A Solid-State Thin-Film Ag/AgCl Reference Electrode Coated with Graphene Oxide and Its Use in a pH Sensor

Sensors

Tae Yong Kim¹  Sung A Hong¹  Sung Yang¹ 

[1] Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea; E-Mails:

关键词: Ag/AgCl;    reference electrode;    pH sensor;    graphene oxide;    iridium oxide pH working electrode;    potentiometer;   

DOI  :  10.3390/s150306469

来源: mdpi

【 摘 要 】

In this study, we describe a novel solid-state thin-film Ag/AgCl reference electrode (SSRE) that was coated with a protective layer of graphene oxide (GO). This layer was prepared by drop casting a solution of GO on the Ag/AgCl thin film. The potential differences exhibited by the SSRE were less than 2 mV for 26 days. The cyclic voltammograms of the SSRE were almost similar to those of a commercial reference electrode, while the diffusion coefficient of Fe(CN)₆³⁻ as calculated from the cathodic peaks of the SSRE was 6.48 × 10⁻⁶ cm²/s. The SSRE was used in conjunction with a laboratory-made working electrode to determine its suitability for practical use. The average pH sensitivity of this combined sensor was 58.5 mV/pH in the acid-to-base direction; the correlation coefficient was greater than 0.99. In addition, an integrated pH sensor that included the SSRE was packaged in a secure digital (SD) card and tested. The average sensitivity of the chip was 56.8 mV/pH, with the correlation coefficient being greater than 0.99. In addition, a pH sensing test was also performed by using a laboratory-made potentiometer, which showed a sensitivity of 55.4 mV/pH, with the correlation coefficient being greater than 0.99.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.