Ultraselective and ultrasensitive detection of H2S in highly humid atmosphere using CuO-loaded SnO2 hollow spheres for real-time diagnosis of halitosis

The CuO-loaded SnO2 hollow spheres were prepared by ultrasonic spray pyrolysis and their H2S sensing characteristics in dry and humid atmospheres for the diagnosis of halitosis were investigated. The loading of CuO to SnO2 hollow spheres decreased the humidity dependence of H2S sensing characteristics down to negligible level, increased the gas response (ratio of resistance to air and gas) in highly humid atmosphere (relative humidity 80%) to 1 ppm H2S from 3.13 to 22.4, and enhanced the selectivity to H2S over CO, NH3, CH3COCH3, C6H6, CH3C6H5, (CH3)2C6H4, and NO at 300 °C. Ultraselective and ultrasensitive detection of H2S under highly humid atmosphere with negligible interferences from other biomarker gases provides a promising and reliable analysis tool for real-time diagnosis of halitosis from exhaled breath.