Water Content of Stratum Corneum in Vivo

Fresh cuttings of plantar corneum show a much higher water content than would be predicted from the in vitro studies on the minimal water content needed for a natural pliability and texture. A simple noninvasive, quantitative technique for assaying stratum corneum moisture through an examination of its electrical properties has been developed. Such a method should have application in studying the time course and character of various militarily significant skin diseases, in evaluating the acceptability of clothing and footwear designs, and in measuring the efficacy of drugs and treatments. The authors have measured the DC electrical resistivity and found a linear relationship between total water content and resistivity over many decades of resistance. The authors also analyzed the problems inherent in conventional 2 macroelectrode techniques and developed a printed circuit 4-point microelectrode probe system driven by a portable 1Hz constant current source and isolation amplifier which is easily applied to intact skin and, on plantar corneum, is independent of the effects of contact resistance and the resistivity of underlying tissues. The bound water fraction has been shown to be responsible for maintaining normal mechanical characteristics of the tissue, and is deficient in certain skin diseases. See also report dated Jan 74, AD-774 278.