A 6.78-MHz Robust WPT System with Inductive Link Bandwidth Extended for cm-Sized Implantable Medical Devices

This paper presents a new technique to design a robust inductive link for Wireless Power Transmission (WPT) to centimeter-sized (cm-sized) Implantable Medical Devices (IMDs). The consequence of this methodology is the bandwidth extension of utilized link to maximize both Power Delivered to Load (PDL) and Power Transfer Efficiency (PTE). Design, circuit implementation, and In-vivo validation experimental results are reported. Different conditions of tests, including three misalignment experiments, are performed with the proposed WPT system to prove the concept of a robust inductive link. The geometry of the Transmitter (Tx) and Receiver (Rx) coils are considered as well as the operating frequency (fp) of the WPT system. The Tx and Rx coils are crafted in a circulated shape with the diameters of 5 and 2.5 cm, respectively. Achieved PTE and PDL are in the range of 0.82%-25.7% and 44.4mW-720mW, respectively. The distance between Tx and Rx coils varies in the range of 1.5 to 4cm.