Maximal Coupling Between Implanted Dipole Antennas and External Sources

Abstract

This thesis investigates the optimization of wireless power transfer between external electromagnetic (EM) sources and implanted dipole antennas within the human body, a critical factor for the effective operation of biosensors in various biomedical applications. The research addresses the complex interaction between implanted antennas and surrounding biological tissues, focusing on enhancing signal transmission. Two innovative approaches are explored to improve the matching between free-space radiators and embedded receivers: the use of dielectric layers forming Fabry-Perot resonant cavities and the deployment of active EM metasurfaces incorporating gain media. The first approach employs dielectric layers to form Fabry-Perot resonant cavities, which optimize resonance conditions to enhance coupling efficiency. This method is designed to maximize EM wave transmission between the implanted antenna and the external source, thereby improving signal strength and clarity. The second approach involves the use of active metasurfaces with gain media, offering a high degree of control over EM wave propagation. These metasurfaces can be precisely engineered to manipulate EM waves, achieving optimal matching conditions and significantly boosting coupling efficiency. Mathematical models are developed to predict the optimal configurations for both methods, taking into account the complex dielectric properties of biological tissues. Extensive numerical simulations validate these theoretical predictions, considering various scenarios, including different distances and misalignment between the implanted and external antennas. The robustness of the matching components in these scenarios is emphasized, highlighting their practical applicability in real-world biomedical settings. The results of this study have significant implications for the design and optimization of medical instruments used in healthcare monitoring, bioelectromagnetic imaging, and diagnostics. By improving the coupling efficiency between implanted and external antennas, these technologies can enhance the reliability and accuracy of medical telemetry systems. This, in turn, can lead to better patient care and outcomes by ensuring more accurate monitoring of physiological signals. Furthermore, the research provides insights into the potential applications of advanced EM metasurfaces in biomedical engineering. The ability to precisely control EM wave propagation using metasurfaces opens up new possibilities for designing miniaturized and efficient implantable devices, which can be used in a wide range of medical applications, from continuous health monitoring to targeted drug delivery systems. In conclusion, this thesis presents a comprehensive study on optimizing coupling between implanted dipole antennas and external sources. By employing dielectric layers and active EM metasurfaces, the research proposes two effective methods to enhance coupling efficiency. The mathematical models and numerical simulations provide a robust framework for designing optimized biomedical systems. The findings have significant implications for the future development of implantable medical devices, promising improvements in healthcare monitoring, diagnostics, and patient care. This research contributes to the advancement of biomedical engineering by addressing the critical challenge of efficient signal transmission in implantable systems and paving the way for more reliable and effective medical technologies.