Wireless Powering and Telemetry of Deep-Body Ingestible Bioelectronic Capsule

In this article, a complete and efficient wireless power transfer (WPT) system, consisting of a full-duplex antenna, a half-wave rectifier, and a WPT transmitter (Tx), is designed and validated for deep-body ingestible biomedical capsules. A two-port full-duplex antenna is adopted to perform seamless telemetry and to act as a receiver for WPT Tx without using a multiplexer circuit. The full-duplex implantable antenna operates at 915 MHz (Port 1) and 1300 MHz (Port 2) and occupies compact dimensions of 8 x 8 x 0.13 mm(3). It maintains high isolation of >30 dB and peak realized gains of -193 dBi at 915 MHz and -17.7 dBi at 1300 MHz. The miniaturization of this antenna is achieved using semicircular slots on the patch and circular slots on the ground plane while mutual coupling between the ports is reduced by a series of metallic vias. Moreover, a low-profile and efficient rectifier is designed at 1300 MHz and integrated with port 2 of the antenna. The suggested rectifier achieves a radio frequency (RF) to direct current (dc) conversion efficiency of 80.4% at an input power of 1 dBm. Furthermore, a patterned patch antenna is designed that acts as a WPT Tx for the biomedical capsule. After examining the individual performance of the antenna, rectifier, and WPT Tx, the overall WPT system is then validated by placing the capsule (rectifier integrated antenna) inside minced pork meat and powered by the WPT Tx. This WPT system is suitable for modern capsule devices due to its features, such as compact size, high gains, high RF-dc conversion efficiency, simultaneous wireless powering and telemetry, and high-power transfer efficiency (PTE).