What is "ion selective electrode"

n. (context chemistry physics English) An electrode whose potential is dependent on the concentration of a specific ion in the solution in which it is immersed.

An ion-selective electrode (ISE), also known as a specific ion electrode (SIE), is a transducer (or sensor) that converts the activity of a specific ion dissolved in a solution into an electrical potential. The voltage is theoretically dependent on the logarithm of the ionic activity, according to the Nernst equation. Ion-selective electrodes are used in analytical chemistry and biochemical/ biophysical research, where measurements of ionic concentration in an aqueous solution are required.