【作者】 吕皞；

【导师】 刘世元；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2011， 硕士

【摘要】 自然界中壁虎具有非常优秀的吸附能力,可以自由行走在光滑的墙壁上,甚至是天花板上。壁虎脚毛的分级层次结构,尤其是高深宽比的微米级刚毛与纳米级绒毛结构,是保证其产生巨大粘附力且能适应不同表面形貌的关键。壁虎脚毛的这些特性在MEMS器件中以及一些爬壁机器人等领域有着极为广阔的应用前景。为此,本学位论文围绕仿壁虎脚毛的纤维阵列制作工艺开展了如下研究。采用厚胶工艺,选用SU-8光刻胶作为纤维阵列材料进行试验,制备出了深宽比高达7的纤维阵列。由于较高的深宽比,纤维之间存在纠结现象,难以通过微模塑成型工艺进一步复制其结构以进行批量化生产。采用半导体工艺中的硅刻蚀工艺,通过ICP刻蚀制作出了多种尺寸的硅孔阵列模具,最高深宽比可达到7以上。利用该硅模具成功复制出聚二甲基硅氧烷(PDMS)微米级纤维阵列。直径小于8μm的纤维阵列,仍然存在纠结现象。无论纤维是否纠结在一起,纤维阵列表面均展现出较好的疏水性,从平面PDMS的水接触角102.7°提升到131.7°以上。提出了一种全新的简单,低成本的双级层次纤维阵列结构制作工艺。该工艺基于以上硅模具,在硅模具表面涂覆一层SU-8光刻胶,利用厚胶光刻工艺制作出微米孔阵列,与硅模具组成两级孔阵列模具。利用该复合模具成功复制出两级PDMS纤维阵列。由于模具可重复使用,因此可以实现批量化生产。经实验发现双级层次PDMS纤维阵列结构的疏水性相比单级PDMS纤维阵列有少量提升,达到145.9°。更多还原

【Abstract】 In nature, geckos have developed complex adhesion structures capable of smart adhesion, the ability to maneuver on different smooth and rough surfaces, even ceilings. The multi-scale hierarchical structure of the gecko foot-hair, especially the high-aspect-ratio structure of its micro-scale seta and nano-scale spatulae is the critical factor of the gecko’s ability to cling to any different surface with strong adhesion force. The incredible characteristics of gecko foot-hair have a very broad prospect of applications in the deployment and disassembly of MEMS devices, wall-climbing robots, etc. Accordingly, the fabrication of high-aspect-ratio micro/nano hierarchical structures mimicking gecko foot-hair has been studied in this degree thesis including the following contents:Thick film photolithography based on SU-8 photoresist was utilized to fabricate fiber arrays. The microfiber array with multiple parameters was obtained. The highest aspect ratio of SU-8 microfiber is 7. Due to high aspect ratio, the SU-8 microfibers tend to be bunched together, making it difficult to creating a mold to relicate the fibers with other polymer for batch process.Utilizing inductively coupled plasma (ICP) etching process, which is very common in the semiconductor technology, the silicon mold with deep-hole arrays with multiple parameters was fabricated. The polydimethylsiloxane (PDMS) microfiber arrays were successfully replicated from the silicon mold. As for microfiber arrays with less than 8μm in diameter, the fibers tend to be bunched together. The hydrophobic property of the synthetic PDMS microfiber arrays was observed no matter the microfibers bunched together or not. The contact angle of water droplets on PDMS microfiber arrays shows increased hydrophobic property of PDMS microfiber arrays than non-patterned PDMS surface, from 102.7°to more than 131.7°.A novel and simple method with low cost for fabricating two-level two-level hierarchical microfiber array was proposed. Utilizing the silicon mold with deep-hole arrays as a substrate, a SU-8 layer with microhole arrays was fabricated on it using thick film photolithography, and form a double layer mold. The two-level hierarchical PDMS microfiber arrays were replicated from the double layer mold. The double layer mold is reusable. Therefore this method is suitable for batch processes. The water contact angle of the two-level hierarchical PDMS microfiber array surface was observed to be 145.9°, which is a little bit higher than the one of single level PDMS microfiber array surface.更多还原