Potentiometric sensors galvanic measurement cells

With regard to in vivo gas-sensing devices, the majority of the work reported to date has involved oxygen-sensitive devices which operate as an electrolytic, not galvanic, type of electrochemical cell (i.e., current measured, not potential). Since such oxygen-sensing catheters are not based on ISEs, they will not be considered in this review. There has been, however, some limited work concerning the development of potentiometric sensors, particularly for in vivo COg measurements. One approach has been to devise... 

The inner filling solution for the sensors is usually 0.01 M NaCl, which is also used to condition the potentiometric sensors. Electrochemical potential is measured with the following galvanic cell Ag/AgCl/bridge electrolyte/sam-ple solution/ion-selective membrane/inner filling solution/ AgQ/Ag. A high impedance pH-mV meter is used to measure the electrochemical potential. Selectivity coefficients are evaluated by the matched potential method (also known as method of mixed solutions), or via the separate solution method. 

Furthermore, it was shown that it is possible to integrate and miniaturize indicator and reference electrodes while maintaining the characteristics of macro-conventional potentiometric sensors [21]. In consequence, it was shown that such electrodes can be placed together on a flat surface. In this way the miniature galvanic cells for flow-through modules, for direct measurements in small sample volumes can be obtained. 

---