Water sorption and electrical properties of a human nail

Background/purpose: Water absorption is important for the overall function of keratinized tissues like the stratum corneum and nail. Hence, measurement of water sorption dynamics and water content of these tissues is of great interest. Methods: We have studied water sorption and electrical properties of a human nail in a measuring cell where the temperature and relative hydration could be controlled. Results: We found the amount of absorbed water to be linearly dependent on ambient relative humidity up to about 70%, followed by a stronger dependency. Furthermore, we found that electrical conductance and capacitance are exponentially dependent on the water content. Conclusion: Both electrical conductance and susceptance are good indicators of water content in the nail. The results also possibly indicate that the capacitance is dependent on the mobility of the keratin chains, while the conductance is probably more dependent on water molecule mobility.