| Abstrak/Abstract |
Sodium-ion concentration c in the dermis layer has been extracted by time-constant-domain electrical impedance spectroscopy (TCD-EIS) with the dermis separation model (DSM). The TCD-EIS with DSM consists of the dermis separation formulation, ridge regression optimization, and distribution relaxation times (DRT) with radial base function. To distinguish the relaxation time of the dermis τ d from the other layers (stratum corneum τ sc , the epidermis τ e , and the fat layer τ f ), the subtracted impedivity was calculated by distant electrode pair z 1 , and close the electrode pair z 2 , based on optimum electrode diameter ϕ and distance l . The numerical optimizations were implemented to optimize ϕ from 0.5 to 3 mm and l from 2 to 8 mm, regarded as DSM sensor parameters. In the simulation, the optimized DSM sensor parameters, ϕ*=1 mm and l *=1 mm, were applied to the skin model under the condition of 1) various sodium-ion concentrations c in the dermis layer, 2) frequencies f from 100 Hz to 1 MHz. In the experiments, the optimized TCD-EIS with DSM was applied to porcine skin under the condition following the simulations. The relation between the distribution function γ and relaxation times τ, were used to evaluate the sodium-ion concentration extraction. Both simulation and experiment results show that the normalized distribution function of the dermis γ* c (ln τ d )decreases with the increase of sodium-ion concentration c . The sodium-ion concentration c in the dermis layer was distinguished properly at dermis relaxation times τ d =10 -2 [s]. TCD-EIS with DSM reveals that the decrease of a normalized distribution function γ* c (ln τ d ), correlates with the increased sodium-ion concentration c injected in the dermis layer. |
