A Flexible pH-Sensing Structure Using WO3/IrO2 Junction with Al2O3 Encapsulation Layer

Abstract

A diode-like current-voltage characteristic in response to hydrogen-ions based on a WO3/IrO2 diode coated with a membrane-like Al2O3 is reported. Microsensors fabricated with the oxides (IrO2 and WO3) will suffer from interference errors in pH-measurements due to their strong responses to environmental redox species. With ionic-conductive and insulation properties, the membrane can mediate the transport of released protons and block the electrons from redox species in solutions. Invoking proton-electron double injection, H+ and e(-) produce redox reactions, which control the conductivity and preserve the continuity of currents across the interface with a good sensitivity (0.168 mu A/pH) between pH = 2 to 12. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.004303ssl] All rights reserved.