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

Low concentration detection and analysis of dissolved characteristic gas Acetylene (C 2 H 2 ) 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 C 2 H 2 . In this work, SnO 2 and NiO thin films were successively deposited by RF sputtering, followed by annealing at different temperatures to prepare NiO/SnO 2 heterostructures, and the C 2 H 2 sensor chips were prepared by MEMS (microelectromechanical systems) compatible process by using the SnO 2 /NiO thin films as sensitive materials. The results showed that the detection limit of the MEMS sensor based on the NiO/SnO 2 (NiO/SnO 2 -2) film annealed at 450 °C was as low as 0.2 × 10 −6 toward C 2 H 2 . The sensor exhibits a high response at 260 °C (S = 7.9 toward 1.4 × 10 −6 C 2 H 2 ), which is about 4.5 times that of pure SnO 2 (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.