傳統上使用質譜儀的氣體檢測方法雖然具有高解析度、高靈敏性以及低濃度檢測極限等優點，但由於儀器本身體積龐大、成本高和繁瑣前處理等，不適合用於現場與即時之疾病檢測上。本論文主要著重於奈米線氣體感測器陣列之研發與感測特性探討以及將其應用於開發呼氣感測吹管(Exhale breath sensing tube)，所開發之感測器包含單根銀奈米線所建構之流速與溫度感測器以及單根二氧化鈦奈米線所建構之濕度與肺癌標記物感測器。
在氣體感測吹管的設計上，本研究以CFD ACE+套裝軟體模擬人體呼氣流量曲線下的暫態與穩態管流型態，並分析其管流邊界層厚度於感測器區域(距離吹管入口25~30公分)變化率3%內，可得吹管最佳管徑與長度分別為1.91公分與30公分；並進而以人體呼氣之動態邊界條件設定入口流量曲線下，管流邊界層在感測器陣列區域其厚度變化率由管長5公分之79.56 % (距離吹管入口1~5公分)降低至管長30公分之2.88 % (距離吹管入口26~30公分)。
在氣體感測實驗上，銀奈米線吹管流速感測器基於熱絲式量測機制，在流速範圍為1.0 ~8.0 L/s (固定溫度25 °C、濕度20 %)，感測靈敏度為3.29 mV/(L/s)，響應時間為560毫秒，恢復時間為1.12秒，訊號雜訊比為28.63 dB (在流速為8 L/s下)，適當感測吹管長度使得流速感測解析度與靈敏度分別提升93.02 %與37.66 %；銀奈米線溫度感測器基於熱阻式量測機制，溫度範圍為25~85 °C (靜態下感測、固定濕度20 %)，感測靈敏度為0.26 Ω/°C，響應時間為1.79秒，恢復時間為1.64秒，訊號雜訊比為49.42 dB (在溫度為85 ℃下)；二氧化鈦奈米線在相對濕度範圍為20~87 % (靜態下感測、固定溫度25 °C)下之最大靈敏度為41.98 %，響應時間為2.14秒，恢復時間為14.86秒，訊號雜訊比為26.91 dB (在濕度為87 %下)，且加長之吹管有效降低人體呼氣濕度的影響達78.88 %；最後，使用呼氣感測吹管進行肺癌標記物2-丙基-1-戊醇(2-PP)在不同流速下(1~8 L/s)的氣體感測(固定溫度25 °C、濕度20 %)，在100 ppb氣體濃度下，二氧化鈦奈米線感測器響應時間為3.64秒，恢復時間為8.79秒，訊號雜訊比為15.85 dB (在流速為1 L/s下)，且加長後吹管穩定的邊界層流動能增加氣體分子的吸附與擴散時間，其感測變異下降43.28 %。在氣體感測選擇性的部分，實驗結果顯示經化學修飾後之二氧化鈦奈米線對於不同有機氣體之選擇比最大為6.38。
總而言之，本論文所發展之創新全整合呼氣感測吹管經由理論推導及模擬與實驗比較驗證，已成功確認於人體呼氣條件下可讓感測器陣列於穩定的流場中得到其最佳的感測性能。本研究所開發之呼氣感測吹管在未來可結合嵌入式系統，具備定點照護或家用醫療診斷工具之優勢與發展潛力，提供早期肺癌診斷、肺功能檢測、其它呼氣疾病與環境安全檢測的應用。

Currently, gas detection using the mass spectrometer is a common method because of its high resolution and good sensitivity. However, due to the bulky equipment, high cost and complicate procedure, it is difficult to use as a breath sensing tool for on-site rapid screening or real-time diagnostics. In this study, we simulated, fabricated, and characterized a disposable lab-in-a-tube gas sensors based on single TiO2 nanowire and single Ag nanowire fabricated and integrated on a flexible plastic substrate, which can detect 2-propyl-1-pentanol (2-pp, one of lung cancer biomarkers), humidity, flow rate, and temperature conditions in flowing gas.
In design of the lab-in-a-tube gas sensor, we optimized the tube size of 1.91 cm in diameter and 30 cm in length by CFD ACE+ simulation package. The simulation results showed that the variation of flow boundary layer thickness in sensor array region (25~30 cm from the tube entrance) is within 3 % at constant flow-rate. And when further simulated with dynamic boundary conditions from human expiratory flow curve, the variation of flow boundary layer thickness decreases from 79.56 % (1~5 cm from the tube entrance) to 2.88 % (26~30 cm from the tube entrance) in comparsion between 5 cm-long and 30 cm-long tubes.
In our designs, we investigated the gas sensing characteristics of the developed nanowire sensors. First, the sensitivity of the Ag nanowire-based flow sensors is 3.29 mV/(L/s) (1~8 L/s, 25 °C, 20 % RH). The response time is 560 ms, and the recovery time is 1.12 seconds. The S/N ratio is 28.63 dB. The flow sensors, which have the improvements in resolution, sensitivity up to 93.02 % and 37.66 %, respectively. Second, the sensitivity of our Ag nanowire-based temperature sensor is 0.26 Ω/°C in the range of 25 ~ 85 °C (20 % RH). The response time is 1.79 seconds, and the recovery time is 1.64 seconds. The S/N ratio is 42.92 dB. Third, the humidity sensing with single TiO2 nanowire showed the maximum sensitivity of 41.98% in the RH range of 20~87 % (25 °C). The response time is 2.14 seconds, and the recovery time is 14.86 seconds. The S/N ratio is 28.63 dB. Fourth, the response and recovery time of our single TiO2 nanowire sensor for 2-propyl-1-pentanol (2-pp, one of lung cancer biomarkers) sensing are 3.64 and 8.79 seconds at the concentration of 100 ppb at the flow rate of 1 ~ 8 L/s (25 °C, 20 % RH). The S/N ratio is 15.85 dB. Moreover, the maximun selectivity of the biosensor is 6.38. Meanwhile, our design decrease the sensing varation and mositure interference of the lung cancer biomarker by 43.28 % and 78.77 %, respectively.
In summary, we simulated, fabricated, and characterized a novel exhaled breath sensing tube with on-tube nanowire sensor array, which showed high performance in a tube. In future, our developed exhaled breath sensing tube can be combined with embedded systems, which has the potential for use in several disease screening from exhaled breath, lung function diagnostics, and enviorment safety.

