Sub-micron-structure machining on silicon substrate was studied by direct writing system of femtosecond laser with the central wavelength of 800 nm, pulse duration of 120 fs and repetition rate of 1 kHz. Three kinds o...Sub-micron-structure machining on silicon substrate was studied by direct writing system of femtosecond laser with the central wavelength of 800 nm, pulse duration of 120 fs and repetition rate of 1 kHz. Three kinds of experiments were conducted: 1) the effect of photoresist on silicon; 2) machinability of different orientations of silicon; and 3) the size of micro-structure and the cross-section shape. Photoresist SU8 was coated onto silicon substrates in thicknesses of 100 μm. SU8 remained on the silicon substrate while the silicon under the machined SU8 was removed after laser machining. Orientations of (100), (110), and (111) silicon substrates were machined with the laser power of 60 μW and the scanning speed of 3 mm/min. Spike morphologies were observed on all three orientations of silicon substrates without obvious directional difference of these spikes on different silicon substrates. In addition, the ablation threshold energies were also similar. In the consideration of ablation energy, one numerical model of the machining parameters has been proposed to simulate the cross-section of the micro-structure. The predicted shape by simulation can fit the profile of the cross-section shape well.展开更多
To the Editor:Traumatic hemipelvectomy(THP),which was first described by Turnbull in 1978,is an unstable ligamentous or osseous hemipelvic injury that involves rupture of the pelvic neurovascular bundle(either open or...To the Editor:Traumatic hemipelvectomy(THP),which was first described by Turnbull in 1978,is an unstable ligamentous or osseous hemipelvic injury that involves rupture of the pelvic neurovascular bundle(either open or closed integuments).[1]THP is a rare and catastrophic injury that is usually caused by high-energy trauma,as in a traffic,motorcycle,and machinery-related accident,and is accompanied by pelvic fractures.[2]THP usually leads to other associated injuries.[3]The mortality associated with open pelvic fracture is approximately 40%,while the mortality associated with THP may reach as high as 100%.[4]However,few studies describe a standardized approach for handling this fatal trauma.展开更多
基金Prof.Hai-Lung TSAI (Mechanical Engineering,Missouri University of Science and Technology,USA) for his laser system and the National Science Council for supporting the research project under the contract No. NSC-97-2622-E-007-004-CC3
文摘Sub-micron-structure machining on silicon substrate was studied by direct writing system of femtosecond laser with the central wavelength of 800 nm, pulse duration of 120 fs and repetition rate of 1 kHz. Three kinds of experiments were conducted: 1) the effect of photoresist on silicon; 2) machinability of different orientations of silicon; and 3) the size of micro-structure and the cross-section shape. Photoresist SU8 was coated onto silicon substrates in thicknesses of 100 μm. SU8 remained on the silicon substrate while the silicon under the machined SU8 was removed after laser machining. Orientations of (100), (110), and (111) silicon substrates were machined with the laser power of 60 μW and the scanning speed of 3 mm/min. Spike morphologies were observed on all three orientations of silicon substrates without obvious directional difference of these spikes on different silicon substrates. In addition, the ablation threshold energies were also similar. In the consideration of ablation energy, one numerical model of the machining parameters has been proposed to simulate the cross-section of the micro-structure. The predicted shape by simulation can fit the profile of the cross-section shape well.
基金by grants from the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515010800)the Major Project under the Science and Technology Development Scheme of Guangdong Province(No.[2020]53-129)the Key Disciplinary Project of Clinical Medicine under the Guangdong High-level University Development Program(Nos.002-18120303,002-18119101).
文摘To the Editor:Traumatic hemipelvectomy(THP),which was first described by Turnbull in 1978,is an unstable ligamentous or osseous hemipelvic injury that involves rupture of the pelvic neurovascular bundle(either open or closed integuments).[1]THP is a rare and catastrophic injury that is usually caused by high-energy trauma,as in a traffic,motorcycle,and machinery-related accident,and is accompanied by pelvic fractures.[2]THP usually leads to other associated injuries.[3]The mortality associated with open pelvic fracture is approximately 40%,while the mortality associated with THP may reach as high as 100%.[4]However,few studies describe a standardized approach for handling this fatal trauma.
