A microelectrode for determination of dissolved oxygen in tissue

¹ Department of Bacteriology, University of Sydney, Sydney, New South Wales, Australia

This microelectrode, which, in principle, resembles the Clark polyethylene membrane electrode, may be used for the measurement of O₂ tension in biological fluids. It is unaffected by the presence of fats, proteins, or hydrated ions in the external fluid and possesses the following characteristics: external diameter, 0.75 mm, O₂ tension to current relationship linear over a range of Po₂ 0–702 mm Hg; accuracy ±0.5% at 150 mm Hg; stability over several hours ±0.5%; response time to 99% at 37 C is 2 min; temperature/current relationship, linear or curvilinear; temperature equilibrium, 1 min; movement/current relationship, logarithmic; approximate maximum effect of movement, 4%. The application of membrane electrodes to the measurement of O₂ within tissues is discussed. The electrodes may also be used to measure the resistance of tissues to dissolved O₂ transport. The concept of "relative available oxygen" is introduced.