A planar, solid-state amperometric sensor for nitrogen dioxide, employing an ionic liquid electrolyte contained in a polymeric matrix

A new type of electrolyte, based on immobilization of a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) or 1-ethyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)-imide (EMITESI) within the structure of partially cross-linked poly(ethylene glycol) methyl ether rnethacrylate (PEGMEMA), was tested for use in planar, solid state amperometric sensors, using nitrogen dioxide as the test analyte. Nitrogen dioxide contained in the air was reduced on a gold minigrid indicator electrode at a potential of -900 mV vs. a Pt/air pseudoreference electrode. The effects of the electrolyte composition, the indicator electrode surface area and the test gas relative humidity on the sensor response were studied. The principal analytical parameters obtained in this study were compared with those published for NO2 sensors containing other polymeric electrolytes and other indicator electrodes. There is no substantial difference in these parameters. however, the present sensor type offers longer response stability and mostly also a lower sensitivity to the test air humidity and thus usefully widens the list of electrolytes available for designing solid-state gas sensors. (C) 2011 Elsevier B.V. All rights reserved.