表面微結構對靜態接觸角與表面附著現象之研究

Abstract

本論文第一個主題係針對液珠與表面微結構間所形成之接觸角進行深入探討，計畫中我們以微機電製程技術在矽晶片上施以體型與面型細微加工技術，設計製作出不同尺寸、形狀、排列方式之疏水性材料陣列微結構，並利用泡滴法方式觀測不同液珠大小與不同粗糙度下接觸角變化之影響，經由上述不同表面微結構下之粗糙度分析討論量測出接觸角之結果。 第二個主題是討論表面微結構對液體附著現象之影響，我們利用滴管注入相同體積的液滴於微結構上，然後使用離心機去旋轉，進一步觀測液珠分佈情況與不同粗糙度、微結構之關係；得到的結果並與第一個主題的研究結果作比較。 實驗結果顯示在相同固液接觸面積比例的微結構，若其微結構間距越大，液珠越容易塌陷於微結構之間；微結構高度愈高，液珠愈不容易塌陷於微結構之間；在相同的固液接觸面積比例下，液珠對十字型微結構的靜態接觸角大於方型微結構。在進行表面附著現象實驗時，有方向性的微結構不論其靜態接觸角太小，主要液珠與次要液珠皆會滲入微結構之間，而混合型微結構不會有液珠陷入的情況。

This study first purposes to investigate the contact angles formed at conditions of various surface microstructures. MEMS fabricated microstructure is performed using the silicon wafer inserts with various dimensions, shapes, and arrangement of hydrophobic materials. The sessile-drop technique is used for contact angle measurements. Experimental examinations of the relationship between contact angle and varieties of solid microstructure roughness are performed. In the second part of the study, we examine the effects of various surface microstructure on the surface adhesion phenomena. MEMS fabricated microstructure on the wafer is performed using previous already designed microstructure and pipets used for dripping droplets on the designed surfaces in association with a centrifuge for providing an additional force source. After droplets pass through the surfaces, the residual fluid and distribution are investigated and the results are compared to the former part. Experimental results show that the droplets tend to immerse in the gap between the microstructures if the gap becomes wider and wider and droplets can not fall into the gap between the higher microstructures. The static contact angle for cross-type microstructures is bigger than the square-type microstructures. Experimental results for surface adhesion phenomena show that the main and minor droplet immerse in the gap between the striped microstructures regardless their contact angle, but the droplet for mix-type microstructures does not show this phenomena.