| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 97 === A pH sensor is an electronic instrument used to measure the pH value that is acidity or alkalinity of a liquid. A typical pH meter consists of a special measuring probe (a glass electrode) connected to an electronic meter that measures and displays the pH reading. The pH sensing electrode has already been a cutting edge technology. A pH sensor is also important for ion-selective electrode (ISE) and biosensor, because pH sensor can be coated with specific sensing membrane to detect other ions and chemical or biochemical solutions, it dose not only limit to detect hydrogen ions. So a pH sensor plays an important role on development of chemical and biochemical science. The hydrogen ions sensing device has several types: electrochemical, optical, piezo-electric and calorimetric, etc.. The most popular form is electrochemical. In this study, we would like to present the potentiometric type.
Up to now, the patients of diabetes mellitus have paid much attention on control of blood sugar. Monitoring the blood sugar concentration becomes regular thing in daily life for diabetes, so the preceding sensing device is vital in medical monitor. A biosensor is a device for the detection of an analyte that combines biological component with a physical or chemical detect component. In this thesis, we fabricated glucose biosensor by potentiometric methods. On the development of biosensor, although the amperometric one has faster response and the accuracy is better, but the potentiometric type is simple in preparation, easy in operation and selective in analytical performance.
Recently, an ITO/PET substrate replaces a glass substrate in photoelectric industries extensively, because the benefits of flexile characteristic and good transmittance. In this article, we utilized R.F. sputter technique to coat SnO2 membrane on ITO/PET substrate and fabricated a potentiometric pH electrode. The ITO/PET substrate make sensor can be fabricated a large amount, due to the thickness of the plastic substrate is thin enough. Finally, we used the sensing characteristic of hydrogen ions sensing electrode to create a glucose biosensor based on chitosan (chi) and carbon nano-tubes (CNTs). The coating of SnO2 thin film makes the basic properties of the hydrogen ions sensing device better, especially in sensitivity and non-ideal effect. Finally, the potentiometric glucose biosensor based on pH sensor is going to be presented and discussed. The sensitivity of the potentiometric glucose biosensor reaches to 0.2443 mV/(mg/dl), because of the effect of mediator of carbon nano-tubes (CNTs), the output response is between 150 mV and 200 mV.
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