[In vivo hydration measurement of the stratum corneum (author's transl)]

A methods is described which allows the humidity measurement of the horny layer of the human skin. The method is based on the correlation between the direct current conduction at 3.0 V and the gravimetrically analyzed humidity of a homogenous skin model. The validity of this model is mainly limited by the nonhomogenous distribution of humidity in the stratum corneum. This method is applied to healthy human skin to find out the dynamic response of the skin to moisturization by water bath. It is a surprising result that 15 min after the bath the horny layer is dryer than before starting the experiment. The kinetic of the humidity change from the moisturization state to the equilibrium state is followed, after a fast initial phase, by a normal exponential decay, which is used as a proof for the applicability of the correlation between the electric conductivity and the humidity of the model for the determination of the overall humidity of the human horny layer.