可調疏水性表面液珠控制與接觸行為研究

Droplets Contact Behaviors and a Droplet Manipulation on the Tunable Textured Surfaces

黃稚游(Chih-Yu Hwang)

指導教授 ： 楊鏡堂

國立臺灣大學/工學院/機械工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02360

摘要

本文主旨在研發主動式調控必液滴表面自由能梯度之方式，開發一數位流體操控平台。原理建立在熱力學最小位能的趨勢現象中，以腔體壓力變化拉伸可調表面液滴接觸角的超疏水性表面，在液滴周圍建立液滴表面自由能梯度，移動液珠達到操控液珠的效果。利用微米結構製程技術在彈性材質上製造具備高液滴接觸角的微米結構超疏水性表面，並製造可調控單點腔體氣壓的陣列。利用真空泵浦對腔體抽氣透過壓力變化對超疏水性表面進行拉伸，改變與液滴接觸的幾何型態，使超疏水性表面的液滴接觸角改變，而出現與原狀態不同的液滴表面自由能，造成超疏水性表面上的液滴表面自由能梯度，最後移動液珠。從觀察彈性材質微米結構超疏水性表面受不同大小壓力力拉伸造成不同表面幾何結構密度與接觸角的關係，以可調控單點腔體氣壓拉伸裝置為核心，結合不同量測儀器如光學顯微鏡、接觸角量測儀等，分別探討各參數定量分析的結果。用固體力學有限元素分析軟體，以數值計算的方式估計壓力大小與位置對彈性材質結構超疏水性表面結構幾何型態的關係，及液滴在該表面接觸形態下會發生的反應，進而估計所施加壓力大小與位置對液滴傳輸行為的影響，將結果與實際操作實驗做對證。本研究開發的液滴操控技術以表面結構改變方式造成液珠表面自由能梯度並以熱力學最小位能原理驅動液珠，在操控的過程中並不會對液珠內部性質造成其他影響，因此具有高度的生物相容性。利用氣壓腔體陣列以壓力調整超疏水性表面局部變形，提升對液滴操控的效率。研究成果可應用於生醫或化學合成的數位流體系統，以簡單有效率且不影響液滴內部性質的方式傳輸液滴，提高液滴混合反應的效率，將會成為數位微流體生化分析系統中的關鍵技術。

關鍵字

微流體 ； 微全分析系統 ； 表面自由能 ； 微液滴驅動

並列摘要

This master thesis features a novel suction-type, open-surface micro-droplet actuation device by constructing a gradient of Gibbs frees energy on a tunable hydrophobic surface. In this device, the tunable hydrophobic surface is consisting a PDMS membrane with upright micro-pillars and PDMS air chambers which sustains the membrane. The hydrophobicity of the hydrophobic surface could be tuned by applying a minus pressure to the air chamber under the surface which induces deformation of PDMS membrane enhancing the change of surface morphology as well as the liquid/solid contacting fraction. The Gibb’s free energy could be changed by different liquid/solid contacting fractions, hence creating a gradient of Gibbs free energy and actuating the micro-droplet subsequently. In this thesis, the membrane deformation and surface morphology are analyzed firstly by finite-element-analysis software and utilizing theoretical solutions to calculate the contacting behavior of micro-droplet and the Gibbs free energy changed of the surface. The detail parameters of the device are designed from the analyzed results. The experimental results prove the feasibility of the theoretical results in this thesis. The concept of droplet actuation of the device is using the Gibbs free energy gradient as driving force. Therefore it can avoid any interference from manipulation of the droplet. The results of this thesis provide a novel design concept for droplet actuation of digital fluidic systems which can be utilized for chemical or biological applications.

並列關鍵字

microfluidics ； micro total analysis system ； Gibbs free energy ； droplet actuation

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