Carbon monoxide sensor
 A carbon monoxide sensor (40) has a substrate arranged with other adjacent or overlaid layers attached thereon (41) defining a first space (43a) into which a unknown gas or gas mixture is introduced into and a second space (43b) communicating with the first space. A carbon monoxide adsorbent (61) is disposed in the second space, and an electrode (56) detects a partial pressure of oxygen in the carbon monoxide adsorbent. A pump cell includes the cell part (42), made of a solid electrolyte conducting oxygen ion, and a pair of electrodes (51, 52). The pump cell substantially removes oxygen from a gas in the first space (43a) while carbon monoxide in the gas is adsorbed onto the carbon monoxide adsorbent (61). Then, the pump cell introduces oxygen into the first space (43a), and a time is measured that the oxygen diffuses from the first space (43a) to the first detecting electrode (56) through the adsorbent (61). Only after an initial flow of the oxygen reacts with the carbon monoxide on the adsorbent (61), the oxygen reaches the first detecting electrode (56). Therefore, the time of transit across the adsorbent relates to an amount of the carbon monoxide in the gas. The carbon monoxide sensor is not affected by the concentration of oxygen in the gas, thereby improving accuracy in measuring the carbon monoxide concentration. 
NGK Insulators, Ltd.
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G01N G01N
inventional inventional
Nobuhide Yasuhiko
Kato Hamada