本研究提出了一微流體感測器，目的在於檢測流速和黏度，尤其是超低黏度之量測。在研究中利用流體引致振動現象，驅動光纖於流速以及壓力影響下之位移訊號，透過頻譜分析之後，以其頻率表達不同流體之流速以及黏度。研究上，主要利用化學蝕刻之後之單模光纖，即光纖懸臂樑，因直徑較小便使得其可橈性較大，容易在微流體系統下隨著流體動力行為而改變，藉由光纖將流體特性訊號以光學訊號輸出，並且透過雪崩二極體（APD, avalanche photodiode）光強度感測器量測光纖懸臂樑自由端處之訊號。研究中，光纖直徑約為9 μm並嵌入在微流體晶片之中，經由綠光雷射耦光至微流體管道之中。本研究透過輸入不同流速時，即產生光纖兩側之不對稱壓力，進而有流體引致振動現象，並帶動光纖振動。在分析上，於APD捕捉訊號時可發現其時域下振動之週期性，通過頻譜分析，將收集到的光強度週期性訊號轉換成頻率，而當液體流速越大時光纖懸臂樑振動頻率也越大，另外一方面，也以黏滯係數為二氧化碳(0.0148 cP)，氮氣(0.0174 cP)，空氣(0.0183 cP)，氧氣(0.0202 cP)，氬氣(0.0223)，進行量測，其振動頻率由於流體黏滯力影響降低，故流速越快其振動頻率也隨之增高，且振動頻率約在液體時的40倍，故流體動態特性，包括流速和黏度可以以此方式檢測。研究結果可知，本研究演示的感測器能夠感測流體樣品的流速0.17 m/s至68.81 m/s 以及黏度從0.306 cP至1.200 cP。此外，在氣體中之結果為0.0148 cP至0.0223 cP，且於去離子水中之量測靈敏度約為3.667 mm/(s•Hz)，即約為40 μL/(min•Hz)，而在氣體中為6.190 mm/(s•Hz)。微流體流速及黏度感測器的研製提供了一個簡單而直接的方法用於在微流體通道之中檢測流體特性，其可以精確的同時量測超低黏滯係數之氣體黏度及流速。

This study developed a microfluidic flow sensor for the detections of velocity and viscosity, especially for ultra-low viscosity detection. An etched optic fiber with the diameter of 9 μm is embedded in a microfluidic chip to couple green laser light into the microfluidic channel. The flow induced vibration causes periodic flapping motion of the optic fiber cantilever because of the pressure difference from two sides of fiber cantilever. Through the frequency analysis, the fluidic properties including the flow rate and the viscosity can be detected and identified. Results show that this developed sensor is capable of sensing liquid samples with the flow rates from 0.17 m/s to 68.81 m/s and the viscosities from 0.306 cP to 1.200 cP. In addition, air samples (0.0183 cP) with various flow rates can also be detected using the developed sensor. Although the detectable range for flow rate sensing is not wide, the sensitivity is high of up to around 3.667 mm/(s•Hz) in test liquid in DI water, and when detecting air the sensitivity is 6.190 mm/(s•Hz). The developed flow sensor provides a simple and straight forward method for sensing flow characteristics in a microfluidic channel.

致謝 i
目錄 ii
圖目錄 v
表目錄 vii
符號表 viii
簡寫表 x
摘要 xi
Abstract xii
第一章　緒論 1
1-1 前言 1
1-2 封閉環境內的流體行為 1
1-3 流速感測原理與流速計 3
1-3-1 流速感測原理 3
1-3-2 光學式流體感測器 3
1-3-3 聲學式流體感測器 5
1-3-4 熱力學式流體感測器 6
1-3-5 流體力學式流體感測器 8
1-4 黏度感測原理與黏度計 11
1-5 文獻回顧 16
1-6 研究動機與目的 22
1-7 論文架構 23
第二章 流體引致振動原理 24
2-1 不同流體行為引致結構物振動 24
2-2 渦流引致振動 25
2-3 紊流引致振動流場 29
第三章 晶片製作與實驗架設 32
3-1 轉能器製作 32
3-1-1 光纖 32
3-1-2 光纖懸臂樑製作 33
3-2 晶片設計與製作 35
3-2-1 晶片之光罩設計 35
3-2-2 晶片製作流程 36
3-3 實驗架設 41
3-4 實驗方法 43
3-5 訊號處理 44
第四章 結果與討論 45
4-1 實驗晶片 45
4-2 流體引致光纖懸臂樑振動過程 45
4-3 振動訊號分析於時域以及頻域 46
4-4 DI water流速與振動頻率之關係 50
4-5 空氣流速與振動頻率的關係 52
4-6 不同液體黏度與頻率之關係 53
4-7 不同氣體黏度與頻率之關係 54
4-8 不同氣體流速與頻率之關係 55
4-9 第一階振動頻率與第二階振動頻率與流速之關係 56
第五章 結論與未來展望 58
5-1 結論 58
5-2 未來展望 59
參考文獻 60
Appendix A 68
Appendix B 70
自述 71

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