Thin-film transistor approaches for ultra-sensitive gas sensing technologies

Gas sensors are essential in environmental monitoring, industrial safety, and healthcare by enabling the detection of hazardous and flammable gases at trace levels. Conventional sensing approaches, including electrochemical, optical, catalytic, and thermal methods, though effective, suffer from limitations such as short operational life, high cost, poor selectivity, and bulkiness. This research investigates the design and manufacturing of TFT-based sensors using indium gallium zinc oxide (IGZO) as the active layer, deposited on flexible polyimide substrates through radiofrequency magnetron sputtering. The devices were fabricated with patterned source–drain electrodes and silicon dioxide gate dielectrics, followed by systematic characterization of their electrical properties. Gas sensing performance was evaluated against ammonia, hydrogen, and carbon dioxide in controlled environments. Results demonstrated notable improvements in response time, sensitivity, and recovery characteristics compared with conventional sensors. The response time of approximately 15 s for NH₃, sensitivity values of 8.7%/ppm for NH₃, 7.3%/ppm for H₂, and 6.9%/ppm for CO₂, along with the low power consumption of about 1.2 µW per operation.