Carbon Monoxide Sensor System and Method

Abstract

A gas sensor having first and second electrodes, an ion conducting solid electrolyte membrane positioned therebetween, first and second electrically conductive gas diffusion layers, first and second electrode contact members for electrically coupling said first and second electrodes to an external circuit, a water reservoir, a gas entry passageway and a water permeation barrier for controlling the transport of water vapor to the ion conducting solid electrolyte membrane. The water permeation barrier is a thin walled member which allows water vapor to diffuse therethrough and evaporate from an exit surface, the thickness of the water permeation barrier controlling the internal relative humidity of the sensor. A method for adjusting the present sensor in-situ due to changes in the current humidity conditions of the sensor so as to keep the gas sensitivity loss within a predetermined range is also disclosed.

1 - 25 . (canceled) 
     
     
         26 . A method for compensating for the sensor gas sensitivity caused by changes in relative humidity comprising the following steps:
 determining the sensor output at a known relative humidity condition;   calibrating the sensor output at the known relative humidity condition to a concentration level of a gas measured by the sensor,   determining a calibration constant based upon the sensor output at the known relative humidity condition;   measuring the resistance and/or capacitance of the sensor and correlating such measurements to the relative humidity condition of the sensor;   periodically adjusting the calibration constant based upon the current measurement of the resistance and/or capacitance of the sensor to compensate for different relative humidity conditions.   
     
     
         27 . The method defined in  claim 26  wherein a controller is coupled to the sensor, said controller periodically measuring the sensor resistance and/or capacitance. 
     
     
         28 . The method defined in  claim 27  wherein said controller automatically adjusts the calibration constant based upon the measured sensor resistance and/or capacitance to compensate for the current relative humidity condition of the sensor. 
     
     
         29 . The method defined in  claim 26  wherein the relative humidity condition of the sensor is the internal relative humidity condition of the sensor. 
     
     
         30 . The method defined in  claim 26  wherein the relative humidity condition of the sensor is the external relative humidity condition of the sensor.