Far-Field Wireless Power Transmission and Measurement for a Leadless Transcatheter Pacing System

Wireless power transfer (WPT) systems are becoming popular for powering advanced multifunctional biomedical implantable devices. This article presents a WPT system that includes an antenna array (located outside the body) and a rectenna (antenna + rectifier), which is integrated inside implanted leadless pacemaker’s capsule. The WPT antenna array transmits power in the industrial, scientific, and medical (ISM) 2.45-GHz frequency band and has a size of 90
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130
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0.762 mm and a gain of 8.1 dBi in the elevation plane and 7.2 dBi in the azimuth plane. The implantable antenna, which is placed inside the leadless pacemaker’s housing, is printed on the Rogers RT/Duroid 6010 Laminate (LM) substrate. It has a compact size of 5
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5
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0.254 mm and operates in two bands: telemetry at ISM 915 MHz and WPT at ISM 2.45 GHz. A voltage doubler rectifier of size 5
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10
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0.254 mm, optimized at the ISM 2.45 GHz, is also tested inside the pacemaker’s capsule housing for the rectification of the received power from the implantable antenna. The highest conversion efficiency of the rectifier is 68% at 0-dBm power. In comparison to other implantable rectennas, the proposed rectenna has the smallest footprint, operates in dual bands, and can transfer the required power from the perspective of commercial pacemakers. The fabricated prototypes are measured individually in the heart muscle mimicking phantom, where the integrated rectenna inside the capsule prototype is placed 60 mm deep inside the phantom for experimental verification, and an external antenna array is located at a 150-mm distance to transfer power to the implanted capsule. Also, the proposed WPT system’s compliance with human safety standards is examined, and it is found that the system is completely safe.