Co sensor and method of measuring co concentration

Abstract

A CO sensor and a CO-concentration measurement method which enables accurate measurement of CO concentration irrespective of the hydrogen concentration of a gas under measurement. By applying a first predetermined voltage between first and second electrodes and , hydrogen contained in a gas under measurement which has been introduced into a first measurement space via a first diffusion-controlling section dissociates, decomposes, or reacts with another element to generate protons. The thus-generated protons are transported from the first electrode to the second electrode via a first proton-conductive layer or protons are transported from the second electrode to the first electrode via the first proton-conductive layer (when the hydrogen concentration of the measurement gas is extremely low), so that the hydrogen concentration within the first measurement space is controlled to a constant level. The gas under measurement having a controlled hydrogen concentration is introduced into a second measurement space via a second diffusion-controlling section , and a second predetermined voltage is applied between third and fourth electrodes and . The CO concentration of the gas under measurement is obtained based on current (a limiting proton current) which flows between the third and fourth electrodes and . Alternatively, the CO concentration of the gas under measurement is obtained from electromotive force generated between the third and fourth electrodes and