First-Principles Algorithm for Air Quality Electrochemical Gas Sensors.

We report here a simple approach that allows for rapid mapping of raw voltage readings to concentrations for parts-per-billion level air quality electrochemical sensors. The key step is the introduction of an auxiliary sensor and then covering it with a thin Nafion membrane, one that is well-known for its both highly efficient and selective permeation of water vapor. This sensor captures any signal that is induced by changes of relative humidity, and such a signal can then be used to rapidly correct for drifts of the main sensor which sees both the target gas and the ambient water vapor. The whole process is entirely based on first principles, preserves physical clarity, is very amenable for implementation by routine sensor users, and delivers data that compare favorably with those from reference instruments. We also suggest that this double-sensor setup can be further condensed into one sensor in which one of the electrodes is coated by Nafion and exposed to ambient air in the same way as the normal sensing electrode.