Use of the FDTD thin-strut formalism for biomedical telemetry coil designs

The finite-difference time-domain (FDTD) method extended by thin-strut formalism was used to study the current coupling between rectangular coils for use in biomedical telemetry links. Further, a new stability condition, different from the Courant-Friedrichs-Lewy stability limit, was derived for the thin-strut method. Results obtained for varying coil sizes and distances of separation show that the thin-strut FDTD formulation, applied to the calculation of current coupling between telemetry coils, is in closer agreement to the analytical approximation than is the standard FDTD code. These results indicate that the thin-strut method is a promising method for the study and the design of coils for telemetry links between implantable and external devices.