Metal oxide nanowire gas sensors for indoor and outdoor environmental monitoring

We present performance results of SnO₂ and CuO nanowire gas sensor devices, where single and multi-nanowire device configurations have been employed in order to optimize sensor design. In particular the response to the target gases CO, H₂, and H₂S has been measured in dry and humid air; both the SnO₂ and CuO nanowire sensors are able to detect CO in the low ppm concentration range, which is important for environmental monitoring. The CuO multi-nanowire devices show an extraordinary high response to H₂S with sensitivity in the low ppb concentration. We present our developments of CMOS technology based micro-hotplates, which are employed as platform for gas sensitive thin films and nanowires. Potential heterogeneous integration of nanowires on the micro-hotplate chips as well as an approach towards gas sensor arrays is discussed. We conclude that CMOS integrated multi-nanowire gas sensors are highly promising candidates for the practical realization of multi-parameter sensor devices for indoor and outdoor environmental monitoring.