Evaluation of oxygenation in the surface layers of biological tissues based on diffuse optical spectroscopy with automated calibration of measurements

To assess the oxygen saturation (oxygenation) in the surface layers of biological tissues (at a depth of 4 mm), a compact system based on diffuse optical spectroscopy (DOS) with reflective measurement geometry in the wavelength range of 520–590 nm is proposed. The experimental DOS device is based on a broadband LED source of probe radiation and a spectrometer using a fibreoptic radiation delivery system. To calculate the oxygenation, an original method is proposed based on measuring the intensity of scattered light at four different locations of the source and receiver on the surface of the object under study (four-measurement method). The developed method allows for the device hardware parameters (optical contact with the tissue, transient characteristics of the radiation delivery system) and does not require any additional calibration measurements. The results of testing the DOS system using the four-measurement method for monitoring the oxygen saturation of tissues during the artificial occlusion of the blood vessels agree with the published data of other research teams.