PULSED PHOTOACOUSTIC STUDY OF THE DIFFUSION OF CHROMOPHORES IN HUMAN SKIN

The technique of pulsed photoacoustic spectroscopy was used to investi gate the diffusion of chromophores in human skin, The kinetic of diffu sion has been studied for five solutions at different concentrations i n a mixture of chromophores, as used in commercial sunscreens. In addi tion to the classical macroscopic interpretation of the diffusion proc ess, a new method is shown to give more detailed information on chromo phore presence at different depths in skin, For the first time, result s are expressed in the frequency domain by means of the Fourier transf orm applied to the photoacoustic signal. The spectra are discussed ver sus the depth in skin samples and the time of diffusion kinetics, This new method of data analysis is shown to be very useful for understand ing the influence of the internal structure of a medium on the penetra tion rate of chromophores into skin.