Title: A precise pH microsensor using RF-sputtering IrO2 and Ta2O5 films on Pt-electrode
Authors: Kuo, Li-Min
Chou, Yi-Chia
Chen, Kuan-Neng
Lu, Chien-Chia
Chao, Shuchi
Department of Electrophysics
Department of Electronics Engineering and Institute of Electronics
Keywords: IrO2;Ta2O5;pH sensor;Proton-electron double injection;Solid-state sensor
Issue Date: 1-Mar-2014
Abstract: In this study, an easily implemented surface modification scheme is reported employing Ta2O5 membrane which covers IrO2 electrode in response to H+ and eliminating redox species interference. Evidence shows that H+ can pass through Ta2O5 films and react with IrO2/Pt electrodes due to proton-electron double injection. A Ta2O5 membrane, an ionic conductor with an insulating property, blocks the transport of electrons generated from oxygen perturbation in the solution. The conduction of both electrons and protons preserve the current continuity across the interface. Owing to proton-electron double injection, IrO2 will be reduced to Ir(OH)(3) during pH detection. The [IrO2]/[Ir(OH)(3)] will remain constant and therefore the Nernstian electrode potential performs stably as a function of pH (-59.447 to -59.504 mV/pH, 2< pH <13). In addition, the proposed pH microsensor displayed high ion selectivity with respect to K+, Na+, and Li+, with log K-H,K-M values (similar to-12.4) and has a working lifetime over one week. (C) 2013 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.snb.2013.11.109
ISSN: 0925-4005
DOI: 10.1016/j.snb.2013.11.109
Volume: 193
Begin Page: 687
End Page: 691
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