Materials and Fabrication Strategies for Biocompatible and Biodegradable Conductive Polymer Composites toward Bio-Integrated Electronic Systems

Biocompatible and biodegradable polymer composite systems equipped with electrical/mechanical functions have been researched as a tool that can be applicable for bio-integrated electronics to obtain a variety of useful information, through formation of reliable interfaces with soft, non-planar skin and organs in the human body. Although previous review articles have explored various types of organic materials (natural/synthetic polymers), including intrinsically conducting polymers (ICPs) as constituent materials for such composites, there has been a lack of consideration of inorganic materials, which may narrow the scope of material options for diverse electrical/functional properties. Indeed, biocompatible and/or biodegradable inorganic elements exhibit high electrical conductivity, various morphologies for effective percolation networks, cytocompatibility, soft mechanical characteristics compared to ICPs, and many functions such as magnetism, photoluminescence, and electrochemical reactivity. This review introduces recent advances in biologically safe and biodegradable conductive polymer composites, including materials selection, relevant fabrication strategies, and various potential applications, aimed at revealing the potential applicability of inorganic elements in conductive composites, which has not been discussed in other reviews. Finally, it concludes with remarks on key issues and challenges to overcome corrosion and oxidation issues of inorganic metals and to improve the electrical performance of composite systems.