Energy-autonomous communication framework for implantable devices using WPT in medical IoT systems

Implantable medical devices (IMDs) are increasingly integrated into Internet of Medical Things (IoMT) platforms for real-time health monitoring and intervention. However, their long-term operation is constrained by limited battery capacity and risks associated with surgical replacement. This paper proposes a wireless power transfer (WPT)-enabled communication framework extending IMD operational lifespan while ensuring biological safety and reliability. A co-design methodology simultaneously optimizes antenna topology, energy-harvesting circuits, and biocompatible encapsulation materials. A multi-objective optimization pipeline adapts transmission parameters to dynamic in-body environments. Simulations show that the proposed antenna architecture achieves 20% higher energy transmission efficiency at 7 GHz compared to conventional designs. The rectifier circuit maintains 88% conversion efficiency under low-input powers (≤1 mW). In addition, a surface-engineered polymer composite exhibits minimal cytotoxicity and stable dielectric performance under chronic implantation. These results validate self-sustaining IMDs and provide a scalable solution for next-generation IoMT ecosystems.