Interrogation of capillary-limited sensors

An electrochemical gas sensor responsive to an analyte gas, comprising:

• a housing comprising a capillary inlet;
• an electrolyte within the housing,
• a working electrode in ionic contact with the electrolyte,
• a counter electrode in ionic contact with the electrolyte, and
• electronic circuitry in operative connection with the working electrode and the counter electrode, the electronic circuitry being configured to operate the gas sensor in a sensing mode during which a signal from the gas sensor is representative of a concentration of the analyte gas measured by the gas sensor and in an interrogation mode wherein the gas sensor is electronically interrogated to test the functionality of the gas sensor by applying an electric signal to the gas sensor to generate a non-faradaic current flow between the working electrode and a counter electrode via the electrolyte without the application of a test gas having a known concentration of the analyte gas or a simulant therefor to the sensor from a container;
• periodically enter the interrogation mode, measure a baseline output of the gas sensor before applying the electric signal to the gas sensor during the interrogation mode, compare the measured baseline output to one or more previously measured baseline outputs from a previous interrogation mode, determine an operational state from the comparison of the measured baseline output to the one or more previously measured baseline outputs;
• and return the gas sensor to the sensing mode if the operational state is determined to be within a predetermined range.

A method of operating a gas detection device including a capillary-limited, amperometric electrochemical gas sensor responsive to an analyte gas, comprising:

• periodically measuring a baseline output of the gas sensor;
• comparing the measured baseline output to one or more previously measured baseline output values;
• and
• determining an operational state from the comparison of the measured baseline output to one or more previously measured baseline output values.