Self calibration of a planar dissolved oxygen sensor

A poor long-term stability of planar microscaled oxygen sensors appears to have prevented their widespread use. This investigation study reports on an approach to enable a continuous long term operation of such sensors by in situ self-calibration. This involves a controlled anodic electrolysis of ambient water to generate an additional amount of dissolved oxygen spreading by diffusion. The response of the cathodic detecting electrode, i.e. the actual oxygen sensor, in relation to the additional oxygen spike is a measure of its sensitivity and the basis for calculating a correction factor. Generating and detecting electrodes are operated sequentially under non-steady-state conditions. In order to test the method, the quality of the corrected sensor signal output versus the uncorrected signal is tested by comparison with a benchmark optosensor signal. The approach is applicable as long as Faraday's relationship between electric charge flow and amount of oxygen generated is valid. The data indicate that an enhancement of a planar oxygen sensor's signal output by the self-calibration procedure can be achieved.