Micromachined catalytic combustion type gas sensor for hydrogen detection

A catalytic combustion hydrogen sensor has been fabricated using the microelectromechanical system technology. The application of hafnium oxide thin films as the insulating layer has been deposited by electron beam evaporation. The semiconductor combustion catalyst tin oxide layer was prepared by chemical vapour deposition. It is a novel application of semiconductor material to a catalytic combustion gas sensor. The resistivity of hafnium dioxide thin film is about 3 × 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 hydrogen at an operating voltage of 4 V and has a higher relative sensitivity and a good linearity for concentrations of hydrogen ranging from 0 to 4% in volume. Good consistency and high accuracy of the micromachined catalytic combustion gas sensor were achieved.