摘要 i
Abstract iii
致謝 v
目錄 vii
圖目錄 xi
表目錄 xvii

第一章 緒論 1
1.1 傳統氣體檢測技術 1
1.1.1 分析化學技術 1
1.1.2 電子鼻 4
1.1.3 傳統氣體檢測技術比較 6
1.2 奈米線氣體感測器 8
1.2.1 奈米線氣體濃度感測器 8
1.2.2 奈米線氣體流速感測器 10
1.2.3 奈米線氣體溫度感測器 12
1.2.4 奈米線氣體濕度感測器 13
1.2.5 場效電晶體奈米線氣體感測器 14
1.2.6 全整合管型氣體感測器 16
1.3 氣體感測特性之探討 17
1.3.1 氣體感測器之選擇性 18
1.3.2 環境因子對氣體感測之影響 19
1.4 研究動機 21
1.5 研究目的與方法 21
1.6 論文架構 22

第二章 氣體感測特性之理論 25
2.1 管流之流體力學行為 25
2.1.1 管流之流體力學基本假設 25
2.1.2 雷諾數(Reynolds number) 27
2.1.3 普朗特數(Prandtl number) 28
2.1.4 邊界層(Boundary layer) 29
2.1.5 氣體濃度擴散理論(Fick’s diffusion law) 31
2.1.6 本研究呼氣感測吹管氣體濃度擴散理論推導 34
2.2 氣體感測器運作原理 35
2.2.1 有機揮發性氣體感測原理 36
2.2.2 氣體流速量測原理 37
2.2.3 氣體溫度量測原理 39
2.2.4 氣體濕度量測原理 40

第三章 呼氣感測吹管之設計與模擬分析 41
3.1 呼氣感測吹管之設計 41
3.1.1 可撓性微奈米感測器 41
3.1.2 氣體感測器微電極陣列設計 42
3.1.2.1 銀奈米線用於氣體流速與溫度感測 44
3.1.2.2 二氧化鈦奈米線用於氣體濕度感測 45
3.1.3 呼氣感測吹管尺寸設計 46
3.2 呼氣感測吹管管流之動態模擬與分析 52
3.2.1 網格收斂性 53
3.2.2 吹管管徑大小之影響 65
3.2.3 吹管長度大小之影響 70
3.2.4 仿人體呼氣之動態管流模擬 76
3.3 結果與討論 82

第四章 氣體感測器之材料與製程 85
4.1 光電半導體二氧化鈦奈米線電紡絲製程 85
4.2 可撓性奈米線氣體感測器陣列製程 86
4.2.1 微電極陣列圖案化製程 87
4.2.2 介電泳組裝奈米線氣體感測器陣列製程 88
4.3 呼氣感測吹管製作 95
4.3.1 紫外光透光貼片 95
4.3.2 輔助加長接管 97
4.4 結論 98

第五章 全整合呼氣感測吹管之實驗結果與探討 99
5.1 發展動機 99
5.1.1 早期肺癌診斷 99
5.1.2 肺功能檢測 102
5.1.3 其它呼氣疾病檢測 103
5.2 奈米線感測器應用於氣體環境參數感測 104
5.2.1 銀奈米線用於氣體流速感測 105
5.2.2 銀奈米線用於氣體溫度感測 107
5.2.3 二氧化鈦奈米線感測器用於氣體濕度感測 110
5.3 呼氣感測吹管氣體感測實驗結果與探討 112
5.3.1 呼氣感測吹管用於氣體流速感測 112
5.3.2 呼氣感測吹管用於氣體溫度感測 118
5.3.3 呼氣感測吹管用於氣體濕度感測 120
5.3.4 不同流速下肺癌標記物氣體感測結果 122
5.3.5 不同溫濕度下肺癌標記物氣體感測結果 126
5.3.6 肺癌標記物與有機氣體選擇性感測結果 128
5.4 結論 130

第六章 總結與未來發展 133
6.1 總結 133
6.2 研究成果 133
6.3 本研究之學術貢獻點 137
6.4 未來研究建議 142

附錄 147
參考文獻 151
作者簡介 157
著作發表 159

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