Clark electrode

However, when he came to publish his results, his article was refused by the editor since the oxygen tension in the blood coming out from the device could not be measured.

[5] The electrode, when implanted in vivo, will reduce oxygen and thus required stirring in order to maintain an equilibrium with the environment.

A discrepancy between the measured partial pressure of oxygen (pO2) between blood samples and gaseous mixtures of identical pO2, meant that the modified electrode required calibration; consequently a microtonometer was added to the water thermostat.

The above reaction requires a steady stream of electrons to the cathode, which depends on the rate at which oxygen can reach the electrode surface.

At this point, the reaction is diffusion-limited and depends only on the permeability properties of the membrane (which is ideally well characterized, the electrode being calibrated against known standard solutions) and by the oxygen gas concentration, which is the measured quantity.