Abstract: A system includes a system housing including an inlet, at least one gas sensor responsive to a first analyte gas other than oxygen within the system housing and in fluid connection with the inlet, and a sensor responsive to oxygen within the system housing and in fluid connection with the inlet. The sensor responsive to oxygen is formed to be chemically separate from the at least one gas sensor responsive to the first analyte gas other than oxygen. The sensor responsive to oxygen is responsive to a change in the concentration of oxygen arising from creation of a driving force in the vicinity of the inlet to provide an indication of a state of a transport path between the inlet of the system and the at least one gas sensor responsive to the first analyte gas other than oxygen.

Abstract: A method of operating a sensor system including at least one sensor for detecting an analyte gas and a control system includes electronically interrogating the sensor to determine the operational status thereof and upon determining that the operational status is non-conforming based upon one or more predetermined thresholds, the control system initiating an automated calibration of the sensor with the analyte gas or a simulant gas.

Abstract: A method of testing a system having at least one electrochemical sensor for detecting an analyte gas within a housing of the system, the housing having an inlet, the at least one electrochemical sensor including an electrically active working electrode in fluid connection with the inlet of the system, the method including biasing the electrically active working electrode at a first potential, to detect the analyte gas and biasing the electrically active working electrode at a second potential, different from the first potential, such that the at least one electrochemical sensor is sensitive to a driving force created in the vicinity of the inlet to test at least one transport path of the system. The method may further include creating the driving force in the vicinity of the inlet of the housing of the system and measuring a response of the electrically active working electrode to the driving force.

Abstract: A method of operating a system having at least one sensor for detecting an analyte gas in an ambient atmosphere and a sensor responsive to oxygen includes providing a volume in fluid connection with the sensor responsive to oxygen. The volume has an open state in which the volume is in fluid connection with the ambient atmosphere and at least a first restricted state in which entry of molecules from the ambient atmosphere into the volume is restricted as compared to the open state. The method further includes placing the volume in the open state, subsequently placing the volume in the first restricted state, and measuring a dynamic output of the sensor responsive to oxygen while the volume is in the first restricted state. The dynamic output provides an indication of the status of one or more transport paths of the system.

Abstract: A method of operating a sensor system including at least one sensor for detecting an analyte gas and a control system includes electronically interrogating the sensor to determine the operational status thereof and upon determining that the operational status is non-conforming based upon one or more predetermined thresholds, the control system initiating an automated calibration of the sensor with the analyte gas or a simulant gas.

Abstract: A method of testing a system having at least one electrochemical sensor for detecting an analyte gas within a housing of the system, the housing having an inlet, the at least one electrochemical sensor including an electrically active working electrode in fluid connection with the inlet of the system, the method including biasing the electrically active working electrode at a first potential, to detect the analyte gas and biasing the electrically active working electrode at a second potential, different from the first potential, such that the at least one electrochemical sensor is sensitive to a driving force created in the vicinity of the inlet to test at least one transport path of the system. The method may further include creating the driving force in the vicinity of the inlet of the housing of the system and measuring a response of the electrically active working electrode to the driving force.

Abstract: A method of operating a system having at least one sensor for detecting an analyte gas in an ambient atmosphere and a sensor responsive to oxygen includes providing a volume in fluid connection with the sensor responsive to oxygen. The volume has an open state in which the volume is in fluid connection with the ambient atmosphere and at least a first restricted state in which entry of molecules from the ambient atmosphere into the volume is restricted as compared to the open state. The method further includes placing the volume in the open state, subsequently placing the volume in the first restricted state, and measuring a dynamic output of the sensor responsive to oxygen while the volume is in the first restricted state. The dynamic output provides an indication of the status of one or more transport paths of the system.

Abstract: A system includes a system housing including an inlet, at least one gas sensor responsive to a first analyte gas other than oxygen within the system housing and in fluid connection with the inlet, and a sensor responsive to oxygen within the system housing and in fluid connection with the inlet. The sensor responsive to oxygen is formed to be chemically separate from the at least one gas sensor responsive to the first analyte gas other than oxygen. The sensor responsive to oxygen is responsive to a change in the concentration of oxygen arising from creation of a driving force in the vicinity of the inlet to provide an indication of a state of a transport path between the inlet of the system and the at least one gas sensor responsive to the first analyte gas other than oxygen.

Abstract: A method of adjusting the output of an electrochemical sensor including a working electrode and a counter electrode, includes: electronically causing a current flow between the working electrode and the counter electrode via an electrolyte without introducing a test analyte to the electrochemical sensor; measuring a response of the sensor to the current demand resulting from the electronically generated current flow; and using the measured response to adjust the sensor output during sampling of an analyte gas.

Abstract: A method of adjusting the output of an electrochemical sensor including a working electrode and a counter electrode, includes: electronically causing a current flow between the working electrode and the counter electrode via an electrolyte without introducing a test analyte to the electrochemical sensor; measuring a response of the sensor to the current demand resulting from the electronically generated current flow; and using the measured response to adjust the sensor output during sampling of an analyte gas.

