稀薄濃度生化樣品收集之微流體元件分析與製作

Analysis and Fabrication of Microfluidic Devices for Concentrating Dilute Biochemical Samples

余吉承(Ji-cheng Yu)

指導教授 ： 陳致真

國立清華大學/工學院/動力機械工程學系/碩士(2014年)

https://doi.org/10.6843/NTHU.2014.00197

摘要

生物感測技術作為分子檢測的平台，提供了生物樣品中的內含物種類，或者已知樣品的濃度測定等相關訊息，在疾病檢測與生醫研究扮演重要角色。在生物樣品檢測實驗當中，待測生物樣品的濃度依據生物體的表現量有所不同，時有樣品濃度過低，無法突破儀器靈敏度極限，導致儀器無法偵測樣品的存在。解決樣品的濃度過低問題，一般性的策略是使用濃縮技術，使待測樣品濃度增加以符合檢測需要。然而，泛用的濃縮技術，如高速離心，對於分子尺寸較小的待測物，需要長時間的離心才有辦法達成濃縮目的，而延遲整體實驗進程，甚至提高生物樣品質變的風險。因此，高效率的濃縮技術，對於生物檢測進程的效率提升有研究的必要。

由於近年微流道系統的發展製作各種生物晶片，使我們得以在小尺寸的生物晶片上完成複雜實驗，是生物檢測的重要發展方向。因此，本文的研究著重於在微流道晶片當中製作元件，有效率的濃縮小分子輔助生物檢測的進程。在實驗的設計上，我們在微流道晶片結構中，製作奈米流道搭配電場的施加，透過電雙層的效應達成有效率的分子濃縮。在製程上我們首先以聚焦離子束(Focused Ion Beam, FIB)，在SU-8模組上加工出奈米線；接著透過黃光微影製SU-8光阻組成的微流道模具，搭配軟式微影製程以PDMS (polydimethylsiloxane )完成微流道晶片製作。由相關文獻中顯示，微流道的幾何結構，會影響分子收集效率的情形。因此，我們的研究重點在於改變微流道寬度結構，探討微流道的幾何結構對收集分子效率的影響。在微流道的幾何設計上，我們對微流道的局部結構，改變微流道寬度(30μm, 20μm, 10μm)，觀測局部流道寬度改變後，對分子收集的影響。

整體研究結果共分為模擬與實驗兩部分，在模擬方面是使用有限元素分析(Finite Element Method, FEM)藉由改變電位的方式來探討不同微流體尺寸寬度與不同奈米流道尺寸之微流體裝置電場與電滲透流差異。在實驗方面，我們先觀測不同尺寸之微米流道寬度與奈米流道對於螢光分子之收集結果。實驗的結果顯示，寬度20μm微流體裝置螢光粒子的收集效率最高，另外當奈米流道尺寸越小時，會使螢光分子的收集效率更加提升。第二部份我們討論元件使用的過程中產生的奈米流道堵塞時，對電雙層強度之影響，用以提供未來元件改善建議。第二部分的實驗結果呈現，當奈米流道堵塞越大時電雙層效果越明顯且集中效果越佳。

關鍵字

聚焦離子束(FIB) ； 奈米流道 ； 有限元素 ； 電滲透流流場

並列摘要

The bio-sensing technology can be acted as an important role of molecular detection platform in disease detection and biomedical research, which not only provides details for bio-sample, but the information of sample concentration. In the experiment of sample detection, the concentration of the sample which should be tested will vary large differences; thus reaches the sensitivity of the apparatus, leading to the disable-detection of the presence of the sample. To manage the problem of low concentration, the common strategy is using inspissation technology, fitting the needs of the detection. However, the above technology, for example, high-speed centrifugation, for small samples, should take longer times and higher the risk of metamorphism. Thus, high efficiency of the inspissation technology should be necessarily researched.

Due to the system of nanochannel, it helps make many kinds of bio-chips; thus helping us to do the complete experiment for bio-sample. Therefore, our research is aimed at making components for bio-chips, making high efficiency progress at bio-detection for concentrating molecules. For the design of this experiment, we additionally fabricate nanochannel with electric field through electric double layer effect to accomplish the effective inspissation of molecules. And for the fabrication part, we first use Focused Ion Beam, FIB, to make nanowires at the mold of SU-8; then we use soft-lithography with Polydimethylsiloxane, PDMS, to finish our microchannles. Based on the references, they indicated that the geometry of the microchannel will affect the molecular-collection of the efficiency. So, our research also aim at changing the width of the microchannel. For our geometry, we design the width of 30μm, 20μm and 10μm respectively, investigating the changing of the width and see what’s affecting our collection-efficiency.

The whole research can be distinguished into two parts, simulation and experiment. The simulation is to use the approach of Finite Element Method, FEM, to change the potential, discussing different kinds of nanochannel-width, microfluidic electric field and electro-osmotic flow. And for the experiment part, we observe the results of the collection of fluorescent molecules in different microchannel-width first. The experiment result indicates that 20μm width of microchannel has the highest collection-efficiency. Besides, when changing dimensions smaller, the collection-efficiency will enhance. The second part we discuss while happening blockage of the nanochannel when used, what will be affected for the electric double layer. The second part shows that while severely blocked the nanochannel, the effect of the electric double layer will be more obvious and finely-collect.

並列關鍵字

Focused Ion Beam (FIB) ； nanochannel ； Finite Element Method (FEM) ； Electro-osmotic flow

參考文獻

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