基於聚乙烯二氧噻吩固態接觸式鉀離子選擇微電極之製備

Abstract

離子選擇微電極常與掃描式電化學顯微術合併使用，進行特定離子訊號的變化以及其於空間中分布的偵測。傳統的離子選擇微電極是採用玻璃製的micropipette來製作。玻璃製的micropipette相對較為脆弱並且需要特殊製程來製作。本研究藉由直接修飾微電極表面來製作固態接觸式鉀離子選擇微電極，並驗證其對於鉀離子通量監測的應用性。首先，本研究針對微電極表面的聚 (3,4-乙烯二氧噻吩) (PEDOT) 薄膜的修飾與調控進行探討，作為固態接觸式離子選擇微電極的基礎。本研究在白金微電極 (直徑10 µm) 上電鍍摻雜了過氯酸根離子的PEDOT薄膜，作為離子與電子訊號之間的轉換層。接著，對鉀離子具有選擇性響應薄膜被浸鍍到其上，作為擷取離子訊號的一層。此固態接觸式離子選擇微電極展現出近乎理論值 (59.1 mV/dec) 的靈敏度 (59.45 mV/dec) 並擁有10-5 M的偵測濃度下限。相對地，沒有PEDOT薄膜的鉀離子選擇微電極在只達到約70%的理論靈敏度 (41.39 mV/dec) 並只有10-4 M的偵測濃度下限。另外，本研究所製作的固態接觸式鉀離子選擇微電極的響應時間約為0.5秒，並且可以成功偵測到普魯士藍薄膜表面在多階段計時電流法以及循環伏安法下進行氧化還原反應時鉀離子吞吐的訊號。可見本研究所提出的固態接觸式離子選擇微電極將可實際作為掃描式電化學顯微術的探針使用，用以監測材料表面離子通量的訊號，也可以整合電化學石英微量天秤作為探討電化學材料表面離子進出機制的基本技術。

Ion-selective microelectrodes (ISMEs) are usually utilized to detect the variation and the spatial distribution of specific ions in corporation with the scanning electrochemical microscopy (SECM). Conventional ISMEs are made with glass micropipette. The glass micropipette is relatively fragile and some special fabrication procedures are needed. In this work, the solid-contact K+ ISMEs were made by directly modifying the microelectrode surface, and its application on the monitoring K+ flux by the them was verified. First, the modification and tuning of PEDOT thin film on the microelectrode was investigated, which is the basis of solid-contact K+ ISMEs. Next, the perchloride-doped poly(3,4-ethylenedioxythiophene) (PEDOT:ClO4) was electrodeposited on the platinum microelectrode (diameter = 10 µm) as the convertor for ion and electric signal. Next, a membrane with a selective response for K+ was dip-coated as a layer capturing the ion signal. The solid-contact ISME showed a sensitivity of 59.45 mV/dec, which was close to the theoretical value of 59.1 mV/dec, and had a detection limit of 10-5 M. However, the K+ ISMEs without PEDOT thin film showed a sensitivity of only 70% of the theoretical value (41.39 mV/dec) and had a detection limit of 10-4 M. The solid-contact K+ ISMEs has a response time of 0.5 seconds and successfully detected the surface K+ when a Prussian blue thin film conducts redox reaction under chronoamperometry and cyclic voltammetry operations. Thus, the solid-contact K+ ISMEs in this work can be utilized as the probe for SECM to monitor the ion flux on the material surface, or integrated with electrochemical quartz microbalance as the basic technique for investigation of ion flux.