Ultrahigh-sensitive WO3 nanosensor with interdigitated Au nano-electrode for NO2 detection

Ultrahigh-sensitive WO3 nanosensors have been developed by using an interdigitated Au nano-electrode for dilute NO2 detection. The interdigitated Au nano-electrodes with a line spacing of 200 nm and various teeth numbers were fabricated on a SiO2/Si substrate by means of electron beam lithography. A WO3 thin film was deposited on the interdigitated Au nano-electrode to be a WO3 nanosensor. The nanosensor exhibited an extremely high sensor response (Rg/Ra = 28) to 0.01 ppm NO2 with excellent response-recovery characteristics. Interestingly, the sensor response increased with increasing the number of teeth in the interdigitated nano-electrode, i.e., the length of interface between oxide grain and Au electrode. This suggests that the nano-design of electrode structure is important for development of a highly sensitive gas sensor.