Wireless Power Transfer System Design in Reactive Near-Field for Implantable Devices

In this paper, a wireless power transfer (WPT) system design for charging the bio-implantable devices in the reactive near-field of the antenna is presented. The proposed system is designed to operate in the industrial, scientific, and medical (ISM) of $2.40-2.4S$ GHz band. The WPT link is constructed with dual-ring slot antenna implanted in a single layer skin tissue model is used as a receiving (Rx) element and a simple patch antenna considered as transmitting (Tx) element. The patch antenna is designed to operate at the ISM of 2.45 GHz, whereas the dual-ring slot is used to obtain wideband characteristics that cover the entire ISM band. The strong mutual coupling between the Tx and Rx elements in the reactive near-field provide high power transfer efficiency for the proposed WPT system. Also, to reflect the real-life application scenario, the analysis of specific absorption rate (SAR) and misalignment between the Tx and Rx element is performed for the proposed system. Finally, the prototype of the Tx and Rx elements are fabricated and experimentally verified by using skin mimicking gel.