Method and apparatus for diagnosing gas sensors
AssigneeIndustrial Scientific Corporation
InventorWenfeng Peng
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Abstract
A method and apparatus for diagnosing defects in electrochemical gas sensors, in which the water vapor pressure of the air surrounding a sensor is suddenly changed by changing to more dry or more humid air, thereby causing a sharp change in the acidity at the working electrode, and hence, a transient current from the sensor. The response of the sensor to the change in water vapor pressure is monitored and is used for sensor diagnostics. Lack of sensitivity of the sensor to the water vapor pressure change is an indication that the sensor does not have appropriate sensitivity to the gas to be detected. The method and apparatus are particularly useful for diagnostic testing of sensors without a gas filter.
Claims16
A method for determining loss of sensitivity of an electrochemical gas sensor including at least a working electrode and a reference electrode, an aqueous electrolyte and a diffusion limited inlet, comprising the steps of:
- connecting the sensor to potentiostat means and means for determining output current;
- establishing a base output current;
- causing a sudden change in water vapor pressure at the inlet, maintaining said changed water vapor pressure over a period of at least a few seconds, and recording a resultant change in output current;
- and
- comparing the change in output current to a standard to determine sensor sensitivity.
An apparatus including an electrochemical gas sensor cell and a means for self-diagnosing a loss of sensitivity of the cell, comprising:
- an electrochemical gas sensor cell including at least a working electrode and a reference electrode, an aqueous electrolyte and a diffusion limited inlet;
- means for causing a sudden change in water vapor pressure and maintaining a changed water vapor pressure at said inlet;
- and
- means for connecting said means for causing with said inlet.
Dependencies are inferred from the claim text.