Extended Embedded Depth Using Cascaded Resonators Near-field WPT System with High Efficiency for Biomedical Implants

A novel multiple cascaded resonators wireless power transfer (WPT) design is proposed to provide an extended implanted depth for biomedical implants. Symmetrical four cascaded resonators are utilized in Tx/Rx to obtain high power transfer efficiency (PTE); each resonator consists of two concentric rectangular loops. KQ-product is calculated for a single resonator and compared with the four resonators WPT; four cascaded resonators achieve higher KQ-product value and produce a maximum measured PTE of 89.5% at a transfer distance of 20 mm. Then, the proposed WPT is tested with human tissue to provide a measured PTE of 76% and 63% at a transfer distance of 15 and 20mm, respectively. Specific absorption rate (SAR) is calculated to estimate the maximum operating power of the source and receiver that guarantees working within the safety standard levels of RF exposure.