Real-time estimation of oxygen concentration in micro-hemo-vessels.

In this paper, a real-time measurement system for non-invasive evaluation of oxygen concentration (PO2) at the microcirculation level is developed. The system has been designed by exploiting the phenomenon of fluorescence quenching. The skin of an anaesthetized hamster, injected with porphyrin, is lighted with pulses; the fluorophore reacts with the oxygen in the blood, producing a fluorescence signal, and the value of the fluorescence lifetime is related to the oxygen concentration. This microcirculation-based instrumentation consists of an electro-optical system, a control circuit and signal processing procedure. The system allows the measurement of PO2 in the range of 0-700 (mmHg) with a standard deviation of 4 (mmHg). Several experiments have been performed in order to characterize and test this system.