A study on oxygen saturation images constructed from the skin tissue of human hand

Under the irradiation of lights of two different wavelengths, the skin image of human hand can be obtained and roughly applied to construct the oxygen saturation image of skin tissue. The penetration (skin) depth of incident light increases with increasing wavelength between 350 to 1000 nm, and the deoxy-hemoglobin (Hb) and oxy-hemoglobin (HbO₂) has a relatively high absorptivity in visible and near-infrared (NIR) spectrum, respectively; therefore, the intensity of diffuse reflected images of skin can be used to compute the oxygen saturation images of skin tissue. In the experiment, three LED light sources (red - 660 nm, NIR - 890 and 940 nm) were applied to construct the oxygen saturation images of skin tissue. The experiments show the oxygen saturation ranging from 84.69 to 88.79 % at the wrist and from 78.09 to 81.81 % at the back of hand when the skin tissue is irradiated by 660 and 890 nm LED light. The results not only could provide the distribution of oxygen saturation but also similar to the multi-spectral imaging method. In the future, the above result can be compared to that of transcutaneous oxygen pressure measurement (TcPO₂), and provide a good reference to build the relationship between the oxygen saturation and healthy index for cardiovascular system in clinical diagnosis.