What is "glass electrode"

n. (context chemistry physics English) Any of several electrodes, having a thin glass bulb, whose potential is dependent upon the concentration of hydrogen or other ions in the solution in which it is immersed; used in pH meters etc.

A glass electrode is a type of ion-selective electrode made of a doped glass membrane that is sensitive to a specific ion. The most common application of ion-selective glass electrodes is for the measurement of pH. The pH electrode is an example of a glass electrode that is sensitive to hydrogen ions. Glass electrodes play an important part in the instrumentation for chemical analysis and physico-chemical studies. The voltage of the glass electrode, relative to some reference value, is sensitive to changes in the activity of certain type of ions.