Biodegradable Conductive Composites for Implantable Electronics: A Review of Materials and Methods

The development of fully biodegradable implantable electronic devices represents a central challenge in modern biomedicine, as successful solutions would eliminate risks associated with secondary surgical removal and the long-term persistence of implants in the body. This review systematically summarizes and critically evaluates recent advances in biodegradable electrically conductive composites that underpin these devices. The discussion focuses on three major classes of conductive components: biodegradable metals (Mg, Zn, W, and Mo), electrically conductive polymers (PEDOT:PSS, PANI, and PPy), and carbon nanomaterials (CNTs, graphene, and rGO) incorporated into biodegradable polymer matrices (PLA, PCL, PLGA, and PLCL). The review compares their electrical performance, degradation behavior, biocompatibility, and processability. It also examines composite fabrication strategies, including electrospinning, coating-based approaches, and additive manufacturing techniques. Particular emphasis is placed on fundamental limitations and associated trade-offs, especially those between achieving high electrical conductivity and maintaining controlled degradation rates. Case studies of representative devices, such as temporary cardiac pacemakers, neurostimulators, and biosensors, illustrate the challenges of harmonizing the properties of functional components. Finally, the review outlines promising future directions, including the design of hybrid materials that combine multiple conductivity mechanisms, which may facilitate the clinical translation of biodegradable electronic systems.