Computational Modeling of Electromagnetic and Thermal Effects for a Dual-Unit Retinal Prosthesis: Inductive Telemetry, Temperature Increase, and Current Densities in the Retina - Artificial Sight: Basic Research, Biomedical Engineering, and Clinical Advances - page 299

Figure 15.14. Process for generating equivalent impedance network of a voxel.
behavior. Contributions from all voxels in the model are then combined to form
the equivalent impedance network that represents the entire model.
Note that the resultant electrical circuit will have nodes coinciding with the
vertices of the model's voxels. One node is assigned the ground potential.
External stimuli can then be modeled as current sources, connected between
two nodes, one belonging to an electrode and the other to the current return.
The equivalent impedance matrix for the circuit is then built and the system
solved for voltages and currents. The X, Y, and Z components of the voxels'
total current density can then be calculated by considering the area normal to
the sub-volume that each lumped impedance represents. Finally, the total current
density vector for each voxel is calculated by adding the contributions of all the
sub-volumes in all three axes, as shown in Figure 15.15.
Figure 15.15. Current density calculation with the impedance method.