嵌入式環盤電極微結構進行次微米電化學反應之研究

Abstract

電化學阻抗式生物感測器具有體積小、成本低、操作簡易及訊號放大的優點，透過電學與化學的轉換，可以讓我們掌握生物分子的資訊，應用在生物感測器上。配合著元件製作技術的尺寸微縮，眾多研究指出微電極結構能加快質傳效應、擁有較高的信噪比以及較低的電壓降，透過設計成微米或奈米尺寸電極陣列，每個獨立電極會並行運行從而放大電流，同時也保留著微小電極的良好特性。這些特性促使我們利用無塵室機台，在成本較低的載玻片基板上製作3D垂直堆疊的金屬-絕緣體-金屬高密度環盤狀微電極陣列，不僅利用3D結構將電極之間的距離縮減到400奈米，並且在感應區域內做不同的結構設計來觀察元件性能。在本論文中，我們使用循環伏安法與電化學阻抗分析法來測量這些元件，我們發現出現穩態趨勢的循環伏安法具有電流放大的效應，電流和電荷轉移率隨著赤黃血鹽的濃度上升而上升，電流甚至與赤黃血鹽的濃度呈線性關係。在出現峰值的循環伏安法趨勢下，電流與掃描速率也呈線性正比。而當我們選擇臨界尺寸為奈米等級的環電極作為工作電極時，可以發現即便與本來的工作電極面積相差100倍，電流的大小卻僅僅小三倍，代表著奈米尺度的元件也具有不乏的電流放大特性。透過縮小電極尺寸至微米與奈米等級時，可以執行更加快速的電化學與化學反應，這是因為電極表面的反應物在高速的質傳下不會限制到電荷轉移的過程。

Electrochemical impedance biosensors have the advantages of small size, low cost, easy operation and signal amplification. We can get the information of biomolecular from the transfer of electricity and chemical. A lot of experiments proved that electrochemical responses at microelectrode structure have special qualities, for example quick mass exchange, have high sign to-commotion proportion, and inconsequential ohmic misfortunes. By designing an array of micrometer- or nanometer-sized electrodes, each individual electrode operates in parallel to amplify the current, while retaining the good properties of tiny electrodes. These properties propel the manufacture of high thickness, horizontally requested varieties of microholes, installing upward stacked metal-cover metal cathode structures and controlled size and thickness of openings. In this thesis, we use cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) to measure the characteristics of these microscale recessed ring-disk electrode (RRDE) arrays with nanoscale interpore spacing. We found that steady-state cyclic voltammetry measurement exhibits current amplification. Current and charge transfer rate increases as the concentration of Fe(CN)63-/4-. Current increasing linearly with scan rates in peak current cyclic voltammetry measurement. As we exchange the ring-disk electrode’s connection, although working electrode’s critical dimension is nanoscale which is a hundred times smaller than before, the current is only three times smaller than another. It represents that nanoscale electrode can also enhance the current. By decreasing the size of electrode to submicro scale, faster electrochemical and chemical reactions should be possible. It is because of that the mass transport will not limit the electron transfer at high rates of it.