Planar solid-state potentiometric carbon dioxide sensors incorporating polymer-gel electrolyte

A novel, planar, carbon dioxide gas sensor is described, comprising an iridium dioxide working electrode and silver/silver bromide reference electrode in contact with a solid, gas-permeable film of nonaqueous polymer-gel electrolyte. The working and reference electrodes are prepared in an interdigitated thick film format by screen printing sinterable inks onto a low temperature cofired ceramic (LTCC) substrate. After firing, a second printing operation is used to superimpose the polymer-gel electrolyte layer. The completed sensor is shown to exhibit a rapid and reversible near-Nerstian response to changing CO2 partial pressure in a CO2/N-2 gas stream at ambient temperatures. The influence of temperature and relative humidity on sensor response is also described, as is the effect of SOx and NOx interferent gases. (C) 2003 The Electrochemical Society.