Ultralow power consumption gas sensor based on a self-heated nanojunction of SnO₂ nanowires

The long duration of a working device with a limited battery capacity requires gas sensors with low power consumption. A self-heated gas sensor is a highly promising candidate to satisfy this requirement. In this study, two gas sensors with sparse and dense SnO₂ nanowire (NW) networks were investigated under the Joule heating effect at the nanojunction. Results showed that the local heating nanojunction was effective for NO₂ sensing but generally not for reduction gases. At 1 μW, the sparse NW sensor showed a good sensing performance to the NO₂ gas. The dense SnO₂ NW network required a high-power supply for gas-sensitive activation, but was suitable for reduction gases. A power of approximately 500 μW was also needed for a fast recovery time. Notably, the dense NW sensor can response to ethanol and H₂S gases. Results also showed that the self-heated sensors were simple in design and reproducible in terms of the fabrication process.