Microdetector for rapid changes of oxygen partial pressure ( pO2) during the respiratory cycle in small laboratory animals

An oxygen microdetector suitable for respiratory experiments with small laboratory animals is described. Its principle structure is an O2‐sensitive dye layer. To measure pO2 the capability of O2 to quench the fluorescence of dyes is used. The instrumental dead space of the detector amounts to 0.1 ml only. The detector indicates 90% of a concentration jump from 20 to 15 vol. % O2 in less than 20 ms without any dead time. Neither O2 nor sample volume are consumed. The special setup of the dye layer prevents CO2, N2O, and the humidity of the gas from affecting the fluorescence quenching of oxygen. The mean standard deviation is 0.95% of the relative fluorescence signal between 9.99 and 59.62 kPa pO2. The detector is suitable to measure rapid changes of pO2 in inspired and expired gases and may be enlarged for use in man.