The Effect of the Closely‐Spaced Working and Auxiliary Electrodes on the Performance of Electrochemical Oxygen Sensor

In this paper the influence of the electrochemical reaction at the auxiliary electrode of oxygen microsensors on the sensor performance was investigated. When the auxiliary electrode is closely spaced to the working electrode, the redox cycling of O₂/H₂O takes place in an electrochemical oxygen sensor. This cycling alters the oxygen distribution around the working electrode and therefore affects the measured cathodic current passing through the working electrode. Calibrations have to be taken out to determine the real O₂/H₂O cycling effects. Furthermore, this redox cycling also provides the possibility to enhance the sensitivity of the electrochemical oxygen microsensor. Experimental results indicate that the sensitivity of the oxygen sensor is enhanced 3.0 times with the on‐chip 10 μm spaced interdigitated auxiliary electrode.