Chemoresistive micromachined gas sensors based on functionalized metal oxide nanowires: Performance and reliability

Chemoresistive micromachined gas sensors with bottom-electrode configuration and based on Pt-functionalized tungsten oxide nanowires are fabricated. The performance and reliability of three types of devices with different electrode gap (5, 10 and 15 μm) are analyzed in dry and humid ambient and towards various analytes (H2, NO2, EtOH, and CO). Results demonstrate an improved response, sensitivity, and stability with better dynamic of the response for the sensors with the electrode gap of 5 μm, showing up to 7-fold higher responses and 32-fold faster responses towards hydrogen compared to the sensors with the electrode gap of 10 or 15 μm. These results are connected with the increment of the density of nanowire junctions across the electrodes with 5 μm gap; separation that corresponds to half of the length of the wires used in this work.