Study of the Electric Field Distribution and Impedance Change in a 2d Multilayer Skin Model Using Interdigitated Electrodes

Abstract

The skin's response to electrical stimuli depends not only on the composition and thickness of each layer but also on the geometry associated with the excitation electrodes. Therefore, an evaluation of the effects of electrode geometry is necessary. This study used the COMSOL Multiphysics^® platform and a 2D model based on a simplified array of interdigitated electrodes connected to the skin. The skin was modeled as a multilayer structure representing the stratum corneum, epidermis, dermis, and subcutaneous tissue. This study analyzed how varying the distance between electrodes (100 µm to 10 mm) affects the electric field distribution and sensitivity to impedance changes after modifying the conductivity of the different skin layers. The optimal distance that maximizes sensitivity to these variations was identified, both in the presence and absence of the stratum corneum. In the presence of the stratum corneum, the maximum change in impedance due to variations in epidermal conductivity was found at an electrode distance of 2.1 mm. In contrast, no maxima were reported for variations in the conductivities of the dermis and subcutaneous tissue. In the absence of the stratum corneum, changes in the electrical conductivities of the epidermis, dermis, and subcutaneous tissue resulted in more significant impedance changes when the electrodes were spaced at 100 µm, 6.6 mm, and 9.1 mm, respectively. These results provide new opportunities for the non-invasive study of skin layers, which contain medically relevant information for drug delivery and disease monitoring using interdigitated electrodes.