Microfabricated amperometric gas sensors

A series of Nafion-based amperometric gas sensors have been constructed using microelectronic fabrication technology. These sensors use a gold sensing-electrode in the shape of a square grid. Three different grid densities were used. To ascertain the optimal design parameters for such sensors, the response characteristics of the various microfabricated sensors were compared to each other and to a conventional `macro´ amperometric sensor. The critical performance criteria considered were sensor response time, structural integrity under operating conditions, selectivity, and sensitivity to the analyte vapor. The response time of the miniaturized sensors was over an order of magnitude faster, although they had a lower sensitivity than conventional sensors. The sensitivity of these sensors was dependent on the total length of the gold-Nafion interface. A model that rationalizes this dependence is presented