A Wide-Band Tissue Numerical Model for Deeply Implantable Antennas for RF-Powered Leadless Pacemakers

Radio-frequency (RF)-based wireless power transfer method is highly desirable to power deep-body medical implants, such as cardiac pacemakers. The antenna is one of the essential components of such system; however, it poses significant design challenges for deep-body applications and must be modeled and characterized correctly to achieve the required performance. In this paper, design and validation of a novel wideband numerical model (WBNM) are proposed for deeply implantable antennas and to enable RF-powered leadless pacing. In particular, we acquired a wideband tissue simulating liquid (TSL) and fully characterized it using a dielectric probe. Based on the measured properties of the TSL, the design and numerical characterization of the WBNM were performed using a hybrid simulation method, i.e., by employing the finite-element method and method of moment. The proposed WBNM was validated experimentally as well as analytically using a reference microstrip antenna. Good agreement between the simulated, measured, and analytical results validated the proposed model. Furthermore, the application of this model and the TSL was demonstrated by the design, development, manufacture, and measurement of a novel metamaterial-based conformal antenna at 2.4 GHz. Moreover, good agreement was found between the simulated and measured results of the proposed conformal antenna. It is evident from the results that the proposed numerical model can be used to design deeply implantable antennas for any frequency, ranging from 800 to 5800 MHz. Finally, the proposed miniature conformal antenna and its successful integration with a leadless pacemaker model present a great potential for future RF-powered leadless pacemakers and other deep-body medical implants.