6.3.4 Noble Metal Added Tin Oxide VOC Sensors as Nonanal Detection for Exhaled Breath Air Monitoring

We have investigated the VOCs-sensing properties of Pt, Pd, Au-loaded SnO2 thick film for exhaled breath air. It has been reported that breaths of lung cancer patients include long methylene chain-aldehydes, such as nonanal. The Pt, Pd, Au-loading for SnO2 type gas sensors is advantage for detect to low concentration VOCs. The Pt,Pd,Au/SnO2 element shows higher response to nonanal than a non-loaded SnO2 element. The combustion of nonanal molecules on the surface of SnO2 grains is assisted by added noble metals. A nonanal-sensing property of the The Pt,Pd,Au/SnO2 depend on an annealing temperature. We installed the sensor element to a prototype of breath monitor with gas-chromatograph system, and analyzed mixed gas including three long methylene chain-aldehyde gases.