Micromachined catalytic combustion hydrogen gas sensor

A catalytic combustion H₂ sensor has been fabricated by using MEMS technology. The application of hafnium oxide thin films as insulating layer has been deposited by electron beam evaporation. The semiconductor combustion catalyst tin oxide (SnO₂) layer was prepared by chemical vapor deposition (CVD).It is a novel application of semiconductor material to catalytic combustion gas sensor. The resistivity of HfO₂ thin film is about 2.4×10¹² Ω·cm at 900°C. Both the sensing elements and the reference elements could be connected in a suitable circuit such as a Wheatstone configuration with low power consumption. The catalytic combustion sensor shows high response to H₂ at operating voltage of 4V and has a higher relative sensitivity and a good linearity for the concentrations of H₂ ranging from 0 to 4% in volume. Good consistency and high accuracy of the micro machined catalytic combustion gas sensor were achieved.