A Multi-Bit Fully Integrated Thin-Film Transistor NO2 Gas Detector at Room Temperature

Inexpensive and compact gas sensing systems are indispensable for accurate air quality monitoring with broad spatial coverage. We report an InGaZnO thin-film transistor (TFT)-based integrated NO
₂
gas detection system that yields a digital output proportional to the NO
₂
concentration. This is the first report on integrated TFT-based detectors where gas concentration is quantified and where simultaneous digital output is provided without additional signal conditioning or analog to digital conversion circuits. It is a low power consuming system with consumption in the order of a few microwatts. It constitutes a highly sensitive and selective fabricated InGaZnO TFT gas sensor operable at room temperature. The response of the TFT in the presence of the NO
₂
as a sensor is evaluated, and it is reproducible with the measured limit of detection as 100 ppb. Such standalone thin-film electronic systems that function as gas-sensitive analog to digital converters pave the way to compact and inexpensive gas sensing systems.