USE OF SOLID-STATE PROTONIC CONDUCTORS FOR OXYGEN POTENTIOMETRIC SENSOR AT ROOM-TEMPERATURE

The use of oxygen sensors based on oxygen conductors such as stabilized zirconia is restricted at temperatures > 300-degrees-C. Oxygen sensors operating at room temperature are however required for many purposes, especially in environmental and biological analyses. We have therefore studied the realization of a simple solid state sensor for oxygen at room temperature, which utilizes a thin film of pellicular zirconium phosphate or NAFION as protonic conductor, a titanium hydride plate as solid state reference electrode and a sensing catalytic electrode of Pt. Such a sensor is based on the H2-O2 mixed potential which is produced at the sensing electrode when short pulses of current are applied. Potential measurements are periodically performed after a suitable delay time forms the end of each pulse. The potential is a linear function over a large range of log P(O2), while, in the most favourable conditions, the sensitivity limit is of a few parts per millions.