Ultra-thin filmed SnO2 gas sensor with a low-power micromachined hotplate for selective dual gas detection of carbon monoxide and methane

We report a metal oxide chemiresistive gas sensor with ultra-thin filmed Au decorated SnO2 as a sensing material on a micro-machined hotplate that combines a micro-heater and interdigitated electrodes. We designed and fabricated the hot plate by micro-electro-mechanical system (MEMS) processes and Au decorated SnO2 thin filmed layer by ion-beam sputtering methods, and investigated gas sensing performance for carbon monoxide and methane gas detection. The gas sensor with 20 nm thickness of SnO2 thin film was operated 100 °C for carbon monoxide and 250 °C for methane detection. The power consumptions were 20 mW and 80 mW for carbon monoxide and methane operating temperature, respectively. Microstructures of material were systemically characterized by FESEM, analytic STEM and AFM. We also discussed the effect of microstructure to gas sensing properties.