Problems and prospects of solid contact ion-selective electrodes with ionophore-based membranes

In Vivo Measurement of Calcium Ion with Solid-State Ion-Selective Electrode by Using Shelled Hollow Carbon Nanospheres as a Transducing Layer

“…The boundary potential at the ISM/solution interface is established due to the electrochemical equilibrium involving ions of both contacting phases, and the electronically conducting substrate is an electronic conductor that is connected to a measuring instrument. Therefore, the potential should be constant at the interface of the ionically conducting membrane and electronically conducting substrate for stably and reproducibly outputting the measured EMF values. , For this purpose, a transducing layer or solid contact remains essential to mediate the charge transfer of this interface and further stabilize the potential. An ideal transducing layer should meet conditions including (a) a large redox capacity or double-layer capacitance to facilitate the reversible ion-to-electron transfer, (b) relative hydrophobicity to decrease an aqueous layer formation at the ISM/solid contact interface, (c) the absence of side reactions, and (d) ease of preparation .…”

“…12 As reported previously, the ISM/substrate interface acts as a condenser when the ISM is directly deposited on the electronically conducting substrate, where the ion-to-electron transduction is mostly interrupted because one of phases is a pure ionic conductor and the other is an electronic conductor. 27 Moreover, the formation of water layer between the ISM and the conducting substrate leads to potential drift. 28,29 It is generally accepted that the measured electromotive force (EMF) is the sum of all the phase boundary potentials in a potentiometric cell, which consists of a solid-state ISE and a reference electrode.…”

Determination of sodium and potassium ions in patients with SARS-Cov-2 disease by ion-selective electrodes based on polyelectrolyte complexes as a pseudo-liquid contact phase

“… 33 However, the application of classical solid contact sensors with ion-selective membranes for the medicine area is difficult due to the necessary miniaturization of the design of problems with the stability and reproducibility of the signal. 34 The most difficult problem in the design of ion-selective electrodes is the increase in the charge transfer resistance. Additional limitations for measuring the electromotive force of an electrochemical cell are imposed using inexpensive high-resistive carbon-containing fibers.…”

Construction and Performance Characterization of Ion‐Selective Electrodes for Potentiometric Determination of Paroxetine Hydrochloride in Pharmaceutical Preparations and Biological Fluids

“…It was observed that the life‐time of the CGE was shorter than that of the liquid membrane electrode although both electrodes were prepared using the same cocktail. This would be due to the formation of water film at the interface between the membrane and the graphite and interaction of the membrane species with the graphite 42. CPE showed a relatively longer working lifetime (26 day) which may be attributed to the diminishing of the ion‐pair leaching from the electrode matrix due to absence of the internal reference solution.…”