All-solid Nafion®-based amperometric sensors for monitoring gaseous oxygen

Abstract

Oxygen reduction has been studied at three different designs of Au/Nafion®-based all-solid amperometric sensors. These consisted of a planar-type sensor (PTS) with all electrodes sputtered on the same face of the Nafion® membrane, a capillary planar type sensor (CPTS) with the introduction of a cover bearing a capillary, and a sandwich-type sensor (STS) with the working and counter electrode layers deposited on different sides of the polymer electrolyte membrane. The response of all sensors depended heavily on humidity and the degree of Nafion® hydration but, unlike the CPTS and STS configurations, no signs of a limiting current were recorded during voltammetric experiments at an open PTS device, indicating the absence of a significant diffusion barrier in that case. All three simple and inexpensive polymerbased sensors compared well with a commercial fuel cell-type sensor, regarding their response to gaseous oxygen concentration changes.