Gas sensor

A gas sensor characterized by comprising a proton conductive layer which conducts protons;

• a diffusion-rate determining portion for determining the rate of diffusion of an analyte gas;
• a measurement chamber communicating with an atmosphere of the analyte gas via the diffusion-rate determining portion;
• a first electrode accommodated in the measurement chamber, the first electrode being in contact with the proton conductive layer and including electro-chemically active catalyst;
• and a second electrode provided outside the measurement chamber, the second electrode being in contact with the proton conductive layer and including electro-chemically active catalyst, wherein
• a DC voltage is applied between the first and second electrodes such that the first electrode is higher in electrical potential than the second electrode, to thereby pump hydrogen or protons, an AC voltage is applied between the first and second electrodes so as to measure an impedance between the first and second electrodes, and a concentration of a catalyst poison gas contained in the analyte gas is obtained on the basis of the impedance.

A gas sensor characterized by comprising a proton conductive layer which conducts protons;

• a diffusion-rate determining portion for determining the rate of diffusion of an analyte gas;
• a measurement chamber communicating with an atmosphere of the analyte gas via the diffusion-rate determining portion;
• a first electrode accommodated in the measurement chamber, the first electrode being in contact with the proton conductive layer and including electro-chemically active catalyst;
• and a second electrode and a reference electrode provided outside the measurement chamber, the second and reference electrodes being in contact with the proton conductive layer and including electro-chemically active catalyst, wherein
• the gas sensor has a first operation step in which a DC voltage is applied between the first and second electrodes such that the first electrode is higher in electrical potential than the second electrode and such that a predetermined potential difference is produced between the first electrode and the reference electrode, and a second operation step in which a DC voltage is applied between the first and second electrodes so as to pump hydrogen or protons, and an AC voltage is applied between the first and second electrodes so as to measure an impedance between the first and second electrodes, wherein a concentration of a catalyst poison gas contained in the analyte gas is obtained on the basis of the impedance obtained in the second operation step.