Stabilization of sensor signal in electrochemical gas sensors

An electrochemical gas sensor for determining a concentration of a target gas in an environment, comprising:

• a housing comprising at least one gas inlet;
• an electrolyte within the housing;
• at least one working electrode in ionic contact with the electrolyte, wherein an output of the at least one working electrode varies over time during exposure of the at least one working electrode to the target gas at a constant concentration as a result of exposure to the target gas;
• at least one counter electrode in ionic contact with the electrolyte;
• at least one secondary electrode in ionic contact with the electrolyte, the at least one secondary electrode being configured so that less of the target gas entering the housing via the at least one gas inlet reacts at the at least one secondary electrode than at the at least one working electrode;
• and
• electronic circuitry in operative connection with the at least one working electrode, the at least one counter electrode and the at least one secondary electrode,
• the electronic circuitry comprising a processor system and a memory system in operative connection with the processor system,
• the electronic circuitry being configured to receive the output from the at least one working electrode and to receive an output from the at least one secondary electrode,
• the electronic circuitry further comprising an algorithm stored in the memory system and comprising a predetermined correction factor f as a parameter in the algorithm,
• wherein the predetermined correction factor f is stored in the memory system at the time of manufacture,
• the electronic circuitry further being configured to determine the concentration of the target gas in the environment in a measurement mode, subsequent to the time of manufacture, via execution of the algorithm by the processor system, wherein the algorithm comprises the formula:
• signal(corrected)=signalWE−(signalBE*f)
• wherein signalWE is the output signal of the at least one working electrode in the measurement mode and signalBE is the output signal of the at least one secondary electrode in the measurement mode, and signal(corrected) is an output which is corrected for drift resulting from extended exposure to the target gas subsequent to the time of manufacture,
• wherein the correction factor f is predetermined and stored in the memory system at the time of manufacture from (i) a ratio of a slope of the output signal of the at least one working electrode to a different slope of the output signal of the at least one secondary electrode during exposure of the electrochemical gas sensor to a test gas including the target gas in a known concentration over a predetermined period of time during an assessment of the electrochemical sensor or (ii) a ratio of a slope of an output signal of at least one working electrode of a second electrochemical gas sensor to a different slope of an output signal of at least one secondary electrode of the second electrochemical gas sensor during exposure of the second electrochemical gas sensor to the test gas including the target gas in the known concentration over the predetermined period of time during an assessment of the second electrochemical sensor, wherein the predetermined correction factor f is not equal to 1.