Modelling the effect of hydration on skin conductivity.

Background Electrical signals are recorded from and sent into the body via the skin in a number of applications. In practice, skin is often hydrated with liquids having different conductivities so a model was produced in order to determine the relationship between skin impedance and conductivity. Methods A model representing the skin was subjected to a variety of electrical signals. The parts of the model representing the stratum corneum were given different conductivities to represent different levels of hydration. Results The overall impedance and conductivity of the cells did not vary at frequencies below 40 kHz. Above 40 kHz, levels of increased conductivity caused the overall impedance to decrease. Conclusion The variation in impedance with conductivity between 5 and 50 mSm−1 can be modelled quadratically while variation in impedance with conductivity between 5 and 5000 mSm−1 can be modelled with a double exponential decay. [ABSTRACT FROM AUTHOR]