Rapid advancements in information processing and embedded systems require high selective and fast sensors. Conventional gas sensors are not suitable for the detection of isomers of organic compounds due to cross-sensitivity and the response time being limited by slow chemical kinetics. Amperometric gas sensors using conducting polymers modified with metal catalysts are a suitable and robust system due to many tunable properties. In this paper, conducting polymer polyaniline was electrochemically decorated with clusters containing precisely defined number of gold atoms to function as an electro-catalyst. The modified polymer composite showed fast reaction rate for the electro-oxidation of alcohols in both liquid and gas phases. The number of gold atoms affected the catalytic activity. Cyclic voltammograms were measured and results showed discriminable patterns between n-propanol and isopropanol even at different gas concentrations. Thus, it was demonstrated that gas sensor arrays can be realized by decorating different number of gold atoms on polyaniline electrodes, to yield defined and different selectivity. Index Terms-Amperometric gas sensor, atomic gold, conducting polymer, electro-catalyst, polyaniline, propanol I. INTRODUCTIONGas sensors have a wide range of modern applications such as their use in breath analysis to detect anomaly in a patient's health, as security devices for monitoring gas leaks, quality control in the food industry etc. [1]. Conventional gas sensors, however, are known to face some common challenges such as cross-sensitivity to humidity [2] and amperometric gas sensors are electrochemical type of gas sensors that are a more robust choice due to their several merits [3] in terms of characteristics such as low power, ease of fabrication, and the ability to perform in humid conditions. Although such sensor characteristics are attractive, they come at a cost of slow

Novel sensing materials have been formed by decorating polyaniline conducting polymers with atomic gold clusters where the number of atoms is precisely defined. Such materials exhibit unique electrocatalytic properties of electrooxidation to aliphatic alcohols, although analytes with other functional groups have not been studied. This paper reports a study of cyclic voltammetric patterns obtained with bi-atomic gold nanocomposite response to analytes with other functional groups for sensor applications. Principal component analysis shows separation among normal-propanol, iso-propanol and ethyl formate/ethanol groups. Indirect sensing of ethyl formate is demonstrated by electrooxidation of the product upon hydrolysis in alkaline medium. Voltammograms of ethyl formate are studied in gaseous phases.

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