Design of conformal, low-cost, miniaturized, battery-free systems for near- and far-field sensing and actuation in healthcare applications

The rapid evolution of wearable and implantable bioelectronic systems requires energy-autonomous platforms that combine electromagnetic efficiency, mechanical flexibility, and scalable fabrication. This thesis investigates the co-design of wireless power transfer (WPT) architectures, conformal antennas, and engineered dielectric substrates to enable battery-free biomedical and Internet of Things (IoT) devices for near-field (NF) and far-field (FF) applications. At low frequencies, an inductively coupled optogenetic platform operating at 13.56 MHz is developed for wireless neuromodulation, employing resonant coil optimization and conformal integration to ensure stable power delivery independent of animal orientation during in-vivo experiments. At microwave frequencies, additive manufacturing techniques are exploited to realize engineered 3D-printed PLA substrates with tailored electromagnetic properties. These materials enable the fabrication of a dual-port, cross-polarized rectenna capable of simultaneous RF energy harvesting and backscatter communication, experimentally validated for indoor localization scenarios. A hybrid NF/FF architecture is further introduced by integrating a resonant inductive link with a 2.4 GHz antenna, enabling concurrent wireless power and data transfer through a compact multi-frequency platform. The electromagnetic behavior of wearable antennas on flexible and lossy substrates is also systematically analyzed, demonstrating the strong dependence of conventional microstrip patch designs on substrate thickness, permittivity, and conductivity. Based on combined analytical modeling and experimental characterization, alternative topologies—such as shielded meandered dipoles—are proposed to improve radiation efficiency, robustness against material variability, and miniaturization. By combining circuit-level modeling, full-wave electromagnetic simulations, additive manufacturing, and experimental validation, this work establishes practical design guidelines for reliable, low-cost, and body-integrated wireless systems capable of long-term autonomous operation in biomedical sensing, neuromodulation, and distributed IoT networks.