Design and Optimization of Inductive Coils for 2FSK-based Power and Data Transmission for Biomedical Implants

The next-generation of neural prostheses such as optogenetic cochlear implants (CIs) can be implemented by a 2FSK-based wireless power and data transfer (WPDT) system over a signal inductive link. Optimizing the power efficiency of the link is imperative to minimize the heating dissipation in tissue and interference with other devices. And to mimic natural auditory perception with high fidelity, data rate is also important. Previous design methodologies for coils are not comprehensive and accurate enough to account for data transmission and operation at dual carrier frequencies. We outline the theoretical foundation of optimal power transmission and compromise it with data transmission. We use this foundation to propose an iterative dual frequencies coils (DFC) design procedure for 2FSK-based WPDT system. Moreover, we execute this procedure at 3.951 and 4.516 MHz achieving power transfer efficiency (PTE) and power deliver to the load (PDL) of 77.4% and 230.25mW respectively, and the data rate reaches 564 Kbps, at 12mm spacing. All results are verified with simulations using MATLAB and measurements using helical coils fabricated on printed circuit boards.