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.

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.

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.

Abstract: The self-calibrating carbon monoxide detector and method of the present invention utilize the gas for which the detector was designed to detect as the calibration gas. Specifically, a carbon monoxide gas generator is included in the detector assembly, and is controller to produce a known amount of CO. The sensor response to the quantity of CO generated is monitored, and the calibration thereof adjusted as necessary. The operation of the gas generator is also monitored, and any failures are flagged for user attention. The gas generator specifically suppresses the generation of hydrogen through the materials used in its construction. Temperature effects may also be compensated either through control of gas generation control parameters or compensation of the sensor output in view of the generator temperature effects.

Abstract: The self-calibrating carbon monoxide detector and method of the present invention utilize the gas for which the detector was designed to detect as the calibration gas. Specifically, a carbon monoxide gas generator is included in the detector assembly, and is controlled to produce a known amount of CO. The sensor response to the quantity of CO generated is monitored, and the calibration thereof adjusted as necessary. The operation of the gas generator is also monitored, and any failures are flagged for user attention. The gas generator specifically suppresses the generation of hydrogen through the materials used in its construction. Temperature effects may also be compensated either through control of the gas generation control parameters or compensation of the sensor output in view of the generator temperature effects.

Abstract: Apparatus and a method for detecting the presence of a predetermined target gas (e.g. CO) is disclosed. The gas has a predetermined pattern of peaks of absorbance to radiation lying within a particular radiation range (e.g. infrared), the absorbance peaks alternating with gaps in which the gas transmits the radiation. A source (12) passes IR radiation through a comb filter (5) and a measurement cell (22) containing the target gas. The comb filter (5) has successive passbands separated by absorbance gaps. The passbands of the comb filter are repeatedly shifted relative to the IR radiation between a correlation position in which they coincide with at least some of the absorbance peaks of the target gas and an anti-correlation position in which the passbands coincide with at least some of the absorbance gaps of the gas.