Solid-state ion sensors with a liquid junction-free polymer membrane-based reference electrode for blood analysis

A set of ion-selective membranes for the measurement of clinically relevant electrolytes, i.e., K+, Na+, Ca2+, H+ and Cl−, and a solvent-processible polyurethane (PU)-based reference membrane were cast on metal electrodes patterned on small ceramic plates, and on silicon-based sensors. Since the liquid junction-free PU membrane-based reference electrode provides a constant potentiometric signal for an extended period of time, accurate determination of blood electrolytes could be made without using a separate reference flow. The PU membrane-based reference electrodes not only improve the mass producibility of miniaturized solid-state ion sensors but also simplify the configuration of flow cell cartridges without compromising their analytical performance.