Abstract: A method of adjusting the output of an electrochemical sensor includes the steps of: simulating the presence of an analyte gas electronically; measuring a response of the sensor to the electronic simulation; and adjusting the output of the sensor as a function of the measured response to the electronic simulation. The method of adjusting the output of an electrochemical sensor having a working electrode and a counter electrode preferably includes the steps of: electronically causing a current flow between the working electrode and the counter electrode; measuring a response of the sensor to the current demand; and using the measured response to adjust the sensor output during sampling of an analyte gas.

Abstract: An electrode for use in an electrochemical sensor includes a catalyst dispersed within an electrolyte. Preferably, the catalyst is immobilized within a matrix of the electrolyte. In one embodiment, the electrode of the present invention includes at least one catalyst/electrolyte layer having a mixture of a powdered catalyst, a powdered, quasi-solid electrolyte and a binder material compressed together. The quasi-solid electrolyte can include a liquid electrolyte immobilized by a high-surface-area, high-pore-volume solid.

Abstract: A combustible gas sensor includes an active element in electrical connection with a measurement circuit. The measurement circuit includes a thermistor network to compensate for the effect of changes in ambient temperature to the resistance of the active element. Another combustible gas sensor includes an active element having a geometric surface area no greater than approximately 0.5 mm2 in electrical connection with a measurement circuit. The measurement circuit includes a compensator that compensates for the effect of changes in ambient temperature to the resistance of the active element without compensating for heat lost by thermal conduction from the active element.

Abstract: A combustible gas sensor includes an active element in electrical connection with a measurement circuit. The measurement circuit includes a thermistor network to compensate for the effect of changes in ambient temperature to the resistance of the active element. Another combustible gas sensor includes an active element having a geometric surface area no greater than approximately 0.5 mm2 in electrical connection with a measurement circuit. The measurement circuit includes a compensator that compensates for the effect of changes in ambient temperature to the resistance of the active element without compensating for heat lost by thermal conduction from the active element.

Abstract: A combustible gas sensor includes an active element in electrical connection with a measurement circuit. The measurement circuit includes a thermistor network to compensate for the effect of changes in ambient temperature to the resistance of the active element. Another combustible gas sensor includes an active element having a geometric surface area no greater than approximately 0.5 mm2 in electrical connection with a measurement circuit. The measurement circuit includes a compensator that compensates for the effect of changes in ambient temperature to the resistance of the active element without compensating for heat lost by thermal conduction from the active element.

Abstract: An electrode for use in an electrochemical sensor includes a catalyst dispersed within an electrolyte. Preferably, the catalyst is immobilized within a matrix of the electrolyte. In one embodiment, the electrode of the present invention includes at least one catalyst/electrolyte layer having a mixture of a powdered catalyst, a powdered, quasi-solid electrolyte and a binder material compressed together. The quasi-solid electrolyte can include a liquid electrolyte immobilized by a high-surface-area, high-pore-volume solid.

Abstract: The present invention provides an electrochemical sensor for the detection of hydrogen cyanide. In general, the electrochemical sensor includes a housing having disposed therein a working electrode, a reference electrode and a counter electrode. The electrochemically active surfaces of the working electrode and reference electrode preferably comprise silver. Electrical connection is maintained between the working electrode and the counter electrode via an organic electrolyte present within the housing. The electrochemical gas sensor preferably further comprises circuitry for maintaining the working electrode at a potential in the range of approximately +40 mV to approximately -40 mV versus the silver reference electrode. Most preferably, the electrochemical gas sensor comprises circuitry for maintaining the working electrode at a potential of approximately 0 mV versus the silver reference electrode.

Abstract: The present invention provides an electrochemical sensor for the detection of hydrogen cyanide. In general, the electrochemical sensor includes a housing having disposed therein a working electrode, a reference electrode and a counter electrode. The electrochemically active surfaces of the working electrode and reference electrode preferably comprise silver. Electrical connection is maintained between the working electrode and the counter electrode via an organic electrolyte present within the housing. The electrochemical gas sensor preferably further comprises circuitry for maintaining the working electrode at a potential in the range of approximately +40 mV to approximately -40 mV versus the silver reference electrode. Most preferably, the electrochemical gas sensor comprises circuitry for maintaining the working electrode at a potential of approximately 0 mV versus the silver reference electrode. The present invention also provides a method of using such a sensor to detect hydrogen cyanide.

Abstract: Accordingly, the present invention provides an electrochemical sensor comprising at least two electrochemically active electrodes, a non-aqueous electrolyte system and a diffusion barrier membrane through which the analyte in its gas phase is mobile but through which the non-aqueous electrolyte system is substantially immobile. The diffusion barrier membrane thus allows an analyte in its gas phase to enter the sensor, while substantially preventing the non-aqueous electrolyte from exiting the sensor.

Abstract: The present invention provides an electrochemical gas sensor for the detection of nitrogen dioxide comprising a housing and a working electrode and a counter electrode disposed within the housing. Each of the working electrode and the counter electrode are fabricated from an electrically conductive carbon. The present sensor also preferably comprises a reference electrode fabricated from an electrically conductive carbon.