(JP2001041926-A)   NOVELTY - A carbon monoxide (CO) gas sensor comprises a detecting unit which has a solid electrolyte membrane (3) between a detection electrode (1) and counter electrode (2). The electrode (1) comprises a reaction layer on a electrically conductive porous material containing an electrochemically active catalyst A. The counter electrode comprises electrochemically active catalyst B on electrically conductive porous material.    USE - For a fuel cell (claimed) and for detecting the concentration of small amounts of CO gas in a hydrogen-rich atmosphere.    ADVANTAGE - The current flowing between the detection electrode and counter electrode is minimized, therefore the drying of the electrolyte membrane due to a temperature raise in the sensor is prevented and the shelf life of the sensor is improved. The sensitivity of the sensor to CO gas is improved. The temperature range and humidity range in which the CO gas sensor is effectively operated are widened. CO gas can be measured stably even when a reference electrode is omitted.    (DE10037233-A1)   NOVELTY - A carbon monoxide (CO) gas sensor comprises a detecting unit which has a solid electrolyte membrane (3) between a detection electrode (1) and counter electrode (2). The electrode (1) comprises a reaction layer on a electrically conductive porous material containing an electrochemically active catalyst A. The counter electrode comprises electrochemically active catalyst B on electrically conductive porous material.    USE - For a fuel cell (claimed) and for detecting the concentration of small amounts of CO gas in a hydrogen-rich atmosphere.    ADVANTAGE - The current flowing between the detection electrode and counter electrode is minimized, therefore the drying of the electrolyte membrane due to a temperature raise in the sensor is prevented and the shelf life of the sensor is improved. The sensitivity of the sensor to CO gas is improved. The temperature range and humidity range in which the CO gas sensor is effectively operated are widened. CO gas can be measured stably even when a reference electrode is omitted.