Mathematical model and device for non-invasive diagnostics of fractional blood saturation level

Mathematical models describing the propagation of monochromatic radiation in biological tissues are considered. It is shown that existing models for assessing the level of blood oxygen saturation in transmitted light do not adequately describe the processes of interaction of optical radiation with biological tissue, do not take into account the absorption capacity of those blood fractions that do not participate in the transportation of oxygen, and, therefore, the obtained results are characterized by low accuracy. A mathematical model for assessing the level of fractional blood saturation by the photometric method in transmitted light using four sources of optical radiation with central wavelengths of 660, 805, 880 and 940 nm is developed. The principle of selection of spectral characteristics of artificial radiation sources is described. The structural and functional diagram of the device for assessing the level of fractional blood saturation is presented, and the principles of its operation are outlined. Using the prototype of the proposed device and an existing pulse oximeter, the levels of fractional blood saturation of 30 subjects were experimentally estimated. The results are presented showing a decrease in the relative error by 0.71 % compared to the certified device, which proves the effectiveness of the proposed prototype device. The obtained results relate to the field of medical technology and will be useful in designing devices for non-invasive diagnostics of physiological health indicators.