液態三氧化鎢/氧化銥二極體葡萄糖感測元件對葡萄糖濃度響應之研究

Abstract

本實驗的目的在於利用一種對pH值有感應的三氧化鎢/氧化銥二極體和葡萄 糖氧化脢 (GOD)固定化技術 (immobilization)，將葡萄糖氧化脢以交叉鏈結的 方式固定於聚乙烯醇 (PVA)薄膜中，製作出一種新的微型化葡萄糖感測元件， 用以感測溶液中葡萄糖的濃度。這個葡萄糖感測元件由於主要以三氧化鎢和氧化 銥薄膜所組成，所以能穩定的在液態環境中工作，不像一般P-N接面二極體或金- 半二極體並不能穩定的在液態環境中操作。實驗發現在固定的偏壓下，通過二極 體葡萄糖感測器的電流將隨葡萄糖在醋酸緩衝溶液 (Acetic buffer solution)中濃 度的增加而減少，由減少的電流多寡，我們就可以知道葡萄糖在溶液中的濃度。 以目前的實驗結果顯示，這個葡萄糖感測器能夠感測的範圍至少在1mM到20mM 之間，而且電流變化量與葡萄糖濃度之指數會具有線性的關係，反應時間約為10 min，而decay time constant約為4min。當反覆的切換兩種不同濃度的葡萄糖溶 液時，實驗顯示這個元件的感測電性是可逆的，並且是具有耐久性的，在經過長 時間的測量後，元件的電流特性並沒有明顯的改變。

A glucose microsensor based on glucose oxidase immobilized over a WO3/IrO2 electrochemical microdiode is tested for rectified sensing current measurement. The use of bovine serum albumin for covalently linking with the GOD enzyme improved the physical immobilization of the enzyme in the polymeric matrix, decreasing its loss of enzymatic activity in time. The oxidation of glucose catalyzed by GOD is sufficiently rapid, and induces changes of the pH value of acetic buffer solution ( pH = 5.5 ) in the enzyme layer. When pH value of the acetic buffer solution decay, the current pass through W03/Ir02; diode would decay too. Our device exhibits reversible and reproducible glucose concentration dependence over the glucose concentration range of 1 mM to 20 mM. The relation between current change and the log of glucose concentration was linear. The reaction time was 10 min and the decay time constant was about 4 min.