Amperometric Detection of Nitrogen Oxides by Means of Interdigitated Array Electrodes

The detection of nitrogen oxides contained in air was investigated using their redox cycles. NO and NO2 gases can be detected by means of interdigitated array (IDA) electrodes made of Au that are fabricated on a gas-permeable membrane. The IDA electrodes were applied to a gas detection system for the first time. Although the membrane is soft and flexible, and has pores, the electrodes can be formed successfully on it by photolithography devised in our laboratory. Between the electrodes, redox cycles are produced, and, hence, the gas sensitivities increase. The reactions in this redox cycles are not simple, and it was confirmed that nitrate produced on the generator electrode reacts with NO gas on the collector in the NO detection system. The increase in sensitivity based on the generation of the redox cycle in amperometric detection appears to be improved by decreasing the distance between the electrodes