A catalytic combustion type methane gas sensor with super low power consumption using MEMS technology was developed for a battery drive type gas alarm. In this study, it is reported the actions of improvement for methane gas selectivity and sensitivity of the sensor from a viewpoint of the reliability satisfaction for practical use. As the method of improving gas selectivity, it was made to offset with constituting a reference element from a Platinum loaded catalyst. For the improvement of methane sensitivity, the amount of loaded Palladium was made to optimize in order to increase gas reactive sites on catalyst. And slit-shaped through-holes were formed on micro heater, as taking advantage of air bridge structure for promoting the gas contact from the heater backside. Methane sensitivity has improved drastically by these complex improvement effects.

One of the main causes of home fires in Japan is smoking in bed, and carbon monoxide poisoning and suffocation account for a high proportion of cause of death in futon smoldering fires. In this study, using a full-scale experiment room model, a smoldering fire initiated by a lighted cigarette placed still on cotton bedclothes was reproduced. The carboxyhemoglobin “COHb” concentration in the blood was compared by monitoring the change in the carbon monoxide “CO” concentrations inhaled into the lung during smoldering fire in a full-scale experiment room model. Early detection of fires and effects on a human body were discussed based on the data and the effectiveness of a CO and smoke alarm placed on an interior wall was examined. As a result, it has been confirmed that the CO detection function of a CO and smoke alarm placed on a wall enables early detection of fire effectively.