Optimization of a multiband wireless link for neuroprosthetic implantable devices

In this paper we have presented the methodology and detailed simulation and measurement results for optimizing the coils that we have used in a new multiband wireless link for high performance implantable neural interfacing. In this method, three individual carrier signals and coil/antenna pairs have been dedicated to the major functions of the link: power transmission, forward data transmission from outside into the body, and back telemetry from inside towards outside. Wireless power is transmitted through printed spiral coils, optimized for carriers operating at 5, 10, and 13.56 MHz. Two different designs have been evaluated for forward data coils. One is a pair of 3-D vertical coils that are wound perpendicular to the power PSCs, and the other is a pair of planar figure-8 coils that are in parallel with the power PSCs. We have compared these designs with respect to their robustness against worst case horizontal misalignments. Finally, measurements are done on a miniature spiral antenna that is designed to operate in an ultra wideband (UWB) spectrum for short range back telemetry across the skin.