Ion‐Selective Electrodes With Ionophore‐Doped Sensing Membranes

Abstract

Recent work in the field of ionophore‐based ion‐selective electrodes (ISEs) has greatly improved our understanding of the thermodynamics and kinetics that describe the response and selectivity of these sensors. These efforts resulted in the lowering of detection limits from micro‐ to subpicomolar concentrations, improvements of selectivities by many orders of magnitude, and major advancements in biocompatibility and long‐term stabilities. This chapter summarizes the current state of the art for an audience that is new to the field, introducing the basic concepts of ISE theory that replaced in recent years the empirical approach of the early ISE history. It illustrates, with specific examples, the design principles of host‐guest chemistry that have been used to develop ionophores for ISEs, and describes with a minimum of equations the recently developed sophisticated concepts for the efficient use of these ionophores in ISEs. Importantly, this chapter shows not only how ionophores are used in modern potentiometry to develop new ISEs but also illustrates how ionophore‐based potentiometry can support host‐guest chemistry by providing tools to determine thermodynamic properties of ionophores, such as stoichiometries and stabilities of their complexes, using only a minimum amount of ionophore.

Flexible Electrolyte-Gated Ion-Selective Sensors Based on Carbon Nanotube Networks

“…This membrane potential adds up to the voltage applied on the gate-electrode and changes therefore the effective potential present at the semiconducting channel. For example, the incorporation of positively charged primary ions results in a membrane potential, which gets more negative by a decreasing primary ion activity present in the sample [34]. Due to this ion-selective response at the membrane/electrolyte interface the transfer curves of the device are supposed to shift towards more positive gatevoltages for a decreasing primary cation concentration present in the electrolyte.…”

Biomimetic supercontainers for size-selective electrochemical sensing of molecular ions

“…This was the first sign that the MOSC molecule could be used for potentiometric sensing. It is worth noting that the understanding of the membrane constituents and resulting potential has been well-established31. Thus, the concentration-dependence of the phase-boundary potential across the MMM│analyte interface (charge separation layer) is governed by the change in the ratio between free 1-Co and the complexed 1-Co within the first few nanometers of the MMM as well as the inclusion of counter-ions (ionic sites)32.…”

Polymer thin films embedded with metal nanoparticles for electrochemical biosensors applications

“…Thus, quantification of minerals needs to be monitored. Simple method, potentiomteric detection continues to be developed to monitor the minerals (Nelson and Cox, 2000) using ISE and it's prepared by polymeric membrane coated metal electrode (Buhlmann and Chen, 2012). MNPPFs was of great significance in development of ISE, because their versatility nature.…”