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標題: | 開發以電流壓力感測器為基礎之微流體黏度計 Development of microfluidic viscometer based on electrofluidic pressure sensor |
作者: | Tse-Ang Lee 李澤昂 |
指導教授: | 陳希立(Sih-Li Chen) |
關鍵字: | 微流道黏度計,電流體電路,惠斯同電橋,壓力感測器, Microfluidic viscometer,Electrofluidic circuit,Wheatstone bridge,Pressure sensor, |
出版年 : | 2016 |
學位: | 碩士 |
摘要: | 黏度在生物醫學應用中扮演著重要的角色,舉凡人類的血液、口水以及尿液等體液的黏度均與健康狀況息息相關。本論文中設計並製造出一種微流體黏度計可應用於樣本體積不大的生物以及生醫樣本量測。其樣本可為牛頓或非牛頓流體,並且該黏度計具有可拋棄之特性。該黏度計中的壓力感測元件可以利用多層次軟性微影技術(multilayer soft lithography technique)直接製造,並且能夠輕易且無縫地整合於一般常用的PDMS 微流體系統中,不需要額外的組裝或是利用無塵室之精密微製造處理。
黏度的量值可以透過流阻亦即改變對流體所施加之壓力與相對應流量量值改變的比值來得到。對於非牛頓流體,除了流阻之外還需要得到冪指數(power-law index)的值來判斷黏度量值。在黏度計內,以充滿離子溶液的微流道構成一具有電子輸出訊號的壓力感測器,其量測原理係利用不同壓力造成電流體電路之電阻值發生變化,並藉由一電流體構成之惠斯同電橋透過輸出電壓的改變量測此電阻值的變化以得到壓力量值,而流量大小則由一注射泵控制,對於非牛頓流體的冪指數可以由惠斯同電橋所輸出之電壓訊號對流量作對數圖得到,配合相關的推導即可得到流體的黏度。 黏度計可量測的範圍大約為1~100 cP,剪應變率約為5 ~1000 s-1,此外,惠斯同電橋的幾何形狀在不同溫度下具有優異的穩定性,隨著溫度變化所造成的誤差會彼此互相抵銷所以不會造成量測的誤差。因此,此量測裝置可輕易地和其他微流道系統做大規模的整合並且廣泛地應用於非固定溫度的實驗環境。 Rheological properties, viscosity, are important in biomedical applications. For instance, the viscosity of body fluids such as blood, saliva or urine have been linked with health condition. A microfluidic viscometer is designed and constructed in this thesis in order to investigate the viscosity of biological and biomedical samples, including Newtonian and non-Newtonian fluids, where large sample volume is not available and disposability of the device is desired. The developed pressure sensing component can be seamlessly fabricated into polydimethylsiloxane (PDMS) microfluidic systems using the well-developed multilayer soft lithography (MSL) technique without additional assembly or sohisticated cleanroom microfabrication processes. Viscosity can be obtained through the flow resistance, ratio of the pressure change to the corresponding variation of flow rate, for Newtonian fluids. For determination of non-Newtonian fluids, an additional parameter, power-law index is required besides flow resistance. A pressure sensor with an electrical readout based on electrofluidic circuits is constructed by ionic liquid-filled microfluidic channels. The pressure sensing is achieved by measuring the pressure-induced electrical resistance variation of the electrofluidic resistor. In addition, an electrofluidic Wheatstone bridge circuit is designed for accurate and stable resistance measurements. A syringe pump is used to control the flow rate. The power-law index of non-Newtonian fluids can be obtained through the slope in a log-log plot of the output voltage shift of the Wheatstone bridge versus the flow rate. Thus, the viscosity can be calculated by the related derivation. The microfluidic viscometer is able to measure viscosity from 1 cP to around 100 cP under a wide shear rate from 5s-1 to more than 1000s-1 with sample volume less than 0.4ml. In addition, the Wheatstone bridge arrangement possesses excellent thermal stability since the temperature fluctuation will be well compensated in the system. Consequently, the device can be easily scaled up with other microfluidic system and can be applied widely in applications where various temperature operations are required. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/49215 |
DOI: | 10.6342/NTU201603132 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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