BaxWOy thick film as a carbon dioxide sensor

Thick film metal oxide semiconductor gas sensors with a Ba_xWO_y active layer have been prepared and evaluated as carbon dioxide gas sensor devices. Ba_xWO_y was prepared by thermal methods and screen-printed as porous thick films gas sensors. The sensor material was characterized by scanning electron microscopy and X-ray diffraction. The sensors gas response was investigated by exposure to varying concentrations of CO₂ gas in synthetic air and mixtures of CO and CO₂ all at a variety of different operating temperatures. Finally the gas response was examined to potential intereferant gases including humidity. It was found that at an operating temperature of 450 °C and a 2500 ppm pulse of CO₂ the sensors gave a gas response of 5.8, higher than current literature values. It was also found that increasing relative humidity enhanced the gas response in contrast to other approaches.