請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/51480
標題: | 觸控顯示器之仿生壓力感測技術與快速液晶槽設計 Biomimetic Tactile Sensing Technology and Rapid Cell Design for Touch Panels |
作者: | Jen-Chieh Li 李仁傑 |
指導教授: | 張培仁 |
共同指導教授: | 施文彬 |
關鍵字: | 多孔隙結構,還原氧化石墨烯,L-抗壞血酸,薄膜孔隙率,重力mura,彩色濾光片,體積因子, Porous Structure,Reduced Graphene Oxide,L-Ascorbic Acid,Membrane Porosity,Gravity Mura,Color Filter,Volumetric Factor, |
出版年 : | 2016 |
學位: | 博士 |
摘要: | 本論文展示一多孔隙結構以改善還原氧化石墨烯薄膜之壓阻因子。將氧化石墨烯與氫氧化銅奈米繩以水相方式混合製作出複合式石墨烯薄膜。由於氧化石墨烯的表面與邊緣存在著許多含氧基使其具有絕緣性、疏水性與較寬的間隔在氧化石墨烯層與層之間,以上缺陷皆限制氧化石墨烯的應用。為了解決氧化石墨烯的導電度與去除氫氧化銅納米繩以形成奈米等級孔洞,我們提出以L-抗壞血酸還原劑來進行氧化石墨烯的化學還原。應用不同的光學光譜來佐證還原氧化石墨烯薄膜的還原程度,透過這些實驗可知L-抗壞血酸是一種有效去除在氧化石墨烯表面與邊緣上含氧基的還原劑並將其還原成還原氧化石墨烯。此外,透過掃描式電子顯微鏡的側向觀察,可以很清楚發現還原石墨烯與擁有多孔隙結構的還原氧化石墨烯在結構型態上的不同。也直接證實這些孔洞的大小與形狀是由氫氧化銅奈米繩所造成的。在不同的施加應變下,我們可以獲得多孔隙還原氧化石墨烯薄膜的原始壓阻因子隨著薄膜孔隙率的增加而單調遞增。當薄膜孔隙率為15.78 %與施加應變小於1 %,可以獲得最大的壓阻因子為46.1。為了提高多孔隙還原氧化石墨烯薄膜的靈敏度,透過以PDMS為材料所製成的微金字塔結構薄膜並調整其特徵尺寸與間距,結果顯示以特徵長度30微米與其三倍間距的微金字塔可以使得多孔隙還原氧化石墨烯薄膜的靈敏度達到-0.26 kPa−1。此外,可以改善壓阻因子的主要機制歸咎於多孔隙還原氧化石墨烯的結構。我們的實驗展示了,當增加薄膜孔隙率時,可以增加多孔隙還原氧化石墨烯的初始電阻而提高壓阻因子。在不同的薄膜孔隙率下,我們也提出穿隧模型來解釋多孔隙還原氧化石墨烯的電子傳導機制。藉由調整薄膜孔隙率可以整理出多孔隙還原氧化石墨烯的初始電阻、穿隧距離與壓阻因子的交互關係。透過此結果可以驗證越大的穿隧距離可以得到更靈敏的感應特性而增加薄膜孔隙率是一個改善多孔隙還原氧化石墨烯的壓阻因子的有效方法。
此外,重力mura為一個不正常的變形,通常發生在大尺寸液晶螢幕的面板上。為了避免變形造成更多的損害,本論文提出一個解析模型用來估計受到已灌入之液晶的靜水壓與熱膨脹所造成彩色濾光片的變形,以此用來預測重力mura的產生與否。在受到外加壓力下,利用一兩端皆為固定端的梁搭配一系列可視為剛體的光間隙子來描述彩色濾光片受力的解析模型。我們也探討關於變形後的彩色濾光片與後方薄膜電晶體層是否有接觸狀況,其結果會影響液晶槽內可以灌注的液晶量。此外,利用三維流固耦合有限元素法驗證本論文所提出之解析模型。結果顯示,體積因子是最主要影響彩色濾光片的變形,亦即與重力mura的產生有高度的相關性。根據模擬結果進行解析模型的修正,建立一個液晶槽設計準則,在未灌注液晶進入液晶槽時,可以預測大尺寸面板是否產生重力mura。 This dissertation shows that a porous structure for a reduced graphene oxide (rGO) membrane effectively enhances its gauge factor. A composite graphene-based membrane was synthesized in a liquid phase by combining a graphene oxide (GO) sheet with copper hydroxide nanostrands (CHNs). An amount of defects on GO surface and edge create complex and unordered carbon atomic networks, which are strongly insulated, hydrophilic and have a wide interlayer spacing from oxygen functional groups. The heavily decorated GO sheets consist partly of bonded sp3 carbon networks, which are quite limited in many applications. Therefore, a chemical reduction treatment using L-ascorbic acid (L-AA) was utilized to simultaneously improve the conductivity of GO and remove the CHNs from each GO sheet. Optical spectral analysis are employed to verify the level of reduction of the rGO membrane and the experiential results indicate that L-AA is an efficient reducing agent for removing the oxygen functional groups on the surface and edge of the GO sheet to form a uniform rGO. Besides, the cross-sectional SEM images easily distinguish the different morphology for rGO and porous rGO membranes. The cross-section shape and the diameter confirm that these pores are caused by the sacrificial CHNs. The intrinsic gauge factors of the porous rGO membrane with varying applied tensile strains were obtained and found to increase monotonically with the increased porosity of the rGO membrane. For a membrane porosity of 15.78 %, the maximum gauge factor is 46.1 under an applied strain of less than 1 %. In order to enhance the sensitivity of porous rGO membrane, through the adjustment of feature size and spacing length for PDMS-based micro pyramid thin film, the sensitivity of porous rGO membrane with 30 um feature size and three-fold feature size can be obtained with value of -0.26 kPa-1. The main mechanism behind the enhanced gauge factor is attributed to the structure of the porous rGO membrane. Our experiment showed that the increment of initial resistance for porous rGO membrane can enhance gauge factor, which is made by increasing porosity. A tunneling model is proposed to illustrate the electrical conduction configuration for a porous rGO membrane with different porosities. The relationships between the initial electrical resistance, tunneling distance, and gauge factor of the rGO membrane were found by adjusting the membrane porosity and the results completely confirmed that a larger tunneling distance leads to more sensitive sensing for a porous rGO membrane and that increasing the membrane porosity is an effective means to enhance the gauge factor of a porous rGO membrane. In addition, gravity mura is an improper deformation, which could be observed in large-sized liquid crystal display (LCD) commonly. In order to avoid further damage due to this deformation, an analytical model is proposed in this investigation to estimate the deflection of the color filter (CF) glass under LC hydrostatic loading and thermal expansion of CF glass in LC cell, which can predict the occurrence of gravity mura approximately. The presented analytical model is described by a fixed-fixed ends beam with a series of rigid photospacer (PS) under applied loading. The contact status between CF glass and TFT substrate is also discussed to examine the contact status between PS and TFT substrate with various volume injection of LC. The accuracy of the proposed analytical model is verified by three-dimensional multi-physics finite element simulation. Those discussed results concluded that volumetric factor is the key parameter to dominate the deformation of CF glass, which is highly correlated to the occurrence opportunity of gravity mura. According to this modified analytical model, it provides further evidences to construct a design criterion of LC cells to avoid gravity mura before LC injection. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/51480 |
全文授權: | 有償授權 |
顯示於系所單位: | 應用力學研究所 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-105-1.pdf 目前未授權公開取用 | 26.69 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。