Patent ID: 8702962

Claim:
A process for sensing carbon dioxide, including the following steps: applying a constant direct current voltage across a pair of electrodes, said electrodes being separated by an electrolyte material containing sodium, said electrodes located between a layer of Alumina substrate and a carbonate layer of auxiliary electrolyte, and, an extra layer of metal oxide selected from the group consisting of SnO 2 , In 2 O 3 , TiO 2 , WO 3 , ZnO, Fe 2 O 3 , ITO, CdO, U 3 O 8 , Ta 2 O 5 , BaO, MoO 2 , V 2 O 5 , Nb 2 O 5 , CuO, Cr 2 O 3 , La 2 O 3 , RuO 3 , RuO 2 , ReO 2 , ReO 3 , Ag 2 O, CoO, Cu 2 O, SnO, NiO, Pr 2 O 3 , BaO, PdO 2 , and HfO 3 and mixtures thereof residing above and in engagement with said auxiliary electrolyte; reacting carbon dioxide with said electrolyte material containing sodium at a first three-point boundary, said first three point boundary being at the joinder of one of said electrode, said electrolyte material containing sodium, and a barium containing auxiliary electrolyte; reacting an oxide of sodium at a second three-point boundary, said second three-point boundary being at the joinder of the other of said electrodes, said electrolyte material containing sodium, and a barium containing auxiliary electrolyte; measuring the resulting current; and, correlating change in current to the concentration of carbon dioxide.