Gas sensors based on silicon chip-to-chip synthesis of tin oxide nanowires

We demonstrate a novel gas sensor device, which is based on silicon chip-to-chip synthesis of ultralong tin oxide (SnO₂) nanowires. The sensor device employs an interconnected nanowire network configuration, which exhibits a huge surface-to-volume ratio and provides full access of the target gas to the nanowires. The chip-to-chip SnO₂ nanowire device has an extraordinary sensitivity to the toxic gas H₂S. A concentration of only 1.4 ppm decreases the resistance of the sensor by ~ 85%, which demonstrates a detection limit far in the ppb range. The SnO₂-nanowire fabrication procedure based on spray pyrolysis and subsequent annealing is performed at atmospheric pressure, requires no vacuum and allows upscale of the substrate to a wafer size. 3D-integration with CMOS chips is proposed as viable way for practical realization of smart nanowire based gas sensor devices for the consumer market.