High‐Efficiency Four‐Coil LCC‐C‐C‐C Compensated Wireless Charging System Operating at 13.56‐MHz Frequency for Deep Brain Stimulation

ABSTRACT This work presents the high‐efficiency and high‐power density wireless charging system for deep brain stimulation (DBS) device. For this purpose, a wireless power transfer (WPT) system using four‐coil LCC‐C‐C‐C compensation is designed for high‐efficiency power transfer. With this system, the battery of the DBS device can be efficiently charged at low power levels. In order to provide high‐power density, the operation frequency of the proposed wireless charging system is selected as 13.56 MHz, which is within the industrial scientific and medical (ISM) band standards. First, circuit description, operation principles, and the design considerations of the proposed WPT system are presented based on power transfer efficiency (PTE) and implantability. Then, the efficiency performance of the proposed charging system is validated on a built prototype. In the validation of PTE performance, pork tissue and air environments and also FR4 and flexible implementation of the receiver coils were considered. Five‐millimeter distance and different misalignment conditions between transmitter and receiver coils were evaluated. Based on measurement results, 27.27% and 25% PTE were obtained in air and pork tissue environments, respectively. Finally, safety of the proposed charging system was evaluated based on SAR simulation in terms of its usability in clinical applications.