Simulation of electric field distribution based on electrode placement
Suhyeok Kim
1, Eunkyoung Park
*11Department of Biomedical Engineering, Soonchunhyang University, Asan, Korea
*Email: ek.park@sch.ac.kr
Wound regeneration is essential for survival. Unhealed wounds can lead to serious complications such as sepsis and tissue necrosis, thereby reducing quality of life [1]. The importance of effective wound regeneration is further underscored by the rising prevalence of diabetes and an aging population, both of which are associated with a higher incidence of chronic wounds. Endogenous electric fields (EF) have been shown to induce cell migration. Applying an exogenous EF to stimulate cell and nerves can effectively promote cell migration and wound regeneration [2]. However, EF distribution through electrical nerve stimulation depends on electrode placement, a factor that remains insufficiently studied. In this study, we aim to analyze the EF distribution based on the electrode placement and optimize nerve stimulation for wound regeneration.
A three-dimensional finite element model of the electrode and wound was constructed using COMSOL Multiphysics 5.5. The cylindrical skin model comprised five layers [3, 4]. A hemispherical wound filled with phosphate-buffered saline was placed at the center [3]. The electrode consisted of silver (Ag) and conductive gel [5, 6]. A cube filled with electrically conductive air was created around the skin to simulate the surrounding environment. Electric insulation boundary conditions were applied to all outer surfaces of the electrode except the bottom surface in contact with the skin. Current density and the norm of the EF were analyzed.
We conducted simulation analyses to compare the electric current and EF generated by different electrode placements. Among the three placements, group 2 exhibited the highest maximum and average current densities in the dermis, followed by group 1 and group 3. Similarly, the overall maximum current density and EF were highest in group 2, followed by group 1 and group 3. EF strength near the wound region was consistently greater in group 2 than in the other groups, regardless of wound diameter. Additionally, Group 3 showed no notable change in average EF at 1 mm from the wound center, whereas groups 1 and 2 showed marked increase at 4 mm diameter compared to 8 mm and 10 mm.
Group 1 and group 2 exhibited high current densities at the edges of both the wound and electrodes, along with greater EF strength at the wound center compared to group 3. As wound size decreased, current density and EF strength increased at both the wound edge and center. In groups 1 and 2, the elevated EF at the wound center, exceeding that of the surrounding skin, may generate vectors opposing the endogenous EF, potentially disrupting directional cell migration [7]. Maintaining a controlled EF gradient at the wound center, as observed in group 2, is beneficial for guiding migration. This study suggests that placing electrodes around, rather than on, the wound enhances healing by establishing favorable EF vectors and offers a promising strategy for optimizing clinical treatment.
This work was conducted with the support of the Korea Research Foundation with the funding of the government (Ministry of Science and ICT) (No. 2022R1A2C2092821, RS-2023-00220534).
1. https://doi.org/10.1111/j.1524-475X.2009.00543.x2. https://doi.org/10.1007/s10439-017-1849-x3. https://doi.org/10.1155/2017/52890414. https://doi.org/10.1007/s11517-013-1079-95. https://doi.org/10.3390/nano60901566. https://doi.org/10.1109/CIC.2008.4749085 7. https://doi.org/10.1016/j.semcdb.2008.12.009
