利用氧電漿增進網版印刷碳膠電極之電化學特性

Abstract

網版印刷碳膠電極近年來被廣泛的應用在電化學感測器中，它有著低成本、製造簡單、可圖案化等的優點，適合用在拋棄式的感測系統，本研究中針對氧電漿處理網版印刷碳膠電極做了詳盡的研究。 我們發現修飾後電極對偵測過氧化氫的氧化電流有明顯的大幅提升，連續使用的再現性良好 (R.S.D= 6.9%, n= 75)，效果可維持超過3各月，接著將葡萄糖氧化酶固定在電極表面上，進行葡萄糖感測，修飾後電極能比未修飾電極的最低偵測濃度的要低10倍，大幅提升了感測的靈敏度，同時顯示出修飾後電極應用在以氧化酶為主的電化學感測器的潛力。 從多巴胺、鐵氰化鉀、鄰苯二酚的循環伏安圖中，我們發現電漿處理大幅提升了氧化還原物質與電極間的電子轉移速率，從電顯圖推測電漿處理能清除掉碳膠電極表層及表層縫隙間不利於電子轉移的黏膠，同時暴露出較多擁有良好電子轉移特性的石墨結晶區域，以達到增進氧化還原物質與電極間的電子轉移速率的效果。最後在尿酸/維他命C複合式感測系統中，修飾過後電極因為具有良好的電子轉移特性，能大幅排除兩氧化還原物質者間的相互干擾，提高了感測的準確度，同時也顯示出修飾後電極應用到複合式感測器的潛力。

Screen-printed carbon paste electrode (SPCE) is widely used in electrochemical sensors in recent years. SPCE exhibits a great potential in the generation of disposable sensing system because it is cost effective, easily mass-produced and easily patterned. In this study, the modification of SPCE by oxygen plasma was thoroughly investigated. Interestingly, the response of oxidative current of hydrogen peroxide was greatly improved at plasma-treated SPCE. It had a good reproducibility in duplicate test (CV=6.9%, n=75) and storage test (over 3 months). The glucose sensor fabricated on the plasma-treated SPCE has a much lower detection limit for glucose than that fabricated on the untreated SPCE. These results indicate that plasma-treated SPCE has the potential for enhancing the sensitivity of oxidase-based electrochemical sensor. The rate of electron transfer between the redox couple and the electrode of SPCE is also greatly enhanced by the oxygen plasma treatment, as demonstrated by the cyclic voltammograms of dopamine, ferricyanide, and catechol. The electrochemical properties of SPCE is improved by the reduction of the separation between oxidative and reductive peak potentials, and approaching to the approximately unit of peak currents for redox compounds. The improvement of the electrochemical properties of SPCE allows the detection of multiple analytes, such as uric acid and ascorbic acid, on SPCE at the same time. Microscopic images of SPCE under the reflective microscope reveal that the surface of SPCE is flattened by oxygen plasma, suggesting the removal of substances from the surface of SPCE. The microscopic images under the scanning electronic microscope further demonstrate that pasting binder, an adhesive material to glue graphite particles to each other and to the surface of solid substrate, is removed. The removal of the pasting binder on the surface of electrode exposes graphite particles and their edge-plane, which facilitates the rate of electron transfer.