Some Milestones in the 50-year History of Electrochemical Oxygen Sensor Development

Fifty years have passed since Leland C. Clark proposed the concept of membrane-covered oxygen sensor. The system consists of a two electrode cell with a thin oxygen-permeable membrane separating the electrodes and the electrolyte solution from the analysed media. Oxygen diffuses through the membrane and is reduced at the indicator electrode. This results in current that is proportional to the oxygen concentration in the sample. The Clark Oxygen Sensor has found wide application in medicine, environmental and industrial monitoring. In 1962 Clark and Lyons described the first biosensor. A Clark oxygen sensor was combined with glucose oxidase to detect glucose levels. In spite of the commercial popularity the output currents of Clark-type oxygen sensors are unstable and oxygen analysers need frequent pre-calibration. In 1963 a different oxygen sensor was reported by Mackereth. This design found wide application in water monitoring in the former Soviet Union.