Ion selective electrode is also called ion electrode. A type of electrochemical sensor that uses membrane potential to measure the activity or concentration of ions in a solution. Ion-selective electrodes have the ability to convert the activity of a specific ion in the solution into a certain potential, and its potential is linearly related to the logarithm of the activity of a given ion in the solution. The ion selective electrode is a membrane electrode, and its core component is the sensing membrane at the tip of the electrode.