Study of the Dielectric Properties of Artificial Sweat Mixtures at Microwave Frequencies

Analysis of sweat is of interest for a variety of diagnosis and monitoring applications in healthcare. In this work, detailed measurements of the dielectric properties of solutions representing the major components of sweat are presented. The measurements include aqueous solutions of sodium chloride (NaCl), potassium chloride (KCl), urea, and lactic acid, as well as their mixtures. Moreover, mixtures of NaCl, KCl, urea, and lactic acid, mimicking artificial sweat at different hydration states, are characterized, and the data are fitted to a Cole-Cole model. The complex dielectric permittivity for all prepared solutions and mixtures is studied in the range of 1-20 GHz, at temperature of 23 °C, with ionic concentrations in the range of 0.01-1.7 mol/L.