Patent ID: 8317998
Filing Date: 2012-11-27
Classification: G01N

Abstract:
1. A method of operating an electrochemical gas sensor, the electrochemical gas sensor comprising an electrode assembly disposed within a housing having a diffusion limiting barrier for gas ingress therethrough, the electrode assembly comprising a gas sensing electrode, a counter electrode, and electrolyte in communication with the gas sensing and counter electrodes, and the electrochemical gas sensor further comprising connectors for connecting the gas sensing and counter electrodes to a sensing circuit, the method comprising: a) exposing, for a first predetermined duration, the electrochemical gas sensor to an atmosphere containing a target gas while the gas reaction capability of the electrode assembly is substantially reduced from a working level, such that target gas is collected within the housing; b) increasing the gas reaction capability of the electrode assembly to a level at which it consumes collected target gas and thereby outputs a signal to the sensing circuit, including an initial transient decay signal; c) monitoring the transient decay signal; and d) analysing the rate of decay of the transient decay signal to determine whether the performance of at least one component of the electrochemical gas sensor is within acceptable limits, wherein, in step (b), the gas reaction capability of the electrode assembly is increased by applying a first bias potential to the gas sensing electrode, and after at least step (c) is performed, steps (a), (b) and (c) are repeated; and wherein, when step (b) is repeated, the gas reaction capability of the electrode assembly is increased by applying a second bias potential to the gas sensing electrode, the second bias potential being different to the first, to thereby determine in step (d) a variation of the transient decay signal with applied bias potential and so determine whether the reaction at the gas sensing electrode is diffusion limited or kinetically limited.