Hydration characteristics and electrical resistivity of stratum corneum using a noninvasive four-point microelectrode method.

We have used a four-microelectrode probe to study the relationship between electrical resistivity (p), water content (wf) water binding, and electrolyte levels in samples of plantar stratum corneum. Untreated samples characteristically showed an exponential relationship between log p and wf. This characteristic was retained but altered quantitatively by factors which increase and decrease the ratio of bound to unbound water, by lipid extraction, and (following extraction) by electrolyte presoak. The theoretical aspects of obtaining similar data from intact stratum corneum are discussed.