Wireless Power Transfer Based on 3-Coil Magnetic Resonance Coupling for Biomedical Implants

Electronic biomedical implants rely on wireless power transfer (WPT) systems to remove their dependency on chemical batteries to avoid potential safety issues. As traditional systems based on the inductive link are limited by their transmission distance, the magnetic resonance coupling (MRC) method for WPT has been proposed to increase the delivered power for mid-range applications. In this paper, we design a 3-coil magnetic resonant WPT system with a small power receiver for micro biomedical implants and evaluate its power transfer capability with a pork steak to mimic the attenuation caused by biological tissues. Operating at 180 kHz, the output of the proposed system can supply 56 mW at 3.3 V for an implanted receiver at a distance of 80 mm, which is 1.5 times more efficient than the traditional 2-coil system under the same conditions. Such a result demonstrates the applicability and improvement of the MRC-WPT system for powering up in-body biomedical devices.