A New Advance in Direct Measurement of Moisture in Skin

In this review the potential application of near-infrared spectroscopy for the in vitro and in vivo characterization of skin is presented. The near-infrared attenuated reflectance spectroscopy allows the determination of the overall skin water content as well as of the various components constituting the skin, i.e., stratum corneum, epidermis and dermis. This technique provides the possibility to di rectly determine the changes in the various types of water (free, bulk, and protein-bound water), which are present in the various skin layers. The assessment of the scattering effects in skin is also possible by means of near-infrared spectroscopy. This method achieves an objective, precise, sensitive, reproducible, non-invasive tool for the examination of the effect of humidity on the different types of water. The in vivo evaluation of the biologica! effectiveness of various dermatologica! or cosmetic preparations is now possible by near-infrared attenuated tota! reflectance measurements.