Date of Award
Master of Science in Electrical Engineering - (M.S.)
Samir S. Sofer
William N. Carr
The fiber optic Oxygen sensor consists of a thin layer of immobilized deoxyhemoglobin at the common end of a bifurcated fiber. Immobilization is done using the alginate gel procedure. The immobilized reagent is separated from the standard oxygen sample by the gel with or without semi-permeable membrane, and the entire configuration is enclosed in an oxygen free sample cell. Light from a tungsten-halogen lamp, filtered through a 405nm filter is passed through one arm of a bifurcated fiber to the sample cell. The reflected intensity (a highly polished aluminum foil or a plate is placed at the bottom of the sample cell ) from the other arm of the bifurcated fiber is measured using a photomultiplier tube and a power meter.
The above procedure is repeated for a 435 nm filter. The ratio of the reflected intensities at 435nm and 405nm gives an indication of the concentration of oxygen in the standard samples. Since this is a ratio measurement, it is insensitive to slow loss of reagent and drift.
The reflected intensities decrease with increase in the amount of deoxyhemoglobin and with increase in the thickness of the immobilized layer. Precautions should be taken to prevent the oxidation of hemoglobin to methemoglobin.
Response time is an important factor in determining the time required for equilibrium to be attained. It takes about 3 minutes to reach equilibrium for a 0.5mm thick layer of immobilized deoxyhemoglobin, coated with the membrane and 2 minutes without the membrane.
Raj, Mendu Govind, "Design of a fiber optic oxygen sensor based on immobilized hemoglobin" (1988). Theses. 1414.