Broadband Implantable Antenna for Wireless Power Transfer in Cardiac Pacemaker Applications

A miniaturized implantable antenna with bandwidth enhancement is proposed for cardiac pacemaker application in MICS band (402-405 MHz) and ISM band (433-434.8 MHz, 902-928 MHz) in this paper. By introducing split resonant rings, the proposed antenna has achieved ultra-wideband characteristics, which can cover from 272 MHz to 1504 MHz, and the relative bandwidth is 138.7%. Additionally, a new wireless power transfer (WPT) system is designed by integrating with aminiaturized metasurface to enhance the WPT efficiency and extend the lifetime of the implantable device. The transmission coefficient S-21 of the WPT system loaded with metasurface is 11 dB higher than the initial system at the resonance point. Furthermore, biosafety is taken into consideration for practical applications. The experiments in the equivalent body environment are performed to demonstrate the reliability of the proposed antenna. The measured and simulated results are in good agreement, which shows that the proposed antenna is appropriate to be applied in wireless power transfer systems.