Construction and Electrochemical Characterization of Microelectrodes for Improved Sensitivity in Paper-Based Analytical Devices

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• 作者：Murilo Santhiago ; John B. Wydallis ; Lauro T. Kubota ; Charles S. Henry
• 刊名：Analytical Chemistry
• 出版年：2013
• 出版时间：May 21, 2013
• 年：2013
• 卷：85
• 期：10
• 页码：5233-5239
• 全文大小：334K
• 年卷期：v.85,no.10(May 21, 2013)
• ISSN：1520-6882

文摘

This work presents a simple, low cost method for creating microelectrodes for electrochemical paper-based analytical devices (ePADs). The microelectrodes were constructed by backfilling small holes made in polyester sheets using a CO₂ laser etching system. To make electrical connections, the working electrodes were combined with silver screen-printed paper in a sandwich type two-electrode configuration. The devices were characterized using linear sweep voltammetry, and the results are in good agreement with theoretical predictions for electrode size and shape. As a proof-of-concept, cysteine was measured using cobalt phthalocyanine as a redox mediator. The rate constant (k_obs) for the chemical reaction between cysteine and the redox mediator was obtained by chronoamperometry and found to be on the order of 10⁵ s^鈥? M^鈥?. Using a microelectrode array, it was possible to reach a limit of detection of 4.8 渭M for cysteine. The results show that carbon paste microelectrodes can be easily integrated with paper-based analytical devices.