CMOS integrated tungsten oxide nanowire networks for ppb-level hydrogen sulfide sensing

We present H 2 S gas sensor devices based on tungsten oxide nanowire networks, which are integrated on CMOS fabricated microhotplate chips. Such CMOS integrated systems are promising candidates for realizing smart sensor devices for consumer market applications. The CMOS tungsten oxide gas sensors were prepared by the deposition of nanowire networks onto interdigitated electrodes on CMOS microhotplates via drop-coating. Drop-coating of a nanowire suspension represents a simple and cost-effective technique for mass production of tungsten oxide nanowire network gas sensors. Utilizing this tungsten oxide nanowire network as gas sensing material we could obtain extraordinary sensitivity to H 2 S: concentrations down to 100 ppb have been detected at different humidity levels. An optimum operating temperature could be determined, where the different humidity levels do not affect the sensor performance.