Membrane with controlled permeability to a particular ion covering an electrode, or separating two electrolyte solutions.
Note: The potential difference of an ion-selective electrode derives from differences in activity of an ion at each side of the membrane.
See: heterogeneous crystalline membrane electrodes, homogeneous crystalline membrane electrodes, rigid, self-supporting, matrix membranes, membranes with mobile charged sites, non-crystalline membrane
Source:
PAC, 2020, 92, 641. 'Terminology of Electrochemical Methods of Analysis (IUPAC Recommendations 2019)' on page 664 (https://doi.org/10.1515/pac-2018-0109)