High temperature NOx sensing enabled by indium oxide thin films

Generation of power using fossil fuel combustion invariably results in formation of undesirable gas species (NOx, SOx, CO, CO2, etc.) at high-temperatures which are harmful to the environment. Thus, there is a continual need to develop sensitive, responsive, stable, selective, robust and low-cost sensor systems and sensor materials for combustion monitoring. This work investigates the viability of microfabricated NOx sensors based on sputtered indium oxide (In2O3) utilizing microhotplate structures. The material becomes resistive when exposed to oxidizing gases like NOx, with its conductivity dependent upon the temperature, partial pressure of the test gas and morphological structure. We believe this device would help increase efficiency and decrease emissions through improved combustion process control, leading to a comparably economic and responsive sensor.