title: A solid-state thin-film Ag/AgCl reference electrode coated with graphene oxide and its use in a pH sensor.
abstract: 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.
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea. tykim9544@gist.ac.kr.
authors: Tae Yong
authors: TY
authors: Kim
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea. griefskysea@gist.ac.kr.
authors: Sung A
authors: SA
authors: Hong
authors: Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea. syang@gist.ac.kr.|School of Mechatronics, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea. syang@gist.ac.kr.
authors: Sung
authors: S
authors: Yang
mesh_terms: D015374:Biosensing Techniques; D004563:Electrochemistry; D006108:Graphite / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry; D012834:Silver / Q000737:chemistry*
chemical_list: D010087:Oxides; D012834:Silver; D010984:Platinum; D006108:Graphite