A Stable Solid-Reference Electrode of BiCuVOx/Perovskite-Oxide for Potentiometric Solid Electrolyte CO2 Sensor

Carbon Dioxide Sensing—Biomedical Applications to Human Subjects

“…A major improvement to the stability of potentiometric sensors has been the addition of a third reference electrode [ 210 , 211 , 212 ], or the use of a solid reference electrode instead of the above-mentioned Na O/O interface [ 213 , 214 , 215 ]. Still, even with this referencing, such sensors usually suffer from some degree of cross-sensitivity towards humidity.…”

“…The performance of a potentiometric sensor strongly depends on the thickness of its different constituents, but also on the choice of the materials used for the electrolyte and the sensing electrode coating. Concerning the electrodes themselves, their composition does not seem to have any significant influence on the sensing performance, since they are often made out of noble metals—such as gold [ 210 , 211 , 216 ] or platinum [ 209 , 212 , 217 ]. The electrode wires are bound to the solid electrolyte using pastes of the same metal—possibly deposited with a stencil—which are further sintered to make an electrical bond between the solid electrolyte and the wires.…”

“…As for the coating of the sensing electrode, various carbonates were explored such as Na CO , Li CO or CaCO , with similar performance. Reference materials such as yttrium stabilised zirconia [ 210 ], BiCuVO -perovskite-oxide [ 211 ], Li TiO /TiO [ 213 , 214 , 215 ] and Bi Nb O [ 212 ] were used exhibiting good stability.…”

“…If the objective comparison of one of the combinations of the above-mentioned chemicals with another is made difficult by the change in form-factor and film thicknesses of the reported works, one can still notice some remarkable facts. At first, in an attempt to mitigate the humidity cross-sensitivity of potentiometric sensors, the addition of barium carbonate to a lithium carbonate sensing material (BaCO /Li CO ) [ 211 , 213 , 215 ], or the addition of lithium carbonate to an indium tin oxide sensing material (Li CO /ITO) [ 216 ] have been successfully explored by several authors, yielding potentiometric sensors with no cross-sensitivity toward humidity. Then, room temperature operation of such sensors was also achieved with good sensitivity at 30 °C on the 300–3000 ppm CO range [ 216 ].…”

Preparation and measurement of standard organic gases using a diffusion method and a NASICON-based CO2 sensor combined with a combustion catalyst

“…The sensor device was fabricated by a method reported elsewhere. 20,21 The device used Li 2 CO 3 -BaCO 3 binary carbonate and a composite of Bi 2 Cu 0.1 V 0.9 O 5.35 and La 0.6 Sr 0.4 Co 0.78-Ni 0.02 Fe 0.2 O 3 as the CO 2 sensing layer and the reference electrode, respectively. Fig.…”