Low Concentration C2H2 Detection by NiO/SnO2 Nanostructured Heterojunction Based MEMS Sensor

Abstract Low concentration detection and analysis of dissolved characteristic gas Acetylene (C2H2) in oil is one of the effective methods for power transformer condition maintenance to ensure safety. The MEMS gas sensor based on the nanostructured material has become a research hotpot for detecting the C2H2. In this work, SnO2 and NiO thin films were successively deposited by RF sputtering, followed by annealing at different temperatures to prepare NiO/SnO2 heterostructures, and the C2H2 sensor chips were prepared by MEMS (microelectromechanical systems) compatible process by using the SnO2/NiO thin films as sensitive materials. The results showed that the detection limit of the MEMS sensor based on the NiO/SnO2 (NiO/SnO2-2) film annealed at 450℃ was as low as 0.2×10-6 toward C2H2. The sensor exhibits a high response at 260℃ (S=7.9 toward 1.4×10-6 C2H2), which is about 4.5 times that of pure SnO2(1.8). Meanwhile, it has an extremely short response time (13 s and 19 s). This study reveals that dissolved acetylene gas in transformer oil can be detected more efficiently by the sensor with nanostructured heterojunctions as sensitive materials.