高深宽比微纳层次结构的仿壁虎毛优化设计与制作工艺研究

发布时间：2018-06-19 18:01

本文选题：壁虎粘附 + 仿生设计　；参考：《华中科技大学》2013年博士论文

【摘要】：以微机电系统(MEMS, Micro Electro Mechanical System)器件可拆卸安装和固定为例的多种潜在应用(如爬壁机器人、微操作、微装配等),迫切需求一种可牢固粘附又能反复使用的粘合方式。目前广泛使用的湿性粘合剂多存在易污染、易脱落、不可重复使用等缺点,因此研制一种克服上述缺点的干性粘合剂将具有十分重要的意义和广阔的应用前景。自然界中壁虎具有非常优秀的爬行能力,无论是水平的天花板还是竖直的墙壁,无论是粗糙的树皮还是光滑的玻璃,壁虎都能快速爬行或纹丝不动,即便是潮湿的环境也能行动自如,这种粘附特性为干性粘合剂的仿生设计与制作提供了极好的范例和启示。壁虎脚毛的分级层次结构,特别是其微米级刚毛/纳米级绒毛的高深宽比微纳层次结构,是保证壁虎既能产生巨大粘附力又能适应不同表面形貌的关键。为此,本学位论文开展高深宽比微纳层次结构的仿壁虎毛优化设计与制作工艺的研究,从壁虎毛粘附机理出发,提出一种基于多约束条件的自底向上的优化设计方法,以及一种基于感应耦合等离子体(ICP, Inductively Coupled Plasma)刻蚀与厚胶光刻工艺的简单低成本的双层阵列制作方法。本文首先对壁虎毛粘附机理进行了研究。通过JKR模型和最小势能原理分析了单根绒毛在顶接触状态与边接触状态下的受力情况,研究了单根绒毛的粘附力与脱附角,解释壁虎如何产生巨大粘附力又能快速脱附；通过分别建立粗糙表面模型和多级阵列模型,模拟了壁虎毛在粗糙表面的粘附与脱附过程,研究了结构粘附力与接触面粗糙度、阵列层级的关系,解释壁虎为何能适应不同形貌的粗糙表面；通过Cassie模型分析了壁虎绒毛的疏水性,通过JKR模型分析了灰尘与绒毛阵列的吸附力,解释壁虎如何同时在潮湿和干燥的环境下保持自清洁特性。其次对仿壁虎毛结构进行了优化设计。对仿壁虎毛结构的层数进行了分析与选择,从增强粘附、保持稳定与适应环境等角度出发,提出单根纤维的最优粘附约束、单根纤维的稳定性约束、纤维之间的防纠结约束、纤维阵列的表面适应性约束、纤维阵列的疏水性约束、纤维阵列的自清洁约束、多级结构的最大粘附能约束,多数能与实际壁虎结构参数相符合,并在此基础上提出一种基于多约束条件的自底向上的优化设计方法,对仿壁虎毛结构进行了优化设计与分析。接下来对仿壁虎毛结构制作工艺进行了探索。研究了基于SU-8胶的厚胶光刻工艺,制作出了最大长径比为6的单层SU-8纤维阵列；研究了基于Bosch技术的ICP刻蚀工艺,制作出了最大长径比为5的单层聚二甲基硅氧烷(PDMS, Polydimethylsiloxane)纤维阵列；在前两个工艺基础上,提出一种结合ICP刻蚀与厚胶光刻的Si/SU-8复合模具模塑成型工艺,制作出了顶层长径比为5、底层长径比为2的双层PDMS纤维阵列。最后对仿壁虎毛结构进行了性能测试。对无结构、单层结构、双层结构的多种样品进行了实验检测,包括疏水性能、法向粘附性能和切向粘附性能,并结合前文理论解释实验现象。单层阵列的平均水接触角为143.6°,双层阵列的平均水接触角为150.4°,有结构样品中测得最大法向粘附强度为1.52N/cm2(单层直径5μm间距5μm长度20μm),最大切向粘附强度为0.79N/cm2(单层直径3μm间距3μm长度15μm),通过对比发现双层阵列相较于单层阵列和平面结构具有更好的疏水性和粗糙表面适应性。
[Abstract]:The present invention provides a kind of dry adhesive which can be used widely . It has very important meaning and wide application prospect .

In this paper , the mechanism of the adhesion of wall - tiger wool is studied firstly . Through the JKR model and the principle of minimum potential energy , the stress condition of single pile in the top contact state and the edge contact state is analyzed , and the adhesion and desorption angle of the single pile are studied .
By establishing a rough surface model and a multi - stage array model , the adhesion and desorption processes of the wall - tiger hair on the rough surface are simulated , and the relationship between the structure adhesion force and the contact surface roughness and the array level is studied , and the reason why the wall tiger can adapt to the rough surface of different shapes is explained ;
Based on the Cassie model , the hydrophobicity of wall - tiger fluff was analyzed , and the adsorption force of dust and fluff array was analyzed by JKR model .

Secondly , the structure of imitation wall tiger is optimized . From the angle of enhancing adhesion , stability and adaptability , this paper puts forward the optimal adhesive constraint of single fiber , the stability of single fiber , the self - cleaning constraint of fiber array , the maximum adhesion energy constraint of fiber array , the self - cleaning constraint of fiber array , the maximum adhesion energy constraint of multi - stage structure , and the optimization design method based on multi - constraint condition .

In this paper , the fabrication technology of imitation wall tiger wool structure is explored . A single layer SU - 8 fiber array with the maximum aspect ratio of 6 is fabricated by the thick glue lithography process based on SU - 8 glue .
A single - layer polydimethylsiloxane ( PDMS ) fiber array with a maximum aspect ratio of 5 was fabricated by ICP etching technology based on Bosch technology .
On the basis of the first two processes , a Si / SU - 8 composite die - molding process combining ICP etching and thick - glue lithography was proposed , and a double - layer PDMS fiber array with a length - diameter ratio of 5 and an underlayer diameter ratio of 2 was produced .

The results show that the average water contact angle of the single - layer array is 143.6 掳 , the average water contact angle of the double - layer array is 143.6 掳 , the average water contact angle of the double - layer array is 143.6 掳 , the average water contact angle of the double - layer array is 150.4 掳 , the maximum tangential adhesive strength is 0.79N / cm2 ( single - layer diameter is 3 渭m , the length is 15 渭m ) , and the comparison shows that the double - layer array has better hydrophobicity and rough surface adaptability than the single - layer array and the planar structure .
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TB17;TH-39

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