Efficient and Low Leakage WPT System With Integrated Uncomplicated Matching Circuit Rectifier Using Metamaterial Director and Isolator for Biomedical Application

Supplying wireless power to biomedical implants presents numerous challenges, including the compactness, efficiency, and biomedical safety of the receiver (RX). In this work, we propose several solutions to overcome these challenges. Firstly, we designed a metamaterial-inspired transmitter (TX) based on a multi-ring resonator (MRR). This transmitter achieves low magnetic loss and is used as a director to supply power to the RX, featuring an integrated uncomplicated matching circuit rectifier. Secondly, to realize the rectifier, we leverage the high coupling achieved through the proposed MRR metamaterial. The rectifier is integrated on the backside of the RX substrate without requiring additional area for further compactness. Additionally, we introduce a metamaterial-based isolator designed to reduce magnetic field leakage on the back side of the system. Importantly, this isolator has been proven to have no adverse effects on the original wireless power transfer (WPT) system's performance. A prototype was successfully fabricated, and both RF-dc simulation and measurements indicate a peak efficiency of 43% and 39%, respectively, at 50 MHz for a 9 mm embedded RX in chicken breast tissue. The TX size is 20 mm × 20 mm, while the integrated RX/rectifier has dimensions of 7 mm × 7 mm.