Interference-free wireless power transfer system for biomedical implants using multi-coil approach

Low-frequency (1-20 MHz) inductive coupling is a leading technique to power biomedical implants wirelessly. Even though these are non-radiating systems, the external and the implant coils can cause sufficient radiated electric field to exceed the federal standards for communication. A multi-coil-based wireless power transfer (WPT) technique is developed to selectively control the currents in the external and implant coils to reduce the radiated electric field. A four-coil WPT system, which can achieve more than 37% reduction in the radiated electric field as compared with a two-coil WPT system with the same dimensions and design constraints, is implemented and used to demonstrate the effectiveness of the proposed approach.