Ion-Partitioning Membrane-Based Electrochemical Sensors

Abstract

The application of ion-partitioning membranes on proton transducers for the development of electrochemical sensors is presented. The ion-partitioning membrane incorporates two different ionophores, one selective to protons and the other to analyte cations, as well as the necessary anionic lipophilic sites. As dictated by the electroneutrality principle, when the concentration of the analyte cations in the sample increases, the analyte cations are extracted into the membrane, displacing protons of equal charge out of the membrane. The pH-sensitive gate of a CHEMFET or the surface of a glass pH electrode is used as an internal transducer for the monitoring of the membrane proton flux. The resulting signal of the pH transducer is related to the concentration of the analyte cation present in the sample. The experiments presented here indicate that the observed CHEMFET's signal is affected by the interaction of the pH-sensitive sensor element with protons released by the polymeric membrane.

Calculated Effects of Membrane Transport on the Long-Term Response Behavior of Polymeric Membrane Ion-Selective Electrodes

“…30 These results clearly corroborate the decisive influence of internal aqueous films on the middleand long-term response behavior of such systems. 30 ISEs with a Larger Volume of Internal Solution. A formally different solution is obtained for membrane electrodes that have a relatively large volume of the inner reference solution, i.e., when V′′ .…”

“…The present theoretical predictions agree with experimental findings published since the submission of this manuscript. 29,30 Ψ′ z (0) ) Ψ′′ z (a i ′ s + K ij a j ′ s ) (a i ′′ + K ij a j ′′)…”

Potential Drifts of Solid-Contacted Ion-Selective Electrodes Due to Zero-Current Ion Fluxes Through the Sensor Membrane

“…Similar effects may be inferred only from a very recent contribution [39]. Today's miniaturized ISEs usually contain a small volume of inner solution, often immobilized as a hydrogel.…”

Bioelectric mechanisms in regeneration: Unique aspects and future perspectives

“…Tools for the characterization of bioelectrical events now include highly-sensitive ion-selective extracellular electrode probes [219, 220], fluorescent reporter dyes, which enable the non-invasive real-time monitoring of pH, membrane voltage, and ion flow in any optically-accessible tissue [221–224] (although much opportunity remains for the development of specific, bright, ratiometric dyes that localize exclusively to the desired subcellular locale), and nano-scale voltage reporters [225]. Especially exciting will be the use of multiple physiological dyes in FACS experiments to identify subpopulations of stem and other cell sets that differ in key bioelectric properties, as has been observed for HUVEC cells [226].…”