Hydrogen-gas concentration sensor and hydrogen-gas concentration measuring device

A hydrogen-gas concentration measuring device, comprising:

• a hydrogen-gas concentration sensor for measuring a hydrogen gas concentration making use of photocatalysis;
• a light source for irradiating the hydrogen-gas concentration sensor with light;
• and
• a data processing unit for measuring a hydrogen gas concentration using the hydrogen-gas concentration sensor, wherein
• the hydrogen-gas concentration sensor having a substrate, and a plurality of hydrogen detecting films formed on the substrate, adjacent to one another;
• each of the plurality of hydrogen detecting films having a thin film layer formed on the substrate, and a catalyst layer formed on a surface of the thin film layer;
• the catalyst layer exerts photocatalysis to hydrogenate the thin film layer reversibly when each of the hydrogen detecting films contacts a hydrogen gas contained in an atmosphere;
• electric resistance values of the respective thin film layers change reversibly with different sensitivities to a hydrogen gas concentration when the respective thin film layers are hydrogenated;
• and
• the data processing unit comprises a resistance measuring section for measuring an electric resistance value of each of the thin film layers of the plurality of hydrogen detecting films, and a measurement controlling section for measuring a hydrogen gas concentration on the basis of the respective electric resistance values of the thin film layers which are measured by the resistance measuring section, wherein
• when none of the electric resistance values of the hydrogenated thin film layers have reached a predetermined limit resistance value, the measurement controlling section measures a hydrogen gas concentration on the basis of the electric resistance value of a thin film layer whose electric resistance value changes with a highest sensitivity to the hydrogen gas concentration, while when the hydrogenated thin film layers include a thin film layer whose electric resistance value has reached the predetermined limit resistance value, the measurement controlling section measures a hydrogen gas concentration on the basis of the electric resistance value of a thin film layer whose electric resistance value has not reached the limit resistance value.