Highly Integrated Two-Port Rectenna System for Wirelessly Powering Multisite Autonomous Vascular Implantable Networks

This study presents a network of highly integrated dual-port implantable rectennas for multisite wireless power transfer (WPT) to miniature implantable vascular devices. The WPT system consists of a flexible transmitter dipole antenna and two-port dual-band implantable antennas that enable simultaneous wireless information and power transfer (SWIPT). The rectenna occupies a compact size of 7.0
$\times$
7.0
$\times$
0.635 mm
$^{3}$
and operates at 915 MHz and 2.45 gigahertz (GHz) with over 25-dB isolation between the two ports. A single-inductor-matched voltage doubler is integrated into the ground layer of the implantable antenna without adding volume or degrading performance, achieving a power conversion efficiency of 73.9% at 5 dBm across a 5.89-k
$\Omega$
load. The rectenna was tested ex vivo at implantation depths varying from 1 to 5 cm in a porcine tissue, resulting in 2.24 mW of dc power transferred at a low input power level of 26 dBm, at an implantation depth of 3 cm. Next, a multisite implantable WPT system with three rectenna channels was demonstrated, achieving output voltages of 1.68 V at an input power of 25 dBm and an implantation depth of 4.5 cm. WPT experiments using micro-LEDs as visual indicators, and quantitative rectenna measurements demonstrate the ability of the system to support multisite autonomous vascular implants.