A Graphical Approach for Human Skin Moisture Evaluation by Electrical Impedance Spectroscopy

A pair of concentrically placed gold electrodes is utilized in contact with human skin surface for moisture evaluation. The electrical impedance spectroscopy is measured within a frequency range of 100Hz to 5MHz. It is showed that, in case of relatively dried stratum corneum, reproducibility of measured impedances will decrease significantly in lower frequency range. The integrality of impedance frequency locus is correspondingly dependent on skin moist state. On the other hand, in case of relatively wetted stratum corneum, an integral locus can be obtained and Cole-Cole arc model can be applied for quantitative calculation. The integrality of the locus is introduced as a supplemental parameter. Experimental results with moistened filter paper as well as human skin indicate that, the skin moisture can be better represented both graphically and quantitatively.