interposer, the measurement setup consists of a micromachined square-to-rectangular waveguide transition. These two devices enable the characterization of such a complex microwave component in four different configurations with a standard two-port measurement setup. In addition, the design of the interposer allows for independent characterization of its sub-components and, thus, for accurate de-embedding from the measured data, as demonstrated in this paper. The measurement setup can be custom-designed for each silicon micromachined device under test and co-fabricated in the same wafer due to the batch nature of this process. The solution presented here avoids the need of CNC-milled test-fixtures or waveguide pieces that deteriorate the performance of the device under test and reduce the measurement accuracy.
关键词： Test-fixture,Orthomode transducer,Terahertz,Multi-port,Measurement,Interposer,Silicon micromachining,Waveguide,DRIE
更新于2025-09-16 10:30:52
-
Fabrication of Silicon Microfluidic Chips for Acoustic Particle Focusing Using Direct Laser Writing
摘要： We have developed a fast and simple method for fabricating microfluidic channels in silicon using direct laser writing. The laser microfabrication process was optimised to generate microfluidic channels with vertical walls suitable for acoustic particle focusing by bulk acoustic waves. The width of the acoustic resonance channel was designed to be 380 μm, branching into a trifurcation with 127 μm wide side outlet channels. The optimised settings used to make the microfluidic channels were 50% laser radiation power, 10 kHz pulse frequency and 35 passes. With these settings, six chips could be ablated in 5 h. The microfluidic channels were sealed with a glass wafer using adhesive bonding, diced into individual chips, and a piezoelectric transducer was glued to each chip. With acoustic actuation at 2.03 MHz a half wavelength resonance mode was generated in the microfluidic channel, and polystyrene microparticles (10 μm diameter) were focused along the centre‐line of the channel. The presented fabrication process is especially interesting for research purposes as it opens up for rapid prototyping of silicon‐glass microfluidic chips for acoustofluidic applications.
关键词： acoustophoresis,acoustofluidics,ultrasound,laser micromachining,particle manipulation,microfabrication
更新于2025-09-16 10:30:52
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Device model for intermediate band materials
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： wide bandgap,resonators,HEMT,micromachining,III-V,microelectromechanical systems,piezoelectric materials
更新于2025-09-16 10:30:52
-
Experimental investigation and optimization of laser induced plasma micromachining using flowing water
摘要： In this study, laser induced plasma micromachining using flowing water (F-LIPMM) was performed to create micro-channels on stainless steel surface. The effects of process parameters (water speed, laser pulse energy, frequency and scanning speed) on the responses of micro-channel width, depth, material removal rate (MRR) and heat affected zone (HAZ) were investigated based on response surface methodology (RSM). The regression models for the machined width, depth, MRR and HAZ were developed, and the adequacies of the developed models were subsequently verified by analysis of variance (ANOVA) method. Finally, grid structures consisting of desired micro-channels were created with the optimum process parameters: water speed of 8 m/s, pulse energy of 10.4 μJ, frequency of 15.8 kHz and scanning speed of 2.7 mm/s. The uniform micro-channels with smooth bottoms, side-walls and small HAZ were obtained, and the results showed that the predicted responses using the developed models were comparable with the experimental results.
关键词： Laser induced plasma micromachining,RSM,Micro-channels,Flowing water
更新于2025-09-16 10:30:52
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Achievement of Very Smooth Cavity Sidewalls by UV Picosecond Laser Micromachining
摘要： Achievement of very smooth cavity sidewalls by UV picosecond laser micromachining. As a contactless and maskless method generating a reduced heat affected zone compared to nanosecond laser, ultrafast laser micromachining is widely used for rapid prototyping and materials processing. Today, most research and development works is devoted to study and control LIPPS occurring at the surface of the cavity bottom. But for many applications, there is a strong need to produce highly smooth sidewalls like for microelectronic sample preparation, microfluidics, waveguides, etc.. A laser based technology allowing to obtain very smooth surfaces (Ra of ~3 nm) already exists but it involves melting of a significant volume of material. So far, to the best of our knowledge, no parametric study aiming at minimizing the roughness of picosecond laser micromachined sidewalls in silicon has been performed. In the present work, picosecond laser micromachining (532 nm and 343 nm) of cavity sidewalls in silicon is studied. The evolution of the surface roughness is deeply investigated experimentally and theoretically as a function of laser and scanning parameters. We demonstrate that RaX, which is measured along the scanning laser beam direction, can be minimized by increasing laser beam overlap and the crater size, in accordance with a simple geometrical model. Experimentally, the minimum RaX is obtained for a beam overlap of ~80% and the largest crater sizes. Beyond 80%, we observed a roughness degradation which is probably due to two main phenomena. The first involves the interaction between the laser beam and the debris, which deteriorates the beam quality. The second is related to the highly heterogeneous ablation occurring for large overlaps, which induces a rough surface. Along the beam propagation direction, the sidewall is characterized by a relatively high waviness which induces a more important height variation than the roughness. The waviness depends mainly on the Rayleigh length. Thus, it can be reduced by using a large focal spot radius and a short wavelength. Once the sidewall is finished, the surface topology does not vary much with the laser micromachining time. Overall, smooth and homogeneous surfaces can be produced by choosing a beam overlap close to 80%. The best results were obtained at 343 nm, which allows to extend the Rayleigh zone, to increase the laser absorption on the sidewall asperities and to improve the induced cleaning thanks to a more confined interaction. The present work demonstrates that very low roughness (< 40 nm) can be achieved on sidewalls of cavities by picosecond laser micromachining. In addition this approach allows the roughness tuning. As it is based on a geometrical model, it is extendable to other materials as long as the surface melting, which may erase the induced periodic structuring, is not significant. This tuning possibility can be useful to modify the surface properties, such as reflectivity, friction and wettability, and therefore adapt the sidewall to different applications.
关键词： smooth cavity sidewalls,waviness,silicon,UV picosecond laser,roughness,micromachining,Rayleigh length
更新于2025-09-12 10:27:22
-
Integral fabrication of terahertz hollow-core metal rectangular waveguides with a combined process using wire electrochemical micromachining, electrochemical deposition, and selective chemical dissolution
摘要： The application requirements of terahertz hollow-core metal rectangular waveguides with a high-working frequency have become increasingly urgent with the rapid development of terahertz technology. Integral fabrication of terahertz hollow-core metal rectangular waveguides can improve considerably the transmission performance of terahertz signals. However, with current manufacturing techniques, the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides is difficult owing to their characteristically small end face size and the need for strict dimensional accuracy and high internal surface quality. In this paper, an innovative combined process of wire electrochemical micromachining, electrochemical deposition, and selective chemical dissolution is proposed firstly to overcome this puzzle. Taking the fabrication of an integral 1-THz hollow-core metal rectangular waveguide as an example, the manufacturing methods involved in each step are described particularly, together with the corresponding experimental investigations. With the end face size of 127 μm × 254 μm, edge radius less than 5 μm, and internal surface roughness less than 0.08 μm, the experimental results satisfy the design requirements for a 1-THz hollow-core metal rectangular waveguide. This study demonstrates that the proposed combined process is flexible, controllable, and suitable for the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides.
关键词： Wire electrochemical micromachining,Copper micro-electroforming,Gold micro-electroplating,Terahertz hollow-core metal rectangular waveguide,High-precision integral fabrication
更新于2025-09-12 10:27:22