Wang Leyan, Zhang Dongxian, Wen Zhenghu, Zhang Haijun
State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, People's Republic of China.
Microsc Res Tech. 2009 Oct;72(10):717-22. doi: 10.1002/jemt.20722.
This article reports a novel laser-induced micro-fabrication method and its monitoring system for three-dimensional (3D) microstructures. The mechanism of the method is that a small zone of thermoplastic material melted by laser heating grows in liquid surrounding environment, solidifying into a convex microstructure, such as micro-dot or micro-pillar. A laser diode (808 nm) with maximum power output of 130 mW is used as power source, and a kind of paraffin mixed with stearic acid and paint serves as the thermoplastic material for 3D microstructure formation experiments. A light microscope system consisting of a charge-coupled device (CCD) and a computer is utilized to realize real-time observation of the micro-fabricating process. The distribution of local temperature rise on material surface created by laser irradiation is simulated. The effects of liquid environment on microstructure formation have been theoretically analyzed and experimentally studied. Experiments are further carried out to investigate the relationship between laser spot and fabricated microstructures. The results indicate that the widths of micro-dots or micro-pillars are mostly determined by the size of focal spot, and their heights increase with the enlargement of laser power density. With this method, a micro-dot array of Chinese characters meaning "China" has been successfully fabricated through computer programming. This method has the advantages of implementing direct, mask-less, real-time and inexpensive 3D microstructure fabrication. Therefore, it would be widely applied in the fields of micro/nano-technology for practical fabrication of different kinds of 3D microstructures.
本文报道了一种用于三维（3D）微结构的新型激光诱导微加工方法及其监测系统。该方法的原理是，激光加热使一小区域的热塑性材料在液体周围环境中生长，凝固成凸起的微结构，如微点或微柱。使用最大功率输出为130 mW的激光二极管（808 nm）作为电源，一种混合了硬脂酸和颜料的石蜡用作3D微结构形成实验的热塑性材料。利用由电荷耦合器件（CCD）和计算机组成的光学显微镜系统实现对微加工过程的实时观察。模拟了激光辐照在材料表面产生的局部温度升高分布。从理论上分析并通过实验研究了液体环境对微结构形成的影响。进一步开展实验以研究激光光斑与加工微结构之间的关系。结果表明，微点或微柱的宽度主要由焦点尺寸决定，其高度随激光功率密度的增大而增加。利用该方法，通过计算机编程成功制造出了意为“中国”的汉字微点阵列。该方法具有实现直接、无掩膜、实时且低成本的3D微结构制造的优点。因此，它将在微/纳米技术领域广泛应用于实际制造各种3D微结构。
