微懸臂梁金表面烷基硫醇分子吸附行為探討

Adsorption behavior of Alkanethiols on Gold-coated Micro-cantilever

段延學(Yen-Hsueh Tuan)

指導教授 ： 陳俊杉

國立臺灣大學/工學院/土木工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02210

摘要

隨著技術的演進，人們開始從巨觀的世界轉而著眼於微米、奈米等尺度的觀察。而微懸臂梁感測器正是這個需求下而誕生的產物。它能夠將如物理上的溫度變化以及化學上的鍵結吸附行為等等，轉變為力學能的形式，讓人們得以量測。
目前對硫醇分子的自組裝有一個看法，這一層分子薄膜並非一開始就能夠非常完整的緊密排列，而是會有一個由躺下(lying-down)到站立(standing up)的一個過程，且當中可能經過許多更複雜的面向，但在此研究中，我們只針對躺下與站立兩個最初與最終的面相做討論。在lying-donw的時候，大部分可供自主裝的區域被覆蓋住。而當過渡到standing-up的狀態時，被覆蓋的面積便釋放出來。而這兩個面向中不同的反應面積，會造成吸附上的分子數量有所不同。
本研究使用了光學量測的方式，分別的量測在不同濃度、不同碳鏈長度硫醇分子控制時間長短，於微懸臂梁金表面形成自組裝分子層(self-assembled monolayers, SAM)時，所造成的表面應力改變。在實驗中發現，在短時間以及長時間的反應下，碳鏈長度相對於表面應力的變化，有著不同的趨勢，而造成這個趨勢的原因，便是由lying-down過渡到standing-up需要數小時的時間。

關鍵字

微懸臂梁 ； 面自組裝 ； 濃度 ； 時間 ； 表面應力

並列摘要

With the advance of micro- and nano-fabrication technologies, a micro-cantilever sensor has been used routinely to detect physical as well as biological signals. It can transfer the physical phenomenon such as temperature change and chemical phenomenon such as bonding or adsorption into mechanics form that can be measured.
It is believed that the self-assembled monolayers (SAM) created by alkanethiol molecules are not well-packed at initial stage of adsorption. At first, those molecules are in the lying-down phase and it takes time to transfer to standing-up phase. When those molecules are in the lying-down phase, most of the reaction areas are covered by the alkyl chain. Once they transfer to standing-up phase, those areas will be released. The different reaction areas will cause different adsorbed molecules.
This thesis studies the kinetics-induced surface stress of SAM adsorbed on gold-coated micro-cantilevers. We use an optical method to measure the surface stresses change among different concentrations, different chain lengths, and different time due to the adsorption of alkanethoil. We found two distinct chain-length effects. During 20 to 60 minutes of adsorption, surface stress will decrease when the chain length increase. After 3 to 5 hours, surface stress will increase when the chain length increase. In terms of different concentration effects, higher concentration will in general induce higher surface stress. Nevertheless, the concentration effect vanish when chain length increase.

並列關鍵字

micro-cantilever ； self-assembled monolayers ； time ； concentration ； surface stress

參考文獻

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