Dynamics of optical and physiological properties of the human skin in vivo during its compression

The results of the study of dynamics of the optical and physiological properties of the human skin in vivo when applying and removing external mechanical compression based on the analysis of temporal changes in the diffuse reflectance spectra of human skin in the range of 400–2000 nm are presented. In the spectrum range 500–600 nm (hemoglobin absorption areas), the temporal dynamics of the skin reflectance coefficients show that skin compression leads to an exponential decrease in the blood content in the skin, while the average time for displacing blood from the compression region is about 4–5 min. After the compression is relieved, the blood filling of the skin is restored exponentially during a time of about 30 s. In the spectral range 700–2000 nm, the peculiarity of the skin reflectance coefficients after skin compression is applied is their monotonic decrease according to a two-exponential law with characteristic times of the order of 10 s and several minutes, which can be caused by the displacement of free and bound water from the compression region.