Wireless Power Transfer to Intra-Abdominal Implants Using an Around-the-Body Loop Antenna

We study the wireless powering of intra-abdominal implants using a wearable around-the-body loop antenna. The study includes the wireless link characterization and modelling of the specific absorption rate (SAR) obtained by an anatomical human body model and a simplified homogenous elliptic cylinder model. We also assess the robustness of the system in terms of the power gain uniformity at the cross-sectional plane of the abdominal cavity. Overall, our system achieves the link power efficiency of -6.6 dB at 7.25 MHz to an implant (2.3-by-2.3 cm square loop) at the center of the abdominal cavity. According to SAR analysis, under the 1.6 W/kg limit, we can transmit 530 mW and the maximum power available at the implant is 149 mW with the voltage amplitude of 3.6 V. Moreover, the voltage at the implant remains above 1 V for transmission power levels down to 10% of the maximum.