The Galvanic cell consists of two electrodes and an electrolyte. A galvanic electrode produces its own current. A silver or gold cathode and a lead anode are immersed in an Alkali electrolyte with a gas permeable membrane separating the sensor from a test solution.

Polargraphic electrodes have a silver anode and a Platinum or gold cathode. A voltage is applied to the electrode to bring about a polargraphic reduction of the diffused Oxygen. A “Polarizing” voltage is provided by the Dissolved Oxygen instrument.