Design of a uniform current density transcranial direct current stimulation device with a multi-layer stepped conductivity sponge

Transcranial direct current stimulation (tDCS) is a noninvasive method of brain modulation that is increasingly used to treat neuropsychiatric disorders and enhance cognitive capacity. Computational modeling provides a valuable tool for designing and analyzing current stimulation devices for the treatment of neurological disorders and diseases. Here we use a three-dimensional finite element model (FEM), we constructed a simulation model and verified the results by reference to experimental data. A multi-layer sponges’ design with step conductivity was presented to reduce the crowded current density distribution and investigated the influencing factors, we identified relevant factors and used them to optimize the sponge. We optimized the sponge design by optimizing the sponge’s stepped conductivity and the thickness. We found that by using the stepped sponge design, the model could meet the impedance matching between the last sponge layer and the skin surface.