Electrochemical pH Sensors for Special Applications

Numerous pH measuring problems require sensors differing from the standards. Several particular examples are described in this paper. Beside metal oxide electrodes manufactured using various fabrication steps, conventional pH glass electrodes can be miniaturized to a limited extent or the usual internal filling can be exchanged with different solid state reference systems. To establish a reversible interface to the membrane glass both compact glass electrodes and thick-film glass electrodes using zinc oxide have been used. The integration of pH sensors in multi-sensor systems is reported and procedures are presented to extend the utilisability of these systems. The importance of reference electrodes for such developments is highlighted.