| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydrogen gas sensor which is small-sized, operates in a low temperature, can be mass produced, is inexpensive, has high selectivity of a gas, high sensitivity and high accuracy, and can measure a hydrogen gas of an extensive range of concentration.SOLUTION: A thin film separated from a substrate by thermal separation is made highly sensitive especially under an extreme low concentration of hydrogen, by introducing oxygen into a heater, a temperature sensor and a hydrogen absorption membrane as well as near the surface of the membrane and obtaining a larger added temperature rise due to exothermic reaction of reductive reaction near the surface of the hydrogen absorption membrane in addition to a temperature rise caused by heat evolution at the time of absorption of hydrogen in an atmosphere gas. Heating by the heater makes the hydrogen absorption membrane discharge hydrogen and, after heating by the heater is stopped, a hydrogen gas concentration in an atmosphere gas is obtained with the use of an output of the temperature sensor after a lapse of time which is equal to or larger than a thermal time constant of the thin film of the time when there is no hydrogen in the heater. A heat conduction type sensor without the hydrogen absorption membrane is provided as well if needed, so that the measuring range of a hydrogen gas concentration can be widened. |
