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標題: | 利用微流體操控技術及多倫反應製作金屬微結構並應用於微流體元件開發 Fabrication of thick metallic microstructures using microfluidic technique and Tollens’ reaction for microfluidic components |
作者: | Tzu-Heng Wu 吳咨亨 |
指導教授: | 沈弘俊(Horn-Jiunn Sheen) |
共同指導教授: | 田維誠(Wei-Cheng Tian) |
關鍵字: | 微濃縮裝置,氣相層析系統,微流體,介電泳及多壁奈米碳管, micro gas chromatogram,microfluidics,micropreconcentrator (μPCT),dielectrophoresis (DEP) and multi-wall carbon nanotube, |
出版年 : | 2012 |
學位: | 博士 |
摘要: | 本研究透過簡易的微機電製程,僅須一道光罩即可完成高效率微型氣相萃取裝置 (Micropreconcentrator)製作,並整合於氣相層析 (Gas Chromatography) 系統,進行揮發性有機氣體 (Volatile organic compounds, VOCs) 之量測與分析。結合微流體操控技術及化學還原反應(多倫反應,Tollens’reaction),發展快速之金屬沉積及高精準度之圖形轉印 (Pattern transfer)技術,將用來製作具有高加熱面積之金屬微結構,做為微型氣相萃取裝置所需之加熱電極。本文中將此技術用來發展兩種不同形式之微型氣相萃取裝置,並完成其特性測試。
相較於利用傳統微機電製程進行金屬蒸鍍,例如:電子束蒸鍍及熱蒸鍍,本研究利用微流體操控及多倫反應所發展之金屬沉積技術,具有簡易及較快速的沉積速度,能沉積厚度約為200 微米之銀微結構作為微型氣相萃取裝置之加熱元件。第一種設計是透過微流體操控技術及化學還原反應,在晶片內部形成四道液體介面,完成四條加熱電極之沉積。並透過熱裂解(Pyrolysis)方式,將碳膜包覆於銀電極表面,作為吸附氣體樣本之材料,完成本微型氣相萃取裝置之製作。當輸入功率為5 W時,具有23℃/s 之加熱速度,到達熱脫附之溫度需23秒。實驗中以濃度為10 PPM之Acetone、Benzene、Toluene及Xylene做為待測樣本,脫附之氣體樣本將經過長度為17公尺之石英管柱進行分離,最後再經由火焰離子感測器偵測分離後氣體之訊號並加以分析。由所量測之層析圖中可計算出其半高寬皆小於6秒,證明具有良好的脫附效果。 第二種設計則是利用乾蝕刻,於晶片內部製作具有高深寬比之柱狀陣列,藉此提升晶片內部表面積。同樣利用化學反應將內部沉積一層銀薄膜做微加熱電極。當輸入功率為5 W時,具有60℃/s 之加熱速度,到達熱脫附之溫度需5秒。經實驗證實,可將半高寬縮小至4秒,有效提高氣相層析分析之準確率。 此金屬沉積技術所製作之垂直電極,也應用於介電泳晶片之開發並進行奈米碳管純化之測試。相較於傳統平面電極僅在微流道底部才具有較高效能,垂直電極能在流道內不同深度的情況下,提供更均勻之電場,透過拉曼光譜分析純化前後之ID/IG,證實垂直電極能提供較高之純化效能。 A simple micromachined process based on one photomask is developed for a novel micropreconcentrator (μPCT) used in a micro gas chromatograph (μGC). Unique thick silver heating microstructures with a high surface area for microheaters of μPCT are fabricated by combining the microfluidic technique and the Tollens’ reaction within a microchannel. In this study, two types of micropreconcentrator were developed and tested. Silver deposition using this laminar flow patterning technique provides a higher deposition rate and easier microfabrication compared to conventional micromachined technologies for thick metal microstructures (> 200 μm). An amorphous and porous carbon film that functions as an adsorbent is grown conformally on microheaters inside the microchannel. The μPCT can be heated to >300℃ rapidly by applying a constant electrical power of ~5 W with a heating rate of 23℃/s. Four volatile organic compounds (VOCs), acetone, benzene, toluene, and xylene, are collected through the proposed novel μPCTs and separated successfully using a 17-m-long gas chromatography (GC) column. The peak widths at half height (PWHH) of the four compounds are relatively narrow (<6 s), and the minimum PWHH of 3.75 s is obtained for acetone. The preconcentration factors are >38 000 for benzene and toluene. The second type of μPCT with high-aspect-ratio pillar array at the adsorption region was designed and fabricated. The silver thin film heater was formed by injecting Tollens’ solutions alternately. Numerous micropreconcentrators were arranged in series to complete the silver deposition for mass production. A heating rate of 60 ℃/s could be obtained with an applied power of 5W. The peak widths at half height (PWHH) of 2.76 s, 3.24 s, 2.88 s, and 3.48 s were examined for acetone, benzene, toluene, and xylene, respectively. A high-throughput micro/nanoparticle separation device with 3D electrodes was manufactured using laminar flow patterning. The 3D electrodes were manufactured to provide dielectrophoresis (DEP) force. Only one photomask was required during the fabrication process without additional vacuum-based metal deposition processes. The optimal deposition condition was tested and two parallel 3D electrodes were successfully formed at the liquid–liquid interfaces. Multi-walled carbon nanotubes (MWCNTs) were purified using DEP force according to the electrical characteristics. Raman spectroscopy, ID/IG ratio, and current-voltage measurements were employed to compare the purification performance between 3D electrodes and planar electrodes. The ID/IG ratio of conducting MWCNTs could be reduced to 0.71. This indicates that 3D electrodes can provide greater purification. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64503 |
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顯示於系所單位: | 應用力學研究所 |
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