Low power virtual sensor array based on a micromachined gas sensor for fast discrimination between H2, CO and relative humidity

A micromachined metal oxide gas sensor operated with temperature modulation allows discrimination between air, H2 and CO in less than 1 s. Furthermore, the actual humidity level and gas concentration can be estimated. We tested gas concentrations of 3–12 ppm H2 and 12–100 ppm CO at five relative humidity levels between 30 and 70%. While H2 can be identified for all concentrations, certain identification of CO requires concentrations above 20 ppm and also determination of the relative humidity level from the sensor data.