The Evolving Role of Materials in Implantable Antenna Design: A Comprehensive Review

This article presents a comprehensive review of implantable antenna technology with a primary focus on the role of materials in shaping electromagnetic performance, biostability, and clinical viability. Core substrate classes—including polytetrafluoroethylene (PTFE)–ceramic laminates, flexible polyimide and liquid crystal-polymer (LCP) films, and bioceramics such as alumina and zirconia—are discussed in terms of miniaturization, loss, manufacturability, and interaction with biological tissues. Encapsulation and coating materials are examined for their influence on resonance stability, specific absorption rate (SAR), and long-term reliability, while conductive and ground materials are reviewed with respect to chemical durability and current distribution. Magnetic and metamaterial (MTM)-enhanced layers are assessed as material-driven approaches for bandwidth enhancement, polarization control, and electrically small antenna design under strong tissue loading. Emerging directions include low-loss rutile TiO2, perovskite microwave ceramics, low-temperature co-fired ceramic (LTCC) platforms, biodegradable polymers, and dielectric resonator antenna (DRA) architectures, which collectively enable reduced RF heating and improved clinical compatibility. By integrating material properties with antenna structures and biocompatibility constraints, this review provides a unified perspective on material-centric strategies for next-generation implantable antennas across established and emerging biomedical frequency bands.