AN-1852 Designing With pH Electrodes (Rev. A)

A pH electrode measures hydrogen ion (H+) activity and produces an electrical potential or voltage. The operation of the pH electrode is based on the principle that an electric potential develops when two liquids of different pH come into contact at opposite sides of a thin glass membrane. This was originally discovered in 1906 by Max Cremer [1]. His discovery laid the foundation for Fritz Haber and Zygmunt Klemensiewicz, who published their findings in 1909, to create the first glass electrode that measured hydrogen activity [2]. Today, modern pH electrodes use the same principles to measure pH in a variety of applications including water treatment, chemical processing, medical instrumentation, and environmental test systems.