硫酸因為其特殊的物理及化學性質，大量的運用在工業製造過程中，所以被稱為「工業之母」。正因為如此，監控濃硫酸中水分含量在工業製程上是非常重要的，然而有關濃硫酸水分感測器的研究卻非常少，僅一光學感測器，其餘皆為傳統的方法，包括滴定法、比重法及Karl Fisher法。但是用這些方法來量測濃硫酸的水分是費時以及操作繁雜的，並無法迅速的量測到濃硫酸中的水分，這在工業製程中是很不便以及沒有效率的。所以發展出一個簡單、價廉、較快速應答以及可安裝在濃硫酸有關的製程上，做為現場監控濃硫酸中少量水分的感測器是相當重要及需要的。

在此研究中以IrO2+Ta2O5的DSA (Dimensional stable anode) 為對電極，並搭配其他材料的工作電極來對90~100%濃度的濃硫酸進行感測。一開始是先以三極式的系統對濃硫酸中水份進行感測，之後再進行感測器的微小化，並利用減小工作電極與增大對電極的面積來設計一個二極式的微感測器來感測濃硫酸中水份是相當重要而且相當有趣的課題。

在濃硫酸含水量感測結果中，以濺鍍矽電極有著最高的靈敏度，但是耐久性與感測電流穩定性則以類鑽碳薄膜較佳。雖然類鑽碳薄膜對於含水量之靈敏度比矽電極要差一些，但是藉由在類鑽碳薄膜中摻雜少量矽原子，可以增加對水份之靈敏度，隨著摻雜入10.2、20.3與31.8at%的矽原子時，對水份的靈敏度也隨之增加為3.5019、6.0182與8.9876 mA/cm2*wt%，並在摻雜入10.2at%的矽原子時，可以比原來的類鑽碳薄膜有著更佳的耐腐蝕性。除了摻雜矽原子之外，同時也探討了施加偏壓對於濺鍍類鑽碳薄膜的影響。類鑽碳薄膜在施加-90V偏壓時具有最佳的耐腐蝕性，而在-60V與-75V所濺鍍而成的類鑽碳薄膜都在尚未完成全部感測時電流已開始呈現不穩定的狀態了。

並對各種電極進行加速性與的耐久性測試，藉由比較其壽命可以知道其耐久度的相對關係，以瞭解在不同製備條件、電極材料與及成分比例對電極耐久度的影響。

Sulfuric acid is widely used in industry because of its important chemical and physical properties and it is called “the mother of industry”. It is very important to monitor the water content of sulfuric acid in industry process. However, the study about water content sensor for sulfuric acid is few. There is only one spectroscopic sensor. The others are traditional methods including titration method, hydrometer method and Karl Fisher method. These methods are still time-consumed and cumbersome in operation for determination the water content of the concentrated sulfuric acid. It is inefficient and inconvenient in industrial process if the water content of concentrated sulfuric acid can not be determined in a short time. Therefore, it is important and necessary to develop a simple, low cost and faster response sensor for instantaneously detecting the water content of the concentrated sulfuric acid by an electrochemical method which can be in situ applied in the processes related to concentrated sulfuric acid.
In this study, DSA electrode coated with IrO2+Ta2O5 was used as the counter electrode and combined with other materials as the working electrode to sense the water content in sulfuric acid in the range of 90~100wt%. A three-electrode system was used to determine the water content in concentrated sulfuric acid at first, and then a microsensor for concentrated sulfuric acid was developed. To develop a microsenor was an interesting and important topic. It was tried to decrease the surface area of working electrode and increased in the counter electrode surface area to develop a two-electrode microsensor without reference electrode. And it would be much easier to reduce the size of the microsenor in this way.
The results of water content sensing performance in concentrated sulfuric acid showed that sputtered silicon electrode had the best sensitivity, and diamond-like carbon (DLC) electrode had the best durability and the most stable signal. Although the sensitivity of DLC for water content was a little worse than that of silicon electrode, it could be improved when small amount silicon was doped. As 10.2、20.3 and 31.8at% (at: atoms) silicon was doped, the sensitivities of DLC for water content were increased to 5.019、6.0182 and 8.9876 mA/cm2*wt%. The DLC thin film had better durability when 10.2at% silicon was doped. In addition to doped silicon in the DLC thin film, the effect of different bias voltage of the substrate for preparing electrode by sputtering was also discussed. The DLC thin film prepared with –90V bias had the best durability and the DLC thin film prepared with –60V and –75V bias got unstable before the sensing test was finished.
The accelerated life tests for each kind of electrode were carried out. The relationship among durability and prepared condition、electrode materials and composition could be realized by comparing their service life of those durability tests.

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