Nanosized Metal-Oxide Semiconducting SrTi 1±x O 3−δ Oxygen Gas Sensors for Low-Temperature Application

The X-ray diffraction and transmission electron microscope results show that nanosized-SrTi1±xO3−δ material se- ries (27 nm) with perovskite structure can be synthesized using the high-energy ball milling technique. The thick-film screen-printed nanosized-SrTi1±xO3−δ -based sensor series with annealing tem- perature of 400 ◦ C are found to have good oxygen-sensing property at near human-body temperature for the first time for such a low temperature. The effect of the deviating stoichiometry of the nanosized-SrTi1±xO3−δ -based sensors on their sensing properties was also investigated. The optimal relative resis- tance (Rnitrogen/R20% oxygen) value of 6.35 was obtained by a nanosized-SrTiO3−δ -based sensor at 40 ◦ C operating temper- ature. Their near human-body operating temperature is much lower than that of the conventional low-temperature semicon- ducting oxygen gas sensors (300 ◦ C−500 ◦ C) and SrTiO3 oxygen sensors (> 700 ◦ C). This can extend the application of the semi- conducting oxygen gas sensors from the conventional high and medium temperature to the lower operating temperature areas such as the medical, environmental, and domestic fields, etc. Index Terms—Low-temperature sensing property, mechanism analysis, nanosized-SrTi1±xO3−δ , the deviating stoichiometry effect.