Electrodes with micro-gaps are fabricated by using dc-sputtering and FIB techniques. SnO2 nanowires
are deposited on the micro-gap (1–30 m) by suspension dropping method to fabricate a micro-gas
sensor. The sensing ability of various SnO2 micro-gap sensors is measured. A comparison between sensors
reveals that the short-gap electrode has numerous advantages in terms of reliability, high sensitivity and
detection of low concentrations of NO2, while the large-gap electrode is relatively sensitive for high
concentrations. Conductance measurements are carried out at different surface temperatures and NO2
concentrations in order to investigate the effects that the gap size has on the overall sensor conductance.
The results suggest that the interface between the electrode and sensitive layer has a very important role
for the sensing mechanism of tin dioxide gas sensors.