Free and bound sodium identification by skin dielectric properties separation algorithm of bioelectrical impedance spectroscopy (spa-BIS) in human skin model

Free and bound sodium in human skin models have been identified by two proposals: skin’s phantom fabrication and skin’s dielectric properties separation algorithm of bioelectrical impedance spectroscopy (spa-BIS). The spa-BIS consist of conductivity-permittivity separation, contact impedance compensation, and a correlation score algorithm based on the vessel with a bipolar electrode. The skin phantom fabrication comprises a recipe combination with temperature-controlled protocol and sodium molarity calculation. In experiments, the human skin models are created to mimic the electrical properties of skin under 1 MHz with several different sodium molarities. Based on five types of human skin models with five samples of each group, the free sodium type conductivity and concentration results R 2 = 0.9903 − following a linear trendline of concentration change in skin tissues theorems with the fRequency range from 1 kHz to 1 MHz , while the bound sodium type results R 2 = 0.9061 − . The spa-BIS compensate 7 − 16 Ω of vessel contact impedance. The dielectric properties of each type have been extracted with less than 10 of the average standard deviation, which is considered an accurate identification method of dermis dielectric properties. The algorithm successfully identifies sodium type: free sodium has a negative, and bound sodium has a positive correlation score trend. As an additional discussion, the different time-dependent effects, the different water content, and different agar content analyses have been provided in this study. As a robust analysis method, the spa-BIS has a prominent performance to replace a 23Na-MRI in terms of free and bound sodium identification. © 2023 IOP Publishing Ltd.